Post by: BernardLanguillier on September 28, 2016, 12:17:28 am
As part of my on-going investigation about Tech cameras for backs, I have started to look into the Alpa offering.
Sounds very interesting, but I cannot find any reference to using tilt with wide tech lenses such as the Rodenstock 23mm f5.6.
- Can this be done?
- Is there another way to use tilt wit wide lenses with any of the Alpa cameras? I understand that the 12 FPS can enable mounting a Canon 24mm T/S, but to me this isn't a very high quality wide.
Overall, I have a hard time understanding how Alpa cameras are superior to their Arca Swiss counterparts?
Thank you.
Cheers,
Bernard
Post by: AreBee on September 28, 2016, 08:05:01 am
Quote
...I cannot find any reference to using tilt with wide tech lenses such as the Rodenstock 23mm f5.6.
- Can this be done?
No. The shortest focal length SB (Short Barrel) lens that can be used in conjunction with the Alpa 17mm tilt adapter (https://www.alpa.ch/en/article/tilt-swing-adapter-0-5-17-mm), if infinity must be reached, is 32mm.
Post by: BernardLanguillier on September 28, 2016, 08:33:07 am
Bernard,
No. The shortest focal length SB (Short Barrel) lens that can be used in conjunction with the Alpa 17mm tilt adapter (https://www.alpa.ch/en/article/tilt-swing-adapter-0-5-17-mm), if infinity must be reached, is 32mm.
Thanks, I am a bit at a loss as to why anyone interested in landscape would pick an Alpa over an Arca with these limitations... ;)
Cheers,
Bernard
Post by: AreBee on September 28, 2016, 09:53:15 am
Quote
...I am a bit at a loss as to why anyone interested in landscape would pick an Alpa over an Arca with these limitations...
I am at a bit of a loss as to why anyone considers tilt mandatory for landscape photography.
Post by: BernardLanguillier on September 28, 2016, 10:19:39 am
I am at a bit of a loss as to why anyone considers tilt mandatory for landscape photography.
There are of course many ways to shoot landscape without tilt, but a major part of the value of shooting with a tech cam over an SLR is often considered to be movements is it not?
Cheers,
Bernard
Post by: Paul2660 on September 28, 2016, 10:36:37 am
Also remember that older 23 HR lenses were known for a terrible flare issue, but Rodenstock seems to have fixed a lot of that with a newer coating. Several photographers I know of have returned older 23 HR lenses to Rodenstock to have this coating added with good results. For my work the 23mm is too expensive and to limited on shifts but optically amazing for sure.
Edit: the 23 and 28 greatly benefit when used with the Rodentstock CF (same filter for both lenses), even on center shot. The 32mm also works better with the CF but more so on shifts of 10mm or more.
Acra will allow up to 5mm of tilt with all lenses, however you can't have tilt and swing together at the same time. You are limited to 15mm of shift with the rm3di unless you rotate the camera 90 degrees to allow your rise/fall to become shift.
For me tilt in MF very important, one thing I miss with the XF system. I prefer as much of the image in focus as possible and most times with the the 28HR (no longer have) or 32 HR-W only .5 to 1 degree of tilt is needed for the look I prefer. With the XF you have back to focus stacking which can be problematic depending on the scene and conditions (wind). But the LCC process of the tech camera wears on me just as much or more.
Paul C
Post by: AreBee on September 28, 2016, 11:05:04 am
Quote
...a major part of the value of shooting with a tech cam over an SLR is often considered to be movements...
Value judgement varies from person to person.
Post by: vjbelle on September 28, 2016, 01:11:29 pm
Victor
Post by: BernardLanguillier on September 28, 2016, 04:14:59 pm
Bernard,
Value judgement varies from person to person.
Indeed. If I may ask a more open question then, what made you select an Alpa for landscape work over an Arca?
Cheers,
Bernard
Post by: Christopher on September 28, 2016, 04:44:42 pm
Alpa makes great cameras, but for me it once again had quite a "nose in the air" flair when discussing their products with them.
In addition I found there cube a joke... I love the idea but announcing something and then at the show: oh it's just a prototype... nothing final... it's just a first design... oh price, no idea yet...
The idea of a modular cube is great, but it just felt like a normal novoflex product with black paint. It could take any load as there was no way to change the "tension" on the movements. However, it was only a prototype...
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Post by: dchew on September 28, 2016, 05:10:08 pm
I chose Alpa over Arca for a few reasons:
First, l don't use lenses shorter than a 24mm equivalent in 135 format. I could give you all sorts of mumbo jumbo about why, but basically it is because I suck a shooting really wide. Therefore, the Alpa tilt limitation of 32mm or greater was not a limitation for me.
Second, I want a small, relatively light and simple system. In my evaluation, the Alpa seemed like the design that would survive my abuse the best. So far so good. However, note the Factum was not released when I made the choice (early 2011) so that camera may have fit my needs.
Third, and this is purely personal preference, I did not like Arca's very long racking helical design.
Basically for me the Alpa STC is the perfect camera for how I shoot and what I like to shoot. It has exactly what I need and nothing I don't.
Dave
Thanks, I am a bit at a loss as to why anyone interested in landscape would pick an Alpa over an Arca with these limitations... ;)
Cheers,
Bernard
Post by: BernardLanguillier on September 28, 2016, 05:15:42 pm
Post by: Theodoros on September 28, 2016, 05:21:22 pm
I can't answer for him, but this photokina once again showed me that it was a good decision to go with Arca and I would do it again.
Alpa makes great cameras, but for me it once again had quite a "nose in the air" flair when discussing their products with them.
In addition I found there cube a joke... I love the idea but announcing something and then at the show: oh it's just a prototype... nothing final... it's just a first design... oh price, no idea yet...
The idea of a modular cube is great, but it just felt like a normal novoflex product with black paint. It could take any load as there was no way to change the "tension" on the movements. However, it was only a prototype...
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Alpa's tilt is a joke.... it moves off axis the entrance pupil of the lens and causes distortions (not to mention the drop of lens performance)... The ALPA GON system is a consequence of making the SERPENT a "modular view camera"... Another joke by ALPA.... Another view camera added to the mass of extremely badly designed cameras that the market is full of, which instead of correcting distortions adds more and affects negatively lens performance on top of that... A camera with all tilts and swings bellow all shifts in 2016? One can't help but to wonder on the (basic) knowledge on optical engineering the designers of such products have.... :o
Post by: voidshatter on September 28, 2016, 05:22:54 pm
Thanks, I am a bit at a loss as to why anyone interested in landscape would pick an Alpa over an Arca with these limitations... ;)
Cheers,
Bernard
Arca is indeed a better choice than Alpa if you take the tilt capability of wider-than-32mm lenses into consideration.
Personally I prefer Alpa for the look and the build quality, i.e. something that can be "exhibited" on the book shelf.
Post by: voidshatter on September 28, 2016, 05:26:05 pm
Alpa's tilt is a joke.... it drops the entrance pupil of the lens and causes distortions... The ALPA GON system is a consequence of making the SERPENT a "modular view camera"... Another joke by ALPA.... Another view camera added to the mass of extremely badly designed cameras which instead of correcting distortions adds more and affects negatively lens performance on top of that... A camera with all tilts and swings bellow all shifts in 2016? One can't help but to wonder on the (basic) knowledge on optical engineering the designers of such products have....
Not sure what you are talking about but I don't see problems when everyone is using CMOS for LiveView in 2016.
Post by: Theodoros on September 28, 2016, 05:32:07 pm
Not sure what you are talking about but I don't see problems when everyone is using CMOS for LiveView in 2016.
What Cmos or other image area has to do with misalignment of optics that are meant to work in an axis? Wrong engineering is bad engineering and thus making mechanisms that cause misalignment (and therefore distortions) is nothing more than bad engineering...
Post by: voidshatter on September 28, 2016, 05:51:07 pm
What Cmos or other image area has to do with misalignment of optics that are meant to work in an axis? Wrong engineering is bad engineering and thus making mechanisms that cause misalignment (and therefore distortions) is nothing more than bad engineering...
Alpa's tilt doesn't interfere with the lens' axis at all. It only affects high precision focus ring's validity, which is not a problem for CMOS. You can even install Alpa's tilt adapter to the digital back to enable back tilting. There is no misalignment of optics.
Post by: alatreille on September 28, 2016, 05:56:52 pm
Acra will allow up to 5mm of tilt with all lenses, however you can't have tilt and swing together at the same time. You are limited to 15mm of shift with the rm3di unless you rotate the camera 90 degrees to allow your rise/fall to become shift.
Paul C
If you use the Rotaslide adapter, you get 24mm each direction.
Post by: Theodoros on September 28, 2016, 06:01:25 pm
Alpa's tilt doesn't interfere with the lens' axis at all. It only affects high precision focus ring's validity, which is not a problem for CMOS. You can even install Alpa's tilt adapter to the digital back to enable back tilting. There is no misalignment of optics.
I'm afraid you are misinformed (probably by the salesman of the equipment)... The entrance pupil of a lens (any lens) is meant to stay on the axis that is perpendicular and crosses the image area to exactly its center... If one uses base tilts, the entrance pupil of the lens moves off this axis... It's like opening a door (Alpa's mechanism practically is/acts like a door)... In a properly designed system, focus shouldn't change if you tilt your lens... That's why T/S lenses of DSLRs use a tilt arc for tilting the lens, instead of a (much simpler and cheaper to make) base-tilt/"door" mechanism...
Post by: voidshatter on September 28, 2016, 06:06:54 pm
I'm afraid you are misinformed (probably by the salesman of the equipment)... The entrance pupil of a lens (any lens) is meant to stay on the axis that is perpendicular and crosses the image area to exactly its center... If one uses base tilts, the entrance pupil of the lens moves off this axis... It's like opening a door (Alpa's mechanism practically is/acts like a door)... In a properly designed system, focus shouldn't change if you tilt your lens... That's why T/S lenses of DSLRs use a tilt arc for tilting the lens, instead of a (much simpler and cheaper to make) base-tilt/"door" mechanism...
Focusing is not a problem for CMOS.
Alpa's tilt would only affect CCD for focusing, nothing else. It doesn't affect image quality.
Post by: Theodoros on September 28, 2016, 06:12:56 pm
Focusing is not a problem for CMOS.
Alpa's tilt would only affect CCD for focusing, nothing else. It doesn't affect image quality.
You haven't understand a word out of the subject, have you? Sensor or other image area has nothing to do with it... doesn't matter... after all you bought your ALPA for its ...looks!
Post by: voidshatter on September 28, 2016, 06:26:11 pm
You haven't understand a word out of the subject, have you? Sensor or other image area has nothing to do with it... doesn't matter... after all you bought your ALPA for its ...looks!
I guess you have touched neither Arca nor Alpa with your hands. If you have used both, then you would be able to understand that the Arca's tilting can be exactly reproduced by Alpa (except focusing).
Post by: ben730 on September 28, 2016, 06:47:56 pm
You should also check the Cambo WRS. I decided to buy the Cambo because it's smaller and faster than Alpa and Arca
although, here in Small-Switzerland, the Arca and Alpa dealers are very engaged to sell their stuff.
I only tested these 2 Swiss Cameras for one day, but I'm afraid, I'm really happy with the dutch Cambo gear and won't switch.
For real wides I use the Digitar 24 and the Super-Digitar 28 (with P25+ and P40+).
If proper focused, they are sharp from 1.5 m to infinity, and I'm sure they will also be sharp with smaller pixels.......
I normally don't see a reason to tilt, except you want to bring on purpose some objects out of focus.....
or as Paul mentioned, increase the image circle, what I have never done BTW....
Cambo also offers tilt for the 28 HR.
But at the end, what ever you choose, they are all great cameras, if you learn how to work with your tools.......
Regards,
Ben
Post by: Theodoros on September 28, 2016, 06:55:21 pm
I guess you have touched neither Arca nor Alpa with your hands. If you have used both, then you would be able to understand that the Arca's tilting can be exactly reproduced by Alpa (except focusing).
To your surprise, I've used both, but use (converted for accuracy) Sinar with multishot backs and Rollei electronic shutters for my very complex interior architectural photography which requires significantly more movements and accuracy than what the cameras discussed here can provide... Other than that, I have a British Mech.Eng degree and have been involved in tech camera designs myself... So, if you don't trust me saying to you that ALPA's tilt mechanism on your camera (and any other tilt mechanism that "rotates" instead of "tilting" by its center the lens) is "bad engineering"... Ask some other (or make a subject) on the matter... Then you'll have all knowledgeable in the forum telling you the same...
Post by: voidshatter on September 28, 2016, 07:11:39 pm
To your surprise, I've used both, but use (converted for accuracy) Sinar with multishot backs and Rollei electronic shutters for my very complex interior architectural photography which requires significantly more movements and accuracy than what the cameras discussed here can provide... Other than that, I have a British Mech.Eng degree and have been involved in tech camera designs myself... So, if you don't trust me saying to you that ALPA's tilt mechanism on your camera (and any other tilt mechanism that "rotates" instead of "tilting" by its center the lens) is "bad engineering"... Ask some other (or make a subject) on the matter... Then you'll have all knowledgeable in the forum telling you the same...
It's no rocket science when you tilt a Rodenstock lens (either Arca or Alpa). The only difference is the alignment between the tilt axis and the entrance pupil. When these two do align with each other, the focus does not change while you tilt. When they don't, then you'll need to re-focus to compensate for the focus shift.
Your statements indicate that you think that the misalignment between the tilt axis and the entrance pupil would cause image degradation. I strongly doubt that you really understand these mechanism clearly.
Post by: Theodoros on September 28, 2016, 07:21:39 pm
It's no rocket science when you tilt a Rodenstock lens (either Arca or Alpa). The only difference is the alignment between the tilt axis and the entrance pupil. When these two do align with each other, the focus does not change while you tilt. When they don't, then you'll need to re-focus to compensate for the focus shift.
Your statements indicate that you think that the misalignment between the tilt axis and the entrance pupil would cause image degradation. I strongly doubt that you really understand these mechanism clearly.
If the entrance pupil is off axis... you get an "eggy" (like an egg) shape projected on your image area instead of a circle... It takes no rocket science for you to understand that... it simply means a distorted image and change for worst of the lens characteristics (out of the ideal)...
Post by: voidshatter on September 28, 2016, 07:30:30 pm
If the entrance pupil is off axis... you get an "eggy" (like an egg) shape projected on your image area instead of a circle... It takes no rocket science for you to understand that... it simply means a distorted image and change for worst of the lens characteristics (out of the ideal)...
When you tilt a Rodenstock lens with an Arca, you rotate the whole lens group. It is equivalent as if you tilt the Rodenstock lens with an Alpa and at the same time do some re-focusing and a little bit of shift of digital back to compensate.
If you get your so called "eggy" shape on a tilted Alpa, then you would also get it on a tilted Arca. Let me give you some hint: try to pick the whole lens group of the Rodenstock as frame of reference for both Arca and Alpa.
Post by: Theodoros on September 28, 2016, 07:36:31 pm
When you tilt a Rodenstock lens with an Arca, you rotate the whole lens group. It is equivalent as if you tilt the Rodenstock lens with an Alpa and at the same time do some re-focusing and a little bit of shift of digital back to compensate.
If you get your so called "eggy" shape on a tilted Alpa, then you would also get it on a tilted Arca.
Nope! when you correct for focus, you correct for the focus plane! not for the misalighment of the lens entrance pupil. The center of the sphere that the cone projected on your image area is part off, is then misaligned, so the projection is not a circle anymore, its an "eggy" shape one.
Post by: voidshatter on September 28, 2016, 07:40:05 pm
Nope! when you correct for focus, you correct for the focus plane! not for the misalighment of the lens entrance pupil. The center of the sphere that the cone projected on your image area is part off, is then misaligned, so the projection is not a circle anymore, its an "eggy" shape one.
Let me give you some hint: try to pick the whole lens group of the Rodenstock as frame of reference for both Arca and Alpa. Try to figure out how the remaining of the system reacts towards the lens in each case. (I hope you understand how the Rodenstock lens is focused - it has no floating lens element.)
Post by: voidshatter on September 28, 2016, 08:11:59 pm
Post by: dchew on September 28, 2016, 09:08:32 pm
The "top" collapses in and the "bottom" extends out.
Theodoros, how is this worse than Arca?
Post by: voidshatter on September 28, 2016, 09:47:58 pm
Do either of you own an Alpa tilt adapter? Cuz that is not how it works. The tilt hinge is in the center, not at one end. See those little screws? They surround the hinge point.
The "top" collapses in and the "bottom" extends out.
Theodoros, how is this worse than Arca?
I've just checked my Alpa tilt adapter and the tilt axis seems to be on the main optical axis. This does not affect our discussion above. Whereever Alpa's tilt axis is, it doesn't change the fact that Alpa can always equivalently reproduce Arca's tilt with some re-focusing and shift.
Victor's point is regarding focus shift while tilting, when Alpa's tilt axis is not right on the entrance pupil of each specific lens.
Theodoros however mistakenly imply that Alpa's tilt would affect image quality.
Post by: Theodoros on September 29, 2016, 04:16:34 am
Post by: dchew on September 29, 2016, 05:52:53 am
So which design do you think is "worse" from that perspective? Shouldn't you really be harping on Arca more than Alpa?
These things are pancake technical cameras. If you (or in this case Bernard) wants a view camera then get a view camera. Or the Linhof Techno. All this time you have been arguing Alpa's design /engineering is bad because it doesn't do something the way a view camera does. Well that's not what it is. And in fact, as pointed out in the other thread, unless the lens board mount has the ability to reposition each lens so it's entrance pupil is precisely aligned with the tilt mechanism, most view cameras have exactly the same problem, albeit to a lesser degree.
Please note for me, and I think most owners of Alpa, Arca and Cambo, none of the above arguments matter. Bernard asked about using these for landscape, while Theodoros is complaining it affects his "very complex architectural photography".
So to summarize, Alpa's design does not work as Theodoros thought, despite his claim that he has used the system before. From the "tilt and refocus" perspective, Cambo is the best, followed by Alpa then Arca.* None of which matters much at all, especially in landscape photography.
Dave
*It's been 6 years since I handled a Cambo. I don't know for sure whether the lens tilt mechanism in the lens mount hinges close to the lens or at the base near the camera, so I'll give it the benefit of my ignorance and assume it is closest to the lens.
Post by: yaya on September 29, 2016, 06:09:58 am
Post by: Theodoros on September 29, 2016, 06:51:00 am
I know that Theodoros, but you didn't answer my question. Isn't it true that Arca's tilt mechanism is in the base of the camera, and therefore is further away from the entrance pupil than Alpa's?
Dave, the tilt mechanism of the Arca is NOT "in the base of the camera" ...only the button (the control wheel) is there!
Post by: BernardLanguillier on September 29, 2016, 08:07:54 am
Anyway, thank you all for your inputs.
Speaking of tilt, I have discovered a great iPhone app called "Tilt calculator"! http://snapi.org/snapi/Tilt_Calculator.html
You probably already all knew about it, but I didn't.
Cheers,
Bernard
Post by: Paul2660 on September 29, 2016, 08:52:57 am
Paul C.
Post by: BernardLanguillier on September 29, 2016, 09:05:51 am
Great app. But for me the best tilt calculator is Live Vew.
Especially with a split view like that on the D810.
Cheers,
Bernard
Post by: vjbelle on September 29, 2016, 09:31:26 am
Great app. But for me the best tilt calculator is Live Vew.
Paul C.
++1
Victor
Post by: dchew on September 29, 2016, 01:55:18 pm
That one is good but in my opinion Torger's Lumariver app is much better. I find it very helpful to play and experiment with Lumariver along with your favorite beverage. It is a very good learning tool that shows what your specific lenses do at various tilt settings.
I was far from expecting this genuine question to generate such a heated debate. ;)
Anyway, thank you all for your inputs.
Speaking of tilt, I have discovered a great iPhone app called "Tilt calculator"! http://snapi.org/snapi/Tilt_Calculator.html
You probably already all knew about it, but I didn't.
Cheers,
Bernard
Theodoros,
Thanks for the response, but the tilt hinge is indeed farther away than Alpa's, in the face of the camera. Not out at or near the lens optics (what I would call the x axis). See the first video here:
Arca Video (http://rodklukas.com/video/)
My memory is bad, but I am happy to see not that bad!
Dave
Post by: Theodoros on September 29, 2016, 03:13:34 pm
Post by: Theodoros on September 29, 2016, 03:23:37 pm
I was far from expecting this genuine question to generate such a heated debate. ;)
Not a "heat" debate at all Bernard... This kind of discussions can be very beneficial to many... It's always best for one to check how accurately things work before he invests on a system... That said, I will insist on the "constant focus" method as to test a system... even if one decides on a tilt/shift lens as to use on his D810...
Post by: Tsbphoto on September 29, 2016, 05:04:41 pm
Unless the tilt of the arca is somehow built into the lens barrel? I do not think this is the case but correct me if i am wrong...
If we look at a view camera as an example we could see how it would never be possible to have rotation around the nodal point for tech cams. Lenses for view cameras are just mounted to a lens board and mounted on the front standard which has the tilt built in. The amount of space that would be required for the lens Barrel on the tech cam is achieved using the bellows and raking the front standard, tilt mechanism and all out.
If we wanted to get closer to a nodal rotation on a tech cam the space needed for the lens barrel woul have to be achieved on the sensor side. We would have to have a barrel and helical mount on the sensor so the tilt would be directly around the lens
Yes? . No?
Post by: Theodoros on September 29, 2016, 05:23:58 pm
Im going to wade into this and ask a stupid question. Since both cameras require lenses to be on different length mounts to achieve infinity focus depending on the focal length and the point of rotation of each is a fixed distance from the sensor plane wouldnt the lens always not be rotated around its nodal point?
Unless the tilt of the arca is somehow built into the lens barrel? I do not think this is the case but correct me if i am wrong...
If we look at a view camera as an example we could see how it would never be possible to have rotation around the nodal point for tech cams. Lenses for view cameras are just mounted to a lens board and mounted on the front standard which has the tilt built in. The amount of space that would be required for the lens Barrel on the tech cam is achieved using the bellows and raking the front standard, tilt mechanism and all out.
If we wanted to get closer to a nodal rotation on a tech cam the space needed for the lens barrel woul have to be achieved on the sensor side. We would have to have a barrel and helical mount on the sensor so the tilt would be directly around the lens
Yes? . No?
Not a "stupid" Q at all...
On the Alpa, the lens has a helical focusing mechanism fitted on it, so it focuses by changing distance between the lens cells, this means that the entrance pupil of it varies depending on the focusing distance... On the Arca, the lens is "fixed" and it is focused by changing its distance from the image area (like on a view camera)...
Post by: Tsbphoto on September 29, 2016, 05:28:00 pm
Post by: Theodoros on September 29, 2016, 05:38:07 pm
So the tilt on the arca is inside at the tip of its "bellows" or its huge throw helical mount?
There is a helical mechanism, but moves the "whole" lens with respect to the image area... Just like a view camera does (it replaces the bellows-yes).
Post by: dchew on September 29, 2016, 05:48:16 pm
What Theodoros says below is not true. The helical on an Alpa moves the whole lens just like on an Arca. At least every Alpa lens I have ever used works that way: 40hr, 43xl, 60xl, 70hrw, 90hrsw, 100hrs, 150xl.
All the technical cameras that rely on a helical for focusing work essentially the same way in that regard.
Dave
Not a "stupid" Q at all...
On the Alpa, the lens has a helical focusing mechanism fitted on it, so it focuses by changing distance between the lens cells, this means that the entrance pupil of it varies depending on the focusing distance... On the Arca, the lens is "fixed" and it is focused by changing its distance from the image area (like on a view camera)...
Post by: Theodoros on September 29, 2016, 06:09:33 pm
Tsbphoto,
What Theodoros says below is not true. The helical on an Alpa moves the whole lens just like on an Arca. At least every Alpa lens I have ever used works that way: 40hr, 43xl, 60xl, 70hrw, 90hrsw, 100hrs, 150xl.
All the technical cameras that rely on a helical for focusing work essentially the same way in that regard.
Dave
Dave.... the Alpa lenses come ready with a focusing helical coil that displaces the two cells of the lens (in distance - the front cell with respect to the rear) between them... The extra ring one fits is dedicated to provide a distance scale for each different lens... https://www.youtube.com/watch?v=QLwD1_z9F98
The rear cell is always constant.
Post by: dchew on September 29, 2016, 06:18:36 pm
That video shows how to mount an HPF ring; I've watched it plenty of times. The helical coil does not displace two cells of the lens. It moves the whole lens in and out just like an Arca does and just like a view camera. There are different HPF rings for different lenses because the diameter of the focus grips are different, the min focus distance is different for different lenses, etc.
Dave
Dave.... the Alpa lenses come ready with a focusing helical coil that displaces the two cells of the lens (in distance - the front cell with respect to the rear) between them... The extra ring one fits is dedicated to provide a distance scale for each different lens... https://www.youtube.com/watch?v=QLwD1_z9F98
The rear cell is always constant.
Post by: Theodoros on September 29, 2016, 06:19:43 pm
Post by: Tsbphoto on September 29, 2016, 06:25:39 pm
Since there is so little video or picture documentation on these types of cams lots of questions will have to do.
Is the tilt at the back or front of the arca helical focus?
Post by: yaya on September 29, 2016, 06:36:50 pm
Post by: Theodoros on September 29, 2016, 06:48:41 pm
I have alpa lenses and know that theodoros was wrong on the focusing part, i chose to ignore it to get to the bottom of where the tilt comes in. Trying to not be argumentative.
Since there is so little video or picture documentation on these types of cams lots of questions will have to do.
Is the tilt at the back or front of the arca helical focus?
If it "holds focus" (as people claim) its ON (at the same plane) as the helical focus... On the Alpa its certainly behind it, recessed with respect to the entrance pupil of the lens... It seems that the Alpa acts like a view camera that has the tilt bellow shift, while Arca (correctly) the opposite...
Post by: BernardLanguillier on September 29, 2016, 06:51:15 pm
Bernard,
That one is good but in my opinion Torger's Lumariver app is much better. I find it very helpful to play and experiment with Lumariver along with your favorite beverage. It is a very good learning tool that shows what your specific lenses do at various tilt settings.
Thanks Dave, just purchased it too. I gave it a quick look and it sounds neat, but I'll have to read the tutorial to understand what it does.
Cheers,
Bernard
Post by: Tsbphoto on September 29, 2016, 07:00:51 pm
This is not the case and really makes me wonder if you know what you are talking about. Look at this picture of an arca with tilt... The whole bellows is tilting thus having the the lens tilt around an arc that is not centered around the lens nodal point. The longer the bellows the bigger the arc
Post by: Theodoros on September 29, 2016, 07:14:06 pm
Theodoros..
This is not the case and really makes me wonder if you know what you are talking about. Look at this picture of an arca with tilt... The whole bellows is tilting thus having the the lens tilt around an arc that is not centered around the lens nodal point. The longer the bellows the bigger the arc
My answer was this "If it "holds focus" (as people claim) its ON (at the same plane) as the helical focus..." and the pictures you post show exactly that... What is you disagree with? And please avoid words like "it makes me wonder if you know what you are talking about", because you already had the answer... it makes you look "mean" than having a discussion...
EDIT: Don't think that anyone that uses a camera as to "test" it, examines its exact design as well... I've already said that my criteria is "holding focus" for what "works right"....
Post by: voidshatter on September 29, 2016, 08:52:11 pm
Despite the fact that I thought that the ALPA tilt was a base one rather than a mechanism that tilts the board by its center, if a camera looses focus when the lens is tilted, it is a proof that the lens hasn't been tilted by its entrance pupil. The focusing system of the lens (either by a helical displacement between the cells or by adjusting the distance between the image area and the lens rear cell) is totally irrelevant and can't -in either case- correct for the position of the entrance pupil. What one does by re-focusing the lens, is correcting for the entrance pupil distance from the image area, it doesn't mean (nor it is the case) that the entrance pupil is moved back to the same point where it was before (although the distance from the image area is the same) and thus, the system looses its geometry (the entrance pupil isn't positioned anymore at an axis that crosses the image area at its center, perpendicular to it).
Losing focus is not a problem for CMOS. As long as you understand what is mean by the blue overlaps the orange in my figure, you should be able to know why I'm specifically addressing your misleading statement regarding image quality.
Post by: Theodoros on September 29, 2016, 09:04:56 pm
Losing focus is not a problem for CMOS. As long as you understand what is mean by the blue overlaps the orange in my figure, you should be able to know why I'm specifically addressing your misleading statement regarding image quality.
Here we go again... Geometry has nothing to do with the kind of image area you use Yunil.... you get distortions!
Post by: voidshatter on September 29, 2016, 09:18:20 pm
Here we go again... Geometry has nothing to do with the kind of image area you use Yunil.... you get distortions!
I feel sad for the technical cameras designed by you...
Post by: dchew on September 29, 2016, 09:20:52 pm
Thanks Dave, just purchased it too. I gave it a quick look and it sounds neat, but I'll have to read the tutorial to understand what it does.
Cheers,
Bernard
Post by: Theodoros on September 29, 2016, 09:40:32 pm
I feel sad for the technical cameras designed by you...
Why? ...because you get distortions (that you aren't aware of) in yours? Let me state it to you once more, ...if you loose focus when you tilt, your system geometry suffers, ...and there is no knowledgeable in this world to tell you otherwise! ;)
Post by: dchew on September 29, 2016, 10:44:20 pm
Why? ...because you get distortions (that you aren't aware of) in yours? Let me state it to you once more, ...if you loose focus when you tilt, your system geometry suffers, ...and there is no knowledgeable in this world to tell you otherwise! ;)
No one disagrees with this statement. All helical technical cameras have slight refocus requirements because the tilt mechanism is behind, not below, the entrance pupil.
It seems that the Alpa acts like a view camera that has the tilt bellow shift, while Arca (correctly) the opposite...
THIS is the statement we all disagree with. You are incorrect here Theo. You have been incorrect about the hinge point on the Alpa tilt adapter, incorrect about how the Alpa helical focus mechanism works, and you are incorrect about this too. There is no quality or distortion difference between the Alpa and Arca designs. In fact, there is a slight but very probably unnoticeable advantage to the Alpa design because the hinge point is either 17 or 34mm closer to the entrance pupil vs Arca, depending on which tilt adapter is being used.
NONE of the technical cameras from Arca, Alpa or Cambo have tilt below the shift.
Dave
Post by: Wayne Fox on September 29, 2016, 10:46:32 pm
Seems the Alpa and Arca are pretty much the same in where the "tilt" occurs, both effectively tilting right behind the focusing helicoid? As far as distortion, I would assume this means there isn't a technical camera that avoid this, especially when it comes to a little longer glass (I tilt with my 70 and 90 frequently when doing pano stitches), since the entrance pupil/nodal point is considerably in front of the tilt plane. This means that whatever distortion might be there, you can't avoid it unless you move to a true bellows focusing system where the tilt is at the lens.
I've never seen any real distortion, so while technically it might be there it seems insignificant to the end goal, and may only be able to exhibit itself with testing and special targets. This may apply less to other types of photography where manmade geometrical objects are in play.
I don't use an app to manage my tilt. I simply use the "focus far/tilt near" method, which to Yunni's point is extremely easy to do with a CMOS back, and to be honest I was pretty good at it with LiveView on my CCD back.
Also I"m not sure what is meant by the term "hold focus". Tilting definitely changes the focus on my Arca. It takes a few iterations of "focus far/tilt near" to dial it in, because as soon as you tilt, infinity loses focus and when finished the helicoid isn't anywhere near the normal infinity mark or near the close focus point of the near object in the shot.
I have had both systems. The Alpa can be much smaller, but having the tilt in the body is nice. Unlike Dave I like the helicoid system of the arca but admit I had the Alpa system before their new focusing rings. I haven't compared prices on glass, but logic tells me one focusing helicoid on the body should make the lenses assemblies a little less expensive than having to put one in each lens. My go to lens is the 40mm rodie but have used tilt on the 28mm rodie on occasion. Again with a cmos back and LiveView either focusing system is fantastic, and the Arca may be a little more cumbersome because of it's extremely fine pitch.
Finally I would agree that tilt is a valuable tool for some images with one of these cameras especially if the style of your work allows the use of tilt. Obviously as soon as you put tall elements in the foreground you have to resort to focus stacking instead, or you get the top of those elements out of focus.
From my perspective, shifting is far more valuable than tilting, it's actually pretty rare I don't shift a landscape image anymore, as I tend to keep my camera level and then use shift for the composition. Only when I hit the edge of the image circle will I then begin to tilt the camera to finalize composition.
I also do quite a bit of shift stitching, especially panos were I can get a nice format with a 3 shot shift on my 40mm.
Post by: BernardLanguillier on September 29, 2016, 10:56:59 pm
Cheers,
Bernard
Post by: Theodoros on September 29, 2016, 11:12:05 pm
I'm going to try one more time Theo,
No one disagrees with this statement. All helical technical cameras have slight refocus requirements because the tilt mechanism is behind, not below, the entrance pupil.
"Bellow" is a resemblance to view cameras in a another (different) conversation... We don't have to mix conversations here, ...do we? We (knowledgeable) know what we are talking about... if a system looses focus, then its geometry is wrong, that is the subject...
THIS is the statement we all disagree with. You are incorrect here Theo. You have been incorrect about the hinge point on the Alpa tilt adapter, incorrect about how the Alpa helical focus mechanism works, and you are incorrect about this too. There is no quality or distortion difference between the Alpa and Arca designs. In fact, there is a slight but very probably unnoticeable advantage to the Alpa design because the hinge point is either 17 or 34mm closer to the entrance pupil vs Arca, depending on which tilt adapter is being used.
NONE of the technical cameras from Arca, Alpa or Cambo have tilt below the shift.
Dave
Who is "loosing focus" then? ...if they all do, they are all wrong... then the "most accurate", is the one that "looses focus" less than the others (the one with the smaller error)... simple isn't it?
EDIT: I just don't like technical cameras having errors... it's not what they are meant to do (by all means)... Still, the Alpa is the one with the most of error... (if focus error is more than the rest)... where do we disagree? ...I don't see the disagreement existing anywhere...
Post by: Wayne Fox on September 30, 2016, 01:22:19 am
Who is "loosing focus" then? ...if they all do, they are all wrong... then the "most accurate", is the one that "looses focus" less than the others (the one with the smaller error)... simple isn't it?I think based on what you have said perhaps yes, all Tech cameras if using tilt are "wrong", since they tilt behind the focusing helicoid and perhaps more importantly behind the spacers require for most lenses. I'm not sure anyone is disagreeing that technically this might be true, I think most of us feel the errors are pretty insignificant and the trade off of using the small tech camera and having tilt available is worthwhile. The other two options to achieve depth of field have their own issues, either shutting down to f/22 and introducing some pretty serious softness from diffraction, or focus stacking which has it's own issues including not being able to use if there are elements moving in the image such as branches, grasses, etc. So I guess I'll stick with tilting to accomplish the goal when I can.
EDIT: I just don't like technical cameras having errors... it's not what they are meant to do (by all means)... Still, the Alpa is the one with the most of error... (if focus error is more than the rest)... where do we disagree? ...I don't see the disagreement existing anywhere...
As far as Alpa being the worst, from looking at the two systems, the Alpa is tilting a few mm further from the film plane than the Arca. So maybe there's a slight difference so technically the alpa is "worse", seems the difference if measured and test would be minuscule if even discernible by a viewer. But question, if the Alpa is tilting further from the film plane, it's closer to the entrance pupil/nodal point, so would that mean the alpa tilt might be better than the arca? (I don't have a way to measure where the tilt occurs, I'm just estimating from looking at pictures that the Alpa is this way, which means it's closer to what a bellows camera does when it tilts the lens board.)
Post by: BernardLanguillier on September 30, 2016, 03:20:10 am
Some cameras, such as my Ebony 45SU and some Sinar cameras, were designed on purpose with assymetric tilt where the tilt axis is offset from the lens center purposedely in order to ease the focusing process. You start by focusing a line in the landscape aligned with the tilt axis in the viewfinder and the rotate around this line. This removes the need to iterate to reach focus.
Now, with the apps we now have, this may be even less relevant considering that we can measure the camera tilt, its height to the ground and get a very accurate recommendation of tilt angle and focus distance to align focus with a given plane such as the ground.
Just like correcting optical distortion isn't a key lens design criteria anymore since we can correct distortion in software (which enable designers to optimize better other aspects), I believe that the focus of tech camera design is changing also to reflect the way people use these cameras as a result of new tools such as Live view on backs, tilt apps,...
Cheers,
Bernard
Post by: dchew on September 30, 2016, 05:57:02 am
You bring up a good point about helical cost. Alpa is more expensive out of the gate and goes up from there. And, as the number of lenses in the bag increases, so does the weight with Alpa. Torger points this out as an advantage of the Linhof Techno. He carries many lenses but each one is simply mounted on a light lens board.
Dave
Post by: Theodoros on September 30, 2016, 06:46:59 am
I expect that in the near future, very few will invest on systems with MFDB used as image area, the most part will be mirrorless with compatible retrofocus lenses that are meant for mirrorbox cameras. Therefore I expect the technical camera market to expand significantly, but the "mini" monorails to dominate it. Then one can have one (only) line of lenses and share them between his normal shooting and technical camera all the same. I also expect the "mini" monorails to be used for motion picture taking.
Post by: Paul2660 on September 30, 2016, 09:57:05 am
I also shift for short pano shots most of the time I use the Arca. I love the fact that you can have the camera in just about any position up or down and since you are moving the back instead of the lens the final pano creation is effortless. No worries of being level or nodal. It does allow for a lot more composition freedom.
Arca has a screw style mechanism for shifting there is no quick release that allows you to quickly slide from the far left to far right. So doing a lot of shifting means a lot of knob turning.
Cambo has the ability to free up the shifting for fast movement to one far stop to the other or you can switch back to the geared style for precise adjustment. Cambo also has an indent that lets you know when you are centered.
Cambo also just annouced a new camera that is based on their smart L bracket that allows for quick rotation of the back by rotating the camera. Nice design.
Paul C
Post by: Christopher on September 30, 2016, 10:02:11 am
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Post by: yaya on September 30, 2016, 10:31:13 am
Thanks for stepping in Wayne. I felt like I was trying to get somewhere with one foot nailed to the floor.
Dave
And not to mention that this whole "error" thing is only relevant of you initially set focus in the centre of the image (and the lens)...
Post by: Paul2660 on September 30, 2016, 10:33:56 am
Just to add to the post above. That is correct for the Arca Rm3di. The Rm2d and factum have only one geared shift ( rise and fall) and just a easy push and pull.
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Thanks Christopher for the catch, I always forget about the Factum and older Acra's.
Paul C
Post by: Christopher on September 30, 2016, 10:40:16 am
These names.... ;)
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Post by: dchew on September 30, 2016, 01:02:15 pm
As usual, the pilot is who holds me back...
:-[
Dave
Cambo has the ability to free up the shifting for fast movement to one far stop to the other or you can switch back to the geared style for precise adjustment. Cambo also has an indent that lets you know when you are centered.
Post by: Theodoros on September 30, 2016, 01:16:13 pm
And not to mention that this whole "error" thing is only relevant of you initially set focus in the centre of the image (and the lens)...
What you mean Yair? The distortion causes the image "circle" projected to have a "eggy" (like an egg) shape, the more the error, the more the shape of the image circle distortion... The whole image captured is affected.
Post by: Tsbphoto on September 30, 2016, 10:09:50 pm
What you mean Yair? The distortion causes the image "circle" projected to have a "eggy" (like an egg) shape, the more the error, the more the shape of the image circle distortion... The whole image captured is affected.
when ever you tilt a lens you will get that distortion... what is the problem?
Post by: Theodoros on September 30, 2016, 10:17:17 pm
when ever you tilt a lens you will get that distortion... what is the problem?
You don't get any distortion if you tilt the lens with the entrance pupil positioned at the center of the circle of which the tilt arc is part of the perimeter.... Additionally you take the most out of your lens.
Post by: Tsbphoto on October 01, 2016, 10:33:50 am
You don't get any distortion if you tilt the lens with the entrance pupil positioned at the center of the circle of which the tilt arc is part of the perimeter.... Additionally you take the most out of your lens.
you are conflating image distortion with the shape of the projected circle. rotating around the nodal point will have no image distortion but the image circle projected on the flat image plane will always have a distorted "egg" shape.
Post by: Theodoros on October 01, 2016, 10:43:24 am
you are conflating image distortion with the shape of the projected circle. rotating around the nodal point will have no image distortion but the image circle projected on the flat image plane will always have a distorted "egg" shape.
What you are saying is different... Rotating around the entrance pupil, will create an elliptical shape plane of focus... Not an "egg" shape at all on the projected image... "Egg shape" means distortion and its created when the "projected cone" from the lens and the image area are not parts of the same (hypothetical) sphere which has the entrance pupil ("nodal" point as you call it) on its center....
EDIT: Don't confuse the shape of the plane of focus with the shape of the image area... They are two different things... On the image area you have parts included in the depth of field range and parts that are not, distortion is irrelevant.
Post by: Tsbphoto on October 01, 2016, 12:04:31 pm
What you are saying is different... Rotating around the entrance pupil, will create an elliptical shape plane of focus... Not an "egg" shape at all on the projected image... "Egg shape" means distortion and its created when the "projected cone" from the lens and the image area are not parts of the same (hypothetical) sphere which has the entrance pupil ("nodal" point as you call it) on its center....
EDIT: Don't confuse the shape of the plane of focus with the shape of the image area... They are two different things... On the image area you have parts included in the depth of field range and parts that are not, distortion is irrelevant.
it really isnt even worth discussing with you anymore. Arca is CORRECT and Alpa is WRONG (even though they both do it the exact same way, go figure) have a nice weekend! cheers!
Post by: voidshatter on October 01, 2016, 12:18:31 pm
it really isnt even worth discussing with you anymore. Arca is CORRECT and Alpa is WRONG (even though they both do it the exact same way, go figure) have a nice weekend! cheers!
It's a waste of time to argue with him. Just, let him have fun ;D
Post by: Theodoros on October 01, 2016, 12:28:16 pm
it really isnt even worth discussing with you anymore. Arca is CORRECT and Alpa is WRONG (even though they both do it the exact same way, go figure) have a nice weekend! cheers!
Who told you that Arca is "correct"? ...everybody has told you that Arca has "less" error... it surely doesn't worth it to explain it to you... your attitude is one that shows no respect... One explains to you what you should already know when you invest in this kind of equipment and you, instead of thank him, you think of it as a "game" that ALPA should win.... Well, here is to you... the "new" ALPA SERPEND and the "traditional" Arca F-classic, are about the worst cameras in the market... The two cameras in production, that officer Scheimplug, if he was around, he would rate for an absolute "zero"....
Post by: dchew on October 01, 2016, 03:15:32 pm
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Post by: Graham Welland on October 01, 2016, 05:10:07 pm
To Bernard's original question, if you want the simplest tech camera that'll provide tilts and swings and rear rise/fall then just go with a Cambo Actus DB. I can use this with anything from a Rodie 23HR through to, well anything long given a long enough base rail and bellows. Ditto with a Linhof Techno, I just prefer the size of my Cambo.
And for Theodoros, it tilts the lens around the optical center, assuming that the optical center is in the middle of the lens board. The tilt mechanism moves the entire board in an arc around that nodal point (unless you've raised the board - there's an optional front shift mount point for it on the base).
I've owned the Alpa for many years and used their tilt adapters. It is true that the axis of the tilt is behind the lens and in a fixed position which technically will move relative to the optical center of the lens if you change focus with the helicoid. However, as has been pointed out a number of times, it is really not difficult to use in the field and just takes small adjustments to dial in front/back focus and if necessary you may have to adjust a little rise/fall to compensate for the image shifting slightly.
Sure, there's theoretical perfection that Theodoros is obsessed with and then there's PRACTICAL usefulness that the pancake technical camera tilt functions provide. In this respect all of the pancake cameras are 'flawed' but they are nonetheless very usable and I've certainly never had any concerns about quality drop off when using tilt adjustments.
Finally there's also one advantage I found with the Alpa which was I could put the tilt adapter on the back of the camera and tilt the sensor vs the lens for looming of the image. Not quite as easy as doing it with a proper 4x5 view camera but still doable in the field, especially with decent CMOS live view. That's a difference between the Alpa approach and the Arca, although you can achieve the same thing with tilting of the entire camera body and then adjusting the tilt on the camera (Theodoros will have a mental breakdown over the geometric accuracy of that set up I'm sure! :) )
Post by: BernardLanguillier on October 01, 2016, 07:03:44 pm
I bought a used Arca R3mDi in the meantime, but it's still good to know there was a better option. ;)
Cheers,
Bernard
Post by: Theodoros on October 01, 2016, 08:06:41 pm
I just prefer the size of my Cambo.
And for Theodoros, it tilts the lens around the optical center, assuming that the optical center is in the middle of the lens board.....
I never said that the Actus mini "tilts the lens around the optical center"..... in fact it doesn't either... The lens board of it is in a parallel plane to the tilt arc's plane. But it can work well with some retrofocus lenses meant for DSLRs...
Thanks Graham, I had somehow overlooked the Cambo.
I bought a used Arca R3mDi in the meantime, but it's still good to know there was a better option. ;)
Cheers,
Bernard
Keep an eye on the Silvestri Flexicam too... That would be my first choice (for use with LF lenses) if I ever was (unlikely to ever be) after a compact technical camera....
Post by: Graham Welland on October 01, 2016, 08:56:10 pm
I never said that the Actus mini "tilts the lens around the optical center"..... in fact it doesn't either... The lens board of it is in a parallel plane to the tilt arc's plane. But it can work well with some retrofocus lenses meant for DSLRs...
Actually, I would agree. The board is actually mounted behind the center of axis but it still works just fine.
Post by: Theodoros on October 01, 2016, 09:15:56 pm
Actually, I would agree. The board is actually mounted behind the center of axis but it still works just fine.
Be careful with some lenses on the Actus.... the difference between the lens board's plane and the tilt plane may be small... but so is the tilt radius... It means that the percentage of error can be significant.
EDIT: May I ask why you choose the Actus over the Universallis Graham? As far as I understand, you mostly use LF lenses, The Actus may be a better choice with retrofocus lenses meant for DSLRs, but the Universallis is clearly much better (or should I say among the best) for use with "tech camera lenses" from Rodenstock or SK... In fact, the Universallis could be an excellent choice for (both FF & MF) DSLR lenses if Arca would care to make the lens boards aimed for these lenses with a recessed mount... I guess they'll be forced to do it (at least for the FF lenses) after the FUJI GFX hits the maket anyway....
Post by: vjbelle on October 02, 2016, 08:08:16 am
Victor
Post by: Graham Welland on October 02, 2016, 05:36:55 pm
Whilst I miss aspects of shooting with the Alpa STC system, I find the Actus DB+ gives me all of the movements I need and a whole lot of extra flexibility in a mini bellows camera. Obviously this only became a practical alternative with the availability of usable CMOS live view - the advantage of the pancake cameras with focus helicoids being that you could use any MF back regardless of live view capabilities and measure/dial in subject distance,