Format for 60x75 inch Gallery Prints - 4x5 or 8x10?

[bglick]

> To summarize, the majority opinion was that inkjets are the sharpest print medium currently available. So it's not just QT who thinks this.


In digital, yes....but optical prints still beat the pants off everything, as the the best darkroom papers can hold about 3x what inkjet paper can hold... of course, the limit is often in the original.... and....

the ink jets are already holding enough detail to be at the eye limit, for a 20/20 person at about 15"....so clearly diminishing returns in most cases...

[Ben Syverson]

the ink jets are already holding enough detail to be at the eye limit, for a 20/20 person at about 15"....so clearly diminishing returns in most cases...

Such as a 60x75" print at any reasonable distance

[bglick]

> Such as a 60x75" print at any reasonable distance


gotta work out the numbers....

10 lp/mm on the print, add in some efficiency losses in the printing process, so

13 lp/mm fed to printer, * 2 * 25.4 * 75 = 50k resolvable pixels

A low DOF shot, either infinity or a 2d plane, can yield about 40 lp/mm on color chrome film, about 30 lp/mm on color neg.

Using color neg

30 *2 * 254 = 15k resolvable pixels

so about 1/3 short of the 10 lp/mm goal to paper...

However, with a long DOF shot, say f64, you will fall below half of this, 1/8 th the max. paper can hold..... (this is the finest glossy ink jet paper, not rag)

But much of this is subjective, as view distance and visual acuity of the observer is the variables that can make or break your goals.... Example, using 20/20 vision, (1 arc minute), the eye limit is at 60 pixels per degree. (pixel = line = dot, etc.)


So at 10" print view distance, one degree = 4.5mm of horizontal print. (simple trig). In which case, 60 resolvable pixels would be the eye limit. (20/20)

In 75", we have 15k pixels / (75*25.4) = 7.9 pixels per mm * 4.5 = 35 pixels, which is about half the eye limit.

But if you push the view distance to 20" (more reasonable, as only kids can focus at 10"), you are at 70 pixels per degree, a bit above the eye limit.

Of course, you can keep tweaking the numbers... if a person has 20/10 vision, at 20" he will see half his eye limit. If a person has 20/40 vision at 20" he will see 2x his eye limit.... as you can see, lots of variables to consider... its best to reverse engineer from your final goal on the final product and take into consideration the avg. visual acuity of the observer.

If you really want to get deeper....next you have contrast and brightness issues. If the print is low contrast, the avg. person can no longer resolve 20/20. But if its a high contrast AND VERY well lit, a persons visual acuity improves, specially if the eye pupil diam. has been driven down to 3mm diam. or smaller, in which case, you need a to increase the resolution on the target to achieve the eye limit... and if the print is a very strong back lit trannie, the eye can resolve double, vs. front lit.... (20/10) But remember, many older people like myself still have excellent visual acuity, 20/13 for me, but Myopia has rid my ability to close focus, so 10" would be an absurd distance to consider, unless everyone over the age of 35 brings their reading glasses to the exhibit...

Keep in mind, this was all done with an example with a very SHALLOW DOF image where you can shoot a killer lens, such as the 150mm SSXL at f11 or a normal lens at f16. But at f64, all these numbers crumble... this is why DOF is 810's nemesis...

Anyway, this should give you a feel for where you need to be at....

confused yet?

[e2aa]

I find this whole DOF issue confusing. Probably b/c I have no experience with large format film.

On one hand, many 4x5 shooters on here seem to complain about 8x10 DOF. On the other hand, most fine art photographers seem to like the DOF and tonality of 8x10.

[e2aa]

Being toyed with? Don't kid yourself.

You underestimate the MF digital stitching process.

If you are up for the challenge, rent a P45+/P40+/P65+ with a Cambo Digital Wide DS and go through the process to get the 4-6 files required for a stitched image that would result in a print similar to a single 8x10 image (60x75). Only after you import to PS (or whatever software you can get) and actually attempt to stitch the 4-6 frames together will you experience my frustration. I guarantee you this is as tedious as anything and the exposures will be very tricky to blend. It will take you hours to get the image looking as you want, if you are lucky. You may have to go take more shots.

The appeal of 4x5 or 8x10 to me is (1) ability to see the entire image on the ground glass before capture and (2) only having one file to deal with in PS.

I know I am naive about LF film as a medium. And I know there are many trade offs. Don't you see that is why I am on here asking questions and wanting to try for myself? I can accept that 4x5/8x10 is difficult and time consuming in its own ways, and more so in general, than MF digital...maybe I will sell the 8x10 after I try, maybe not.

In a few years, after Phase One has produced a p85+++ that produces a file from one shot that equals 8x10, then I will forget about film.

Re-reading the original post, I have to say I'm starting to agree. In what universe is stitching a few frames of MF digital MORE work than shooting, developing, scanning and dustbusting 8x10?

[bglick]

> On one hand, many 4x5 shooters on here seem to complain about 8x10 DOF. On the other hand, most fine art photographers seem to like the DOF and tonality of 8x10.


for the non technical photographer, this can be confusing.... in a nut shell, it comes down to aperture diffraction, i.e. the higher the f stop, the lower the aerial lens resolution, hence the lower the recorded resolution on film. Jumping up 2x in a format size, requires double the f stop to achieve the same DOF.... which means, the same composure and the same resolution on the same final size print. Now, this effect varies between formats, I will try to summarize....

For considerable DOF shots... such as
35mm f8,
MF f16,
4x5 f32,
8x10 f64.

35mm to MF..... very marginal loss (nature of short fl lenses)...this means even with relatively long DOF, MF will come close to 2x the recorded resolution.

MF to 45 ...... significant loss, resolution gain down to about 1.5x

45 to 810 ...... very significant loss, resolution gain down to 1.3x

Now, if there is shallow DOF, or no DOF, such as infinity or 2d plane (brick wall mural), then each jump up on format will provide about 1.8x the resolution as the previous format.

This is why you should pick your formats carefully.... sometimes bigger is only marginally better. However, there is other things to consider such as film type and film grain, as well as enlargement factor. In this digital age, if the film is scanned, grain is less of an issue today vs. when film was optically enlarged for a print.... grain removal software does an excellent job.....

That's as simplified as I can make it...

Now you see the value of stitching.... assuming the subject is cooperative, it can't be beat.... the digital post processing tools today are amazing... the capture can be digital or film, it doesn't matter...

[bglick]

out of curiosity, why such problems stitching a few P1 MF shots together?

[rdenney]

I find this whole DOF issue confusing. Probably b/c I have no experience with large format film.

On one hand, many 4x5 shooters on here seem to complain about 8x10 DOF. On the other hand, most fine art photographers seem to like the DOF and tonality of 8x10.

The larger the format, the less the depth of field at a given aperture. Those fine-art photographers make use of 8x10's lack of depth of field, which can produce effects just not possible with smaller cameras. But if it's a uniformly sharp image you want, you have to stop down considerably to recover the depth of field lost by going to the larger format, and that smaller aperture allows diffraction to creep in. Diffraction causes a loss of acutance, but so does not being in focus. Not being in focus is usually worse than diffraction, but prints of the size you are considering viewed up close really put any loss of sharpness on display.

If we work from 5 lines/mm as the target resolution (a sharply resolved print viewed without a magnifying glass at 10 inches), we'll need at least 10 pixels/mm to make those lines, and more if they are diagonal. Your 75" print needs 250 pixels/inch, or 18750 pixels in the height of the image. That's close to my own experience with Epson prints, where the visual differences between a print at 240 pixels/inch and higher pixel densities are subtle indeed--I need a magnifying glass to see them.

An Epson flatbed scanner will give you about 10,000 pixels from the long dimensions of 4x5 at the limit of its capability--not enough for such a print. The 8x10 will give you about 20,000 pixels, and that is enough for your print.

The enlargement of the 8x10 will be 7.5x. 7.5 times those 5 lines/mm is 37.5 lines/mm that need to be present on the film. If they aren't, then the pixel resolution may be fine but the optical resolution won't be. With 4x5, the enlargement is 15x, which will require 75 lines/mm from the lens. Large-format lenses will only deliver that at optimal aperture and exactly on the plane of sharp focus. Depth of field doesn't mean more stuff is in focus, it just means more stuff appears to be in focus. The larger the print, the more exacting are the standards for depth of field.

DOFMaster uses a point standard of sharpness (characterized by the circle of confusion) of 0.2mm for 8x10, but that's based on the assumption of a 10" print. At 75 inches, it should be divided by 7.5, which is .026mm, or something like 1/1000". With 8x10 focused at 10 feet, the depth of field will be 0.35 feet at f/22--not much. F/22 is probably the sweet spot for the typical 300mm normal lens for 8x10. Focused at 100 feet, the depth of field extends from 84 feet to 124 feet--again, not much.

For 4x5, the standard of sharpness based on a 10" print is 0.1 mm. At 75 inches, in should be 0.013mm, or around 1/2000". With 4x5's 150mm normal lens focused at 10 feet, the depth of field at f/22 will be 0.74 feet, twice what it is for 8x10. Focused at 100 feet, the depth of field is 91 feet, more than twice the 40 feet that it is for 8x10. So, with the same exposure and the same standard of sharpness for the final print, which is dictated by the visual acuity of a person with good eyesight viewing the print from 10 inches away, the 4x5 will have more depth of field and thus more of the scene will be in apparent sharp focus.

With the 8x10, the only solution would be to stop the lens down to f/45, requiring four times as long an exposure. That's why your 5-second exposures will be 80 seconds for 4x5 (assuming you were getting away with f/11 on medium format) and 1280 seconds on 8x10, plus the effects of reciprocity, in order to get the same basic image.

But f/45 will show more diffraction than f/22, and that will undermine the lens resolution across the board, and the image will not hold up to close scrutiny because of that.

So, we have competing causes of inadequacy:

1. The image can be undermined by too few pixels.
2. The image can be undermined by enlarging beyond the lens's optical capabilities.
3. The image can be undermined by insufficient depth of field to render those scene elements in apparent sharpness that need to appear sharp.
4. The image can be undermined by diffraction caused by too small an aperture.

What you are are seeking is a dynamic balance between these competing influences. If you can photograph your subject with the depth of field allowed by 8x10 and a practical shutter speed and optimal aperture, then that is the format that will not require more than lenses can deliver or more than a reasonable scanner can deliver.

But if 8x10 doesn't provide sufficient depth of field for your subject, then parts of your subject will either be out of focus or the aperture you'll need to get them in focus (if it's even available on the lens) will cause visible enough diffraction to become the limiting factor in achieving your print size. You might be able to solve the problem using 4x5, and going to a higher level of scanning to achieve the number of pixels you need. You'll also need good lenses used carefully.

Medium format would require very high-end scanning (or capture) to obtain a sufficient number of pixels, else that would constrain the final image. Also, the degree of enlargement would require more than lenses can deliver, even at their sweet spot.

If you can relax the viewing distance requirement and thus the standard of sharpness, it all gets easier. But at this point, it mainly depends on your subject and the required depth of field. (Of course, one of the main benefits of a view camera is the ability to tilt the focus plane usefully, and this can often solve a focus problem without increasing depth of field.)

Not present in my discussion is the tonality issue. Larger formats most assuredly have better tonality, but while this is a subtle effect of great importance to many fine-art photographers, I'm not sure a reasonable solution space doesn't already cover all your options.

As with all system decisions, it comes down to understanding your requirements first.

By the way, DOFMaster is quite useful for calculating depth of field. At your print size, however, you need a much stricter standard than it uses--choose your own circle of confusion, following my calculations above.

Rick "offering the same reasoning as others in different words in case it helps" Denney

[bglick]

> An Epson flatbed scanner will give you about 10,000 pixels from the long dimensions of 4x5 at the limit of its capability


You are dealing with marketing information, not hardcore data... Epson scanners must over scan by a factor of several times after exceeding about a 6x enlargement factor. A $400 scanner will not match the performance of a $40k scanner....the sad reality of the equipment in our field....





> With 4x5, the enlargement is 15x, which will require 75 lines/mm from the lens. Large-format lenses will only deliver that at optimal aperture and exactly on the plane of sharp focus.


You are confusing aerial resolution vs. recorded resolution.... assuming color film....




> F/22 is probably the sweet spot for the typical 300mm normal lens for 8x10.


f32 is much more commonplace, at least with all the MTF data I have looked at....





> So, with the same exposure and the same standard of sharpness for the final print, which is dictated by the visual acuity of a person with good eyesight viewing the print from 10 inches away, the 4x5 will have more depth of field and thus more of the scene will be in apparent sharp focus.



The reality is, DOF does not change with format. This assumes same composure, same sharpness at the near / far for the equal size final prints. When you double the format size, you double the fl, since enlargement will be 1/2 with the larger format (vs. the smaller format) you half the cc to compensate for the reduced enlargement factor. You will end up with the same Hyperfocal distance for both formats. F stop and cc are inversely proportional to each other in the DOF equation.


There is two benefits of larger format as it relates to DOF... the first is the center of the image will be sharper.... as DOF represents the min sharpness of the near and far points only. Secondly, less grain in the larger format and often better tonality...


Of course, there is some major drawbacks in larger formats as well.... each time you double the format, you loose two stops of shutter speed... this makes the capture more sensitive to motion and camera vibrations, which both can further reduce resolution. The larger the camera, the more sensitive it can be to noises, wind, etc.




>But f/45 will show more diffraction than f/22, and that will undermine the lens resolution across the board, and the image will not hold up to close scrutiny because of that.


See my comments above.... this is self correcting...





> But if 8x10 doesn't provide sufficient depth of field for your subject, then parts of your subject will either be out of focus or the aperture you'll need to get them in focus (if it's even available on the lens) will cause visible enough diffraction to become the limiting factor in achieving your print size. You might be able to solve the problem using 4x5, and going to a higher level of scanning to achieve the number of pixels you need.



other than grain, you will end up in the same place, see my comments above. The limitation here is the amount of resolution recorded at capture... scanning at a higher resolution will not create more resolution in the film.....


/

[rdenney]

>You are dealing with marketing information, not hardcore data... Epson scanners must over scan by a factor of several times after exceeding about a 6x enlargement factor. A $400 scanner will not match the performance of a $40k scanner....the sad reality of the equipment in our field....

With all due respect, I'm dealing with the results I get scanning my own 4x5 negatives in my own V750. And I compare those results with the 6x7 scans from my Nikon 8000ED for which I paid four times as much, which also provides about 10,000 pixels at similar pixel quality from 6x7 (using the glass carrier).

Many, many testers have concluded that the Epson flatbeds are good to about 2000 pixels/inch if used carefully, and my results do not refute those claims.

I did not say that the pixels would not be sharper with a drum scan, but they are sharp enough to do what I said they would do. I can make basic corrective sharpening in Photoshop with a radius of 0.9 or 1.0 pixels with scans at 2400 pixels/inch. That would not be possible if there were no resolvable edges at the pixel level.

And I don't know where you priced a V750, but I wish I'd only paid $400 for mine.

I did say, that if he wants 20,000 pixels from smaller than 8x10, he's going to have to upgrade his scanning capability beyond what is possible with an Epson flatbed.

You are confusing aerial resolution vs. recorded resolution.... assuming color film....

But that does not undermine the principles being discussed or the conclusions. And the OP clearly didn't catch all of what you said, because he asked a question central to your explanation. I thought a different way of describing it might help.

You'll notice that I converted those decimal representation to fractional representation with one significant figure. These are approximations intended to demonstrate the effect and the underlying principles. Without knowing the OP's specific requirements, the numbers are just not much help: Too much precision in pursuit of too little relevance.

Rick "noting that we came to basically the same conclusion by somewhat different paths" Denney