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Author Topic: Another useless MF-D800 comparison ;)  (Read 9909 times)
ErikKaffehr
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« Reply #40 on: October 22, 2013, 01:49:43 PM »
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Hi,

Why would that be?

I would think Nikon uses contrast based AF in live view and that should be very similar to live view manual focus at actual pixels. Regarding Hasselblad I got the impression that AF is quite accurate. I only have a Hasselblad V, but I feel that manual focus is not exact, even when I use 3X monocular.

This image shows the line pairs my eyes resolve with VLF+loupe (red) , Hartblei 4X magnifying loupe (blue) , PM5 + 3X monocular (yellow). As you see, the sensor can separate 5 additional groups.

Best regards
Erik


That is theoretically impossible.
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EricV
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« Reply #41 on: October 22, 2013, 01:55:05 PM »
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It is a simple test and it shows two simple, unsurprising facts:
-that 50 mpix is more than 34 ....
I suspect it shows more that 50mm is a longer focal length than 35mm.
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BartvanderWolf
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« Reply #42 on: October 22, 2013, 02:01:00 PM »
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I suspect it shows more that 50mm is a longer focal length than 35mm.

The 43% additional magnification you'll get at infinity focus surely helps ...

Cheers,
Bart
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jerome_m
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« Reply #43 on: October 22, 2013, 02:44:04 PM »
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That is theoretically impossible.

You are probably thinking about live view, but I meant "manual focus on the ground glass". On the Hasselblad, the AF system is extremely accurate and picks differences that cannot be seen on the ground glass of the viewfinder. Manual focussing with live view tethered could be even more accurate, but live view is not really usable on the H3D. Besides, I cannot read the screen of a laptop outside in the light. And, in theory, I could probably focus manually and download the pictures for examination at 100%, etc... but this would be extremely slow, fraught with errors and difficult to do in the field because of the light, while the AF system of the Hasselblad will just pick the right focus about each time.

The Nikon supports live view, but the image is very pixelated and difficult to be seen in sunlight. But the contrast AF detect routine of the live view mode of the Nikon gives perfect results.
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Slobodan Blagojevic
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« Reply #44 on: October 22, 2013, 03:46:35 PM »
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... Why would that be?...

I had in mind that any auto focus system relies on certain tolerances, ie, the system considers it is sufficiently "in focus" when certain parameters are inside a certain range. In other words, if the subject distance is 10', then the system will stop focusing when it finds itself within +/- 10.x'

Manual focus with a live view and a 10x magnification, however, shall be more precise.
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Slobodan

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eronald
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« Reply #45 on: October 22, 2013, 04:11:10 PM »
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It is interesting that a confrontation with a Hasselblad conclusively demonstrates ... the rather mild shortcomings of a moderately priced Nikon 35mm system owned by a hundred thousand consumers.

Now the idea that someone might do the same test with an off the shelf Phase system (random, not cherry picked) - that is enough to make some dealer hairs turn grey, and put a smile back on Bernard's face Smiley

Edmund

« Last Edit: October 22, 2013, 04:21:12 PM by eronald » Logged
jerome_m
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« Reply #46 on: October 22, 2013, 04:26:50 PM »
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It is interesting that a confrontation with a Hasselblad conclusively demonstrates ... the rather mild shortcomings of the Nikon 35mm system owned by a hundred thousand consumers.

This is quite an amusing way of seeing things... but you are right. Indeed modern digital 135 cameras allows us to take pictures of a quality high enough to be enlarged to huge sizes (at least for landscape pictures). To show these differences, I had to resort to a complicated procedure which is the equivalent of devising a special scene where the smaller camera will fail and enlarging the results to wall size.
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ErikKaffehr
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« Reply #47 on: October 22, 2013, 04:45:56 PM »
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Hi,

I would believe that contrast sensing AF in LV maximizes image contrast. The same I do when focusing manually.

Lloyd Chambers usually complains about AF-precision in his reports, but he did not complain about the Hasselblad on focusing, he perhaps forgot to complain.

I would suggest that the precision of the focusing mechanism matters. I can see LV manual focus is not 100% accurate, but pretty close. Than there is of course the issue of focus shift

Best regards
Erik



I had in mind that any auto focus system relies on certain tolerances, ie, the system considers it is sufficiently "in focus" when certain parameters are inside a certain range. In other words, if the subject distance is 10', then the system will stop focusing when it finds itself within +/- 10.x'

Manual focus with a live view and a 10x magnification, however, shall be more precise.
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BernardLanguillier
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« Reply #48 on: October 22, 2013, 05:12:53 PM »
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This is likely correct, and it would be easy to test.  Focus manually on the corner(s).  Is the center then noticeably soft?  If field flatness is the problem, then a possible solution is focus stacking, as an alternative or addition to horizontal/vertical stitching.

Exactly.

Cheers,
Bernard
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eronald
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« Reply #49 on: October 22, 2013, 06:50:17 PM »
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This is quite an amusing way of seeing things... but you are right. Indeed modern digital 135 cameras allows us to take pictures of a quality high enough to be enlarged to huge sizes (at least for landscape pictures). To show these differences, I had to resort to a complicated procedure which is the equivalent of devising a special scene where the smaller camera will fail and enlarging the results to wall size.

I think its is a neat and simple test. Can't wait to see people use it on their "other" MF brands.

Edmund
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BernardLanguillier
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« Reply #50 on: October 22, 2013, 07:21:43 PM »
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I think its is a neat and simple test. Can't wait to see people use it on their "other" MF brands.

Edmund

I also cannot wait to see it applied to other focal lengths. I have a Zeiss 55mm f1.4 on order and would be more than happy to participate in a comparative test against the Hassy 80mm f2.8 that I used to own on my H1. Wink

As far as 35mm lenses, a retest with the Sigma 35mm f1.4 that seems to exhibit at lot less field curvature, while being twice cheaper, would seem fair. I'll fully support the test results then.

Besides, it would also be interesting to see to what extend DxO 8 can improve the performance of the DSLR lenses by applying automatically different levels of sharpening to different parts of the image depending on the local level of sharpness of the lens.

Cheers,
Bernard
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eronald
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« Reply #51 on: October 22, 2013, 07:41:21 PM »
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I agree - but at the moment a test against the other MF and Canon and Sony out-of-box would be interesting. The D800 does pretty well with a stock lens, but we all know what will happen to a more recent entrant Smiley

Edmund

I also cannot wait to see it applied to other focal lengths. I have a Zeiss 55mm f1.4 on order and would be more than happy to participate in a comparative test against the Hassy 80mm f2.8 that I used to own on my H1. Wink

As far as 35mm lenses, a retest with the Sigma 35mm f1.4 that seems to exhibit at lot less field curvature, while being twice cheaper, would seem fair. I'll fully support the test results then.

Besides, it would also be interesting to see to what extend DxO 8 can improve the performance of the DSLR lenses by applying automatically different levels of sharpening to different parts of the image depending on the local level of sharpness of the lens.

Cheers,
Bernard

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ErikKaffehr
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« Reply #52 on: October 23, 2013, 12:08:50 AM »
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Hi,

I agree with Jerome on this. I don't know how exact Hasselblad AF is, but I am pretty sure manual focus on ground glass is never exact. Reason is that I intended to adjust focusing screen using a peak 15X loupe by having camera at best focus position and adjust focusing screen for best sharpness, but it was absolutely sharp  even with 15X and also with 15X magnification on the split image.

Best regards
Erik
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jerome_m
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« Reply #53 on: October 23, 2013, 02:29:11 AM »
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I also cannot wait to see it applied to other focal lengths.

I might do that eventually, but the difference is bigger with short focal lengths, because these are harder to build. 50mm and above are close to perfection on the D800, when used at reasonable apertures.

There is also a problem with the test itself: it is not adapted to long focal lengths. With telephoto lenses, the atmospheric haze becomes a problem. I don't normally use this test above 100mm (in 35mm format).

I should also say that am not interested in trying every lens of the planet to find the best one for the D800. If I need a higher quality that what the standard Nikon lens can do, I have the Hasselblad. If I need even more than that, I have a panorama head.

Last but not least, I am also not interested to do tests on order, just to please random photographers on the Internet. I won't go and buy the Sigma 35mm or Zeiss 50mm from my own money just to please you, while I have zero interest for these lenses. When I do these lens tests, I do it primarily for myself, to see whether my lens work correctly and to see which one to choose for a particular use. I published the pictures on my flickr account primarily for me as well, because it is a convenient place to access them. Eventually, some people found about the pictures in forums and, just as in this thread, I go nothing but trouble for my work. People started complaining:
-that my test procedure was wrong
-that the comparison was hard to do (I present most pictures as they are shot and not conveniently rotated)
-that I should publish curves and figures instead
-that I should have tested a different lens, the one that they were interested in, etc...

There is nothing for me in exchange, even a thank you note is rare. I don't make money from advertisement and I am not interested in doing that. Whatever exposure I got did not translate into interest for my other pictures, on the contrary. In the beginning, I hoped that other people would feel motivated to do the same tests with lenses I did not own (I would have benefited from that), but even that did not happen.

So, if you are interested in Nikon lenses on the D800, you can check the pictures at:
http://www.flickr.com/photos/jerome_munich/collections/72157630303966522/ but do not expect me to make much more effort than that.
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marcmccalmont
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« Reply #54 on: October 23, 2013, 05:31:32 AM »
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Some RAWs for those who are interested
Base ISO, f6.3, focused on the middle (4th) building
IQ180/cambo WRS/Rodenstock 70HR
Nikon D800E/Leica 28-90 ASPH
Marc Smiley
https://dl.dropboxusercontent.com/u/82427039/CF002562.IIQ
https://dl.dropboxusercontent.com/u/82427039/DSC_1957.NEF
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Marc McCalmont
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« Reply #55 on: October 23, 2013, 05:36:47 AM »
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Last but not least, I am also not interested to do tests on order, just to please random photographers on the Internet. I won't go and buy the Sigma 35mm or Zeiss 50mm from my own money just to please you, while I have zero interest for these lenses.

No issues Jerome.

I am just pointing our the fact that your tests depicts a view of the D800's potential for landscape work that is, IMHO, undervaluing its potential based on a single data point. I would not have reacted had you simply described it as a test of the field curvature of the Nikon 35mm f1.4 and its poor value as a landscape lens. But you seemed to extrapolate this as a more generic assessment of the D800.

I understand that you have 2 systems you can pick from and that you are not really interested in finding out how good the D800 could be, and that is fine of course.

As far as the 35mm f1.4 goes, I would consider selling my Nikon and get the Sigma plus some cash if I were you, but what does a random photographer on internet know?  Wink

The following test does not speak about field curvature but shows the 2 lenses to be borderline excellent in the corners at their optimal aperture of f5.6 (very little difference of resolution compared to the center). They don't specify the distance of the test target, but it typically is a few meters away. So the hypothesis that field curvature at infinity may be the culprit is increasingly credible.

http://www.photozone.de/nikon_ff/792-sigma3514dgfx?start=1
http://www.photozone.de/nikon_ff/596-nikkorafs3514ff?start=2

How about the request made to try refocusing the Nikkor in the corners to see whether you can achieve higher levels of resolution? Are you not interested in that test? It seems important as it would validate the relevance of this test procedure in which you have invested a lot of time it seems.

Cheers,
Bernard
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jerome_m
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« Reply #56 on: October 23, 2013, 06:01:31 AM »
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Some RAWs for those who are interested
Base ISO, f6.3, focused on the middle (4th) building
IQ180/cambo WRS/Rodenstock 70HR
Nikon D800E/Leica 28-90 ASPH

Thank you for the pictures. It seems that your IQ180 and Rodenstock lens are working very well indeed.

On the Nikon picture, I find it a bit strange that the middle and right hand buildings are correctly focussed, the front elements also appear to be sharp, but the left hand buildings appear a bit fuzzy.
« Last Edit: October 23, 2013, 08:09:53 AM by jerome_m » Logged
eronald
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« Reply #57 on: October 23, 2013, 06:13:56 AM »
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Bernard -

 So the Nikon could do better? It could have a straighter lens mount?  Or a better aligned lens?  Well, the same goes for the Hassy. Oh, and are you sure that his D800 and Nikon lens are not usually what a customer gets when paying money?

 BTW, Jerome has done the Nikon a favor - it meets expectations, as far as I'm concerned. Reasonably priced, no major issues, decent results. Do you really expect a stock Mercedes sedan to outrun a stock Ferrari?

 I think Jerome's contribution is a useful test of system quality that can be employed by a working photographer in real world conditions. Let the guy be. He has contributed his methods and images, you are welcome to reproduce them.

Edmund



No issues Jerome.

I am just pointing our the fact that your tests depicts a view of the D800's potential for landscape work that is, IMHO, undervaluing its potential based on a single data point.

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jerome_m
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« Reply #58 on: October 23, 2013, 06:31:13 AM »
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I am just pointing our the fact that your tests depicts a view of the D800's potential for landscape work that is, IMHO, undervaluing its potential based on a single data point. I would not have reacted had you simply described it as a test of the field curvature of the Nikon 35mm f1.4 and its poor value as a landscape lens.

The tested Nikon lens indeed exhibits field curvature, I never said it does not. If you had taken the time to actually download the full, unrotated, resolution pictures taken with that lens you would have seen it. It is quite clear on these picture as one can actually follow the plane of focus in the front field.

You see: this is the problem with this discussion and the reason why I said that the comparison is useless to begin with. You are not interested to find out about optics or cameras. If you were, you would have found out, because the problem with field curvature is there to see, plain as day, in the actual pictures. But you have not noticed it, because you are not actually interested in finding out. You are only interested in proving to others that your particular camera of choice is "as good" as a MF and if a test does not give that particular result, you will demand that the test is redone under different conditions until it does. That is not the way to learn things.


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But you seemed to extrapolate this as a more generic assessment of the D800.

I am extrapolating this test and the whole collection of lens test I already did to a more generic assessment on all 24x36 wide-angle lenses, actually. I am not limiting myself to the D800. The problem we see with that 35mm lens is more general, you will not find a 35mm with this kind of homogeneity on 24x36 cameras.


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How about the request made to try refocusing the Nikkor in the corners to see whether you can achieve higher levels of resolution? Are you not interested in that test?

No, I am not interested in landscape pictures with sharp corners and out of focus center. Let me suggest something else: since you rave about the Sigma 35mm, what about you getting your D800 out in a field and taking the same kind of photos to show us how that particular lens works for landscape? It is a very simple test and anybody can do it.
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sailronin
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« Reply #59 on: October 23, 2013, 08:09:05 AM »
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the Nikon is soft through the entire image.
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Thank you for looking, comments and critiques are always welcome.
Dave

http://sailronin.smugmug.com
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