Hasselblad HCD 24mm on HTS.

[NickT]

As an aside I have a pizza client and they want hires images of pizzas sharp from front to back. I use the HTS with an 80mm and 7 degrees of tilt and it works well. My point being it's not just for architecture.

Nick-T

[jerome_m]

Rectilinear distortion varies with the distance from the subject to the camera, and there is only so much software can do when there are straight lines at very different distances from the camera.

I don't think that this statement is quite true. Distortion varies with the position of the focus ring, yes. But not directly with the distance between subject and camera. Of course, indirectly, the position of the focus ring is linked to the subject distance, but I think that distortion is the same for out of focus elements than for the focus plane.

Phocus, the software from Hasselblad, reads the position of the focus ring from the exifs. It uses it to correct distortion. In my experience, the results are great with straight lines looking straight on all subjects. Basically, when you use Phocus, distortion is non-existent for all H lenses.

[jerome_m]

As an aside I have a pizza client and they want hires images of pizzas sharp from front to back. I use the HTS with an 80mm and 7 degrees of tilt and it works well. My point being it's not just for architecture.

Yes, indeed. I would even say that the HTS has been originally designed with this kind of use in mind and not for architecture.

[David Eichler]

Yes, indeed. I would even say that the HTS has been originally designed with this kind of use in mind and not for architecture.

The fact is, though, a significant minority of architectural photographers who use medium format are using Hassleblads, whether with HTS 1.4 or not I am not sure. I would be interested to know why they are doing that instead of using "tech" cameras.

[synn]

I have no horse in this race, but I recall a series of videos a german magazine made pitting a phase one kit against a Hasselblad kit. Their conclusion was that the Hasselblad had the edge in the studio because of Trufocus, but the Phase on a tech cam did better for architecture than the blad with HTS.

I don't think this is necessarily a bad thing. If you look at the blad ecosystem, it is very much geared towards a studio user. Things like Trufocus and tight integration of body and back are things a studio person appreciates and a tech user couldn't care less about. The displays on the backs haven't been updated because they probably feel that these cameras would almost always be used tethered. Their promotional materials almost always feature advertising/ fashion portraiture and very rarely architecture and landscape. I believe the HTS was developed as an ingenious  (And relatively low cost) solution for T/S for a Blad user who has invested into their ecosystem. Again, more for product/ studio work rather than field work.

I believe that Blad has chosen the niche they want to focus on and tot heir credit, they have come up with some unique solutions that work really well for that market. You can make them run another race, but it's not what they focus on and for sure, the results won't be as good as brands/ products that are specialized for that task.

[David Eichler]

I don't think that this statement is quite true. Distortion varies with the position of the focus ring, yes. But not directly with the distance between subject and camera. Of course, indirectly, the position of the focus ring is linked to the subject distance, but I think that distortion is the same for out of focus elements than for the focus plane.

Phocus, the software from Hasselblad, reads the position of the focus ring from the exifs. It uses it to correct distortion. In my experience, the results are great with straight lines looking straight on all subjects. Basically, when you use Phocus, distortion is non-existent for all H lenses.

See figure 5 on this Web page: http://toothwalker.org/optics/distortion.html

An automatic software lens profile correction cannot deal with this situation. Admittedly, however, the example represents an extreme case, with the ruler held very close to the lens.

[jerome_m]

See figure 5 on this Web page: http://toothwalker.org/optics/distortion.html

An automatic software lens profile correction cannot deal with this situation.

The distortion in that fig. 5 is similar to the one exhibited by the HCD 24 or HCD 28 lenses. Phocus corrects it automatically. The correction system in Phocus is much more powerful than you appear to think and includes thousands of data tables directly computed from the lens ray tracing software.

[David Eichler]

The distortion in that fig. 5 is similar to the one exhibited by the HCD 24 or HCD 28 lenses. Phocus corrects it automatically. The correction system in Phocus is much more powerful than you appear to think and includes thousands of data tables directly computed from the lens ray tracing software.

You can't seem to wrap your mind around what I am talking about. I think maybe we went over this before somewhere else and you still didn't understand. I can't try any harder to explain. If I am wrong, I would expect the Hassleblad rep to correct me immediately, since he seems quite active in this forum.

[jerome_m]

You can't seem to wrap your mind around what I am talking about. I think maybe we went over this before somewhere else and you still didn't understand. I can't try any harder to explain.

Obviously, yes: I don't understand your concerns about distortion. I have used the HCD 28 extensively. It has a fair amount of "moustache" distortion, uncorrected. Corrected, I have never seen it produce anything else than straight lines. Let me add an example, since this thread lacks pictures:


Tree twig and glass wall.

Maybe you are not convinced because everything is at the same distance on the picture above? Let me try something else:


Art piece without self portrait.

Or, maybe, this one. You are welcome to align a ruler to the floor tiles:


Underground passageway perspective.

If I am wrong, I would expect the Hassleblad rep to correct me immediately, since he seems quite active in this forum.

I have not noticed a "quite active" Hasselblad representative in this forum.

[David Eichler]

Obviously, yes: I don't understand your concerns about distortion. I have used the HCD 28 extensively. It has a fair amount of "moustache" distortion, uncorrected. Corrected, I have never seen it produce anything else than straight lines. Let me add an example, since this thread lacks pictures:


Tree twig and glass wall.

Maybe you are not convinced because everything is at the same distance on the picture above? Let me try something else:


Art piece without self portrait.

Or, maybe, this one. You are welcome to align a ruler to the floor tiles:




Underground passageway perspective.


I have not noticed a "quite active" Hasselblad representative in this forum.

You second and third examples are in the range of what I am talking about. They are not ideal for the purpose, however. Nevertheless, if you look at the bottom of the underground passage photo, you will see pincushion distortion, which also appears to a lesser degree at the extreme sides, whereas further away in the scene there does not appear to be any significant curvilinear distortion.

[jerome_m]

if you look at the bottom of the underground passage photo, you will see pincushion distortion, which also appears to a lesser degree at the extreme sides, whereas further away in the scene there does not appear to be any significant curvilinear distortion.

The illusion of pincushion distortion comes from the fact that the ground is not flat in that underground passage. It is designed this way so that water flows in the gutters left and right. If you look at the straight lines on the ceiling (which is flat), they look straight.

[torger]

The requirement of 100% distortion-freeness, a classic large format advantage, is becoming extinct. The only wider lenses that does it decently today is the SK Digitar wides, and they're not as popular as the Rodenstock Digaron-W wides which have a bit better sharpness but more distortion. The trend goes towards "large format digital" becoming as distorted as any other format, and you have to rely on raw converter lens corrections.

[David Eichler]

The illusion of pincushion distortion comes from the fact that the ground is not flat in that underground passage. It is designed this way so that water flows in the gutters left and right. If you look at the straight lines on the ceiling (which is flat), they look straight.

This is not a good example then. Also, the lines in the ceiling that you reference are not easy to see. And, by the way, thank you for not letting us know in advance that some lines which we might assume to be straight in real life are not. But, do you know that for a fact about the floor? It makes sense, but I see no gutters or drains along the sides for collecting water. In any case, I also pointed out some pincushion at the very edges of the sides. You are not saying those lines are curved in real life, are you?

Also, it would have been helpful if you had corrected the slight vertical convergence.

[jerome_m]

This is not a good example then. Also, the lines in the ceiling that you reference are not easy to see. And, by the way, thank you for not letting us know in advance that some lines which we might assume to be straight in real life are not.

Obviously, I did not remember that the floor was arched, or I would not have posted that particular picture. Sorry.

The lines on the ceiling can be seen on the original picture, which you can download in high resolution by clicking on it. On the second post, I drew a red line with Photoshop and it covers the original ceiling mark completely.

In any case, I also pointed out some pincushion at the very edges of the sides. You are not saying those lines are curved in real life, are you?

I drew a red line on the right hand side of the picture above. It appears to cover the seam between the tiles perfectly.

[Ken R]

I am hired to shoot a lot of Architecture projects.

I find that some of the most important things I need are extreme wide angle coverage (the 14mm L II lives on my 5D3 for most Arch projects although on occasions I use the 24mm TSE II) but be able to use longer and fast lenses for shallow dof shots, working speed (most times the client asks for a LOT of shots and I have very limited time available in the project), processing speed (most clients need the images finished right away, incredibly a simple thing like dust cleaning can really set me back but with the Canon 5D3 Canon has managed to keep the sensor incredibly clean with the sensor shake even after years of heavy use also stitching and image blending are mostly out of the question but I use them in a pinch sometimes) also good dynamic range is key. That is one area where the Canon lacks a bit but I have learned to expose the sensor to extract the most out of it and most times it is enough.

So even though I have a tech camera and a PhaseOne IQ160 I rarely if ever take it on those jobs even though the image quality is beyond comparison. The Phase has just so much more dynamic range and resolution it is unreal.

I though about using the IQ160 on a SLR system for those jobs (I have a H1) but neither the Hasselblad H system or the PhaseOne system have an SLR lens that has the angle of view comparable to a 14mm or 15mm lens on a 35mm DSLR. I would need to get the uber expensive and somewhat flare prone but awesome Rodenstock 23mm HR-W or one of the (also very expensive) FPS solutions that will allow the use of my 24mm TS-E with the back (might be wide enough).

but there is still the speed issue...

If I had the time to work then the Arca RM3di I have is just about the perfect camera for Architecture. Even with the 40mm HR-W I have I could stitch images to gain precious horizontal angle of view and more.

All that said, the HTS is a viable alternative although the 1.5x crop is somewhat of a dealbreaker for me at least.

[BAB]

+1
1.5x is the problem

[jerome_m]

It seems that many people want extra wide angles for architecture. I am not so sure about that: I find that the 24mm on the HTS already exaggerates the perspective too much when shifted, and the resulting focal length is only 36mm.

Also: I do not understand the advantage of tech cam on that specific point. The widest lens from Schneider Kreuznach is a 34mm, which is about the same focal length as what I get on the Hasselblad. Rodenstock has a 23mm and a 28mm Digaron lens, but they have reduced image circles and can only be shifted so much. Only the 32mm has an image circle large enough to be shifted decently.

Last but not least, I tried to compare the MTF between a few lenses. It is not easy, one must first find curves computed for the same l/mm values and aperture, and then scale them to the same image circles. Here is the result between the HCD28 + HTS combination (in red) and Schneider Kreuznach Apo-Digitar XL 43mm (in grey), both at f/11. Values are given for 20 l/mm and 40 l/mm.