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02-27-2021, 02:46 PM   #16
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QuoteOriginally posted by AstroDave Quote
Unless those are some special kind of fluorescent lights, you ought to be using something else! You are likely to get some funny colors in your copies. See this shot of a CFL spectrum.



Incandescent bulbs would be best (although perhaps with a heat problem), and most LEDs will be better than CFLs (but you might still have a flicker problem for short exposure times).
Those are D50 lamps ... and luckily it does not matter much.

The reason why it doesn't matter is that in contrast to a natural scene, where you have a mix of various wavelengths leading to different stimuli, you have constant absorption spectra of the dyes in color film (B&W is no problem anyway). All the metamerism has already happened in the analog photographic process, because it will represent the continuous spectrum of emissions of the scene by three or four different dyes in the negative or positive, attempting to quantify the stimulus in our eyes. So any awkward spectrum of the lamp in the digitization process can be compensated by a profile matrix, as long as your capture distinguishes the components reasonably well. In fact, even three distinct spectral lines would be enough to digitize color material.


Of course it's easiest if you have a high quality light source, so that the camera's filter array and matrix can do the job for you for a variety of materials. The Osram D50 lamps in my light table are fairly good and better than many scanner's CCFLs, just their flickering due to old-style ballasts is a problem that leads to uneven exposure with the slow electronic shutter. Even decent electronic ballasts will produce enough high-frequency flicker that you'll see ripples. Long exposure times (ND Filter) even them out. Using pixel shift gives a nice boost to fine details and Rawtherapee's motion mask display confirms that exposure is even enough.

02-27-2021, 03:03 PM   #17
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I frequently use an old 90mm Tamron macro, the negs on a 25 year old light box and a K1 on a tripod! Good results if, as has been said, watch for front reflections and keep the lens perpendicular to the light box.
02-28-2021, 01:35 PM - 1 Like   #18
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QuoteOriginally posted by Lord Lucan Quote
Sorry, but what is PF ?
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03-02-2021, 02:59 PM   #19
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QuoteOriginally posted by Lord Lucan Quote
Sorry, but what is PF ?
QuoteOriginally posted by tryphon4 Quote
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I thought it stood for Pentax Forums!


Steve

03-02-2021, 03:02 PM   #20
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QuoteOriginally posted by tryphon4 Quote
Vignetting is also a parameter to take into account, if you plan to fill the frame with the neg.
Probably won't be a problem due to the different frame ratios. Making the 645 negative fit wastes a lot of the K-1 frame's real estate.


Steve
03-02-2021, 09:49 PM   #21
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Thank you!!

Thank you all for the detailed information. I ordered a Panagor Auto Macro Converter for my FA 50mm/f 1.4 lens to start with. Bob 256 thank you for the idea to reflect a pinhole lightsource back onto itself to orient the sensor parallel to the negative. And yes, my preference is a vertical configuration but none of my lenses could focus closely enough to fill the frame with the negative. I went long instead with my 8-320mm at 320mm just to see if my existing camera could be a solution instead of buying a flatbed scanner. If the Panagor is not good enough, I'll get an F-DA 50mm as Jens suggested. I'll post some pics as I make progress.

Have a great week,

Mike
03-03-2021, 02:40 PM   #22
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I use the F-series 50mm f2.8 macro. It was cheap, and I can set everything manually and no worry about accidentally changing the aperture or whatever. I do 6x6 and 6x7 and 35mm with it, so you’ll be fine with 645.

03-12-2021, 04:25 PM   #23
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QuoteOriginally posted by hypermodern Quote
I use the F-series 50mm f2.8 macro. It was cheap, and I can set everything manually and no worry about accidentally changing the aperture or whatever. I do 6x6 and 6x7 and 35mm with it, so you’ll be fine with 645.
There are a couple of these listed on eBay right now (3-12-2021) for around $150US. Good choice for copying what you described, and much better than a regular 50mm for copy work.
04-18-2021, 06:35 AM   #24
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I use the DFA 100mm MACRO:
Here the result: How do you scan your film? - Page 3 - PentaxForums.com
Here the summarized setup: How do you scan your film? - Page 3 - PentaxForums.com
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