Suggested backlight sources for scanning film with DSLR

Nate Weatherly posted a pretty thorough reply to a post on Facebook with generic recommendations for light sources that would work better than LED plates such as tracing panels etc. I know @Richard1Karash has done a pretty detailed comparison of different light sources as well.
Perhaps it would be a good idea to make a separate thread with information about specific products that are known to work well for various setups (vertical “copystand” type setups, horizontal rails and bellows type setups, etc)?
I know it would be really helpful to me - I’m currently using a huion tracing tablet and seeing colour casts similar to examples in recent FB posts.I’m sure there are other artificial light noobs out there that would find this useful as well :slight_smile:

Edit: Wrong Nate referenced

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Just to generalize, the following seem to be the most important factors when picking a light source for scanning film with your digital camera:

(BTW, these factors are true whether you are using Negative Lab Pro to convert your negative film scans, or something else!)


1. You want a High CRI (Color Rendering Index)

The Color Rendering Index (CRI) is a scale from 0 to 100 percent indicating how accurate a “given” light source is at rendering color when compared to a “reference” light source. The higher the CRI, the better the color rendering ability

When digitizing negative film with a digital camera, having a high CRI light source is VERY important. The the differences in colors within the orange mask are incredibly small, so if your light source is not able to pick them up, there isn’t really anything you can do in post to correct for it.

Here’s a good video showing some examples of the effect of having a high CRI on color reproduction.

If the light source you are looking at for scanning film negatives doesn’t have a CRI listed, I would consider this a BIG RED FLAG.


2. Good separation of color channels in Spectral Sensitivity Curves

This is a subject that Nate Weatherly has looked into more than I have, but makes a lot of sense.

The paper that was traditional used in darkroom prints of color negative film had narrow bands of receptivity to red, green and blue, that were clearly separated. This is particularly true of the red channel, where modern digital cameras sensors are sensitive across a broader spectrum of red wavelengths (including yellow/orangish light).

(graph credit to Nate Weatherly)

Basically, all this means that modern digital camera sensors will pick up more interference with the orange mask than photo paper would.

The ideal solution to this is to have a light source that produces distinct, narrow bands of red, green and blue light, that are in a similar range to photo paper spectral sensitivity.

I haven’t seen too much written about this outside the private Negative Lab Pro users facebook group, but examples of seen are extremely compelling.


3. You want Even Illumination and Predictable Results

This is a bit tougher to quantize. Also, there are things you can do in your set up to help with this.

Using a Kaiser Slimlite Plano, I’ve never had any issues with even illumination, and the results are the same every time.

In my experience, it is very difficult to get perfectly even illumination if you are not using a professional LED light table solution (for example, a home-built led table, flash setup, old tungsten light table, etc)

Even pre-built setups can have some issues…

Here’s a look at a Portra-Trace LED light table that was giving a users poor results. To the naked eye, it appeared to be even lighting, but by taking a photo the led table directly (and then added contrast to approximate the contrast during a negative conversion process), you can see it is terribly uneven!

This is one of the biggest issues I see with the files that users of Negative Lab Pro send to me…

If you convert your negative notice “orange blobs”, particularly around the borders of your film, it is probably a light source issue

Having the predictability is why I prefer using a LED light table instead of some of the other options (like flash) where I would expect a higher level of variance between setups - but I’m sure with the right steps, you can make a non-LED light table solution work quite well.


4. Also consider how “collimated” or diffused the light source is in your setup

Collimated light is when the beams of light are being emitted parallel to each other. The opposite of collimated light is diffused light, where the beams are scattered and non-parallel.

Collimated light has two effects when DSLR scanning a film negative:

  1. Collimated light produces sharper looking scans (whereas diffuse light will produce softer scans)
  2. Collimated light produces more contrast in scans

Which is better? Well, it’s really a matter of opinion and the debate has been going on for a while (in a darkroom setting, you can choose between using a condenser head (for collimated light) or a diffusion head.)

But I would say this:

  • If you like the sharpness and detail you see in drum scanners or dedicated film scanner (like Nikon Coolscans), try to get a more collimated light source.
  • If you prefer the “softness” of a traditional fine-art print, go for a more diffused light source

So, which light source should I get?

I’ll let members of the community jump in, but here are my personal observations based on my own experiments and files users have sent me:

:white_check_mark: Recommended LED Panels:

  • Kaiser Slimlite Plano (CRI = 95, very even)
  • iPhone or iPad, especially newer models with OLED (must elevate film off surface!). While the reported CRI is not high, it has spectral sensitivity curves more similar to film paper, resulting in less color interference from the orange mask. It is also a more “collimated” source of light, meaning it will produce sharper results than diffuse light sources.
  • Any modern Samsung Galaxy/Galaxy Note s7, s8, s9, pixel 3, etc
  • Walimex Pro LED (CRI = 90)

:no_entry_sign: NOT Recommended LED Panels:

  • Huion tracing tablet (unlisted CRI)
  • Artograph light pads (unlisted CRI, although reportedly ~80 CRI)
  • Porta-Trace (observed unevenness)

:sunny: Other options worth exploring (not LED panel)

  • Flash with a UV filter
  • Solux 4700k Daylight Halogen bulb
  • GE Reveal or Chromalux tungsten light bulb with a CTB gel or an 80a filter.
  • Strobe
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My take. See animated gif below comparing several sources, all NLP conversions full auto. While many can be tuned in with the NLP sliders, here’s what I see on autopilot:

  • iPhone 7 (or 8 or X, but not earlier models) is surprisingly the winner
  • Kaiser panel
  • Any good high CRI bulb. Several manufacturers are now making “Photo” quality bulbs, passing standards higher than CRI. Try SORAA “Vivid Light” for example.

Avoid $30 tracing panels. The $100 LED panels are probably good.

Here’s my comparison, draw your own conclusions.

TestBox-Fuji200-A7-PB4-5WayCompare

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Avoid the TikTeck $29 panel on Amazon.

I suggest everyone experiment, one good frame of a color checker in direct sunlight, then see what NLP does with your light source.

Wishing you all good shooting!

New recommendation: If you can use an MR16 bulb, SORAA “Vivid Light” MR16 bulbs seem excellent, comes in 3K and 4K, but these two may not be that different. With my usual testbox, SORAA bulb, and NLP 1.31, I think I have the best auto conversion yet.

Previous winner for illumination was the iPhone 7 (8 and X have same screen). Here’s a comparison, both with NLP 1.31, Frontier, Film=Fuji, and then Brightness to -6. Otherwise Auto. Both are slightly warm (not corrected).

190402-TestBox-SORAA4k-vs-iPhone7-NLP1-31

The iphone 7 is a POOR light source with regards to CRI, R9 (deep red) and overall color rendering when measured with the i1Pro2 and Babelcolor CT&A program. CRI of 73, deep red rendering R9 of MINUS 19.

iphone7_2019-04-28_Full-report_600DPI

With regards to a constant “hot light”, the Solux 4700K is THE reference source to beat. Easily surpasses the SORAA LED in all regards. Take a look at the spectral distribution in the upper left panel, a D50 match. There aren’t any “hot blue” ramps like those found in the Profoto, Alien Bee or other flash units, nor are there any “blue pump” peaks like those found in 99% of the LEDs on the market. Glance over the right hand panels and you’ll find very little deviation from ideal. The bottom chart is a sampling of 99 different colors and their accuracy. Previous chart of the iphone 7 was quite ragged. Look at the Solux 4700K - darn near perfect. I’m using the MR16 4700K in my setup. Be advised however that the larger PAR38 Solux does NOT have the same performance and the CRI drops down to low 90s, R9 deep red goes down to mid 50s with the larger sources. Reason? In the large PAR38 / PAR series, only the bulb is coated with the patented vapor deposited film. The MR16 utilizes the ENTIRE interior reflector with the coating.

solux4700k_2019-04-28_Full-report_600DPI

The Soraa Vivid series in PAR30L configuration. This is after a 3 minute warmup. Note that this is considered one of the BEST LEDs out there on the market, even better than the Kaiser LED panel. Still, check out the bottom 99 samples and the overall spectral graph. Not even close to the Solux 4700K, but when compared to other LEDs, Soraa is one of the best as of this writing. My money though is on the new Nichia Optisolus series.

SoraaVivid_2019-04-29_Full-report_600DPI

@PM01 - thanks for this awesome info. Would love to see your setup (and maybe a few scan examples) over on the scanning setup thread:

You wrote, “iPhone 7 is a POOR light source…”

Yeah, look at the spectrum, and you don’t want to use this light source to evaluate artwork. It’s not a high CRI.

But, as I wrote, it’s surprisingly good as a light source for camera-scan of color-neg and then inversion in NLP. Why? What does this tell us about the importance of CRI for the light source? I don’t know, but will keep investigating.

Yes, of course Solux has been the gold standard. Kodak/Pakon adopted this for their terrific 235 scanner. Is it still? I have all these bulbs. Grand question: Solux puts out a lot of heat (50W) compared to LEDs and iPhones. Is there an advantage to this bulb? And, if so, it is big enough to be worth the bother of accommodating the heat?

My examples posted above were probably NLP 1.2; will be worth rechecking.

Is there an easy way to mount a 50W MR16 bulb, such as the Solux 4700K, so that it can be used with DSLR scanning? I have searched and searched online and I can’t find any actual lamps to hold the bulb. I’d love to be able to try an MR16 bulb for my backlight.

I had trouble with this.

Solutions:

  • Buy a MR16 track lighting head, take it apart, and rewire as needed
  • Buy this pack of MR16 sockets, attach to something that can stand some heat, or just hold it in place with a clamp.

You want the GU5.3 base, not the GU10.

Thanks Richard. I read about this new LED backlight on Reddit, and I ordered one. I have to say it is a huge upgrade from my previous LED light (a cheapo tracing tablet). Here are the specs:

  • 95 CRI (or so they say, I don’t have a way to test that)
  • very bright at full settings
  • very finely textured surface is has a matte finish and seems to generate few if any Newton Rings
  • even distribution (passed the “underexposed picture of it” test)
  • adjustable color temp and brightness
  • it can work on cable or on battery
  • at $58, it’s less than half the price of a Kaiser Slimlite Plano
  • doesn’t get very hot after being on for several hours
  • when I’m not using it, I can use it as a video or photo light with the hotshoe mount.
  • can be used on tripod/lightstand (e.g. when using a Nikon ES-2) or can be laid on its back (e.g. when using a copy stand). if you plan on using it on it’s back I’d recommend resting it on four small blocks (maybe wood or rubber) so as not to block the vents.

I think the RALENO Led Video Light should go on the “Reccomended LED Panels” in the top post ( hint: @nate )

There is also an older version that is half the price and has the same features, but it isn’t as bright, has a smaller battery, and doesn’t support charging while using, which could be limiting. Still, at $35 it could be a good budget budget panel that provides 95 CRI.

What are good light sources for camera-scan with NLP?
I have done experiments and posted on this over the past few months. Tonight I updated my conversions with NLP 2.0.0 of my Fuji 200 test box negatives with a range of light sources.
I can recommend these lights as giving the best colorful results, listed alphabetically:

  • Flash, with or without RA54 filter
  • Kaiser panel
  • Solux 4700°K incandescent bulb
  • SORAA 4000°K LED bulb
    In addition, I can say the iPhone 7 (or 8 or X) gives a very good result.
    Hope this is helpful.

Here’s the comparison Flash and Kaiser. Excellent conversions, nice clean whites, good colors. (Frontier, PreSat 4, Standard, Film=Fuji, minor adjustments to light/dark).

Shutter speeds for the tested light sources. All at f/5.6 at 1:1, so this is an effective aperture of f/11:

  • iPhone and Kaiser panel about 1sec
  • SORAA and Solux bulbs, depends on positioning and diffusion, but I shot at about 1/30th
  • Electronic Flash at your camera sync speed

Hello,
Does anyone know if there is a difference between the old Kaiser Slimlite LED and the new one Kaiser Slimlite Plano in terms of CRI.

Thank you.

Here’s a new option, a crafted box about 1.5" high with built-in LED light source and nice aluminum negative carriers for 35mm and MF.

http://skier.com.tw/web/en/Products/products_ad.jsp?gs_id=CY1473322516411&fbclid=IwAR0oQvd5IslO77Y5hwbmdxQKC3i3WRb4JRnrpaAk_91v2_CxYvj-wWYcX2w

First, the product is quite good; the web site is spotty. Communication with the guy in Taiwan is excellent. If you like the item, go ahead and order with confidence. Delivered to me in the US exactly one week after ordering.

This is the product: A wooden box, internal LED illumination, good looking negative holders. Plugs into US 110v power; switch in the line cord. (European editions??)

Internally, there’s a power supply and an LED panel that just about fills the box, 1/2" below a diffuser.

Light from this panel is bright. For camera scan at 1:1, f/5.6 nominal aperture, exposure will be around 1/100th. Far brighter than a Kaiser panel. This box is designed for camera-copying, while the Kaiser is designed for judging transparencies. (In similar setup, I had exposures of about 1 sec with Kaiser.)

Spec for the back light is 5600°K and 97CRI. I measured (iPhone Pocket Light Meter app) at 5100°K. Pretty good.

How good is the light? I’ll compare to flash which is my “gold standard” (along with Solux). Test conditions: UV filter. 1:1 shot with Sony A7. Good blocking of all stray light. Convert in NLP 2.0 using Nate’s recommended settings for a neutral conversion (Basic, PreSat 5, Linear+Gamma) and I used Film=Fuji.

I think that’s an excellent comparison. Good colors all around, no cast on the white t-shirt. All with no manual adjustments. (Another big bravo to Nate!)

Negative holder for 35mm is nicely creafted aluminum. Care taken so that sliding the negative through cannot scratch the image area. I worried this might let the negative be not-flat, but it looks pretty good. Opening shows part of sproket holes and some rebate. (iPhone shot of the opening with a negative.)

MF negative holder is a nice design. Adjustable for formats. Minimum opening is 56mm x 60mm. Max is 56mm x 91mm. Advertised as 6x45 to 6x7, but I think it’s 6x6 to 6x9.

Question is how does this compare to a Kaiser panel? My answer: It’s thicker (about 1.5"), includes negative carriers, it masks extraneous light, and the quality of light is at least as good. For backlighting for Camera-scan for NLP, in a vertical setup, I think this is quite good.

One more: It’s not setup for slides, but you can place a slide on top of the 35mm carrier, just fits left-to-right. Will work fine for slides one at a time.

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Excellent review, @Richard1Karash - thanks so much for sharing. Seems like a really great light. Just went to order one and it looks like it is already on back order (the Negative Lab Pro kiss of death!). Have one on back-order and can’t wait to try!

Wow, guess I ordered just in time, then! I ordered mine sunday evening, and it just shipped, so I guess I got one of the last in stock. Sorry, Nate! :worried:

Really looking forward to trying it out, though! :smiley:

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