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Author Topic: Interesting comparison of IQ180 and 8x10" film  (Read 31784 times)
ErikKaffehr
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« on: September 22, 2011, 12:17:24 PM »
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Hi,

I did find the comparison interesting. My understanding is that the IQ180 is better than 8x10". I'd expect the difference to be smaller.

One observation is that the IQ180 images were made at f/11 and f/16. I would expect MF digital to work best at f/5.6 or f/8. Don't know about large format film, is it necessary to stop down to f/32?

Conventional wisdom used to be that 20+ full frame is comparable to 67 analog, and MF digital to 4x5", so I'm somewhat surprised that latest generation MFDBs can match and surpass 8x10" on film. On the other hand this was exactly what Michael stated in his initial preview of the new MF backs.

Best regards
Erik
« Last Edit: September 22, 2011, 07:13:04 PM by ErikKaffehr » Logged

Jack Flesher
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« Reply #1 on: September 22, 2011, 01:07:57 PM »
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The real issue is getting a "perfect" capture on 8x10 film since so much can prevent it.  For example, film flatness alone is difficult in a traditional holder. Traditionalists using LF for critical capture used a spray mount to hold the film, or even vacuum backs if hyper critical. By contrast, the digital sensor is dead flat.  Next issue is focus accuracy on the GG, and GG alignment with every holder's film plane, and holders are not all that exact. 

A comment on focus accuracy: when I got my Betterlight scanning back, I thought I was an outstanding GG focuser. I used a 10x loupe and usually nailed my film shots. The Betterlight had a real-time electronic focus mode that actually measured each color channel separately. Anyway, I focused my 210, a light wide on an 8x10, at a 30 meter tree via the GG and took the shot at f16. I could immediately see the actual PoF in the file was closer to 300 meters. I turned on the electronic focus, and adjusted per  -- the adjustment required a bump to my focus knob of about 0.5mm -- basically as fine as I could move the focus knob on my Arca F-Metric -- and that put the focus point right at 30 meter. But, I could not "see" the difference on the GG through my 10x loupe.  Moreover, I was amazed that f16 on the 210 would not carry more than about +/- 25% of the PoF focus area for critically sharp DoF. That is when I sold my remaining 8x10 film camera outfit. The 4x5 and Betterlight went away as soon as I decided to get a P45+...

But, I will say that if you do get a near perfect capture on 8x10, it is a stunning thing to look at.
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mattpallante
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« Reply #2 on: September 22, 2011, 01:17:43 PM »
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When I think of maximum image quality, I don't think of scanned film. I would say the ultimate for 8 by 10 film image quality would be that film and a traditional contact print. I would be interested in comparing that contact print with a like sized print from the IQ180. Certainly you can do more work much easier with the IQ180. My perspective is I'll never have the money for a IQ180, but I would have the money for a used 8 by 10 camera and lens. As far as f stop goes, I think you would be better off at f11-f22. Just sayin......... Wink

Matt
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Bill VN
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« Reply #3 on: September 22, 2011, 03:02:26 PM »
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It should also be mentioned that at f32, lens diffraction comes into play. Testing at f11 might bring sharper results with 8x10.
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Ray
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« Reply #4 on: September 22, 2011, 06:49:24 PM »
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It should also be mentioned that at f32, lens diffraction comes into play. Testing at f11 might bring sharper results with 8x10.

Indeed!  Even if one has succeeded in getting perfect focus and perfect flatness of the film, one can't expect a lens to be tack-sharp at F32.

On the other hand, even F32 with 8x10" format does not provide the same DoF as F11 on the IQ180. The diagonal of 8x10" film is approximately 4.8x the diagonal of the IQ180 sensor, therefore for equal DoF one should use an F/stop number which is 4.8x greater, that is, somewhere between F45 and F64.

However, this tendency to use a shallower DoF with the larger format, when making comparisons with a smaller format, seems to be a fairly common practice, in order not to place the larger format at too much of a disadvantage.

It would be interesting to see comparisons also using f2.8 with the IQ180 and F11 with the 8x10 format. But maybe lack of film flatness would be too much of a problem.
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theguywitha645d
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« Reply #5 on: September 22, 2011, 07:10:37 PM »
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If I am correct, Avadon did his 8x10 portraits at larger apertures. I am sure you would get sharper results. I don't think this test is definitive, but it is suggestive. For all intents and purposes you can have 8x10 images out of an 80MP MFD back.

To be fair, they are not identical images. The process imparts character to the image. That does not make 8x10 film obsolete. There are going to be things you can achieve with the large image area and tonal and color palette that you cannot get with the IQ180.

And we need to put in context that we are looking at 100% crops which are far from any real viewing distance we could get no matter how big you make the images.

Nice test. Interesting results.
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madmanchan
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« Reply #6 on: September 22, 2011, 08:04:01 PM »
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I think the point of the comparison setup was to get DOF approximately the same (as if you were trying to get the same landscape shot with two different systems).
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Jack Flesher
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« Reply #7 on: September 22, 2011, 09:13:48 PM »
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32, 45 and 64 are the typical "working" apertures for landscapes in 8x10 because of limited DoF -- it's where "The f64 Group" got their name -- it's what they determined the optimal aperture was. I'd occasionally use f90 on 8x10 if needed. For 4x5, f32 is not uncommon for shooters wanted to extend DoF as far as possible.  Yes, diffraction goes up, but generally at typical enlargement factors, the gains from aperture DoF far outweigh the losses from diffraction.  The next issue is lenses with large enough IC's to cover 8x10 to begin with -- generally one that laid down over 30 LPmm would be considered stellar, 20 average. Keep in mind that a 4x enlargement of 8x10 generates a 16x20 print...  

However, when you start comparing at the pixel level, scan or digital original, diffraction is what you see soonest assuming the lens is sharp enough to begin with. (The less sharp a lens, the harder it is to see diffraction, and per above, 8x10 lenses are not all that sharp.)  So optimally, an 8x10 lens would probably be shot at f16 or f22 while digital MF lens closer to f8 IMHO.  The gains of f16 would possibly improve the shown 8x10 result by a small visible amount, but at the end of the day I think the author did a reasonably credible job given the constraints of the medium.
  
« Last Edit: September 22, 2011, 09:21:12 PM by Jack Flesher » Logged

DanielStone
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« Reply #8 on: September 22, 2011, 09:41:22 PM »
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...Keep in mind that a 4x enlargement of 8x10 generates a 16x20 print...  
  

its a 2x enlargement btw Wink.

And to be fair, the 745dpi scan isn't even close to getting a "fair" fight between the two. 2000dpi(the "sweet" spot for ANY format IMO, on ANY scanner, drum/flatbed or Imacon) would have been best, and then downsample.

Working in 8x10 can be a chore. No doubt. I use it as one of my primary formats. Primarily to contact print(even with color negatives), simply because I like the simplicity of the process.

All you gear heads get you panties in a twist on these things. Get out an make some photographs.

there are still some people shooting 8x10 film for jobs. This guy(Mitchell Feinberg) even had a digital back made for PROOFING ONLY! To me, it shows he's committed to film capture.

I don't know who scanned the film, but the screen scanner they mentioned is pretty old. Yes it gives results, but poor results compared with more recent drum scanners. They should have had Lenny Eiger do the scans. He's pretty much as best as they come in the business of scanning.

Another thing: they aren't comparing PRINTS. I mean, what dumba$$ who goes and spends $70k on kit doesn't want to make prints, and just look at them on a screen? Buy a point and shoot if all you want to do is look at them on the computer. Photography used to be about making great prints. Now its about how it looks on the screen. Or at least on this test it seems that way to me...
-Dan
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JeffKohn
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« Reply #9 on: September 22, 2011, 09:51:07 PM »
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its a 2x enlargement btw Wink
So are you saying that if you lay two 8x10's side by side, you get a 16x20?Huh
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theguywitha645d
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« Reply #10 on: September 22, 2011, 09:55:20 PM »
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So are you saying that if you lay two 8x10's side by side, you get a 16x20?Huh

Magnification is linear...
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photodan
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« Reply #11 on: September 22, 2011, 10:45:40 PM »
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The image quality of the IQ180 may indeed be better than 8x10 scanned film, and better in more ways than just sharpness. However the test that was done is not valid at all in my opinion. Let's take just the sharpness issue.  First- the color film used was not optimal. Having shot 8x10 color films for years (before giving up the impractical beast, at least for me), the film stock makes a big difference. Fuji Provia for example has finer grain and more sharpness than the Ektachrome. The new Portra 160 has less grain, and probably more sharpness.

As others have mentioned, shooting at f32 will show the effects of diffraction, on the screen, and perhaps at huge prints sizes. F16-22 was usually the sharpest for me (however where Depth.Of.Field. didn't matter at all, for some lenses the best sharpness was at f11). Of course if you want large D.O.F and camera movements won't cut it, then stopping down is necessary. For an 8x10 a lot of stopping down is sometimes necessary (f32 and smaller) and that is a big weak point of shooting 8x10.

8x10 can have a unique look due to the small D.O.F (well, at least compared to much smaller imaging sizes). When printed via analog means 8x10 can have a special ultra smooth look, no matter how close one looks at the print (contact print or moderate size, say 20x24). Not even lightjet or inkjet prints from the best scans have this look. There are advantages to printing digitally however I have yet to see that special look.

Film holders/film flatness and groundglass/focusing accuracy.  Another big weak point of 8x10. However I was able to get excellent results using Toyo holders and a Tachihara camera (not to mention an Ebony brand model), and using a 7x loupe to focus. I was lucky that the particular cameras I had were fairly accurate.

The scanning that was done for the test: This is utterly puzzling - why use a lower-grade scanner, and to scan at such a low resolution, for this type of test? the testers might have gotten better results shooting 4x5" film  and scanning at a higher res - more film flatness and greater D.O.F. The answer seems to be that since the film results weren't that sharp (as seen via a loupe) then  there was no reason to scan it  at higher res. Actually, there was not point to scan it at all then - due to the film and f-stop issues.

And that sums it up - what was the real point of this test? Shooting less than optimal film, non-optimal f-stop, and sub-optimal scanner and  ridiculously low resolution, renders this test of not much use. Yes, IQ180 may very well be better. But this test does nothing to prove that point.
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ErikKaffehr
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« Reply #12 on: September 22, 2011, 10:52:34 PM »
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Hi,

The author clearly indicates higher resolution scanning would not help. Airy disk diameter at f/32 would be around 42 microns, lenses are said to perform at 20-30 lp/mm. The 20-30 lp/mm figure would grant 1600 PPI scan. My impression scanning 120 film has been that 1600 PPI was enough, but 3200 was wrangling out more detail. I would prefer a higher resolution on the scans, but I presume they used the equipment they typically would use.

Id suggest that this was tried to be a realistic test. It's very easy to criticize tests made.

Finally, I see nothing wrong with analyzing the data digitally. Most of the printing is done digitally nowdays.

Best regards
Erik


its a 2x enlargement btw Wink.

And to be fair, the 745dpi scan isn't even close to getting a "fair" fight between the two. 2000dpi(the "sweet" spot for ANY format IMO, on ANY scanner, drum/flatbed or Imacon) would have been best, and then downsample.

Working in 8x10 can be a chore. No doubt. I use it as one of my primary formats. Primarily to contact print(even with color negatives), simply because I like the simplicity of the process.

All you gear heads get you panties in a twist on these things. Get out an make some photographs.

there are still some people shooting 8x10 film for jobs. This guy(Mitchell Feinberg) even had a digital back made for PROOFING ONLY! To me, it shows he's committed to film capture.

I don't know who scanned the film, but the screen scanner they mentioned is pretty old. Yes it gives results, but poor results compared with more recent drum scanners. They should have had Lenny Eiger do the scans. He's pretty much as best as they come in the business of scanning.

Another thing: they aren't comparing PRINTS. I mean, what dumba$$ who goes and spends $70k on kit doesn't want to make prints, and just look at them on a screen? Buy a point and shoot if all you want to do is look at them on the computer. Photography used to be about making great prints. Now its about how it looks on the screen. Or at least on this test it seems that way to me...
-Dan

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Jack Flesher
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« Reply #13 on: September 22, 2011, 11:38:24 PM »
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its a 2x enlargement btw Wink.



2x in print parlance, 4x in resolution parlance.
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NicolasBelokurov
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« Reply #14 on: September 22, 2011, 11:48:32 PM »
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I would prefer a higher resolution on the scans, but I presume they used the equipment they typically would use.

I don't think anyone serious about 8x10 (or large format, or any film format!) would TYPICALLY use a 745dpi scan.... and if they do, they are
1). probably not the most competent or reliable testers
or
2). very competent and smart but realize that a prodigital/antifilm website publishing an article with some 8x10 film camera (they could even use some vintage 80 years old camera with the same results) tearing to shreds the latest and greatest gadget will not be very popular with the digital industry
« Last Edit: September 22, 2011, 11:50:11 PM by NicolasBelokurov » Logged

ErikKaffehr
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« Reply #15 on: September 23, 2011, 12:10:16 AM »
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So what resolution do you use when scanning 8x10"?

You can present your tests here on LuLa, but be prepared that there will be a lot of critics picking that apart...

Best regards
Erik


I don't think anyone serious about 8x10 (or large format, or any film format!) would TYPICALLY use a 745dpi scan.... and if they do, they are
1). probably not the most competent or reliable testers
or
2). very competent and smart but realize that a prodigital/antifilm website publishing an article with some 8x10 film camera (they could even use some vintage 80 years old camera with the same results) tearing to shreds the latest and greatest gadget will not be very popular with the digital industry
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NicolasBelokurov
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« Reply #16 on: September 23, 2011, 12:38:20 AM »
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You can present your tests here on LuLa, but be prepared that there will be a lot of critics picking that apart...

Best regards
Erik



Well, I think that criticizing the selected scene or the camera make or the time of day the shots were made or the tripod used would be "picking apart" the test. Noting the not so fair scanning setup when comparing digital images is a valid observation and it's not a minor one. Would it be fair to compare a Nikon and a Canon FF digital cameras with the Nikon shooting raw and Canon lowest quality jpegs?
Best regards
P.D. I use 4x5 not 8x10

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lenny_eiger
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« Reply #17 on: September 23, 2011, 12:57:38 AM »
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I'm sorry, but I do scanning (and printing) for a living. I have an Aztek Premier, which has an optical resolution nears its 8,000 ppi scanning limit. This is only the last in a series of tests of scans vs digital where the digital camera is the best that money can buy and the scan is made by a cheap junky scanner. In this case, it isn't so much the scanner itself, but the idea that you can't get any more than 745 ppi. It's just plain ridiculous and the article should be pulled. It's clearly misleading.

Lenny Eiger

EigerStudios
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« Reply #18 on: September 23, 2011, 01:23:29 AM »
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The article surprised me.  I recently visited Rodney Lough's gallery in Vegas and most of his images are scanned 8x10. A few are now Phaseone, but I think some (or all) of those have been stitched.  I know a year ago when I chatted with him there, he didn't feel the p65 was as good as 8x10 film, but seeing as how he's doing a capture integration workshop maybe he thinks the IQ180 is. But in examining his prints (including finding a grasshopper on a blade of grass in a 40x60 print with a magnifying glass) I'll be honest ... they look every bit as good and maybe even better than what I see from my current IQ180.

Every time I visit his gallery I'm tempted to try 8x10 film (mainly so I could say I've been there done that), I always come to my senses a few days later before I actually get home from Photoshop world and start searching for the stuff on ebay.  I didn't have the patience for a tech camera ... I'm sure 8x10 film would be much more challenging.
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macz5024
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« Reply #19 on: September 23, 2011, 02:42:48 AM »
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Hi

The internet can show images as precise as some worn out newspaper paper - therefore I would like to add this link:

http://www.markuszuber.com/8by10.html

Markus
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