Thank you for confirming my suspicions.
I will work out the final details in my DSLR scanner and post results here soon. I still have a few questions, which I will probably find answers to here.
Reading all he DSLR Scanner posts of this forum certainly helped me a lot to make it all happen, so a big thank-you to all of you!
DSLR Scanner: Light Sources
Hi guys,
I know it's not exactly a light source question, but I've been having some issues with a Canon 100mm 2.8 macro (non-L) lens having a slight horizontal vignette at the bottom (?). i.e. if I turn the DSLR upside down, the vignette goes to the top. Does anyone know if the L version of the Canon 100mm macro would be better... Or what lenses are people using for their scanning?
Thanks so much!
I've used a 55mms Nikkor micro, a 75mms capo Rodagon d f/4, a 50mms Componon s, a Mitutoyo Mplan Apo 2x, .... All worked well. Each has a magnification where it works best. I prefer the Rodagon at 1x for scanning.
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
Thanks Peter for your reply... Any lenses closer to 100mm?
Oh, and while I'm at it, what RAW converters/software are people finding works best?
The vignetting problem can also be fixed in software. It's an extra step, but works well.
CaptureOne has a built in fix for this, see: http://www.largeformatphotography.in...=1#post1146865
But it can also be done with e.g. Photoshop. You need to take an image of the lightsource only, and later put this as a layer on top of your negative image; then put the lightsource image into "Divide" mode; you may have to adjust the levels a bit for the lightsource layer to prevent high-light blowout. It works really well though, just an extra step. For negatives I found that to be the only way to get an even light distribution.
Okay, I'm late to the discussion and I have not read all 19 pages of this discussion so I don't know if this had been mentioned previously or not (a search didn't turn up anything). Nichia has a pair of high power LEDs that produce both 92CRI and either 4500K or 5500K color temperature light (219 and 219B, respectively). Would an array of these LEDs produce the quality of light needed to do this?
Hi Peter,
I wondered if you could help me with a comparison, from what I was reading, the 75mms apo Rodagon has nice specs at 1:1, but the review mentioned slightly lower contrast to a "modern macro lens." Which brings me full circle, do you know how this lens would compare to a Canon 100mm 2.8L IS Macro... I'm gathering that the Canon lens might perform a bit better... any thoughts?
Thanks!
@PCC, as far as I know, no one has tested such LEDs so the jury is still out on CRI requirements/benefits. I did find a ribbon style LED strip that purported to be high CRI but upon powering it up it began smoking and I had to pull the plug on 'em. They were a chinese brand that seems to have disappeared from the face of the earth. Go figure.
Heat is a factor. The LEDs you mention are high output. They will generate a lot of heat in an array layout. You'd need to experiment with the quantity/spacing/size of lamp/diffusion to get the most even illumination for the intended format size. Peter and I have been using RGB LED ribbons from Lee Valley, branded Armacost. They are tightly spaced and low output so not that much heat to deal with. We can also dial in a neutral light relevant to the film type, compensating for color neg mask, tinted B&W, etc. if desired. I don't have any comparisons done with other LED types unfortunately. It's unclear at this stage also how significant CRI actually is to DSLR scanning. I did do a spectral response test and found that the lamp from my much loathed V700 (personal bias? : ) scanner had a pretty psychedelic set of peaks and valleys. Nothing like a black body spectrum such as an incandescent bulb. Not exactly scientific data I'm presenting here, is it. Maybe it's of use.
I haven't used that lens, but I have used 55mm and 105mm Micro Nikkors. The Rodagon is better, which isn't at all surprising. The only lenses that I know of that are better at 1x are some of the super expensive Printing Nikkors. You can get higher resolution going past 1x, for instance my best lens for that is a Nikon 5x MM (Measuring Microscope) lens, but the number of frames needed to cover big film is prohibitive, and I doubt that most big film would benefit from such high resolution. I've tested it with 35mm Technical pan, and maybe I can see a slight difference from 1x at 300%..... Imo, dynamic range and freedom from noise are more important for scanning. At 1x with a good lens on a good dslr we have enough resolution.Originally Posted by madumi
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
I agree with Daniel. Film scanners, even many professional ones, don't have high CRI light sources. My Cezanne doesn't. My Nikon Coolscan didn't. I expect that you just need good output at the wavelengths that the sensors are optimized for, but as Daniel says, it'd be fun to compare.
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
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