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The A7r versus MFDB

Bill Caulfeild-Browne

Well-known member
Ever since I got the A7r five months ago, I've been wondering how well its files would print compared to my Phase DF and IQ180 back. Today, being a bit bored with our poor weather, I decided to find out.



I mounted the FE 55 mm f1.8 on the Sony and exposed at f8, ISO 200.
The Phase was equipped with SK 80 mm LS lens also set at f8 and ISO 200. Although both cameras were Gitzo-and-Cube mounted I felt the higher ISO was needed because it was a bit breezy and I wanted to freeze the trees.

As you can see, the horizontal field of view is almost identical with the 80 mm SK lens providing a slightly wider field of view. Exposure was "the right" as light as possible without losing the detail of the white lighthouse. Both files were processed in C1 at defaults; no additional sharpening was performed.

Because most of the prints I sell are around 30-50 inches wide I decided (arbitrarily) to print to 36 inches at 300 dpi on a 16 inch roll, cropping the pics to 7 inches high. As most of the rest of the frames were sky or water there didn't seem much point in printing those bits too.

I printed on a Canon Image Prograf at 16 bits on Epson Premium Luster.

Here's what I see in the prints.

1. To my surprise, given the DXO scores, the MFDB file has clearly greater dynamic range - I think one can see this even in the jpeg above.

2. There is better detail and micro contrast in the MF file - but the difference is not huge. The Sony files hold up extremely well.

3. The MF file is more accurate as respects colour.

4. A 36 inch print isn't far off the native size of the Sony file but as size increases the MF will surpass it. I made several prints from a 50% crop and MF was clearly ahead as one would expect.

My conclusion is that up to 36 inches, the Sony file is just about as good as the MF for resolution. Beyond that, no contest!

Just some fun !
 

Quentin_Bargate

Well-known member
Bill,

Of course, the question is how many people print bigger than 36" wide? Thats roughly the max width of a print on an Epson 7900 printer. As a Hassy owner I'm glad MF wins out, but the A7r is more versatile day to day. With a future 50mp A8r or whatever, I can see little purpose to MF in many outdoor situations unless tilt / shift is needed.

Interesting.
 

Don Libby

Well-known member
Good question Quentin, I'd say 50% of my prints are in the 30x40 range while the other 50% are 40x50, 30x60 or larger panos. A lot depends on the subject matter.
 

tashley

Subscriber Member
Tests I did a while back with the D800 versus IQ 180 suggested strongly to me that the smaller sensor had better DR but that it was distributed differently and required different curves in post to bring it out, and usually a different exposure too...
 

dwood

Well-known member
The fact that a D800, D800E, or A7R with good glass and good technique 'gets there' on large prints (or very close) when compared to late model MFD, is really quite something, isn't it? Given the cavernous price delta between these systems, I would expect the MFD rig to maybe make me dinner once in a while. :D
 

Bill Caulfeild-Browne

Well-known member
I should remind you all that the FE 55mm I used in the test is one of the sharpest available in this format.

I have found making large prints with the FE 24-70 OSS is more problematic. This shot (which I have shown here before) begins to fall apart at 36 inches!

 

iiiNelson

Well-known member
Even at such a small size you can see a high difference in detail. It would be nice to see how the A7r compares to the 40MP backs as the resolution is a bit closer. I'm sure the MF would still win but wonder by how much.
 

philip_pj

New member
Bill, I'd be interested in your comments on the accuracy of reported ISO levels on the DxO website, which indicate huge overstatement by P1 at ISO 200; and everywhere else for that matter:

Sony A7R versus Phase One IQ180 Digital Back - Side by side camera comparison - DxOMark

I know less than nothing about MFD - in the DxO chart, the a7r at measured ISO73 (claimed ISO100) gives a DR of 14.07 stops; the P1 at measured ISO60 (claimed ISO200) gives a DR figure of 12.55 stops.

At the same aperture, the s/speeds or histograms might tell you a story, as Sony's ISO200 is actual 148, very different to P1's 60. Or else DxO's data are suspect, of course. Come what may, I keep advising users to use the lowest ISO they can on the a7r (or any Sony FF), you pick up a stop going from 200 to 100, and get a 'denser' looking file, very robust too.

Either way, we can very likely agree the a7r sensor has huge reserves of DR, and on the other measures it matches or beats the back at higher than ISO100, both being very linear. It also has fine shadow recovery if you wish to expose more normally to retain more of the highlight tone range, and lift shadows a little. I like the topmost of these images, but I 'see blue' due to decades in the back country in low light.

It's a fine little camera, and a very fine 55mm lens - if they can produce just a few more as good, FE is likely to have a very rosy future. Thanks so much for posting!
 
M

mjr

Guest
Bill

Great that you are able to use both side by side, exciting times for all photographers, the equipment is so good at both ends of the scale, shame I don't get help with what I point it at!

I have a question regarding your process and I guess for all you guys who test this stuff. I often see statements like "Both files were processed in C1 at defaults; no additional sharpening was performed" and "straight from the camera" or whatever, is there a reason for that? I ask because to my mind, the camera technology has improved greatly but it's nothing without proper processing and by not working to optimise a shot in post then all you're really showing is C1's or Lightrooms default processing of a RAW file. Having done a lot of experimenting with my own images, I have found that the biggest change in my own work has been switching to C1, it blows me away but not necessarily when I open the file.

I could be wrong but to my mind, modern software gives you the tools but doesn't necessarily do the job for you, just opening the file and printing it seems like such a waste.

Why don't people testing stuff just process the file to it's full potential? I want to see what the A7r and 180 can really do side by side, I want to see the finished image and see what the differences are on a shot you'd be happy to sell. As it is, what's being shown is simply the processors interpretation of the file with no input from the shooter. In these shots Bill, is the difference with proper curves, sharpening and processing bigger or smaller between the 2 files, it would seem more relevant?

I may be missing the point with these tests and I'm sorry if that's the case, I get frustrated when I see posts that proudly show a file straight from the camera, surely having spent huge amounts of money on a camera people would want to process it properly? Why do people show a finished shot and then show what they call "the RAW file unprocessed" it just seems so irrelevant, it's data and all they are showing is their processing softwares starting point.

That sounds like a rant, not meant to be honestly, just a question about how people test!

Mat
 

Georg Baumann

Subscriber Member
Thanks for that Bill.

As for the economic side of things, the IQ180 alone leaves a 45K hole in your account if I am not mistaken, gaining what percentage in return in image quality?

I think you answered this from a quite practical point of view here. As for the larger print requirements, Chiek's technical A7R adaptation would be one possible answer.

The next iteration of the A7R might close that already small gap even further, I would not be astonished.
 

Ben Rubinstein

Active member
I was thinking the same at Mat. The colour profile for the A7r in C1 is IMO awful and the sharpening, as with every camera, needs to be carefully controlled. The curve provided by C1 as standard for either camera can hardly be assumed to be the last word as to the DR of the camera. The test is useful but not using C1 defaults as a baseline.
 

Bill Caulfeild-Browne

Well-known member
Y'all make good points! My original goal was to do a quick & dirty comparison with as little human intervention as possible - but of course the results are heavily influenced by the raw converter. For example, the shadows in the Sony file could have been easily lifted to make it resemble the MF file more closely.

I'm going to do a further comparison where I'll expose at the best ISO for each camera, the optimum aperture for each lens and then process each the best way I know how!

Interesting though, that when my wife happened to glance at the prints I made yesterday, she exclaimed "Isn't that one so much clearer!". She was looking at the MF print.

Stay tuned.
 

Bill Caulfeild-Browne

Well-known member
OK, so here's another approach! A rather dull misty day but very little wind to move the trees around. I set up the cameras with their optimum ISOs and apertures. I exposed so the lighthouse was on the verge of clipping.

Note that my qualitative comments are from poring over the prints, not the screen.

A7r with FE 55, at F 5.6, ISO 100.
IQ180 with SK 80 LS at F8, ISO 35.

In both cases I used C1 to wring the most out of the files (bringing up shadow detail primarily.) I corrected for purple fringing and aberrations though the SK lens was automatically adjusted in C1. I sharpened for inkjet printing. I think the files were about as good resolution-wise as I could make them.

The 36 inch prints, like yesterday, were hard to tell apart and I haven't shown them again. The DR is excellent in both cases, holding all the detail in the lighthouse and in the dark areas under the trees. The Phase file is superior with a loupe but at normal viewing distance there's little discernible difference.

I then printed a crop of roughly half the frame, which would be the equivalent of a 60 inch print.



This time there is no contest. The Phase file is crisp and clean and the sign on the left side is easily legible, whereas it cannot be read in the Sony file. The sky has a subtle gradation not present in the Sony file. The bare trees and the communication mast are a bit fuzzy in the Sony print but crystal clear in the Phase print.

My conclusion is the same as yesterday - up to 36 inches, with the FE 55 lens, the Sony holds it's own. For the bigger print, let's just say I'm not giving up my MFDB!
 
M

mjr

Guest
Morning Bill

Sorry if I sounded a little short in my post yesterday, maybe I just don't understand the whole approach to testing but to my mind, this is so much more valuable as a guide to what can be produced by the different equipment.

In the real world we'd only ever shoot at optimum aperture for the scene and equipment and we'd process the file to our taste, testing by not doing that in an effort to get a standard shot to compare against just doesn't make any sense to me.

In this case, even on these small jpegs you posted it's clear there's a difference, it's great to know that printed up to 36" there is little in it and for those not printing larger than that then if final print is the main consideration it's clear that MF is not the only option, great for all of us who don't have the cash for these higher mp backs.

Thanks for going to the effort!

Mat
 

Georg Baumann

Subscriber Member
The sky has a subtle gradation not present in the Sony file.
Perhaps I am wrong, I would explain this with the higher bit depth of the Phase files, as a result there is a smoother color graduation.

With 14 bit you get 16,383 tones per channel per pixel, and with 16 bit a significant higher count of 65,532.
 

douglasf13

New member
Perhaps I am wrong, I would explain this with the higher bit depth of the Phase files, as a result there is a smoother color graduation.

With 14 bit you get 16,383 tones per channel per pixel, and with 16 bit a significant higher count of 65,532.

I'm not so sure, because the 16bits in MFDB is pretty much a marketing thing: Digital Medium Format / 35mm equiv difference - FM Forums

That being said, the A7R's raw files are compressed, and that could be the difference. They are essentially what the "cRAW" option used to be on the A900.
 
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