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Author Topic: 645D - Are my expectations unreasonable? Near-edges very soft at infinity [imgs]  (Read 8375 times)
tho_mas
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« Reply #40 on: January 10, 2011, 12:17:13 PM »
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Do you think that they represent a "fair comparision"?
"fair" is always hard to define when you have to mix formats. Do you shoot the same horizontal dimensions? Or the same vertical? Or the same diagonal? And so on.
But I didn't look at the images in detail anyway... so I don't know.

Here's a comparision of a number of different cameras (645 + 35) that has been posted numerous times.
http://www.flickr.com/photos/dos-chin/sets/72157614936120567/
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ErikKaffehr
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« Reply #41 on: January 10, 2011, 12:46:20 PM »
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Hi,

Here are my impressions from that test: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/41-phase-one-images-for-download

In short I'd suggest it's a good comparison, except for outdoor portrait. I'd also would prefer a comparison with Nikon D3x instead of Canon 1DsIII and Nikon D700.

The reason I don't think the outdoor portrait is not a correct test is that a normal lens (50/1.Cool is used at full aperture, it's just not sharp. The idea is to have short DoF, but that is better achieved with a longer lens.

It's very clear that DR in P65+ is much better than 1DsIII, it has very clear shadow detail. I have done my owns raw processing using Capture One demo to convert sample files to DNG.

Best regards
Erik

Thank you. I will try to have look at those files. Do you think that they represent a "fair comparision"? (I note that the URL seems to be that of a MF camera manufacturer)

Of course, the image display chain can be a potential limitation. I am using a new, calibrated Dell 2711 27". I guess that others here will have better displays than myself, one reason why measurements are nice to have alongside real-world images.

-h
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ErikKaffehr
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« Reply #42 on: January 10, 2011, 01:06:22 PM »
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Hi,

I have an issue with tonality, because in my view tonality has everything to do with postprocessing and little with sensor. The sensor itself is a linear device, in essence, and just delivers a signal. Interpretation is done in postprocessing. So I cannot see how MF cameras can have better tonality. If they have better DR, that could be helpful in achieving better tonality.

I have downloaded the files and played around with them. In my view the P65+ was vastly superior to the Canon 1DsIII in DR. Both lenses had an incredible amount of lateral chroma, by the way, but that could be cleaned up in postprocessing.

My findings are here: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/41-phase-one-images-for-download

I have done a similar comparison on the Leica S2, using images from "Diglloyd":
http://echophoto.dnsalias.net/ekr/index.php/photoarticles/38-observations-on-leica-s2-raw-images
The emphasis in that article was on aliasing/Moiré. If found it pretty clear that the S2 was impressive in sharpness, but I actually found that the Nikon D3X was better in DR.

Finally I also run a comparison on the Pentax 645D. In this case I made actual prints and looked mainly at resolution. The Pentax was sharper than the D3X. The images I analysed were not appropriate for checking DR, but I guess that the Pentax is pretty impressive in the DR area.
http://echophoto.dnsalias.net/ekr/index.php/photoarticles/51-a-closer-look-at-pentax-645d-image-quality
Some unexpected Moiré was visible. I have seen some aliasing in most MF samples I looked at carefully, so lack of OLP-filtering comes with a price.

To sum it up: the samples I have seen deliver on promise regarding sharpness. I don't think that Leica S2 has better DR than Nikon D3X. Aliasing may be a problem at some times. It seems that stopping down to f/11 on 6 micron pitch sensors can eliminate most aliasing artifacts due to diffraction.

Best regards
Erik



Here are RAW-file comparisions (I think Canon 1DsIII / P65+ & D700 / P65+):
http://www.phaseone.com/de-DE/Downloads/Sample-images.aspx

You can play around with the files.
You need Capture One Pro to do so… there's a free 30day trial on the website.
Note that some images already contain settings (i.e. not "preset" settings; they are adjusted for certain purposes. There was an article these files refer to, hence the adjustments applied to the captures. But I don't know whether or not the article is still available somewhere... )
Also note that in terms of tonality a "comparision" of course is seriously limited by the quality, gamut and linearity of your monitor.




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tho_mas
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« Reply #43 on: January 10, 2011, 01:35:34 PM »
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It seems that stopping down to f/11 on 6 micron pitch sensors can eliminate most aliasing artifacts due to diffraction.
depends on the lenses. The 65+ bridge shot from that comparision is at f11 and shows moiré (at infinity). I've also seen other f11 shots from a P40+ / P65+ showing moiré. Both are 6µm sensors.
My P45 (6.8µm) shows moiré even at f16... depending on the lens.
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vduault
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« Reply #44 on: January 16, 2011, 09:56:31 AM »
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back to the 645D 55mm....

what does give your lens stopped down ?(the one you bought, not the brick wall tests found on the web)
are those soft edges still here at f/11 ?

can you show us an uncropped picture too ? because we don't have any idea about the size of your crop :/
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