PDA

View Full Version : Purely Theoretical Musings on Resolutions and Formats...

Scott Rosenberg
27-Jun-2007, 18:06
i have a question regarding the amount of information captured on film, as i am new to such ponderings. i have spent the past many years blissfully shooting sheet film and happy as a clam in mud doing so. however, due to some recent overseas travels i have also started working with a mamiya 7 system. the 6x7 outfit was bought for times when i could sacrifice a little image quality for the convenience of shooting with the small RF. at least that's what i initially thought. however, much to my astonishment, the prints i was able to make from the M7 held up to enlargement as well as 4x5 even when printed at a decent size (30" in the long dimension). i was quite surprised by this so started doing some thinking on the matter and came up with the following reasoning...

the mamiya 7 lenses at f/8 are capable of resolving somewhere around 110 lp/mm
most large format lenses, such as the 110xl, at f/22 are capable of resolving somewhere around 60 lp/mm

i choose these as these are common working apertures for me. now, taking the approximate film size into account, one gets the following...

4" x 5" at 60 lp/mm = 46,451,520 lp
6cm x 7cm at 110 lp/mm = 50,820,015 lp

am i correct in assuming that the relative closeness of the amount of information captured by the respective formats explains the similar quality of the prints? it seems to my simple mind that if there is a comparable amount of information on the film then the enlargements are going to be close, regardless of the size of the original.

but then i am likely oversimplifying things here and hoped to elicit corrections from those more knowledgeable than i.

i appreciate any inputs,

clay harmon
27-Jun-2007, 19:39
Don't forget that another variable is the ability of the film itself to resolve the line pairs. Tech Pan in 6x7cm is likely to outresolve Royal-X Pan in 4x5.

Donald Qualls
27-Jun-2007, 19:53
Faster lenses (three stops faster common working aperture) in the 6x7 more than offset the advantage of larger film with respect to film grain -- ISO 100 in 6x7 has about the same grain (as found in the final print the final print) as ISO 400 in 4x5, but the 6x7 can shoot one stop faster shutter even with the slower film, if both are at their common working apertures.

I got a similar shock today, scanning some 6x9 on 120 negatives I shot in my Speed Graphic with my recently acquired Adapt-a-Roll 620. The 120 (even at ISO 400) actually looked better than what I've been getting with ISO 400 sheet film. I finally realized it was different brand film; the rolls are Foma, while the sheets are Forte, and there's a big difference in grain between Foma 400 and Forte 400...

Do a similar comparison with still faster lenses and still slower film and you might find 35 mm even competes -- Tech Pan (or one of the occasional partial replacements that pop up, like Bluefire Police) in 35 mm at f/4 may well outperform Plus-X in 6x7 at f/8. And then where are you?

Paul Metcalf
27-Jun-2007, 21:37
am i correct in assuming that the relative closeness of the amount of information captured by the respective formats explains the similar quality of the prints? But when you enlarge, you have to enlarge more for the smaller format, so you need more resolution. But I suspect your overall shoot-to-print process probably has something that is more critical for producing quality prints so the resolution differences don't really show up between MF and LF.

Scott Rosenberg
28-Jun-2007, 09:59
clay:
i haven't done any testing yet (planned for this weekend) but i've heard that the 25 speed rollei films are tops in resolution. i couldn't locate any tech pan, but the 25 pan is supposed to be very good, and the 25 ortho is supposed to be as good as tech pan with a claimed resolution of 330 lp/mm.

donald:
good point re: grain size relative to the overall area of the film - i hadn't considered that. as i mentioned, i'll be trying some 25 speed stuff this weekend to see how that influences what i'm seeing from 6x7. it's size relative to the area should be basically the same as fp4+ in 4x5... it sure is good to have options.

paul:
i understand what you're saying re: enlargements and you bring up an excellent point to which i don't know the answer. of course a 6cm x 7cm film will have to be enlarged more than a 4" x 5" film to get each to the same print size. the enlargement delta being comparable to the delta in the film area - assuming each piece of film contains the same amount of information. however, if instead of thinking in terms of the size of the original we think in terms of how much information the original contains, does it stand to reason that two pieces of film with the same amount of information enlarged to the size print will require the same amount of enlargement regardless of the area of the film from which they were derived? that is to say, if film A contains 10 units of info and film B contains 10 units of info, and if i am going to make a print that will require 20 units of info, then both will be doubled regardless of the size of the film?

again, i might be oversimplifying things, but if i think in terms of how much information i've got on the film versus how much i'll need to enlarge based on the ration of the areas, does it matter what size the original is? or does it only matter how much information each has? i have no idea, but will be testing for this.

in the case of the 4x5 with LF optics (~60 lp/mm) versus 6x7 with M7 optics (~110 lp/mm) the increased resolution of the M7 glass seemingly makes up for the reduced film size, and the amount of information contained herein is roughly comparable - 4.6 x 10^7 lp versus 5.0 x 10^7 lp. i would assume, therefore, that when enlarged to the same print size, the prints would be roughly identical. in fact, if this reasoning is sound, the 6x7 film would need LESS enlargement, as it contains slightly more information.

again, i've only recently become concerned with such matters and am hoping some of you with more experience and knowledge can correct any flawed logic.

Michael Alpert
28-Jun-2007, 10:45
i would assume, therefore, that when enlarged to the same print size, the prints would be roughly identical. in fact, if this reasoning is sound, the 6x7 film would need LESS enlargement, as it contains slightly more information. . . . i've only recently become concerned with such matters and am hoping some of you with more experience and knowledge can correct any flawed logic.

The same print size would mean a higher degree of enlargement for the smaller negative. Small prints (enlarged to about 4x5 inches from the 6x7 negative) will look the same because, in this size, the limiting factor is the resolution of the photographic paper, assuming that the negatives are very sharp.

Larger prints will always favor the larger negative. The greater resolution of the medium-format lenses and finer-grain film are will not save prints made from smaller negatives from becoming soft when compared with larger negatives. The measure of resolution, in practical terms, is the contact print. When making enlargements one needs to learn what to accept (i.e., what one's personal quality-standards are) by comparing enlargements against contact sheets.

Ron Marshall
28-Jun-2007, 10:54
Photodo used to have, and may still have, a comparison of the resolving power of 35mm, 6x6 and LF, under optimal conditions. They measured the resolution obtained on TMY of each format. LF won, but not by much. The greatest benefit, according to them, for a larger format is smoother tonal gradation and less grain, assuming constant print size.

Bruce Watson
28-Jun-2007, 11:03
The same print size would mean a higher degree of enlargement for the smaller negative. Small prints (enlarged to about 4x5 inches from the 6x7 negative) will look the same because, in this size, the limiting factor is the resolution of the photographic paper, assuming that the negatives are very sharp.

Larger prints will always favor the larger negative. The greater resolution of the medium-format lenses and finer-grain film are will not save prints made from smaller negatives from becoming soft when compared with larger negatives. The measure of resolution, in practical terms, is the contact print. When making enlargements one needs to learn what to accept (i.e., what one's personal quality-standards are) by comparing enlargements against contact sheets.

Indeed.

And there's more to photography than just sharpness. One of the other ways a bigger negative shines is in tonality. Having more film area helps make smoother tonal transitions and gives a larger range of tones. IOW, when you make same size prints the one from the larger negative usually looks smoother. That combination of excellent sharpness with excellent smoothness is one of the reasons I like LF so much.

All that said, there's no reason not to use a medium format camera when traveling if it will do what you want. And it sounds like it works for you, so go for it.

Greg Miller
28-Jun-2007, 11:06
Are you talking about wet prints or scanned / digital prints? If you are scanning, are you using the same scanner for both formats?

Emmanuel BIGLER
29-Jun-2007, 09:49
Since i'm using both 6x9 and (recently) 4x5" film sizes, I feel concerned by this discussion and an Idea I had was that it depends whether you scan and print your images digitally or if you enlarge them with a traditional enlarger.

My feeling is that even with a good scanner when you scan a certain area of film with more DPI the effect of grain increases like in a classical micro-densitometer analysis (definition of the RMS value, the smaller is the aperture, the bigger is noise). So in fact even if you can have a higher resolution 6x9 image, if you get more noise/grain in your scan, you are more or less cheating in the contest vs. 4"x5 where smaller noise will be recorded in the digital scan of a bigger image with the same final number of recorded samples. For exactly the same number of samples bigger samples in a 4x5" film-image generate a much less noisy digital file. And and it is easier with bigger samples to get an acceptable image with an amateur-grade flatbed in 4x5" than in 6x9 : in a sense for the amateur, scanned 4"x5" is the amateur medium of choice, scanned 6x9 being the choice of professionals who can afford a top-class scanner !

In traditional enlargements and prints, the grain pattern is actually transformed depending of the king of illumination (point source, classical bulb + condensers, diffuse/cold-heas/color head) and image transfer properties in the optics. Final noise in te analog image might or might not be visible in the enlargement, we are quite accustomed to incorporate the grain pattern in our analysis of a traditinal silver halide image. The issue of grain pattern and their transformation in a classical enlargement is more complex than in a micro-densitometer or a scanner, but the idea is : since we are speaking about resolution, can we actually get rid of noise in the final image assessment ?

sanking
30-Jun-2007, 07:38
Since i'm using both 6x9 and (recently) 4x5" film sizes, I feel concerned by this discussion and an Idea I had was that it depends whether you scan and print your images digitally or if you enlarge them with a traditional enlarger.

I agree with some of Scott's conclusions that in certain circumstances it might be possible to get greater image quality with a Mamiya 6 than with 4X5.

However, Emmanuel makes a very good point in that this will be highly dependent on how you print. If you scan and print, for example, you will need a really high quality scanner to pull 105 lppm out of a negative or transparency, some 5400 ppi. Fact is, you won't come close to a real resolution of 5400 ppi with any of the consumer flatbed, where the real optical resolution is often less than 50% of stated resolution. And for that matter you won't get it with a dedicated film scanner such as the Nikon 8000, with maximum resolution of 4000 ppi. Or for that matter, with some drum scanners where resolution is limited to about 4000 ppi.

So if one scans to print you really must have a very high quality scanner to take advantage of a camera that can produce 105 lppm on film.

Sandy King

cotdt
23-Feb-2008, 20:42
For consumer scanners, the 4x5 will look better than smaller formats no matter what. But with the enlarger, the medium format can look identical to the 4x5. Actually, I remember somebody did a test showing 35mm Technical Pan film vs. 4x5 each enlarged to 30x40" inches. And nobody could tell what camera made what print even up close.

They say that 100 lp/mm is the limit for lenses, but this seems to not be true, but a limitation of measuring equipment. In theory, good lenses at big apertures should be able to get arbitrarily large resolutions. Some lenses have been tested to be sharper center resolution at f/2.8 than f/4, which is sharper than f/5.6, etc. Witness the sharpness of Technical Pan film on 35mm, or those new 14MP point and shoot digital cameras with their super small sensors (they really can get 14MP resolution at very low ISOs, which violates the idea of a 100 lp/mm limit).

vijayn
23-Feb-2008, 22:47
Scott - some observations on your calculations:

1. Your calculations are actually in lines/mm, even though you say lp/mm - lp/mm means line pairs per millimeter, and 60 line pairs per mm requires 120 linear pixels to capture.

2. Since you are using lines/mm, your figures are about right. MF roughly resolves 50 line pairs/mm and LF roughly 30 line pairs/mm. Based on those numbers, yes, the total information in 6x7 at 50 lp/mm is roughly equal to 4x5 at 30 lp/mm.

3. Grain, resolution and sharpness, while related in a film based system, don't quite follow a simple correlation like in digital. In film, grain alone is not the sole determinant of resolution; this is because we perceive the worst instance of grain in an image and our brain assumes that the entire image is that grainy. In reality grain size is dependent on exposure (or development and exposure to be precise), so it is possible for film to resolve details finer than the worst apparent grain in the image. Pixel sizes are fixed regardless of exposure, so the whole thing is different for digital.

4. It is therefore possible therefore to achieve the same resolution with 35mm as with 4x5 in the same sized print, but at different levels of perceived grain. This is what was aptly demonstrated by the photodo experiments.

5. By and large though, smoother tonality seems to beat raw resolution; there are people who say that 6 Megapixels outperform 8x10 even - even though this is quite impossible. The image processing software in our brains sometimes plays these tricks - it sort of compensates for the lack of information in the absence of grain, but in the presence of grain it doesn't, so we feel that there is less information in a grainy image.

6. There is an answer as far the final print goes, a la The Hitchhikers Guide - it is six. As long as you are under 6x linear enlargement, your images will show good tonality, no grain, tack sharpness etc. With some of the ultra fine grained modern films and some digital magic, you can stretch this limit to about 10. Based on this, I could go 8x10 from 35mm, 16x20 from 6x7, 24x30 from 4x5 and 48x60 from 8x10. With some grain reduction software, some unsharp masking etc I could probably go higher, maybe 10x12, 24x30, 40x50 and 80x100 respectively, but this would be pushing it. Of course this assumes an arbitrarily close viewing distance for the print. If you were doing billboards that would be viewed from 100ft away, you could use 35mm or 6MP for 30 ft x 50 ft images.

Sheldon N
24-Feb-2008, 09:28
This is a bit of a revived thread from last year... Not sure if Scott is going to run across it again, but I'll throw my .02 cents into the mix.

Sandy hit the nail on the head with the scanning problem. It's very difficult to get 110 lp/mm scanned and pull all the detail off the film. 4x5 is much less demanding in that regard.

Scott and I were out shooting last year, and he did a test comparing the Mamiya 7II and 43mm lens against the Schneider 80XL on 4x5. If I recall correctly, there wasn't much difference in the final print quality. I don't remember his digital workflow or how he scanned it, though.

FWIW, after the tests Scott sold the Mamiya 7II and is getting himself a Cezanne scanner for 4x5. :)

Mark Sawyer
24-Feb-2008, 10:25
A related question, when making 16x20 prints from 6x7 cm and 4x5 negatives, would the quality of the enlarging lens be more critical for the medium format? I confess, I'm not sure myself...

ic-racer
24-Feb-2008, 15:44
but then i am likely oversimplifying things here and hoped to elicit corrections from those more knowledgeable than i.

i appreciate any inputs,

The title does say "Theoretical Musings..." so here we go...

I don't claim to be knowlegeable, however, I do have some experience I can share (which, I suspect, will coincide with views already posted). I am kind of a 'format fanatic' and am interested in the inerplay between format size and its effect on my photography.

For example, last night I enlarged Minox and 35mm. The night before that I enlaraged 8x10 and 4x5. The night before that I enlarged 8x10 and 6x9. I also do 16mm 'spycamera', Regular 8 B&W reversal movies (the 7mm 'normal lens' is about one-half that of the Minox) and 6x6cm.

The thee main parameters that I am concerned with in terms of artistic expression are 1) Resolution, 2) Depth of field and 3) Hand-holdability, or camera size.

Generalizations can always get one in trouble, but without writing a book on my experiences, I can say that the lenses on small camers can be real gems of optical engineering, but 'film is film' and the more you enlarge film, the less resolution you will get.

You can 'leap frog' one format over another with high acutance film (my favorite is Copex microfilm) but the order of 'bigger format is better' is always restored if the same film is used in all cameras compared.

I love mathematical models because they can show when our senses are fooled. For example a race car driver feels as if his sliding car actually speeds up when it leaves the pavement and hits wet grass. But we know from mathematical models of conservation of energy (and emperical telemetry) that this is a trick of the senses.

Practiclal models of photographic print resolution involve a definition of 'viewing distance' and results can vary considerable, depending on how this 'viewing distance' is defined. So, my experience would suggest one just 'be aware' when looking at the math and equations.

This is the 'LARGE FORMAT' forum, so do you really think anyone will not say 'Bigger is Better' :D

Seriously, though, if one loves film (like I do) then its 'Minox all the way' when it comes to flaunting the inherent characteristics of film.

cotdt
24-Feb-2008, 15:54
in the future when everyone uses Zeiss Makro-Planars and ISO 5 SuperFilm, everything will be diffraction limited.

ic-racer
24-Feb-2008, 16:11
A related question, when making 16x20 prints from 6x7 cm and 4x5 negatives, would the quality of the enlarging lens be more critical for the medium format? I confess, I'm not sure myself...

Kind of depends on how 'quality' is defined. ie resolving power or flatness of field or coverage.

Short answer: Yes. The more the 'power of magnification' the more critical things need to be.

Long answer: Just speaking from years of enlarging experience, 'mismatching' lens format (ie using a 4x5 lens to enlarge 35mm) shows that the center resolution of most name brand lenses is good enough to not make a difference. The things that are going to have more of an influence on higher power magnification enlargements are are changes in optical field flatness as magnification range moves outside of a lenses design limits, film flatness and alignmnent, and less importantly, selecting an aperture that produces an acceptable level of diffraction for the resulting print size.

cotdt
24-Feb-2008, 16:19
Short answer: Yes. The more the 'power of magnification' the more critical things need to be.

that implies that the greater the magnification, the worse the quality. but i have found that not to be true with my 50mm minolta enlarger. it seems to be designed for big enlargement (>10x) and if you do a small 5x enlargement, the quality is terrible. my EL-Nikkor is the opposite and 5-10x enlargement seems to be the sweet spot. Here, I can get maximal sharpness at f/5.6 or even f/4, extremely sharp from corner to corner. I would say that this \$40 enlarger lens is optically perfect. However, if I go smaller than 5x, the quality actually goes down.

good enlargers with modern lenses are much cheaper than drum scanners, or even consumer scanners. they are being dumped everywhere for \$10. scanners tend to have trouble if the detail on the film is too dense.

Leonard Evens
24-Feb-2008, 17:30
One additional factor that should be considered is the covering power of the lenses. Medium format lenses are generally designed to cover just the frame, while large format lenses must allow for some movement. A lens designer intent just on covering the 4 x 5 frame probably could do better and such a lens would outdo a typical medium format lens on a 6 x 7 frame, when the results were enlarged to the same size final print. That my contention may be true is borne out by my experience with a Horseman 980 6 x9 camera and three Horseman lenses. That camera has view camera movements and the lenses are designed to allow for movement. There is no doubt that I can do better now with my 4 x 5 outfit for the same size final image after enlargement. The Horseman does pretty well, but it is not up to 4 x 5 standards.

Also, I'm a bit puzzled about the figures being tossed around. I did medium format photography for many years starting with a Rollie with a 2.8 Planar, which is a superb lens. I also have a Mamiyaflex with 105 and 180 mm lenses., and of course the Horseman. I've measured the resolutions of my lenses several times and I never came up close to 100 lp/mm. I haven't done any resolution tests with my 4 x 5, but I have cropped some 4 x 5 images down to about 6 x 7. I was surprised at how well the lens did. Visually, at least, I couldn't see any loss of quality compared to what I was used to with my medium format equipment.

Finally, it is important to remember that when you compose different elements of a photographic system, the resulting resolution is always less that that of the least element. In order to get it right, you need to do a complex mathematical analysis using MTFs, but there ae a couple of rough rules of thumb. One asserts, for example, that the resolution resulting from two components of equal resolution would be half that of their common resolution, while the other asserts that the resulting resolution is about 70 percent of that. In any event, there is a sizable reduction from such a combination. If the higher resolution of the two is much larger than the lower resolution, the result will be slightly reduced from the latter. Given all that, you would need extremely high resolution film not to reduce the resolution of the lens significantly. Such films exist, but it is more likely that, in practice, we are going to use film with resolution comparable to that of the lens.

In connection with this combination effect, if you are measuring resolutions, it is best not to take photographs of a resolution target and examine them. You should try to look at the aerial image directly under high magnification. If you don't, you may just be measuring the resolution of the film. . I've also done that when estimating resolution; it is easier than it might seem.

tjvitale
27-Feb-2008, 15:27
I don't doubt the Mamiya Mount 7 lens resolution data you quoted.

Where did you get it? Can I have copies (510-594-8799 fax) or the URLs. I like to use the data in a spreadsheet (you can have a copy) I've been constructing on lense resolution over the past few years.

Photodo.com has MTF data that show very flat, high contrst, 40 lp/mm plots for several Mount 7 lenses. I have not seen lens data sheets with such high resolution numbers for MF lenses; haven't seen it for 35 mm mount lenes either.

Looking for data.

Tim Vitale
510-594-8277

cotdt
27-Feb-2008, 15:32
Also from Photodo. Forget the Mamiya resolution figures, Zeiss 35mm lenses claim 320 lp/mm on B&W microfilm:

http://www.photodo.com/topic_96.html

Which I don't doubt, because every measurement of these lenses I've seen shows that it outresolves the measuring instrument. Although 320 lp/mm does seem a bit high, though.

Gordon Moat
27-Feb-2008, 15:51
http://www.hevanet.com/cperez/test/fourcameras.html

You might find this test including the Mamiya 7 to be of interest. Remember that when MTF graphs are made, they are done on a practical level, and rarely to test limits. So that 40 lp/mm might be the best you can do hand held, which is the manner in which a Mamiya 7 was intended to be used. Place that Mamiya 7 (or really any camera) onto a tripod, and very likely the ultimate resolution can be improved.

Some of the Zeiss testing is done under very ideal conditions, while other testing is based upon light transmission and not results on film. The main issue is that other people have trouble repeating the results from Zeiss. Unfortunately, this is missing the point entirely, which Zeiss make about resolution. In the view of Zeiss, when your lens resolution is the greatest aspect in your imaging chain, then it becomes the least of your worries. To put that another way, if your lens resolution is beyond your film resolution, then your film choice is a greater limit than your lens choice; this is a practical way to use this information.

Take a look through other data that Chris Perez and others have compiled while testing large format lenses. It seems that with tripod mounted large format gear, it is fairly straight forward to get 60 lp/mm on many different lenses. I think this is a practical application for comparison with other formats, and more realistic than theory.

Ciao!

Gordon Moat Photography (http://www.gordonmoat.com)

sanking
27-Feb-2008, 16:09
http://www.hevanet.com/cperez/test/fourcameras.html

You might find this test including the Mamiya 7 to be of interest. Remember that when MTF graphs are made, they are done on a practical level, and rarely to test limits. So that 40 lp/mm might be the best you can do hand held, which is the manner in which a Mamiya 7 was intended to be used. Place that Mamiya 7 (or really any camera) onto a tripod, and very likely the ultimate resolution can be improved.

Gordon Moat Photography (http://www.gordonmoat.com)

My recollection is that these tests were done one Tmax-100 film with the AF 1958 resolution chart, so at 100&#37; (or close to it) contrast.

I have a Mamiya 7 camera with several lenses and have no problem at all getting resolution figures of 80+ lines per millimeter on Tmax-100 film (which has resolutin of close to 200 lines per millimeter, with any of the Mamiya lenses at apertures of f/4 or f/5.6. My tests were done on a tripod with the AF target. And this is with exposure and development that gives a CI of about .55 for normal printing, not at high contrast

Sandy King

tjvitale
27-Feb-2008, 17:54
Many thanks for the references.

Love all that resolution data by Perez in the "4 camera" essay.

Would it be reasonable to say that 35mm & MF lenses can't do much better than 120 lp/mm.

I saw Photodo.com's reporting on Zeiss claims of 250 & 320 lp/mm for the 50 & 85 ZF lenses. Does anyone have the Zeiss Newsletter that data was pulled from? Is there MTF data to prove the claim or just the end point remarks?

After all the research I've done, I find it hard to believe that any over-the-counter lens could deliver more than 200 lp/mm.

Tim Vitale
510-594-8277

sanking
27-Feb-2008, 18:29
Many thanks for the references.

Love all that resolution data by Perez in the "4 camera" essay.

Would it be reasonable to say that 35mm & MF lenses can't do much better than 120 lp/mm.

Even with the same equipment and target (Mamiya 7, 80mm lens and AF target) I find 120 lp/mm impossible to achieve when exposing Tmax-100 for EFS of 100 and developing for a CI of about .55. I could possibly get there by rating the film at EFS 200 or 400 and developing for a higher CI. Perez indicates that he rated the film at EI 100, but does not indicate the CI to which he developed the film.

Another way of testing film/developer combinations is contact printing the very high resolution chrome on glass targets. If you work with these targets you will find that exact exposure and development is critical for getting maximum resolution. In fact. Even when contact printing on Tmax-100 film, and optimizing exposure and development, I have never been able to get more than about 150 lp/mm on this film, which is supposed to have resolution of 200 lp/mm.

Sandy King

Peter K
27-Feb-2008, 18:36
Would it be reasonable to say that 35mm & MF lenses can't do much better than 120 lp/mm.
No, it is much easier to make a short focal lens with high resolution as a lens used in the field of LF. E.g. a Tessar 50mm gives a better resolution as a Tessar 250mm.

High resolution lenses where used in the field of microphotography, later also for making microelectronic circuits. Some lenses for cinematography like the Kern Switar and the Cine Ektar where used in this field. But the resolution differs. So one has to select the best lens from a batch of lenses in the factory.

An interesting source in this field is:
G. W. Stevens, Microphotography, Photography and Photofabrication at Extreme Resolution, London Chapman and Hall 1968.

cotdt
27-Feb-2008, 19:46
TMAX is not good for testing resolution because it is too low. TechPan and similar microfilms are much better. But if TMAX can do 100 lp/mm, then the TechPan images look to have 4x the resolution, so at least 200 lp/mm is definately there. I guess I'll give the same comparison link again between TMX vs. TechPan:

http://www.nealcurrie.com/t-comp2.html

Robert A. Zeichner
27-Feb-2008, 21:12
There are some commonly used formulae for calculating the combined resolution of a particular lens and the film on which its image is being formed. I have often referred to one of these as the glass half full formula and the other, the glass half emtpy version. In the latter case the net resolution of lens and film are equal to the product of each divided by their sum. If a lens had a resolution of 100 lp/mm and the film had the same, their net resolution would amount to 50 lp/mm. Using the more optimistic formula, a lens and film of that resolution would have a net resolution of roughly 70% of the lesser of the two. In either scenario, the net resolution of lens and film would never exceed the weaker of those two links in the chain and always be somewhat less. That said, it is interesting to note that certain lenses made by Zeiss for use in making micro circuits have been rated at something like 5,000 lp/mm. To achieve that specification, it is necessary to use ultraviolet light! With visible light, there are theoretical limits that are much less. Of course in an application as specific as making micro circuits, we are dealing with flat fields, high contrast, almost non-existent geometric distortion and no consideration at all for chromatic performance. Resolution, while a good indicator of how sharp one's results might be, is by itself not enough to make a good pictorial lens. There are some excellent articles by Erwin Puts on the topic of photographic lens resolution and related issues here:

http://www.imx.nl/photo/film_2/the_resolution_of_fine_deta.html

cotdt
28-Feb-2008, 09:29
Curiously, Nikon also claims something like 5,000 lp/mm for their lenses, but they cost over a million dollars each. Those lens tests that cite 100-150 lp/mm max tend to be done at f/8 where diffraction becomes an issue and those figures are close to the theoretical maximum. You have to find a really sharp lens and test at f/2.8 IMHO. Modern computer-designed lenses should be able to get over 200 lp/mm. I have zero evidence of this but it seems reasonable based on what I've seen. The Zeiss Makro-Planars would be good candidates.

sanking
28-Feb-2008, 10:40
TMAX is not good for testing resolution because it is too low. TechPan and similar microfilms are much better. But if TMAX can do 100 lp/mm, then the TechPan images look to have 4x the resolution, so at least 200 lp/mm is definately there. I guess I'll give the same comparison link again between TMX vs. TechPan:

http://www.nealcurrie.com/t-comp2.html

I looked at the site above but frankly don't understand the point. How can the comparison be meaningful if the scans were made, as noted in the text of the study, with a cheap scanner? Assuming the cheap scanner was something on the order of an Epson 4990 or higher, maximum true resolution possible is on the order of 2000-2200 ppi, or about 40 lp/mm. I have been able to capture up to about 160 lp/mm on Tmax-100 film when contact printing with high resolution chrome on glass resolution targets. What can I learn about this film from a study that uses a cheap scanner that most likely can not capture much more than 40 lp/mm?

Other point. I am interested in resolution tests but only to the extent that they serve my interests in using films that give good pictorial results. I tried some of the microfilms years ago and while there is no question but they have very high resolution my experience was very negative in terms of obtaining a good tonal scale. Also, my understanding is that the Kodak TechPan film you reference is no longer available, in any format. And, since I don't use 35mm at all, are any microfilm type films available for MF or LF cameras? If not, the film is rather a moot issue for me.

Sandy King

cotdt
28-Feb-2008, 12:45
they were scans from prints so resolution of cheap scanner is not that big of an issue. i'm convinced that microfilms can give much better resolution than fast ISO 100 films, and my rough calculations tell me that TechPan can take full advantage of the available resolution of 8x10 paper.

you can get the full total scale from techpan by using kodak's special developer for it, Technidol. if you look really hard, you can still find 4x5 TechPan film. i saw some on ebay a few months ago. i think they used to make 5x7 and 8x10 TechPan films as well, before I was born.

Don Hutton
28-Feb-2008, 13:07
they were scans from prints so resolution of cheap scanner is not that big of an issue. i'm convinced that microfilms can give much better resolution than fast ISO 100 films, and my rough calculations tell me that TechPan can take full advantage of the available resolution of 8x10 paper.

you can get the full total scale from techpan by using kodak's special developer for it, Technidol. if you look really hard, you can still find 4x5 TechPan film. i saw some on ebay a few months ago. i think they used to make 5x7 and 8x10 TechPan films as well, before I was born.
That's great - they don't make Techpan nor Technidol anymore, so what's the point? You going to spend your life scouring Ebay for single rolls of film which you have no clue as to how they have been stored and are likely to be many years out of date? Why get excited about a film and developer combination which is unobtainable? It's my experience, that making good prints requires far more than fine grained film. In fact I've seen fabulous 16x20 prints made from very grainy 35mm TriX. I've also seen superb 40x50 inch prints made from 4x5 negs with that film you believe cannot produce a decent print - Tmax... Go figure.

cotdt
28-Feb-2008, 13:16
That's great - they don't make Techpan nor Technidol anymore, so what's the point? You going to spend your life scouring Ebay for single rolls of film which you have no clue as to how they have been stored and are likely to be many years out of date? Why get excited about a film and developer combination which is unobtainable?

I have a big secret stash of Kodak TechPan and Technidol in my freezer, including some 4x5 sheets. Besides, there are other microfilms now with similar properties to TechPan.

It's my experience, that making good prints requires far more than fine grained film. In fact I've seen fabulous 16x20 prints made from very grainy 35mm TriX. I've also seen superb 40x50 inch prints made from 4x5 negs with that film you believe cannot produce a decent print - Tmax... Go figure.

That's why this thread is a "purely theoretical" discussion. Of course the lighting and composition of a picture will almost be the most important. But the fact remains that that "16x20 print made from very grainy 35mm TriX" will not be critically sharp, I know because I use TriX a lot, and it does not even come close. For such 16x20 prints from 35mm, TechPan is the only way to the Light.

Julian Boulter
28-Feb-2008, 13:29
I would say that an important consideration to add here is image size and focal length.

I've been comparing Velvia transparencies of similar scenes shot with my Mamiya RZ67 with 110mm lens to my Arca 4x5 with 110 XL Super Symmar, to the eye the transparencies look very similar in quality and if anything the 6x7 just edges it.

Then I thought about it, even though the formats are different, the focal lengths are the same so if I were to take a shot of say a distant landscape with both cameras, the elements of the shot would be the same size on film e.g. trees, mountains etc. The only difference would be that the 4x5 shot would be a wider view of the scene. With the assumption that a larger image size should reproduce better, there should be no gain in quality using the larger format in this situation at any magnification using the same film (aside from quality/resolution of the lenses and the wider view).

However if I were to move in close to a plant and fill the frame using both formats, then the image from the 4x5 will be larger on film and I would then gain all the advantages of using the larger format.

If I were then to use a 210mm on my 4x5 for the distant landscape, the elements of the shot would be roughly twice the size of those shot by the 6x7 with 110mm lens and the field of view would be similar, then I would see an advantage due to the larger image size.

This is all theory by the way so please shoot me down where necessary!:p

cotdt
28-Feb-2008, 13:35
Julian Boulter, what you say is all true, but here the OP is comparing say a 50mm 6x7 lens versus a 110mm 4x5 lens to get the same picture from the same spot. In addition, to get the same depth of field, the 6x7 lens might be using f/11 while the 4x5 would be using f/22.

sanking
28-Feb-2008, 13:54
they were scans from prints so resolution of cheap scanner is not that big of an issue. i'm convinced that microfilms can give much better resolution than fast ISO 100 films, and my rough calculations tell me that TechPan can take full advantage of the available resolution of 8x10 paper.

you can get the full total scale from techpan by using kodak's special developer for it, Technidol. if you look really hard, you can still find 4x5 TechPan film. i saw some on ebay a few months ago. i think they used to make 5x7 and 8x10 TechPan films as well, before I was born.

I have no doubt but that TechPan has more resolution than a medium speed pictorial film like TMAX-100. However, the resolution of TMAX-100 with my Mamiya 7 lenses ia already so high (80+ lp/mm) that the only way I can pull out all the detail is with a drum scan of at least 4000 spi, maybe 5500 spi. At that point I can make prints 35X44" at 300 dpi or higher, resolution on print well beyond the threshold of human vision.

But in any event, TechPan is no more. So what other films like it are available in MF or LF? Just in case I might want to send some of my negatives off to Lenny Eiger to have scanned on his Azteck Premier at 8000 spi? I am curious about the limits of quality.

Sandy King

Nathan Potter
28-Feb-2008, 22:08
Historically I used to test lens resolution for microchip design using Kodak High Resolution Glass Plates (HRGP). The emulsion was thick and very slow but could achieve about 2000 lp/mm. I also used Kodalith Ortho photo mechanical film when larger format images were required but the development was very critical to control image creep. It may be that there is some current ortho mechanical film still available from other than Kodak that will achieve much better resolution than Tech Pan but I haven't kept up with the market.

I'm inclined to sort of agree with Sandy that it's hard to believe any panchromatic lens say in the 35mm to 6X7 format can achieve better than 150 line pairs per mm. resolution. To do better would require narrowing the bandwidth (using more monochromatic light) so as to reduce the lens sensitivity to chromatic aberration. This is the trick used for the extraordinary current microcircuit lenses mentioned above where reducing the illuminating wavelength proportionately increases the resolution. Additionally using a narrower bandwidth further increases the resolution. Currently monochromatic 190nm eximer laser light sources are in use for extreme resolution although I didn't think that it had reached the 5000 lp/mm. range stated above.

Leonard Evens has mentioned above that the proper method for determining resolution is to examine the aerial image directly with the apparatus mounted on a stabile optical bench and using a focusing telescope to capture the image plane. This eliminates the film variable as well as any vibrational variables and so delivers the intrinsic lens resolving power at the selected aperture and angle of view.

Jim Jones
29-Feb-2008, 08:32
. . . I am interested in resolution tests but only to the extent that they serve my interests in using films that give good pictorial results. . . .Sandy King

Yes, indeed. Lens testing on micro film at optimum apertures in monochromatic light can generate figures appropriate for exaggerated ads, but the results might not grace many galleries or homes. Some of my lenses aren't super sharp or contrasty, but they have produced pleasing images. Also, my old Ford sedan provides reliable, comfortable, and economical transportation, even if it isn't a Ferarri. That's what is important.

Joerg Krusche
29-Feb-2008, 13:01
Hi,

the 110 lp/mm on 6x7 format with a standard 100 film, was that lines per mm or line pairs per mm i.e. if it was line pairs that would mean 220 lines per mm .. sorry for asking this so lately in this discussion.

Joerg

ic-racer
29-Feb-2008, 13:39
that implies that the greater the magnification, the worse the quality. but i have found that not to be true with my 50mm minolta enlarger. it seems to be designed for big enlargement (>10x) and if you do a small 5x enlargement, the quality is terrible. my EL-Nikkor is the opposite and 5-10x enlargement seems to be the sweet spot. Here, I can get maximal sharpness at f/5.6 or even f/4, extremely sharp from corner to corner. I would say that this \$40 enlarger lens is optically perfect. However, if I go smaller than 5x, the quality actually goes down.

good enlargers with modern lenses are much cheaper than drum scanners, or even consumer scanners. they are being dumped everywhere for \$10. scanners tend to have trouble if the detail on the film is too dense.

I can share many of your expierences with those lenses and ones similar (like the Minolta 30mm) and those are good points. I actually was hinting more to the fact that when enlarging Minox to 16x20, a few micrometers of buckle can spoil things, while I suspect I could easily tolerate a whole millimeter of buckle or mis-alignment when enlarging 8x10 negatives to 16x20.

Now that I think of it there is ONE thing that is better when enlarging the mini negative. That is 'evenness of illumination.' I think it is more of a engineering challange to make big enlarger light sources that have even illumination.

sanking
29-Feb-2008, 14:35
Hi,

the 110 lp/mm on 6x7 format with a standard 100 film, was that lines per mm or line pairs per mm i.e. if it was line pairs that would mean 220 lines per mm .. sorry for asking this so lately in this discussion.

Joerg

It was not my study but I am pretty sure that the resolution values were given in lines per millimeter, not line pairs per millimeter.

Sandy King

tjvitale
29-Feb-2008, 16:18
Where do you see those Nikon claims for 5000 lp/mm?

cotdt
29-Feb-2008, 16:31
Where do you see those Nikon claims for 5000 lp/mm?

somewhere on the nikon industrial lenses website, but i can't find the link anymore. they are the lenses used to make your computer chip, so very very high resolutions are needed. these lenses cost millions of dollars each. i would love to own one.

Robert A. Zeichner
29-Feb-2008, 18:13
Here is a link to the Zeiss site in which their micro chip lithography optics are described:

http://www.smt.zeiss.com/C12567B0003C017A/Contents-Frame/BF914264CDE20058C1256D580037B4B1

Ken Lee
29-Feb-2008, 18:24
Medium format is vexing. The cameras are certainly more portable than LF cameras, but it seems to me that unlike View Cameras, nobody every came up with an optimal design.

Those fabulous Mamiya results presume no cropping, and a steady tripod with cable release or self-timer. The camera is lighter than a view camera, but then again, it's got a limited focusing range. And... it's a rangefinder. And it's roll-film. You have to develop all the shots together, so forget about DBI, BTZS, etc.

Once you start cropping those MF images, the number of lines per millimeter starts to slip, and your blood pressure starts to rise commensurately. "I spent \$2k to get a decent scanner for this thing... but I'm still tossing data away ?".

Or... you could get a nice cheap 4x5 or 5x7 with a merely OK lens, and with the same tripod and cable release, you get to use an infinite variety of lenses, with no limit on focusing range and parallax-free viewing. You also get to use an affordable scanner, and develop the negatives individually or together... etc.

I have 3 medium format folding cameras from the 1950's. I love them, but I don't try to squeeze every micron of data out of them. They fit in the pocket, and are good enough to make nice grainless 11x14 images. For serious work, I use a View Camera.

Nathan Potter
29-Feb-2008, 21:46
The issue of resolution comparing medium format to large format has been touched on in other threads. I would add to Kens' comments above by saying that the swing and tilt ability of a view camera allows one to make use of the Schiempflug relationship by keeping an extended subject field in critical focus whereas a fixed film plane will have to rely on the hyperfocal lens setting at an undesirably high f/no for extended depth of field. Resolution is degraded to a series of circles of confusions away from the actual film focus point (airy disc) by stopping down the lens of a fixed image plane camera (not to mention creeping diffraction effects). In practical photographic situations one usually is faced with depth of field situations and the flexibility of the view camera seems unsurpassed.

Nate Potter, Austin TX.

sanking
29-Feb-2008, 22:43
Ken,

No way to compare Mamiya 7 to medium format folders from the 50s. Resolution of Mamiya 7 is way beyond the capability of the old folders.

If Leica is an optimal design for 35mm, as many people believe, then Mamiya 7 is an optimal design for medium format,IMO. No, compared to view cameras there is no close focus, no perspective control, and no shift and tilt to control plane of focus. That said, my personal belief is that in the majority of typical landscape scenes Mamiya 7 can equal or beat 4X5 performance on the negative and at the same print size.

But, as we have discussed before, in order to pull all of the detail out of a Mamiya 7 negative, and make it competitive with 4X5, a drum scan is necessary. Even a dedicated film scanner like the Nikon 9000 leaves a lot of detail on the table when scanning well-exposed Mamiya 7 negatives and transparencies.

Sandy King

cotdt
29-Feb-2008, 23:10
But in any event, TechPan is no more. So what other films like it are available in MF or LF? Just in case I might want to send some of my negatives off to Lenny Eiger to have scanned on his Azteck Premier at 8000 spi? I am curious about the limits of quality.

Sandy King

Hi Sandy, for MF the Rollei Pan 25 is very similar to the old TechPan:

http://www.freestylephoto.biz/sc_prod.php?cat_id=403&pid=1000001679

Should allow for massive enlargements, but for normal contrast you need the same kind of special microfilm developer that TechPan used, such as Technidol or something similar like this:

http://www.freestylephoto.biz/sc_prod.php?cat_id=301&pid=1000002500

If you go for it, please keep us informed with your results!

sanking
1-Mar-2008, 10:59
In a previous message I wrote, "my personal belief is that in the majority of typical landscape scenes Mamiya 7 can equal or beat 4X5 performance on the negative and at the same print size." Majority may push the envelope just a bit much, so I would amend this to Mamiya 7 in 6X7 cm format can equal or beat 4X5 with many typical landscape scenes. 4X5 is clearly a more flexible system and there are situations where the use of swings and tilts is crucial to getting adequate depth of field without closing down the lens too far.

If movements are not required I am pretty sure that if we only consider resolution Mamiya 7 can virtually always equal 4X5. The optics of Mamiya 7 system are sharper, and this fact, together with the relatively small difference in magnification factor of a 6
X7 cm negative compared to 4X5, pretty much equals out the two formats. In terms of tonal values I believe one will need to use a slower film (finer grain) in 6X7mm to match 4X5 in any size larger than about 11X14.

Sandy King

Dan Fromm
1-Mar-2008, 13:33
Joerg, I've been ignoring this thread for a while. Just notice that you'd posted to it so read your contribution.

I get your point, couldn't agree with you more. But I expect you'll be ignored.

Best,

Dan

Joerg Krusche
1-Mar-2008, 13:43
Dan,

agreed, had two beers, sorry !

Joerg

sanking
1-Mar-2008, 16:01
Hi Sandy, for MF the Rollei Pan 25 is very similar to the old TechPan:

http://www.freestylephoto.biz/sc_prod.php?cat_id=403&pid=1000001679

Should allow for massive enlargements, but for normal contrast you need the same kind of special microfilm developer that TechPan used, such as Technidol or something similar like this:

http://www.freestylephoto.biz/sc_prod.php?cat_id=301&pid=1000002500

If you go for it, please keep us informed with your results!

Thanks, I may give this a shot.

However, my current working procedure with Mamiya 7 for B&W is Fuji Acros in Pyrocat-HD. This combination gives me such high resolution (80-100 lp/mm) and fine grain that the only way I could take advantage of higher performance in a film would be with a drum scan at about 6500 spi *effective* resolution. If the Rollei film can do 150 lp/mm I would need a drum scan at about 8000 spi to take advantage of it.

Sandy King

Ken Lee
1-Mar-2008, 16:45
Sandy - It would be great to see a some samples. Could you share a few ?

sanking
1-Mar-2008, 17:33
Sandy - It would be great to see a some samples. Could you share a few ?

Ken,

The remarks I have made re: Mamiya 7 6X7 cm format versus 4X5 have all been opinion based, and presented as such, as opposed to presented as fact. The only way to really compare results from the two formats is to do a series of side-by-side comparisons, and then optimize results for a number of final print sizes. This will require a lot of planning and a fair amount of work, as I am sure you understand. At this point in time I don't have any real good comparison results to share.

Sandy King

Ken Lee
1-Mar-2008, 17:52
I understand. And we know that when you perform a study, you like to do it properly. Your judgements and recommendations have never lead me astray. I'll accept this information as more of same.

Steve Hamley
1-Mar-2008, 18:34
Folks.

I think Sandy nailed it - my own opinion is that if you can get the picture with the Mamiya 7(II), it will equal 4x5 in terms of resolution. I have both. If you need movements or more than a limited lens range, 4x5 wins every time. I carry the Mamiya for scouting and travel. For really serious stuff, it's 4x5 (or 8x10, or 8x20).

BTW, on a recent trip to Columbus, OH, Jim at Midwest said the Mamiya 7 and 7II are still holding their value due to the quality of lenses, film flatness, yada, yada. Pretty incredible these days for a MF film platform.

Cheers,

Steve

sanking
1-Mar-2008, 18:41
I understand. And we know that when you perform a study, you like to do it properly. Your judgements and recommendations have never lead me astray. I'll accept this information as more of same.

Ken,

You will find on the web lots of opinion on the Mamiya 7 versus 4X5 issue. However, when it comes to MF versus LF most people tend to discount other opinions and the chicken lids come down. That is, folks have their opinion and are sticking to them.

But consider this. Two weeks ago I was at in Toronto at one of the top high end printing labs in North America. While I was there a customer was there to pick up some 30X40" color prints. One of the printers there, a person with long experience and a very discerning eye, looked at the prints, and remarked, 8X10? The customer replied, no, Mamiya 7II and drum scanned Velvia.

If one of the top professional printers in North America looks at a 30X40" print from a MF camera and on first glance finds it to be on a level with 8X10 quality, I am impressed.

Sandy King

2-Mar-2008, 02:38
Hello Sandy,

After reading your comments on the Mamiya 7, 4x5 movements and scanner resolution I wonder why you don't shoot with a 6x9 view camera and superior lenses such as the Rodenstock S series?

I have considered selling my TK 45 and moving to the smaller TK. I scan with a Imacon and would enjoy a more portable system. I hike long distances and the TK with 3 lenses can hurt.

David Millard
2-Mar-2008, 07:43
Hello Sandy,

After reading your comments on the Mamiya 7, 4x5 movements and scanner resolution I wonder why you don't shoot with a 6x9 view camera and superior lenses such as the Rodenstock S series?

I have considered selling my TK 45 and moving to the smaller TK. I scan with a Imacon and would enjoy a more portable system. I hike long distances and the TK with 3 lenses can hurt.

Thanks for bringing this up Spencer. I don't know why "view camera" and "medium format" are so firmly considered to be mutually exclusive categories in many people's heads, but I find rollfilm view cameras to be a great combination of quality and convenience.

sanking
2-Mar-2008, 08:29
Hello Sandy,

After reading your comments on the Mamiya 7, 4x5 movements and scanner resolution I wonder why you don't shoot with a 6x9 view camera and superior lenses such as the Rodenstock S series?

I have considered selling my TK 45 and moving to the smaller TK. I scan with a Imacon and would enjoy a more portable system. I hike long distances and the TK with 3 lenses can hurt.

Could you not find a roll film back for the TK 45 and experiment with the smaller format to make sure it will suit your needs?

The major issue I have with MF is that you need a drum scanner or professional flatbed with true resolution of over 5000 spi to pull out all of the detail in a negative made with a very sharp lens.

Sandy King

2-Mar-2008, 09:01
Yes, I have a roll back and I am going to make some test. But, I guess I need to ask the question in a different way.

I have access to an Imacon. The maximum resolution for 4x5 is 2040ppi/16bits. Would I get equal results or better if I had the 6x9 and used a scanner with 5000 ppi? I thought the image size effects the resolution of the scan?

A more portable camera that gives me full movements would be ideal if I could get the same quality. I print most images 28x36 inches at 240ppi. If my calculations are correct that is about the limit for a 4x5 scan at 2040ppi. I am printing to an Epson 9600. One is dedicated to color and the other NK7.

How are you printing your final images (print size, paper, printer, etc…) and why do you need to scan at such high resolution? Do you convert the files to another set of numbers after the scan?

sanking
2-Mar-2008, 09:28
Yes, I have a roll back and I am going to make some test. But, I guess I need to ask the question in a different way.

I have access to an Imacon. The maximum resolution for 4x5 is 2040ppi/16bits. Would I get equal results or better if I had the 6x9 and used a scanner with 5000 ppi? I thought the image size effects the resolution of the scan?

A more portable camera that gives me full movements would be ideal if I could get the same quality. I print most images 28x36 inches at 240ppi. If my calculations are correct that is about the limit for a 4x5 scan at 2040ppi. I am printing to an Epson 9600. One is dedicated to color and the other NK7.

How are you printing your final images (print size, paper, printer, etc…) and why do you need to scan at such high resolution? Do you convert the files to another set of numbers after the scan?

Spencer,

If the effective resolution of your scanner for MF is really 5000 spi, and if you can can about 80-100 lp/mm of detail on your negative, and if you use a fine grain film, I think it is likely that you can get as much quality from 6X9 cm MF as from 4X5 scanning at 2040 spi.

My comments about needing a drum scan to pull all of the detail from a MF negative with 80-100 lp/mm of detail is a theoretical assumption that one would want to pull maximum quality from the negative, not because I make very large print. My own printing is done with digital negatives in carbon transfer or pt/pd, and I tend to print small rather than large. For example, I just printed last night sixteen 5X7 digital negatives from 6X4.5 cm original negatives that I scanned at 2540 spi on the Leafscan 45. I will contact these same size in carbon transfer for the portfolio.

Sandy King

2-Mar-2008, 09:40
THANKS. I understand. Now I will do my own research. Do you give workshops on digital negatives and carbon prints?

Spencer

sanking
2-Mar-2008, 09:47
THANKS. I understand. Now I will do my own research. Do you give workshops on digital negatives and carbon prints?

Spencer

I am scheduled to do a workshop on carbon transfer printing in June at the Photogrpher's Formulary in Montana. I also do one-on-one workshops in my own workspace in South Carolina.

Sandy King

2-Mar-2008, 10:34
I grew up in Atlanta and my parents live there. I travel south from Boston occasionally to visit them. Where is the nearest airport? If believe you are a professor at Clemson University? How do I make appointments for your workspace? I would need to learn the entire process. Do you a website?

Spencer

sanking
2-Mar-2008, 10:43
I grew up in Atlanta and my parents live there. I travel south from Boston occasionally to visit them. Where is the nearest airport? If believe you are a professor at Clemson University? How do I make appointments for your workspace? I would need to learn the entire process. Do you a website?

Spencer

I do not have a personal web site at this time but you can read about carbon printing in my article at http://unblinkingeye.com//Articles/Carbon/carbon.html

There is also a small portfolio of my work here. http://store01.prostores.com/servlet/thecontactprintersguild/Categories?category=PHOTOGRAPHER&#37;3ASandy+King

Nearest airport to my home is GSP (Greenville-Spartanburg, SC). I live about 20 minutes from the airport.

I was a professor at Clemson University for many years but retired last year.

I prefer to schedule carbon workshops October through May. In the summer, with high humidity, I like to print with the iron processes (vandyke, kallitype or pt/pd) so I am usually off my carbon game from June through September.

Sandy

cotdt
7-Mar-2008, 03:46
they test Minox lenses with TechPan film, and got 177 lp/mm f/3.5. so assuming TechPan itself has a resolution of 320 lp/mm, then that means that Minox lens has an aerial resolution of 360 lp/mm.

http://www.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=000KCo

they also test the Nikon 17-35 f/2.8 lens and also got over 400 lp/mm aerial resolution (200 lp/mm on TechPan).

So 35mm can hold its own, with the best microfilms. But there is no really good color films, even Velvia 50 can't hold nearly as much resolution as medium speed ISO100 B&W film.