Sure, it can work. Why not?
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Sure, it can work. Why not?
Since this popped back up, I made a discovery this week. When I tried my initial experiment with my 5D several years ago, I found my 50mm Compact Macro (with life-size converter) resolved grain, but the grain was bigger than it seemed under a loupe.
Well, duh. It was aliasing. My 12+ megapixel 5D, at 1:1, has a resolution of about 2800 spi. I remember from old film scanners, like my former Minolta Multi II, that aliasing was a problem with some film.
I found this out because I’m once again trying to make headway on digitizing my old Kodachromes much more efficiently than running them through the scanner. I came upon an old Nikon PB4 bellows, with the slide duplicating attachment. I thought I might get better results than I had gotten with my Illumitran, which could never manage contrast with its internal strobe, or overcompensated with the contrast control unit even on its minimum setting. I mounted an old 55mm Micro-Nikkor and put a Kodachrome slide in it. The result was an almost perfect histogram, but with radical graininess. That’s when the bell rang in my head.
My 5D is 13 years old so I thought maybe it’s time to upgrade, but I’m already mid-spending-spree in a Pentax 645z kit, so I cheaped out and bought an experienced 5DII, for about a fifth the price of the current model. The 21mp sensor will give me about 4000 spi at 1:1. That should eliminate aliasing.
Of course, I could also scan 4x5 with the 645z, which gives about 4800 spi at 1:1, with no AA filter. I do have the 120mm Macro, which does focus to 1:1. 16 photos would cover 4x5 with plenty of overlap for stitching. Hmmm.
(And I have other plans for that bellows: 1. It’s a more rigid design than the macro apparatus I built for scanning 4x5, 2. The tilt will help with photographing watch faces—a current interest—and 3. I found an old but late model 100mm Bellows Takumar that might find a happy home on those bellows.)
Rick “who wants to put a book together of old slides for a friend who accompanied me on those excursions, who needs a little uplift this year” Denney
No, it won't, at least not if you want to copy B&W film, chromogenics excluded. My LS-9000, which delivers nominally 4000 spi, does nasty things to Tri-X. I don't know for sure how far one needs to go - 6000? 8000? But 4000 plainly isn't enough. Mind you, it's adequate for chromogenic films; the dye clouds degrade gracefully under less than perfect description. And it might be OK for a film like TMX, where the grain is so fine there's no prayer of capturing it other than under a microscope. But ISO 400 or old-fashioned-grain medium-speed silver films - no.
FWIW, I did some experiments with a rented 5DsR and a 75mm Apo-Rodagon-D 1:1 on a bellows a few months back with the hope that 6792 pixels in 24mm would give me a visible improvement. But nothing doing - couldn't focus it reliably enough with that camera's live view to achieve any advantage.
At some point it will work - a DSLR or medium format DSLR will combine enough pixels with good enough live view at the pixel level so one can actually achieve the theoretical resolution. But so far as I'm concerned, we're not there yet.
EDIT: Another observation: the 5DII has an AA filter. That, not the nominal resolution, may well take care of what you're perceiving as aliasing - at the cost of actual resolution. Depending on how far you want to enlarge and on your taste in image character, it may work for your purposes even so.
Live view is not accurate enough in my experience. No, I don’t know why. I use a Velmex 4000 Unislide, and focus is determined by looking at full res files.
Need to do the arithmetic to check this, but I suspect we're not yet at the point of getting 1 pixel = 1 effective dot in the LCD.
Checking the full-res files is of course the acid test. It would be practical for me if I had a dedicated setup with a precisely- and rigidly-aligned mounting stage so that I didn't have to go through tedious trial and error for every exposure. Maybe someday... or if and when live view gets to be good enough, that should solve the problem.
I put a 1.7x magnifying loupe on a LCD while focusing. Some can connect external monitor and it can be even better.
For what I like high-end scanners: calculated resolution is their optical resolution. With cameras it's more like only 70% of calculated. You can see it in my tests.
But for what I like cameras plus high-end lens is that the image is calm and undistorted.
I can only report my experience with my D600. Shooting tethered to a big screen and focusing with live view was not optimal.
On my D7200, copying 35mm BW negs using a lens on a bellows, live view focus is dodgy. Part of it is that just a breath on the focus knob moves focus too quickly. I do better on the ground glass.
What about using an eyepiece magnifier?
Rick “thinking we need a grain focuser” Denney
Can't have a grain focuser until you have enough resolution in the imaging sensor to capture the grain cleanly. And then you need a live view that will let you actually see it, at 1:1, as you are setting up the capture. Note that AA filters, sensors that record images through a Bayer (or other) matrix and live view LCDs that build the displayed image out of separate RGB dots are not our friends in this task.
Everything else we're talking about is just fiddling with different ways of looking at an inherently mushy capture in the hope that we can somehow make it look slightly less mushy.
EDIT: To be clear: current technology accessible to consumers is not up to the task of an exact reproduction of the original down to the grain level, so we all have no choice but to compromise at some point, and everyone is entitled to decide for themselves how good is good enough. And we shouldn't forget that copying film on film is also a very lossy process - no illusions here about a lost golden age when everything was perfect.