rephotographing film as a means of scanning

Discussion in 'Digital Darkroom' started by chris_autio, Sep 4, 2020.

  1. I've been doing this over the years in a haphazzard approach to show clients specific images that I haven't yet printed. Now I see that excellent equipment is now available using a 5600 kelvin light board. And good U-Tube videos to prove it. I am ready to jump in, but would like some heads up from those who have practiced it seriously. Just like making a film, I plan on editing out a lot. Buy new negative sheets. Reorganize. Are you really able to extract the sharpness level to see grain in 100 speed film?
     
  2. Yes. For 35mm film at least. All that's needed is a camera with 24 megapixels or more.

    There have been quite a few threads in this and other fora on the subject. Do a search.

    Here's a 100% cropped section of colour negative copied with 24mp and 36mp digital cameras, and with a film scanner.
    Scan-Copy_comparison.jpg
    The grain is most faithfully rendered in the 24mp copy IMO. The 36mp camera used has an AA filter, which appears to have distorted the grain pattern slightly.

    I don't have a T-max 100 example to hand, but a 24mp digital copy of that comes out grain-sharp as well.
    Do you have a link to what you have in mind?
     
    Last edited: Sep 5, 2020
  3. Absolutely.

    Done with care, lots of things "work". It's more a matter of workflow and convenience. Most films do not produce additional quality in scans above 4000 ppi, regardless of the means used.
     
    digitaldog likes this.
  4. It is via the Digital Lisa, Slimlite Plano light table. It looks like quite a few steps using a magnetic edge to flatten the image. I'll be using a Nikon 850 with a Micro Nikkor 55mm. Looks great on all my medium format, but will need a macro spacer to fill digital to the full frame of 35 mm negatives and positives. May just make my own box, with Plexiglas atop, and use my flash units. Program promotes Lightroom, but I am most familiar with Photoshop. Just gotta jump in. Hoping to make them sharp enough for at least 20x24s
     
  5. Best bet is to find a decent enlarger negative carrier. Just pinning the film down on a bit of glass or perspex isn't going to hold it flat enough.

    My filmholder is a 35mm neg carrier from an unknown large-format enlarger - a DeVere maybe? Anyhow, it's two chrome-plated steel plates with register pins to guide the film and a 24x36mm cutout in the centre. Quite heavy; enough to hold the film flat and prevent it from shifting.

    I'm using flash for film copying, and it eliminates any vibration issues. Otherwise you need a really rigid and stable copying stand. A flash lighting table can easily be rigged up with a piece of 'opal' perspex (plexiglass) on top of a 3-sided box, with a 45 degree white card underneath to reflect a speedlight upwards. Much cheaper than a commercially-made light box if you already own a speedlight.

    The other advantage of a speedlight is that the light output can usually be varied over a 6 or 7 stop range and will swamp any reflection of ambient light from the film surface. Otherwise you might have to work in dim room lighting, or shield the film from ambient light.
     
  6. Thanks Rodeo, flash is a great reason to eliminate vibration and extra reflection. I have heavy duty negative carriers. (my 4x5 carrier pins edges of sheet for taut flatness). I have a cheap copy stand but I'll most likely just use my tripod stem inverted. (I have to mention my Manfrotto was worth the $300 I paid for it 25 years ago. It's been in and out of streams, muck etc. and still works well to this day.) Great idea on the 45 degree method to eliminate glare.
     
  7. Ah, but then you have the issue of squaring up the camera with the film surface - not trivial if you want edge-to-edge and corner-to-corner sharpness.

    A cheap option a couple of years ago would have been to buy an enlarger and just use the column and baseboard, but darkroom stuff seems to have come back in fashion lately with inflated prices.
     
  8. I use a Nikon ES-2 film holder to copy slides and film strips with a 55/2.8 MacroNikkor and PK13 extension tube (macro spacer?). That will work on any Nikon DSLR, although I use it on a Sony A7Riii (42 MP, no AA filter). The whole assembly screws rigidly together, so vibration is not a problem with either flash or continuous light. I prefer to use continuous light, for better exposure control. I have a couple of CRI 95 lamps, but a desk lamp with an ordinary daylight LED bulb works just fine. I set the white balance on an empty holder and go from there. A typical exposure is 1/4 sec at f/8, which beats 2 minutes of scanning by a bit.
     
  9. I had some time to tinker about with some T-max 100 negs today. Developed in HC-110 the grain is too fine to resolve fully at 24 megapixels. However, the effect of diffraction in the copy lens makes the pixel number moot. Anything smaller than f/5.6 at a 1:1 RR and you can't resolve the grain no matter how many megapixels your camera has.

    Same applies to a darkroom enlargement as well I would think.

    FP4plus is a different matter!
     
  10. Made beautiful lightbox with 45 degree angled foam core within. Used a couple different lenses, with MicroNikkor being best. Tried f/32 as well as f/8 to see if indeed there was that sweet spot of the lens. 1/4" thick Plexiglas under negative holder. Tried several 6x9 cm negatives that were sharp (Ilford Pan). Not unhappy and definitely not surprised that the process does not yield a sharp image. If one is happy with an 6" x 9" print from a rephotographed negative... fine, but I am printing these negatives 23 x 39 inches and getting great sharpness. The only other potential improvement may be utilizing a polarizer atop light table and a polarizer on lens in order to "directionalize" the lightwaves.
     
  11. Ideally you'll use 5.6 or 4 (optimum for true macro lenses) and you'll have locked up your mirror if you're still using a DSLR (as opposed to mirrorless)...that's assuming you scan or photograph your neg and print with a good printer (as opposed to enlarger).
     
  12. Huh? What good would that do?
    Unless you have really strong reflections coming off the top of the film, and the answer to that is to simply make a black card tube to fit between copying lens and negative to keep ambient light off.

    Ambient light reflections shouldn't be an issue anyway if you're using flash to illuminate the film and keeping the shutter speed to 1/125th or higher.

    WRT lack of sharpness. As Terry stated above, use the widest aperture you can get away with, and no smaller than about f/6.3. Even at f/5.6 there's a small but noticeable softness due to diffraction, but film or field curvature might demand stopping down to that, or a little lower.

    Your Nikon D850 should have enough pixels for what you want to do. Are you happy with its direct digital files on 24" x 36" prints? If so, then there's absolutely no reason why your copied negatives shouldn't be just as sharp.

    There are only a few suspects in the lineup for unsharp copies -
    1. Vibration
    2. Diffraction
    3. Film curvature or waviness
    4. Lack of enough pixels
    5. A poor copying lens
    6. Bad focus

    I know that the 55mm Micro-Nikkor should rule out reason 5, and using flash should eliminate suspect 1. The D850 should also eliminate 4. So that only leaves diffraction, poor focus or lack of film flatness really.
    I'm assuming that you've accurately paralleled up the film and camera back. Dangling the camera off the underside of a tripod over your light-box really isn't good enough. The whole setup needs to be rigidly linked, as it is in an enlarger.

    P.S. I'm using an 80mm Rodagon enlarging lens on a bellows to digitise my film. I find it works even better than a micro-Nikkor.
     
    Last edited: Sep 17, 2020
  13. Specular reflections from the film would have to come from a source within 25 degrees of the optical axis (50 mm). They're most likely to arise from reflections from the camera or mount itself. The flash or any light source should be well-masked to prevent spill. More likely is a reduction in contrast due to diffuse reflections from the film. Neither issue can be controlled by the use of a polarizer.

    Resolution of Velvia color film is roughly equivalent to 6 MP (80 lp/mm). The copied image only approaches that value asymptotically as the resolution of the copying device increases. At 24 MP, the camera resolution (disregarding the lens) approaches twice that of the film (1.73x), so that the resolution of the image is mostly that of the film itself. At 1:1 magnification, the relative aperture is two stops smaller than the nominal value. At a setting of f/5.6 f/11 equivalent), the uncertainty due to diffraction is on the order of 9 microns, only 2/3rds that of the film alone (12.5 microns). This is significant, but not the controlling factor.

    The distinction between resolution of line-pairs v lines is academic. In order to measure resolution objectively, you need to determine the difference between two adjacent lines rather than the subjective "fuzziness" of a single line. There is only one "difference".
     
  14. Not giving up yet. It is ambient diffraction of light coming through 1/4" plex that I thought I could inhibit with polarizers.
    Otherwise, Nikon camera settings 125 with flash, 64 ISO Raw. 6" x 9" negative flat in negative carrier. I suppose that rules out all variables except a poor lens or bad focus.
    I tried opening it up as a much larger file and got surprisingly good results. 16 bit 30 x 30. Reduced it to a 19.9 MB jpg. Enclosed detail is approximately 3% of whole image. detail.JPG
     
  15. Very happy with a Super B 13 x 19 print. Grain is evident from edge to edge. This was shot on Ilford Pan with a FujiGW690III fixed lens.
    The enormous project now is to set up a workflow reshooting years' of photography on film such that they are shot equally well. I would like that press camera in college that was solidly connected to the ceiling. We fed 16 x 20 films through a set of rollers that had a silver recovery unit.
     
  16. Sorry, but that makes no sense.
    Your setup does have a lot of extraneous light around the negative carrier though, and just a piece of black card or paper around the carrier would sort that out.

    I definitely wouldn't be happy using a camera on a wobbly boom arm for critical copying. There's no guarantee that the focus is going to stay unchanged from when you set it to the time you trip the shutter. Nor that there's absolute plane-parallelism between camera and film.

    I'm using a Bowens Illumitran for film copying.
    Illumitran.jpg
    Unfortunately it'll only cope with 6x7 film, maximum. It also needed a few modifications and the addition of a flash slave to cope with its ridiculously high trigger voltage.
    Not sure if the similar Honeywell Repronar can handle 6x9.
     
  17. My wife found a mint Omega enlarger for free. It is solid with smooth minute vertical adjustIng. Too bad it’ll end up as my new copy stand. To be continued...
     
  18. Better than ending up in a crusher!
     
  19. I think if you do the math, you will quickly see that to resolve 80 lp/mm takes more than 6mp. You won’t find anyone thinking 35mm Velvia only has 6mp of Rez...and your figure of 80 LP/mm is proof of that. My Canon 10D didn’t get close to what I get from Astia and Velvia.
     

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