Compare final print resolution, different formats

[Eric Leppanen]

I think Bill's test results are useful in illustrating tendencies, not absolute in the real world but something which the photographer should be aware.

Some time back I looked at theoretical maximum lppm at various apertures, and used these as a rough guideline for selecting the best camera system for a particular application. I tend to use 8x10 for infinity shots; grand near-to-far landscape compositions amenable to tilt; and intimate scenes which require little depth of field. Otherwise I will use a smaller format. On balance, I have found 4x5 more gratifying for landscape work than 6x7 (I own a Mamiya 7 also) because I keep running into depth-of-field limitations with 6x7 normal and moderately long lenses due to lack of movement capability (WA lenses are OK). Since IMHO I get better results with 4x5 @ f/45 than 6x7 @ f/22, I typically use the M7 only when I need it's portability or ease-of-use, or need to shoot without a tripod.

Of course to get the most out of 8x10 you need to use top-notch lenses, which many folks do not. I'm getting significantly sharper infinity shots with my relatively exotic APO Tele Xenar convertible than the popular Fuji 600C and Nikkor 800/1200T. On balance I get sharper results (particularly at the edges) with my 300mm APO Sironar-S than the popular 300mm Nikkor-M or Fuji-C. Most folks figure enlargement factors are smaller with 8x10 so they use cheaper lenses, which is fine for contact prints but defeat the purpose of using the format when enlarging. I do relatively large digital prints (30x40") so increased sharpness in the negative does show up in the print.

[Michael S. Briggs]

The photodo article is well worth looking at: http://www.photodo.com/art/35_m9.shtml. But perhaps make your own conclusions from the data that they show. Comparing photos 3 and 4, the 35 mm T-Max 100 has an small edge in resolution compared to 9x12 cm Tri-X, but is a lot grainer. Comparing photos 4 and 6, T-Max 100 in 35 mm and 9x12 cm, the differences don't look "surprising small" to me. Perhaps if all you care about is the finest bars that you can resolve on a test chart...

[Doug Dolde]

To me charts like this are completely useless. Obviously bigger is better but you can't wrap it all up in a nutshell that's anymore accurate than +/- 25% or so.

[QT Luong]

Please try to be a bit more supportive, or at least more kind. In the same spirit, there is another chart that I think would be more interesting. Assume your subject consists of a foreground at distance X and a background at infinity, and you are trying to get the same image (same camera position and field of view) with different formats, and are using the optimal f-stop in each format for this task. Draw a chart that consists of the resolution on film for different values of X, normalized for the film format.

[Neal Shields]

I think this sort of thing is helpful to overcome what I consider borderline unethical marketing of digital cameras.

It brings me back to the night I was at a camera club meeting standing in front of a display of 11x14 contact prints that were excellent both artistically and technically and a fellow camera club member told me he was getting simular results from his Nikon D-100.

There is nothing wrong with his likeing his camera and his results but it is somewhat sad that he has been lead to believe that there isn't a difference.

[Graham Patterson]

I think this work does show the number of variables involved in this sort of comparison. And this is without adding enlarging variables for film output and raster processing controls for digital files.

I know there are different characteristics in the various 35mm, roll-film, and 5x4 equipment I have available. If I repeated these tests myself, I am sure the results would deviate. I would be surprised if the deviation was linear, but the trend would be the same.

We carry comparatively large cameras, with relatively few 'frames' available, because we see an advantage in the controls and the results. I am also impressed with the results obtainable from digital equipment with suitable subjects and a recognition of the strengths and weaknesses of that medium. Personally I would miss the darkroom approach if I had to do yet another aspect of my life at a computer workstation. But I'm too anxious to use what I have than to argue the merits of what I do.

Ultimately, any photographic system is designed to meet a level of expectation. Cameras and lenses used for general photography do not have to exceed that benchmark.

[John_4185]

QT Luong Please try to be a bit more supportive, or at least more kind.

In the same spirit, there is another chart that I think would be more interesting. Assume your subject consists of a foreground at distance X and a background at infinity, and you are trying to get the same image (same camera position and field of view) with different formats, and are using the optimal f-stop in each format for this task. Draw a chart that consists of the resolution on film for different values of X, normalized for the film format.

Aw man, homework? Is it due tomorrow?

Frankly, I believe the author could do us a real service and explain exactly what he is trying to demonstrate. Clarity is important. How many readers so far have just glossed over numbers and seen nothing they can understand? Just me? No problem if it's just me, but give me some specifics that I can take to the shrink! Okay? They won't let me into the fun house there for no reason.

Please.

[bglick]

jj... > In reality, the newcomers will make so many mistakes that if the lens were magically perfect, it wouldn't help them.

I think this is a very unfair generalization..... I went from 35mm straigtht 8x10 with no formal training and found the transition very easy.... at best, I read one book to get started to grasp some of LF uniqueness, such as tilt and bellows extension factors, etc. There is a lot fo 35mm shooters that are VERY knowledgeable in photography, which leads to an easy transitions.

> the metrics are so very elementary and obvious that from day-one I never needed to elaborate upon them in order to justify a larger and sometimes smaller format.

Elementary? Hmmmm, thats odd, the extensiveness of knowledge and calculations to acheive this type of information took me a good 20 hrs, and considering I am an engineer to begin with, I would not consider this elementary. Some of the most complex problems rarely involved high level math, yet the application of the problem is very involved and often very confusing. I would surely put this chart in that category. The fact you never needed an assistance to justify an larger or smaller format, certainly does not mean there isn't others that can benefit from the contribution. It's possible, not everyone is as "photographicaly gifted" as you are? And last I looked, that's what these forums are for right? People helping people?

> Topics mired in optical bench racing are usually begun with an abstract, generally poorly qualified case and go on forever with silly minutiae.

Optical bench? Not here jj, just real world testing or interpolation of such. Very practical in my view. It too me years of testing to reach these conclusions.

> it's all just someone reinventing data, often with irrelevance and in error.

It's interesting how you can draw such conclusions based on one chart. You truly must be gifted, you might be our equivalent of the "Einstein of Photography" ? Anyway, thanks for your contributions, they were very informative.

Frank...

> The practical questions might be along the lines of "If I use really fine grained film in a smaller format could I match or exceed the quality of faster film in a larger format?" Given that you might be able to shoot with a larger aperture and slow film in a smaller format versus needing to stop down and shoot with faster film with a big camera.

Exactly....and its applications like this which can create many, many graphs.... in my case, I was simply trying to reduce the comaprison down to, the same color film, using existing optics and film /sensor in each of the formats.

> The real world answer depends on many more factors than the ultimate test results. If you want to capture still leaves on a windy day, or shoot a fleeting moment - those are the questions that most often determine camera choice, even when you are willing to work as hard as possible to get the "ultimate" quality.

Yes, this chart is not a substitute for general photographic knowledge of many of the variables that can effect a shot. For example, the one point that should have been at least mentioned is.....as the format size was increasing, the shutter speed was decreasing. So when considering two formats close on the list, such as MF and 4x5 in extreme scenes, one has to consider additional losses from subject movement when shooting with 4x5.

Eric....

> Of course to get the most out of 8x10 you need to use top-notch lenses, which many folks do not. I'm getting significantly sharper infinity shots with my relatively exotic APO Tele Xenar convertible than the popular Fuji 600C and Nikkor 800/1200T. On balance I get sharper results (particularly at the edges) with my 300mm APO Sironar-S than the popular 300mm Nikkor-M or Fuji-C. Most folks figure enlargement factors are smaller with 8x10 so they use cheaper lenses, which is fine for contact prints but defeat the purpose of using the format when enlarging. I do relatively large digital prints (30x40") so increased sharpness in the negative does show up in the print.

hence why I stated how I put LF in its best light, using results from only the sharpest lenses, such as Schneider Super Symar XL, 110, 150, Fuji 240A....... I compared all formats in their best light....

Doug, > To me charts like this are completely useless. Obviously bigger is better but you can't wrap it all up in a nutshell that's anymore accurate than +/- 25% or so.

First, one of the great findings of this test was bigger is NOT always (much) better when you consider some of the draw backs of LF such as shutter speed....it cleraly showed just how close the differences can be. And to get any photographic general comparison to +/-25% is usually good enough considering its hard to just get in the ball park.....

Anyway, the lesson I learned is, it's exhausting to share what I consider useful and valuable information..... In the future, I will surely not burden the forum...

QT > Please try to be a bit more supportive, or at least more kind.

Thanks for the life raft.....sheeeeesh.....

> In the same spirit, there is another chart that I think would be more interesting.
Assume your subject consists of a foreground at distance X and a
background at infinity.........

Would you beleive this was my initial goal, and my first crack at this! I based everything on Hyperfocal distances and then graphed the results at different hyperfocal distances. However, I find the hyperfocal calculation in general to be much to general, as so little in taken into consideration, such as lens shaprness, lens MTF, efects of diffraction with 1/R, defocus as it combines with diffraction. So instead, I reduced this chart to using real lenses and test results at different f stops.... one would have to back track with this chart and say, "I know I need this f stop for a given near/far", then find that subset on the graph.

Neal > I think this sort of thing is helpful to overcome what I consider borderline unethical marketing of digital cameras.

I agree with this.... digital results are often highly exaggerated. I have tested digital extensively, and just like LF with its MTF of lenses, MTF of film, film flatness issues, etc.... well, digital has its own subset of issues, whereas there can be NO generalizations that are accurate...

Just to share a brief synopsis of my digitial testing.... I have found that the best DSLR's using CMOS sensors (one shot - not scanning backs) are capable of resolving a range of that is shocking....for example, under a best case scenario, a digital sensor can record up to 77% of its pixel density in lp/mm, when shooting a B&W line chart which is oriented in the same XY pattern as the sensors grid - with interpolation, sharpening, etc. . Quite impressive, huh....

but then, using RED line patterns on the diag. of the sensors grid (full exploitation of sensors XY grid weakness and Green Bias), the best the sensor can resolve is 35% of the sensors lp/mm. This set of two variables show a variance of 100% in resolvability. Add less sharp lenses, and this value can fall as low as 25%. Now, add higher ISO's, moire sensitive patterns, less than optimum f stops, etc., then you can acheive even worse results. Although digital overcomes the film flatness issue, current technology demonstrates amazing vulnerablility to other variables which produce test results from "amazing" to "terrible" .....

So when I read / hear digital results, I wonder just how many of the factors worked in favor or against the sensors weaknesses / strengths. In my chart, I presented digital in a good light also, using the best optics, best interpolation of RAW files and sharpening....

[John_4185]

With respect and appreciation for your enthusiasm and effort, Bill, I still find the report shy of the kind of detail I am accustomed to in scientific studies. It should at least begin with a cogent statement of objective(s), then move into the method in detail, end with a summary ... well, you have seen the stuff. (And gee, don't use boxed bars.)

I still don't get it, but maybe I'm stupid. It's likely that I am. Or distracted. See, I've got this grand unified theory thing to finish, then the quantum computer simulians to iron out (that's what we eggheads call 'bugs' now), and then, what was it... oh yeah, Peace on Earth.

[bglick]

jj > With respect and appreciation for your enthusiasm and effort, Bill, I still find the report shy of the kind of detail I am accustomed to in scientific studies. It should at least begin with a cogent statement of objective(s), then move into the method in detail, end with a summary ... well, you have seen the stuff.

jj, I did this test for my own purpose, not to publish it in a scientific journal. I agree that it sure would be nice to have the graph be fully documented with every detail with pages of footnotes and descriptions, results of prior test data, interpolations, etc. etc..... But, I just don't have the time to produce such documents. Many can gain 90% of the benefits in its current form.

> I still don't get it, but maybe I'm stupid.

Well, I explained it several times, and the concept is very simple.... the title of the graph says it best..... it demonstrates the resolution that can be acheived on a 8" print using different formats, at different f stops, (whereas they all produce the identical DOF) I doubt you are too stupid to understand the concept (as you suggested), but, possibly you are too smart to grasp such simple data? Just a thought... I am burnt out trying to explain it....