What does this one image say about color rendering, tonality, skin tones, transition to background etc. Just one image at one distance at one focal length in one sort of light. I dont believe its that easy.
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Is there a compelling reason to move to MF?
- Thread starter Abstraction
- Start date
kdphotography
Well-known member
Dog.
Give me a minute, I need to find my graphs and charts on the type of dog best suited....
Can't remember at the moment---Kodak DCS Proback 645M or Phase P30....
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M
mjr
Guest
I have a Gordon Setter pup, he's pretty cool, I can post a crop of his eye if anyone needs proof?
Mat
Mat
jerome_m
Member
What I meant is: the image is a best case scenario. Not too much problems with colors, transitions, rendering, etc... Optimum aperture and standard focal length. Yet, the sides are fuzzy on the 24x36. To my eyes, the fuzziness is pretty obvious.
ErikKaffehr
Well-known member
Hi Paul,
Yes, and that is quiet interesting. I guess that this is a lens Tim Ashley would call tricky.
What I see is that:
Now, we can go back and look at the MTF curves I would be pretty sure that we see some field curvature. The full aperture figure would indicate that, and we see some astigmatism (tangential and sagittal curves differ):
The corner here is in the foreground and it may be that field curvature works to our advantage. If that would be the case, we could look at a bottom. That should have a focus point more backward on the Distagon so the Canon would be sharper. Distagon left, Canon right. What I seen is that the Canon lens is better in this position. So, observations confirm deduction.
What I feel I can learn from this? One thing is that the MTF data tells a lot about the lens. For instance, for me the MTF curves of the Distagon seem to indicate field curvature and the simple test we did above indicate this is the case.
The other point is that some lenses are tricky. They can deliver very good image quality at a point of the image and deliver disappointing quality in another part.
Regarding field curvature, Tim Ashley published an article cowritten with Rogera Cicala of Lensrentals here: Tim Ashley Photography | Field Curvature - a Layman's Guide (or How to Focus a 'Tricky' Lens)
Roger found later that field curvature and astigmatism varies quiet wildly when stopping down: https://www.lensrentals.com/blog/2014/09/field-curvature-and-stopping-down/
Tim Ashley has some very nice demo of that issue here: Tim Ashley Photography | Leica M 240 with 35mm F1.4 FLE - some observations
I can see that artist don't like curves and measured data, but engineers like me can actually learn a lot from curves and make good use of what we have learned, so we can save money on stuff to buy and spend on picture taking opportunities. (I could have made something like a half dozen trips to Yellowstone if I did not buy that Hasselblad / P45+ combo. Curiosity has it's price.)
Some folks, like our friend Paul seems to sit on both sides of the fence. A great artist but also looks at things measurable and makes an educated choice…
Best regards
Erik
Yes, and that is quiet interesting. I guess that this is a lens Tim Ashley would call tricky.
What I see is that:
- The first row (centre) is pretty similar
- The second row (close to right edge) the Canon image is clearly better
- The third row (near corner) the two are close again
- The fourth row (corner) the Distagon is clearly better
Now, we can go back and look at the MTF curves I would be pretty sure that we see some field curvature. The full aperture figure would indicate that, and we see some astigmatism (tangential and sagittal curves differ):
The corner here is in the foreground and it may be that field curvature works to our advantage. If that would be the case, we could look at a bottom. That should have a focus point more backward on the Distagon so the Canon would be sharper. Distagon left, Canon right. What I seen is that the Canon lens is better in this position. So, observations confirm deduction.
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What I feel I can learn from this? One thing is that the MTF data tells a lot about the lens. For instance, for me the MTF curves of the Distagon seem to indicate field curvature and the simple test we did above indicate this is the case.
The other point is that some lenses are tricky. They can deliver very good image quality at a point of the image and deliver disappointing quality in another part.
Regarding field curvature, Tim Ashley published an article cowritten with Rogera Cicala of Lensrentals here: Tim Ashley Photography | Field Curvature - a Layman's Guide (or How to Focus a 'Tricky' Lens)
Roger found later that field curvature and astigmatism varies quiet wildly when stopping down: https://www.lensrentals.com/blog/2014/09/field-curvature-and-stopping-down/
Tim Ashley has some very nice demo of that issue here: Tim Ashley Photography | Leica M 240 with 35mm F1.4 FLE - some observations
I can see that artist don't like curves and measured data, but engineers like me can actually learn a lot from curves and make good use of what we have learned, so we can save money on stuff to buy and spend on picture taking opportunities. (I could have made something like a half dozen trips to Yellowstone if I did not buy that Hasselblad / P45+ combo. Curiosity has it's price.)
Some folks, like our friend Paul seems to sit on both sides of the fence. A great artist but also looks at things measurable and makes an educated choice…
Best regards
Erik
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ErikKaffehr
Well-known member
Re: Corner drop off
Hi Jerome,
I would love to agree with you, but I can't.
Why I can't? One reason is that our vendors don't give us data for high frequencies. Hasselblad, Zeiss and Leica all use the frequencies 10/20/40 lp/mm. Rodenstock and Schneider have some MTF data at 15/30/60 lp/mm. That may be a bit better than the usual 10/20/40 lp/mm but is not even close to the 97 lp/mm the IQ-180 has, just as an example.
More importantly, it is long established knowledge that low frequencies dominate human vision. So low frequency MTF is far more important than high frequency MTF. Also high MTF at resolution limit is not really desirable as it causes aliasing artefacts. Common knowledge…, would you find my remark ignorant, here is a source: https://en.wikipedia.org/wiki/Aliasing
Here is a paper by Zeiss on interpreting MTF curves, a lot of good wisdom: https://www.zeiss.com/content/dam/Photography/new/pdf/en/cln_archiv/cln30_en_web_special_mtf_01.pdf
Perceived quality can be measured by SQF, a value based on integrating the MTF over the contrast sensitivity curve of human vision. You find a good discussion of the concept around page 7 in this document from Zeiss: http://www.zeiss.com/content/dam/Photography/new/pdf/en/cln_archiv/cln31_en_web_special_mtf_02.pdf
Now, that I have suggested some litterature for insights, here is the real reason I would not agree with your point:
In real world, we either see images as prints or on screen at small resolution. In neither case can we really see pixel level detail. In print, the fine detail is normally at a size where the CSF (Contrast Sensitivity Function) of human vision is low. On screen size images most of the detail is thrown away anyway.
If you make a very large print and view very close, we would be able to see high frequency detail. Lens MTF data doesn't say much about that region, that applies to lenses from Hasselblad, Leica and Zeiss. Schneider and Rodenstock gives a lot more data.
You can measure MTF using Imatest. I do it often, but not in the corners. Why I don't do that? Because it needs a very large target. Ideally something like 50x focal length is needed, but also because I am not so terribly interested in corners.
In the case I have shown, the Zeiss Distagon performs better in the extreme corners but the Canon performs better at the edges and just a bit in from the corners. Most of the older Zeiss designs drop of significantly at the last few millimetres of the diagonal. The newer lenses are designed for a larger image circle, it seems.
Best regards
Erik
Hi Jerome,
I would love to agree with you, but I can't.
Why I can't? One reason is that our vendors don't give us data for high frequencies. Hasselblad, Zeiss and Leica all use the frequencies 10/20/40 lp/mm. Rodenstock and Schneider have some MTF data at 15/30/60 lp/mm. That may be a bit better than the usual 10/20/40 lp/mm but is not even close to the 97 lp/mm the IQ-180 has, just as an example.
More importantly, it is long established knowledge that low frequencies dominate human vision. So low frequency MTF is far more important than high frequency MTF. Also high MTF at resolution limit is not really desirable as it causes aliasing artefacts. Common knowledge…, would you find my remark ignorant, here is a source: https://en.wikipedia.org/wiki/Aliasing
Here is a paper by Zeiss on interpreting MTF curves, a lot of good wisdom: https://www.zeiss.com/content/dam/Photography/new/pdf/en/cln_archiv/cln30_en_web_special_mtf_01.pdf
Perceived quality can be measured by SQF, a value based on integrating the MTF over the contrast sensitivity curve of human vision. You find a good discussion of the concept around page 7 in this document from Zeiss: http://www.zeiss.com/content/dam/Photography/new/pdf/en/cln_archiv/cln31_en_web_special_mtf_02.pdf
Now, that I have suggested some litterature for insights, here is the real reason I would not agree with your point:
In real world, we either see images as prints or on screen at small resolution. In neither case can we really see pixel level detail. In print, the fine detail is normally at a size where the CSF (Contrast Sensitivity Function) of human vision is low. On screen size images most of the detail is thrown away anyway.
If you make a very large print and view very close, we would be able to see high frequency detail. Lens MTF data doesn't say much about that region, that applies to lenses from Hasselblad, Leica and Zeiss. Schneider and Rodenstock gives a lot more data.
You can measure MTF using Imatest. I do it often, but not in the corners. Why I don't do that? Because it needs a very large target. Ideally something like 50x focal length is needed, but also because I am not so terribly interested in corners.
In the case I have shown, the Zeiss Distagon performs better in the extreme corners but the Canon performs better at the edges and just a bit in from the corners. Most of the older Zeiss designs drop of significantly at the last few millimetres of the diagonal. The newer lenses are designed for a larger image circle, it seems.
Best regards
Erik
Were the other images any less real?
Not only in the corner. The 2/3 zone is critical, especially for wide-angle and zoom lenses.
But you are still using MTF curves with values of 10, 20 and 40 cycles/mm, which would be adequate for 12 Mpixels sensors. For the A7RII, we would need curves at 100 cycles/mm, wouldn't we?
- - - Updated - - -
Your wish is my command:
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jerome_m
Member
Re: Corner drop off
If you are not interested in large prints, there is no need to examine crops of raw files at the pixel level, which amounts to looking at details from a huge print with a magnifier.
Indeed, if all one wants is to see the pictures on screen, the resolution of a MF camera is not needed.
Large prints is what I have always been talking about. On large prints, the difference in camera resolution becomes obvious. On large prints, lens defects become obvious.
If you are not interested in large prints, there is no need to examine crops of raw files at the pixel level, which amounts to looking at details from a huge print with a magnifier.
M
mjr
Guest
I take it you aren't suggesting that people who aren't interested in measurable data don't make intelligent choices Erik, that would be absurd.
As someone who has no interest in charts at all, I see them as having no bearing on my purchases or use of equipment because they tell me nothing that using a lens doesn't, nothing at all. I can use a lens how I want to use it or see how someone else has used it in vaguely similar circumstances and learn everything I want to know. You need to look at a chart, take some shots and come to the conclusion that the chart is correct, what's the point?
Mat
ErikKaffehr
Well-known member
Hi,
Yes, that is a good point.
From what I have seen shooting with the Hasselblad for two and a half year is that those advantages don't apply for me. A good indication may be that only one MFD image made it to the wall but quite a few with the older Sonys. But, this is an area were mileage may vary.
Making that experience needs some prolonged shooting. I really enjoyed shooting with Hasselblad, but I don't think it will see much use in the coming time.
Best regards
Erik
Yes, that is a good point.
From what I have seen shooting with the Hasselblad for two and a half year is that those advantages don't apply for me. A good indication may be that only one MFD image made it to the wall but quite a few with the older Sonys. But, this is an area were mileage may vary.
Making that experience needs some prolonged shooting. I really enjoyed shooting with Hasselblad, but I don't think it will see much use in the coming time.
Best regards
Erik
ErikKaffehr
Well-known member
Hi,
That is what I have written:
"I can see that artist don't like curves and measured data, but engineers like me can actually learn a lot from curves and make good use of what we have learned, so we can save money on stuff to buy and spend on picture taking opportunities. (I could have made something like a half dozen trips to Yellowstone if I did not buy that Hasselblad / P45+ combo. Curiosity has it's price.)
Some folks, like our friend Paul seems to sit on both sides of the fence. A great artist but also looks at things measurable and makes an intelligent choice…"
I am saying that a great artist, whom I was responding to, looks at things measurable and makes an intelligent choice. I don't think it implies that other photographers don't make intelligent choices. That interpretation is indeed possible, but it is not the intended one.
I am not a professional photographer. What finances my work is analysing and solving technical problems, so for me it is quite natural to use curves and measurable data. Not everything is measurable, of course, but data is certainly helpful in making decision.
Just as an example, Paul often shoots in windy conditions and he sometimes needs relative fast shutter times for his subjects needing good high ISO capability, so he wants a CMOS based back. But, he is also aware that CMOS backs don't play that well with certain lenses, due to lens cast and cross talk.
So, Paul checks on all discussions regarding lens selections and shift limitations, after which he can make an educated choice. OK, I should have used the word educated instead of intelligent…
Thanks for making the point!
Best regards
Erik
That is what I have written:
"I can see that artist don't like curves and measured data, but engineers like me can actually learn a lot from curves and make good use of what we have learned, so we can save money on stuff to buy and spend on picture taking opportunities. (I could have made something like a half dozen trips to Yellowstone if I did not buy that Hasselblad / P45+ combo. Curiosity has it's price.)
Some folks, like our friend Paul seems to sit on both sides of the fence. A great artist but also looks at things measurable and makes an intelligent choice…"
I am saying that a great artist, whom I was responding to, looks at things measurable and makes an intelligent choice. I don't think it implies that other photographers don't make intelligent choices. That interpretation is indeed possible, but it is not the intended one.
I am not a professional photographer. What finances my work is analysing and solving technical problems, so for me it is quite natural to use curves and measurable data. Not everything is measurable, of course, but data is certainly helpful in making decision.
Just as an example, Paul often shoots in windy conditions and he sometimes needs relative fast shutter times for his subjects needing good high ISO capability, so he wants a CMOS based back. But, he is also aware that CMOS backs don't play that well with certain lenses, due to lens cast and cross talk.
So, Paul checks on all discussions regarding lens selections and shift limitations, after which he can make an educated choice. OK, I should have used the word educated instead of intelligent…
Thanks for making the point!
Best regards
Erik
M
mjr
Guest
Erik, we are polar opposites when it comes to photography, probably everything else too! I learn something from almost everyone who posts on here, even if its how not to do something, but I find your posts actually depress me, as someone who has a huge amount of passion for what I do for a living and for pleasure, I take absolutely nothing from what you post. Now obviously I don't expect that to have any bearing on you at all, why would it, but I will do us both a favour and not respond or read them anymore and make use of the ignore function, seems crazy to actually do that but it's definitely for the best.
Good luck with the Sony, I hope you enjoy it.
Mat
Good luck with the Sony, I hope you enjoy it.
Mat
Abstraction
Well-known member
It's either you see a compelling difference or you don't. I don't see a MAJOR difference. All things being equal, I'd say yes, but there's the 400lb gorilla in the room - cost.
Yeah, I agree. I don't need a MF camera. The differences are too subtle to justify the price. I just can't see myself plopping down that kind of money on corner sharpness that you need to inspect with a fine tooth comb to see. I'm not saying it's not there and I'm not saying that all else being equal, I wouldn't get MF myself, but not for that kind of money.
Your arguments absolutely make sense and I agree with you, but it's that pesky cash that just ruins everything. I couldn't possibly justify the price difference to myself. There are too many other things that I could do with that money that would make my life better than MF, even a Pentax 645z, which is pretty affordable by MF standards is unjustifiable in terms of price vs gain. What I see are the marginal differences that just aren't worth it to me.
Jon Warwick
Member
After the many pages that I've followed here - and don't get me wrong, i think they've been informative and i really appreciated them - i don't think the conclusion is any different to anything we didn't probably already know.
i.e., tight crops tell one virtually nothing.
If I compare a 350mb drum scan from my Mamiya 7 and and the same size scan from 4x5 (same film too, i.e., Acros 100), and do tight crops of the two and peer at them on a computer .... guess what, the detail (i.e., "resolution") looks really, really similar.
But print them out to 50x40", and the 4x5" is far superior to the medium format film in terms of "look", i.e., tonal transitions, 3D'ness etc.
Similarly, when i compare a 50x33" print between a Leica S and a 35mm FF ..... guess what, i see the difference in tonal transitions, smoothness, 3D'ness etc, all to the advantage of the Leica S .... and so do complete guinea pigs that I've used too that have no interest in photography.
Just to be be clear, these are prints done at 300dpi on an Epson 11880 at arguably London's highest end print shop.
Resolution is one thing on SCREEN, but the "look" and "dimensionality" of what i'm looking at in a PRINTS is quite another.
One thing I don't disagree with is the idea that pixel size is important .... I kind of assume that Leica with low 38MP cameras of S2 / S 006 / 007 is -- in reality -- looking to achieve a good balance between resolution AND acuity / tonality / SNR / less probs with diffraction / less "stressing" of lenses (even though the S lenses are probably some of the best lenses in MF ever made) ...... what does that achieve?? It achieves a very unprocessed, smooth, and "natural" look.
i.e., tight crops tell one virtually nothing.
If I compare a 350mb drum scan from my Mamiya 7 and and the same size scan from 4x5 (same film too, i.e., Acros 100), and do tight crops of the two and peer at them on a computer .... guess what, the detail (i.e., "resolution") looks really, really similar.
But print them out to 50x40", and the 4x5" is far superior to the medium format film in terms of "look", i.e., tonal transitions, 3D'ness etc.
Similarly, when i compare a 50x33" print between a Leica S and a 35mm FF ..... guess what, i see the difference in tonal transitions, smoothness, 3D'ness etc, all to the advantage of the Leica S .... and so do complete guinea pigs that I've used too that have no interest in photography.
Just to be be clear, these are prints done at 300dpi on an Epson 11880 at arguably London's highest end print shop.
Resolution is one thing on SCREEN, but the "look" and "dimensionality" of what i'm looking at in a PRINTS is quite another.
One thing I don't disagree with is the idea that pixel size is important .... I kind of assume that Leica with low 38MP cameras of S2 / S 006 / 007 is -- in reality -- looking to achieve a good balance between resolution AND acuity / tonality / SNR / less probs with diffraction / less "stressing" of lenses (even though the S lenses are probably some of the best lenses in MF ever made) ...... what does that achieve?? It achieves a very unprocessed, smooth, and "natural" look.
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GrahamWelland
Subscriber & Workshop Member
Jon,
I agree with you but I fear you're just barking at the moon in this thread. I was told that if someone said that they shot medium format digital just because they can, that this thread would end.
Well, I did. It didn't ... :banghead:
I agree with you but I fear you're just barking at the moon in this thread. I was told that if someone said that they shot medium format digital just because they can, that this thread would end.
Well, I did. It didn't ... :banghead:
stephengilbert
Active member
These things rarely end well:
MFD is like a joke … if you have to explain it … well … 
If one cannot afford MFD, or would prefer to spend their money on something else, then it is natural to select something else. What is nice these days is that there IS something else.
Even though I'm a die-in-the-wool advocate, I've talked more people out of MFD than into it.
To each their own.
- Marc
If one cannot afford MFD, or would prefer to spend their money on something else, then it is natural to select something else. What is nice these days is that there IS something else.
Even though I'm a die-in-the-wool advocate, I've talked more people out of MFD than into it.
To each their own.
- Marc
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Landscapelover
Senior Subscriber Member
I am an amateur but a passionate landscape photographer, therefore, cost-effective doesn't apply much to me. I try to get the best I can afford.
I posted a lot but >90% of my posts were pictures I took. Whatever Graham, Mat (mjr), fotografz and few others said, I believe them even the comments were not based on scientific supports. I believe them because they've always made great photographs.
I know I've always lost money for photographic equipments, MFD is much worse than Nikon or Canon and I accept it. I wish I would be satisfied with only Nikon, Canon or Sony. I hope that day will come so I can save a lot of money.
There are a lot of photographers who uses only 35mm DSLRs and make outstanding photographs and I truly admire them. FM Forums is my favorite.
My reasons for MFD are simple.
- I can afford.
- It gives me more pleasure. Comparing with cars is quite reasonable. You don't need Mercedes Benz. It's luxurious and you pay for it.
- Print! Print! Print! It definitely gives me a better image quality, not from 30" display but from large prints. No matter what the comparison of images on the net is. To me, a notation of "35mm DSLR giving the same IQ as IQ180" is BS.
I haven't read GETDPI as much nowadays. There are a lot of people who do not passionate in MFD but you see them all over medium-format forums, both at GetDPI and LUL. I just don't get it.
It's time to get a routine, having a cup of Starbuck before heading to a sunrise destination.
Have a great weekend!
Best regards
Pramote
Zenfolio | Pramote Laoprasert Photography
I posted a lot but >90% of my posts were pictures I took. Whatever Graham, Mat (mjr), fotografz and few others said, I believe them even the comments were not based on scientific supports. I believe them because they've always made great photographs.
I know I've always lost money for photographic equipments, MFD is much worse than Nikon or Canon and I accept it. I wish I would be satisfied with only Nikon, Canon or Sony. I hope that day will come so I can save a lot of money.
There are a lot of photographers who uses only 35mm DSLRs and make outstanding photographs and I truly admire them. FM Forums is my favorite.
My reasons for MFD are simple.
- I can afford.
- It gives me more pleasure. Comparing with cars is quite reasonable. You don't need Mercedes Benz. It's luxurious and you pay for it.
- Print! Print! Print! It definitely gives me a better image quality, not from 30" display but from large prints. No matter what the comparison of images on the net is. To me, a notation of "35mm DSLR giving the same IQ as IQ180" is BS.
I haven't read GETDPI as much nowadays. There are a lot of people who do not passionate in MFD but you see them all over medium-format forums, both at GetDPI and LUL. I just don't get it.
It's time to get a routine, having a cup of Starbuck before heading to a sunrise destination.
Have a great weekend!
Best regards
Pramote
Zenfolio | Pramote Laoprasert Photography
Amen!
jerome_m
Member
Just to be clear: I've always said that large prints is where the difference is obvious. I just cited imaging-resource crops because it actually amused me that a site devoted to picturing test charts and brick walls would actually show a difference, yet the people who are interested by pictures of test charts and brick walls ignored it.
You might not see a compelling reason in each and every image/light/subject, but in many you will (at least I do).