Luminous Landscape Forum
Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: BernieKohl on January 27, 2012, 07:47:53 am
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I've been mainly photographing with film and finally decided to buy a digital back for the Alpa 12 system. The only one I've had hands-on experience with was a PhaseOne P45+. From what I've seen and read color shift is quite an issue with lenses like the 28 from Schneider. So I've been wondering about which back is most tolerant to camera movements? Resolution is not as important to me as being able to shift/tilt without constantly having to worry about lens cast.
My top priorities:
Low amount of lens cast
Durability (will be mainly used in the field)
Low power consumption (have to rely on solar and wind chargers)
CF card slot
V mount (for my 503CW)
I'd be glad to hear from people with experiences using wide angle lenses with movements on view cameras. Especially with backs that feature larger photosites such as the Aptus II 8.
Thanks in advance,
Bernie
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Any DB without microlenses - and in that respect the P45+ is a great performer. I use it with the 28 with no problems. The freedom from extreme color shifts + it's long exposure capability is the reason why I haven't traded it in (if only Phase would stick this sensor in an IQ body!)
Jim
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Once you stick with a 49 x 36mm sensor you should be fine. I use the Hasselblad H3D 39 with the 24mm, 28mm, 35mm and 47mm Schneider with no color shift. With hindsight I probably would have gone with the P45 also. As Jim says the long exposures is something I really would love to have. I can shoot up to a sneaky 80 seconds when I use the back on the Cambo. Even though I'm only supposed to get 60. Don't know why. All I know is I'm glad it does. Would love to shoot longer than that though. What I like about the H3D is I believe with Phase One you have to wake up the camera when shooting, which to me seems like a pain in the ass, especially when shooting a series of shots for a panoramic :D
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Any DB without microlenses - and in that respect the P45+ is a great performer. I use it with the 28 with no problems. The freedom from extreme color shifts + it's long exposure capability is the reason why I haven't traded it in (if only Phase would stick this sensor in an IQ body!)
Jim
exactly my reason for holding tight to my 45+. it's a great db. a great workhorse with my alpas: stc, max, swa
rh
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I can only second all said by others here, the P45+ works fine with short to very short FL lenses. It is with larger sensors like in the IQ 160 and IQ 180 from PO or the Aptus II 10 and Aptus II 12 that coverage, corner sharpness and CCs become an issue.
Thierry
exactly my reason for holding tight to my 45+. it's a great db. a great workhorse with my alpas: stc, max, swa
rh
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Once you stick with a 49 x 36mm sensor you should be fine. I use the Hasselblad H3D 39 with the 24mm, 28mm, 35mm and 47mm Schneider with no color shift.
hi enda,
i own an h3d-39 too, and would love to switch to a view/plate camera (arca rm3di) for architectural and landscape.
how do you deal with the back?
focusing? power supply?
if i could afford it, i would love to have an IQ back with its "liveview-like" feature and the perfect screen
(this is what i hate the most about my h3d)
but guys like you make me hope that i can stay with my gear and can get good results too ;)
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you can get the tech cameras with H mount
I used the Quantum Turbo 3 battery which has a low voltage power outlet and a firewire adapter purchased from capture integration.
another option is the Bigwave power supply. not as much juice though
you also need a lens synch port to H-39 back cable.
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i heard from the bigwave solution - isn't it selled as HD+?
would be an option.
what about switching to an cfv back - is the cfv-50 the same quality, as the h4d-50 - it should be i guess.
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It is with larger sensors like the IQ 160 and IQ 180 from PO or the Aptus II 10 and Aptus II 12 that coverage, corner sharpness and CCs become an issue.
If you compare the P45+ and the IQ180 they are almost the same size: 49,1 x 36,8 mm vs. 53,7 x 40,4 mm. Stitching two images I could cover a much larger area than the IQ180 but still have less color cast. According to this Optechs article (http://www.optechsdigital.com/Pixels_and_Micro_Lenses.html) "symmetric" micro lenses and smaller photosites actually decrease the amount of color cast. Nevertheless it appears to be quite the opposite. I was also considering the Hasselblad CFV-50 for a while but couldn't find any information on how well it worked on technical cameras.
Is the P45+ officially recommended by Alpa for larger movements?
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Dear Bernie,
AFAIK, the P65+ and the IQ 160 have the very same sensor, with a pixel size of 6 micros. Although not as critical as the IQ 180, both the P65 and the IQ 160 show visible CC with very short to even medium-short FL lenses with a non-retrofocus lens design (Schneider vs Rodenstock HR).
IQ 160/180 - P65 with Schneider/Rodenstock Short FL (http://forum.getdpi.com/forum/medium-format-systems-digital-backs/26755-iq180-end-schneider-lenses-compared-rodenstock-6.html)
As I understand it from OptechsDigital, they mean to say that the casts are less using a newer "symmetric" design as compared to the previous design of micro-lenses.
Alpa does not recommend any back in particular, officially or not, we are just trying to share our experience from users. Also we are not saying to not use these backs but be aware of the problematic and how to solve the issue. In other words, do your own tests under your own shooting conditions and needs and decide by yourself if it works for you or not.
Best regards
Thierry
If you compare the P45+ and the IQ180 they are almost the same size: 49,1 x 36,8 mm vs. 53,7 x 40,4 mm. Stitching two images I could cover a much larger area than the IQ180 but still have less color cast. According to this Optechs article (http://www.optechsdigital.com/Pixels_and_Micro_Lenses.html) "symmetric" micro lenses and smaller photosites actually decrease the amount of color cast. Nevertheless it appears to be quite the opposite. I was also considering the Hasselblad CFV-50 for a while but couldn't find any information on how well it worked on technical cameras.
Is the P45+ officially recommended by Alpa for larger movements?
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I have to say that I am a bit baffled: While you get less color cast using a P45+ in comparison to a P40+, I'd say there is no way to use the P45 with wide angle lenses without LCCs. When I had to make up my mind which way to go, I compared the P45+, the Aptus 8 and the P40+. Color cast with the P45+ was worse than expected and not acceptable. So I'd say it's of little help that it is less severe than using a P40+: You still need LCCs.
The attached LCC shot (yes, the sensor was incredibly dirty) is from a test of the P45+ with, if I remember correctly, the HR-Digaron W 40mm.
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Dear "mjon",
Just to clarify my position: I did not mean to say that one does not need to perform a "white shading" with a P45, I would even recommend to do so with any digital back and even with longer FL lenses: a sensor never has a linear response all over its surface, as shown here.
In addition to this, I also need to say that your colour cast showed here (due to the non-linear response of the sensor) has nothing to do with the type of colour cast produced by short FL lenses (non-retrofocus) on sensors with micro-lenses or with larger sensors like the ones used in the IQ DBs (due to the strong angle at which the light hits the pixels).
Important remark: the non-linear sensor response can be corrected to a certain extend in factory (internal factor), the effect of the light incidence on the pixel cannot (external factor).
Best regards
Thierry
I have to say that I am a bit baffled: While you get less color cast using a P45+ in comparison to a P40+, I'd say there is no way to use the P45 with wide angle lenses without LCCs. When I had to make up my mind which way to go, I compared the P45+, the Aptus 8 and the P40+. Color cast with the P45+ was worse than expected and not acceptable. So I'd say it's of little help that it is less severe than using a P40+: You still need LCCs.
The attached LCC shot (yes, the sensor was incredibly dirty) is from a test of the P45+ with, if I remember correctly, the HR-Digaron W 40mm.
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Thierry, this wan't meant to offend you, apologies if it came across like this! I was referring to various early postings in this thread.
All I wanted to say is: I don't see a huge advantage in using the P45+ when it comes to the issue of color cast (this is not to say, that there is no point in chosing the P45+ over a back based on a Dalsa sensor etc.!): The fact that there is less color cast doesn't make life easier when I have to take a LCC shot anyway. And I'm with you: I'd recommend doing so even with longer lenses.
jon
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Jon,
I didn't take it as an offense at all, no apologies needed.
:)
I just wanted to make aware of the difference between CC due to sensor response and due to light angle when hitting the sensor. It's 2 different things, one can always be corrected (sensor response), the other is more difficult to deal with (angle of light).
Best regards
Thierry
Thierry, this wan't meant to offend you, apologies if it came across like this! I was referring to various early postings in this thread.
All I wanted to say is: I don't see a huge advantage in using the P45+ when it comes to the issue of color cast (this is not to say, that there is no point in chosing the P45+ over a back based on a Dalsa sensor etc.!): The fact that there is less color cast doesn't make life easier when I have to take a LCC shot anyway. And I'm with you: I'd recommend doing so even with longer lenses.
jon
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Like with pretty much any DB it's recommended to take LCC calibration shots when using the P45+. Where the P45+ (and other non-microlens DBs) starts to shine is when you shift. This is shown by the test CI did a while back (10mm of fall) using a Schneider 35mm (symmetrical design, short back focal length) lens - fall-off is basically negligible - and for shifts beyond 10mm the amount of 'work' the LCC has to do to correct the image is far less than on a comparable back with microlenses:
(http://www.captureintegration.com/wp-content/uploads/r2-scene-crop-copy.jpg)
Link to original post at CI (http://www.captureintegration.com/tests/phase-one/)
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I must say this is quite an interesting comparison. It clearly shows that both the P40+ and the P65+ share the same kind of microlenses which appear to be less prone to fall-off from symmetric lenses such as the Schneider 35 mm XL. The P65+, of course, has more fall-off due to its larger size. But what about the color shift from lens cast? I took the liberty of processing the EIP files from the P65+ and the P45+ without LCC (see attachment). To me the P45+ is the clear winner. Even though the color cast can be corrected, I'd say add another 5 mm of fall and the file from the P65+ becomes unusable.
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Like Thierry said there is a difference between the color cast from the wide angle lenses and the much stronger color casts with the P65, the IQ160 and worst of all the IQ180. If you want to use the lens movements to any great extent I think you will have to stay clear of them if you plan use a Schneider lens set up. I believe the Rodenstocks work much better because they are physically longer and of the retrofocus design. I have never shot with a Rodenstock but that seems to be the consensus in numerous posts. The color casts I get with the Schneider lenses on the H3D/Cambo Wide DS are completely removed using the scene calibration tool in Phocus. Of course the great thing about taking your calibration shot for each new movement and new lighting scene is that you can be guaranteed of getting a perfect white balance. This is especially useful for interior architectural work where moving even a few meters can change the colour temperature. Once the color cast is removed from your calibration shot, you than use the neutralization tool to get the color temperature correct. You can be guaranteed that the "neutral" tone you are picking is really neutral. One thing I really like about Capture one is that the vignetting tool is adjustable. With phocus it's all or nothing and sometimes it goes a bit too far, so the corners appear to bright for my liking.
Has anyone any info on color casts with the H4D 60 when used with Schneiders. It also has a larger sensor. I haven't read anything anywhere. If you have I'd love to hear your feedback.
Maybe a camera to consider is the H4D 50. It has the 49 x 36mm sensor.
Bernie, getting back to you about your earlier question I too use the Quantum Turbo 3. It's made my life so much easier. I can easily do a full days shooting on the view camera. I actually had 5 Bigwave batteries and they were a complete waste of money. In total they cost around the same as the Quantum. My issue with the Bigwave power batteries was that they would only last about 20-30 minutes before shutting themselves off. The Hasselblad requires 12-18W of power when the Li-Ion grip is not used; the HD+ supplies 9W of power – so the digital back is draining the HD+ at a 200% rate when used on the view cameras. When the BigWave falls below the ability to provide the higher power, it shuts off to avoid circuit damage. I connect the Quantum to my H3D with a Firewire 800 adaptor available from Leaf (kindly recommended to me by Yahir on LL) The adaptor was a bit too tight to fit in the Firewire slot on the camera but some DIY shaving off with a blade sorted that out no problem.
Believe it or not I just use the viewfinder and the distance scale on the Schneider lenses when shooting and to be honest I just use my previous experience to select the focus distance. I also use photo buddy on my iphone (a very useful tool) Don't forget I use wide angle lenses so focus isn't a huge issue really. If I have a huge depth of field to worry about I shoot at f16. Like you say the Live view is such a useful tool. I mostly shoot with lens movements and I sometimes have to take a a fair few test shots to tweak things. This is especially so when shooting architectural shots in a tight space or when shooting something linear straight on where the camera has to be 100% perpendicular to the subject. With live view things become a lot simpler. You sort out your composition pretty much straight away. The touchscreen with an instant 100% view of the image is another huge plus.
It isn't the liveview or the touch screen that takes the image. So you have to ask your self what type of image do you want to take. If you want to use the wide angle Schneiders and especially if you like lens movements (crucial for a lot of architectural work) than you simply can't reap the benefits of the IQ160 and IQ180. You could use the IQ140 but because of the 1.3 crop factor it defeats the purpose. Alternatively you could go for the Rodenstocks (which are a lot more expensive) If you want to shoot with the Schneider than you'll have to choose from the 49 x 36mm sensor cameras (unless the H4D 60 proves otherwise)
I would love to hear anyones experience with the H4D 50 or H4D 60.
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I shoot a IQ 160 on a Cambo and with my 35xl with Center filter you need a LCC even with a straight shot. Just no getting around it there is a color cast. I can also shift to a max 12mm before I get into trouble. The 35 XL will not work on a IQ 180. I have shot the new 23 Rodie and you can go about 3mm. The new 32 Rodie about 15mm but with all of them you need to shoot a LCC . You want correct color than it's just a fact of life with wide angles. I have not shot the new SK 28 on my 160 but my bet no more than 5mm movements. I have the new SK 60 and just for comparison sake I can shift to 20 mm no problem and I only really need a LCC for light fall which is pretty minimal but dont need it for color cast. End Of day it's all about the lenses image circle and the wides are limited for every back you will run into some limitation. Really just need to test your back whichever that maybe and find your limits but thinking your not going to need to shoot LCC is really bad thinking. You need to shoot LCC
BTW there should be very little if any difference between a Alpa, Cambo or Arca when it comes to movements and LCC given a certain lens. It's really about which back you use and what limitations on Image Circle size the lens will have. End of day no matter what back you have to get correct color you need to shoot LCC's. It will vary on backs but you still need to do it if you want accurate color. Really more of a concern is how much movement you can get with a back and a lens before it turns to mush. As far as LCC's just count on doing it with wides . That's just a good general rule.
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As I thought Guy. It's such a pity about the strong colour casts on the IQ. The system seems like a solution to so many problems, whether it be the the pixel count, high res touchscreen, the live view, the low native ISO amongst others benefits but unfortunately with the colour cast issue it's just not worth changing. These great tools aren't what make a great image at the end of the day. I'd literally have to change my style of photography re. movements. :(
The Rodenstocks seem like a solution but I'm afraid it's just not financially viable
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But it's really a moot point anyway cause you have to do LCC anyway and than your image is correct. What counts is after the LCC not really before. Now if there is really a restrictions than the IQ 180 would have it. Simply because you really have to buy a Rodie 23, 32,40 or a SK 43 as your lens choices and the very wides are 8k. I can still use a 23, 28 but a relatively cheap Sk 35 which a 180 cannot. The only real lens I cannot is the 24 other than that I'm good to go. The real movement restrictions are the lenses image circle more than anything. Now outside these the IQ series is the best back bar none on a tech cam. The LCD , 100 -400 zooming and very detailed plus focus mask are worth every cent on a tech cam. Not to mention live view which I put on the bottom of the list as far as functionality over the ones above. In all truth I waited to go tech cam until the IQ series was out. Cuts the guessing game into a more convinced I nailed it thinking before packing to go home. So end of day worth it to me.
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Hi Guy.
Unfortunatly all these great features mean nothing if I can't get a workable image because of the extreme colour casts on the Schneiders which can not be corrected without a significant drop in quality. LCC is an affect you get with all view cameras but no where near the extent you get with the IQ's. From what I've read the 28mm is unusable even with no movements. Not much point when one of its main selling points is that it is a very wide angle lens with a very large image circle facilitating very large lens movements.
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Well I can't speak for the Sk28 but what I heard is a no go on the IQ 180 but will work on the 160 i will be trying that in two weeks and update here. Now not sure the 23 would work past 3mm since it gets cut off past 3mm that is with a 180 or 160. So probably the same for any FF back for that matter. I agree there is more head room with the Rodie's but again the 23 and 32 are 8k. I got about 15mm with the 32 and yes less color cast and more movement than my SK 35 so that is a pretty equal comparison. Sad news is about a 5 k difference. At least myself going with the 160 I can use the SK 35 which really is a great lens but I do have limits on it. But I can do a 2 shot stitch at 15mm left and right and squeeze a 28 focal length. The problem here is costs , image circle and wide angles. You absolutely no doubt about it will have to make compromises until you at least get to the Rodie 40 and SK 43 than life gets a little easier. Plus you can stitch these 2 40,43 and get pretty wide with good rise and fall to boot. But yes the Rodie's by design have more headroom over the SK in the very wides after that they both scream going up in focal length. Honestly I will put my SK 60 XL against anything out there it's that good. So I don't want to be down on the SK's but the Rodie's in the very wides are more friendly.
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hi enda, hi guy, and others here in this fascinating topic...
i would like to know, which lenses you are using in particular. and which movement they allow. or which ones you recommend for landscape an architectural work.
i'm pretty near to get into an large investment in an arca, but it seems to be a bit more complicated with the choice of lenses as i used to believe.
so it would be a great thing, to know your specific experiences with those lenses.
cheers,
thomas
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Technically the Schneider lenses are superior since they are symmetric, but I guess only multi-shot or non-Bayer sensors can reproduce the difference in sharpness. Regarding distortions I'd say Rodenstock kept them incredibly low for a retro-focus design plus they can be corrected in post whereas color shift has its limitations. Personally I would rather have the SKs though since I see them as the better investment considering future sensor improvements.
Since color cast appears to increase with smaller photosites and micro-lenses shouldn't the Leaf Aptus-II 5 with a pixel pitch of 9 micron and from what I've read no micro-lenses have hardly any issues with color cast? After studying the available backs for two weeks now I am most intrigued by the Sinarback eMotion 75 LV, which has a lot of positive response – even on this forum with many of P1 users.
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With tech cams and wide angles, LCC are a fact of life regardless the back you are using. True, some backs (IQ180) are more susceptible than others (IQ160, P65+), but LCC is still a must with every back. I hate using superlatives, but somebody prove me wrong. If LCC is too much trouble, then maybe your better off with an SLR. Just because there are colorcasts, doesn't mean it's broken.
As I thought Guy. It's such a pity about the strong colour casts on the IQ. The system seems like a solution to so many problems, whether it be the the pixel count, high res touchscreen, the live view, the low native ISO amongst others benefits but unfortunately with the colour cast issue it's just not worth changing. These great tools aren't what make a great image at the end of the day. I'd literally have to change my style of photography re. movements. :(
The Rodenstocks seem like a solution but I'm afraid it's just not financially viable
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Hi Alan
I think you may have misunderstood me. I know that the LCC is a way of life with wide angle lenses on view camera/digital backs. This is easily removed in Phocus or Capture 1. The colour casts one gets when using the wide angle Schneiders on the IQ180 can not be removed as the affect is too strong.
Here is a link to Getdpi (http://forum.getdpi.com/forum/medium-format-systems-digital-backs/27729-wide-lens-iq-180-shoot-out-digitar-28xl-versus-digaron-32hr-w.html) where it is further explained.
There are numerous posts on this. The Digitar 35 XL and 43 xl Lenses I believe also have strong color cast again widely reported on getdpi.com.