And many contributed before NASA to provide the required science.Originally Posted by calebarchie
And many contributed before NASA to provide the required science.
Why is 9000? needed. I thought the 2300 of the V700/750/800/850 was perfect. Isn't that what you have been telling us for years?
(I am breaking a lot of rules here - some of my own, but I justify it as being only a brush on the surface of all the work involved, pretty much irrelevant being from over year ago now - did I mention I now have neurological condition and require brain surgery soon? Thank you for comments anyhow)
So let me get this right, you didn't manage to procure an image of this claim? Isn't that like the anti-thesis of science? Sorry I am so confused right now... but (re)search and you shall find, I guess.
This is with the Nikon EL 2.8 50mm at x3 and f/5.6
Let me explain that my USAF 1951 slide is defective in some places, I bought it for $25 knowing it had defects in many group 7 patterns (and 5.3 and 5.5), no problem because I wanted it to rate a V850. The Nikon D5100 was not mine, a friend came with it and we made the test without the SD card in "shop mode", the rest of shots were made with the smartphone just to show the method. When I placed my SD card I took a defective pattern, but when I saw it my friend and the D5100 had flied. I needed a DSLR with tiliting screen to focus.
Anyway I can ensure you that the sharp shapes that are seen at 7.5 are exactly like they are, squares with some ripples, as seen in the Leitz microscope I use. Anyway the shapness that is seen in the high 7 group element boundaries is atonishing, I said 9000 as a conservative number, but I'm pretty sure it really goes beyond 10000 in the Group 8.
Anyway I proposed a "particular" (perhaps innovative, I don't know) method to measure that, this is a dslr without lens on the easel, with flipped screen.
Many people have a Nikkor EL 50 at home, and many have a DSLR with tilting screen. So many may check it if they want.
So I saw well 7.5 with my eyes but I only have this image as a proof. But just see that Group 6 is way sharper than in your sample.
Is it a surpise that a EL 50 2.8 is (on film) 200lp/mm able ?
That target is not in the best shape and unfortunately cannot really make much of it. You should also avoid modifying results despite test conditions (like setting bp/wp/converting to b&w if colour sensor) to alter perceived resolution. It throws out all other factors including bayer limitations, flare and optical aberrations (fringing and so forth) which you need to evaluate as a whole in such a system.
You are modifying your posts after I have posted mine. Sorry, this is just affecting fluidity of conversation and I am not so sure if there are any other reasons for it either.
Any case, I am just going to walk out of this to avoid any further unnecessary energy expenditure in my current condition, sorry..
Ok, thanks. I desire you recover soon your health.
This is the original crop, still very contrasty, as histo shows.
Frank, I think the same, 2500 efective dpi is enough for most LF jobs. In fact this matches what LF lenses usually resolve in practical shots, 40lp/mm or 50. I'm not alone saying this. Anyway YMMV.
While a top notch lens may deliver 70 lp/mm in a lab test it happens that in practical shots little may be in perfect focus but in DOF, also at f/22 4x5 lenses at diffraction limited, film flatness, aligment, shake...
Also I've always said, and I reiterate, that a drum extracts near twice the effective pixels (area) from sheets and that has an effect if the shot is (not usual) technically perfect and iat same time we enlarge well beyond 1m.
But then it happens that a drum scan at 4000 dpi is very expensive and usually sheets are drum scanned at 2000 dpi, and in such a case the V850 resolves more.
Why 9000? I don't say why, what I say is that a DSLR scanner may deliver +9000 with a reversed enlarger lens and long draw, which is just the enlarger setup. This would require to stitch many crops for LF.
Also it's clear that if one wants 5000 dpi (faster) with that setup then it can be done by lowering the enlarger's head.
And I've also said that sometimes the V850 comes a bit short for 35mm film, because tipically 35mm lenses resolve more lp/mm than LF lenses.
You can avoid the need for a flip out screen if you tether the camera. Most cameras support this.
Interesting! And I do believe that lots of older lenses are quite good just as you wrote about your Rodagon. I was "scanning" with a rodenstock 80mm APO enlarging lens fit to my Rolleiflex 6008AF with multishot back with the negative over a light table masked. In review, the best results I got this way were better than my iQSmart3 can do (by a small but noticeable margin in micostep mode). But the big problem was focusing since the DOF was rather thin . Now I see your idea to project the negative and this makes a lot of sense since the DOF would be larger this way and focusing accurately less of a challenge.
Posting Permissions
Reply With Quote
Bookmarks