Re: ye olde film v D debate, a bit long
William Robb wrote: [...] Note, if all you want the lens for is shooting resolution charts, then go hard, and your 100 lp/mm number is probably as good a guess as any, and film is not the limiting factor, as Tech Pan will resolve over 200lp/mm at 1000:1. If you want to know what the lens will really do in a pictorial situation, toss the USAF chart, it's isn't worth the paper it's printed on. The best resolution test I have found is distant tree branches against the sky on a still day. William Robb And examine the negative with a loupe... (A great way to get dissatisfied with your lab's printing work!) In a use-what-you-have mode, being a city dweller, I shoot a lot of distant telephone and power cables against the sky. at least with your method, when you're done, you still have some scenery with trees. keith whaley
Re: ye olde film v D debate, a bit long
I just wanted to point out that the subject line for this thread is one of the world's greatest understatements. A bit long Oh, yeah... -- Mark Roberts Photography and writing www.robertstech.com
Re: ye olde film v D debate, a bit long
- Original Message - From: Tom Addison Subject: Re: ye olde film v D debate, a bit long 40lpmm is surely the likely resolution of a really good lens-film system... go back and have another look.. Sure, 1/( 1/40 + 1/40) gives.. 20. William Robb
Re: ye olde film v D debate, a bit long
- Original Message - From: Mishka Subject: Re: ye olde film v D debate, a bit long you are entitled to your opinion of course. for the rest of the world, a real world test vs USAF http://www.hevanet.com/cperez/test/fourcameras.html Yup. I would have left out the USAF chart myself, but he seems to have done a good real world test. btw, in my original post i haven't even mentioned either contrast or USAF. and, for discussion of digital sensors, resolution on film is absolutely irrelevant. You can't separate subject contrast from the mix and claim to have an accurate result, unless you are totally uncredible. From: Mishka Subject: Re: ye olde film v D debate, a bit long finest lens resolve far more than that. even on film. I was responding to your post on the subject. I hadn't noticed that you had introduced an irrelevancy. William Robb
Re: ye olde film v D debate, a bit long
On 14 Mar 2004 at 7:30, William Robb wrote: you are entitled to your opinion of course. for the rest of the world, a real world test vs USAF http://www.hevanet.com/cperez/test/fourcameras.html Yup. I would have left out the USAF chart myself, but he seems to have done a good real world test. All my USAF chart and real world tests seem to dutifully correlate, so much so that I now trust the USAF chart tests (which are far easier to perform and provide absolute comparisons if required). Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
Re: ye olde film v D debate, a bit long
--- Rob Studdert [EMAIL PROTECTED] wrote: We were talking 35mm format. So what would be the advantage of providing more than 14MP density on a 35mm frame? You know that drawing an analogy to RAM capacities is entirely inappropriate in this case. Pass the coffee Time for maths! in round figures 14Mp is; lets say 4800x2900. Take the long side of 35mm = 36mm and think of lines per mm. well great film and ggreat lenses may deliver 80 lpmm but that is probably a theoretical figure few people get in practise One line is a discernable pair of light dark transitions so it takes TWO pixels 4800/36/2=66.67 lpmm!!! we are getting near to the best that lenses can provide. Or are we? The resolution of a system of more than one resolution is not as great as the best figure... No it is:- 1/rsum=1/r1+1/r2+1/r3 etc. so a lens that give 80lpmm and a sensor that gives 67lpmm yealds 36.5lpmm!!.. Conclusion, there is a reason for more pixels right up to the point where the resolution of the sensor exceeds the resolution of the lens by an order of magnitude (10x) Then your pics will only be limited by the quality of the lens! That's about 1.5Gig pixels! Anyone care to compute where in this problem the wavelength of light will start to come into play?... time for bed here.. Tom Addison, an electronics engineer who works for physicists, a folk singer and flute player, Oh and I've been using Pentax cameras since my (now ex) wife bought me one in 1977...That's all folks.. ___ Yahoo! Messenger - Communicate instantly...Ping your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html
Re: ye olde film v D debate, a bit long
- Original Message - From: Tom Addison Subject: Re: ye olde film v D debate, a bit long Time for maths! Figure out what it needs to be for 40 lpmm, which more closely resembles what the finest lenses really churn out. William Robb
Re: ye olde film v D debate, a bit long
On 13 Mar 2004 at 19:12, William Robb wrote: Figure out what it needs to be for 40 lpmm, which more closely resembles what the finest lenses really churn out. That's easy *ist D delivers a system resolution with top end lenses of almost 45lpmm, a little more would be nicer but probably not necessary. If I need more data I usually up-format :-) Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
Re: ye olde film v D debate, a bit long
finest lens resolve far more than that. even on film. difraction limited lens can get 100 lp/mm at at f5.6, 50% mtf. so the 40 lpmm is mostly limitation of the film, afaik. mishka William Robb wrote: Time for maths! Figure out what it needs to be for 40 lpmm, which more closely resembles what the finest lenses really churn out. William Robb
Re: ye olde film v D debate, a bit long
Come on now, Bill. He just did it for 36 lpm. 40 lpm is an overall system figure. The arial resolution of the lens is much higher, as is the film resolution. Folks have explained all this on the list over and over. Still we keep getting these outbursts of mumble-jumble. Tom gave the formula for any number of items in the system. Overall-res = 1/((1/lens-res) + (1/film-res) + (1/enlarger-lens-res) + (1/elargeing-paper-res) + (1/viewing-loupe-res)) you can add any thing else you can think of to the equation, the answer will always be lower than the lowest figure in the equation. A diffraction limited large aperture lens can have arial resolutions around 600 lpm. The finest grain BW film around 200 lpm. 1/(1/600) + (1/200) = 150 lpm. Which is about the maximum resolution for a film based system. We are talking Tech Pan here, and maybe a $5000 50mm lens. With a good 50/1.4 Pentax lens we are talking maybe 100 lpm. The same Pentax lens with color negative film you are talking that 40 lpm you mention (on film, a print would be far lower). -- William Robb wrote: - Original Message - From: Tom Addison Subject: Re: ye olde film v D debate, a bit long Time for maths! Figure out what it needs to be for 40 lpmm, which more closely resembles what the finest lenses really churn out. William Robb -- graywolf http://graywolfphoto.com You might as well accept people as they are, you are not going to be able to change them anyway.
Re: ye olde film v D debate, a bit long
- Original Message - From: graywolf Subject: Re: ye olde film v D debate, a bit long Come on now, Bill. He just did it for 36 lpm. 40 lpm is an overall system figure. The arial resolution of the lens is much higher, as is the film resolution. Folks have explained all this on the list over and over. Still we keep getting these outbursts of mumble-jumble. Tom gave the formula for any number of items in the system. Overall-res = 1/((1/lens-res) + (1/film-res) + (1/enlarger-lens-res) + (1/elargeing-paper-res) + (1/viewing-loupe-res)) Well, then, here is the math for a quality optical system using a good quality colour film: 20. William Robb
Re: ye olde film v D debate, a bit long
- Original Message - From: Mishka Subject: Re: ye olde film v D debate, a bit long finest lens resolve far more than that. even on film. difraction limited lens can get 100 lp/mm at at f5.6, 50% mtf. so the 40 lpmm is mostly limitation of the film, afaik. Lens tests are universally (and erroneously) done using a high contrast (50:1 or higher) test chart. This gives totally useless information for the pictorial photographer, since lens resolution is directly tied to subject contrast. If a lens is tested at the more reasonable 1.6:1 toc, then more useful resolution information is made available. Note, if all you want the lens for is shooting resolution charts, then go hard, and your 100 lp/mm number is probably as good a guess as any, and film is not the limiting factor, as Tech Pan will resolve over 200lp/mm at 1000:1. If you want to know what the lens will really do in a pictorial situation, toss the USAF chart, it's isn't worth the paper it's printed on. The best resolution test I have found is distant tree branches against the sky on a still day. William Robb
Re: ye olde film v D debate, a bit long
- Original Message - From: Mishka Subject: Re: ye olde film v D debate, a bit long finest lens resolve far more than that. even on film. difraction limited lens can get 100 lp/mm at at f5.6, 50% mtf. so the 40 lpmm is mostly limitation of the film, afaik.
Re: ye olde film v D debate, a bit long
William Robb wrote: If you want to know what the lens will really do in a pictorial situation, toss the USAF chart, it's isn't worth the paper it's printed on. The best resolution test I have found is distant tree branches against the sky on a still day. William Robb you are entitled to your opinion of course. for the rest of the world, a real world test vs USAF http://www.hevanet.com/cperez/test/fourcameras.html btw, in my original post i haven't even mentioned either contrast or USAF. and, for discussion of digital sensors, resolution on film is absolutely irrelevant. best, mishka
