Is DSLR scanning "better" than flatbed scanning?

[etn]

I manually focus every frame and check it on the screen at 10x. I don’t change the focus on the lens, which could change the scale or introduce distortion, but I use a Linhof macro rail on my copy stand for fine focus by moving the camera.

Isn't this how macro is done anyway? set the magnification ratio on the lens and focus with the distance to the object?

 

[etn]

I'm curious as to how the backlight chosen to illuminate your film (prior to photographing with the dslr) affects your picture? Obviously it could colour your image. Sometimes I've also noted that fluorescent bulbs and digital cameras don't play well together resulting in a dark banding. Do people run into this with dslr scanning? I used to have this issue with my xray viewer and phone camera not playing well together.

Fluorescent bulbs are not a continuous light source - they are modulated at 50 or 60 Hz (mains frequency). if your exposure catches a time when the bulb does not emit any light you will get dark banding. To prevent against this you can increase exposure time. Another alternative is to use a continuous light source such as LED with a continuous power supply (battery or regulated mains power supply).

The color of the light source indeed has an influence on the picture. Ideally the light source's color should be located on the Planckian locus, i.e. the black body radiation (the black line on the chromaticity diagram below). Then you can correct it with the color temperature setting of your camera or RAW-processing software. If the color of the light source is not on the Planckian locus, you cannot correct the color cast by means of the color temperature setting. This is why the color temp setting cannot compensate for the color cast of color negative films.



I use a white LED light box. Its advertised color temperature is 5500K. Before scanning I take a couple shots of the "empty" light box with various exposure times and use this as a white point reference for RAW conversion of the scanned images.

See:
https://en.wikipedia.org/wiki/Black-body_radiation
https://en.wikipedia.org/wiki/Planckian_locus

 

[markjwyatt]

Fluorescent bulbs are not a continuous light source - they are modulated at 50 or 60 Hz (mains frequency). if your exposure catches a time when the bulb does not emit any light you will get dark banding. To prevent against this you can increase exposure time. Another alternative is to use a continuous light source such as LED with a continuous power supply (battery or regulated mains power supply).

The color of the light source indeed has an influence on the picture. Ideally the light source's color should be located on the Planckian locus, i.e. the black body radiation (the black line on the chromaticity diagram below). Then you can correct it with the color temperature setting of your camera or RAW-processing software. If the color of the light source is not on the Planckian locus, you cannot correct the color cast by means of the color temperature setting. This is why the color temp setting cannot compensate for the color cast of color negative films.

View attachment 232954

I use a white LED light box. Its advertised color temperature is 5500K. Before scanning I take a couple shots of the "empty" light box with various exposure times and use this as a white point reference for RAW conversion of the scanned images.

See:
https://en.wikipedia.org/wiki/Black-body_radiation
https://en.wikipedia.org/wiki/Planckian_locus

My Durst slide copier has a full filtration system for the light. For slides I normally use the standard tungsten light and let white balance take care of it. For some older Kodachromes I copied, which had a strong yellow cast, I found it helpful to bump up the magenta and Cyan to counter the yellow, and I felt the results were better.

 

[villagephotog]

In my experience the best of the Betterscanning film holders (I tried all except liquid) was the adjustable version. Fussy process using many tiny screws to get finest focus (once-and-done).

That's the holder I use. I obviously can only speak for my particular experience with my individual V700, but on mine, I have a +- of about 2/10s of a millimeter on the best sharpness height. Meaning: I get best sharpness when the film holder is 2.2mm above the platen (according to betterscanning's distance reference). In the range from 2.0mm to 2.4mm, it's pretty hard for me to see differences, but I can definitely see a loss of resolution at 1.8mm and 2.6mm, and it gets progressively worse if I go further in either direction. So the depth of field on the scanner lens is pretty slim.

As for the AN glass, it may not make a big difference with many of my negatives (not sure because I haven't tested without it), but when I have one with a strong curl, or an oddball curl (has happened when I had a little trouble loading the developing reel), I'm glad to have it. It definitely goes some way to forcing the film to lay flat. It is another surface (actually two surfaces) that has to be kept clean and dust-free, however, and that's a little troublesome.

 

[villagephotog]

The color of the light source indeed has an influence on the picture.

Yes, I feel like this is the biggest overlooked issue with camera scanning, especially in the quick-and-dirty discussions of it that you see a lot on YouTube etc. It doesn't matter much at all if you're scanning black-and-white film, but it's definitely an issue if you're scanning color.

I've many times seen somebody expounding on how easy it is to get great results with camera scanning, and it turns out they are using their iPad or a cheap LED flashlight as a light source. You look at their scans and there are obvious color casts and shifts that they don't see. But, hey, if they are happy, that's all that matters (I mean that truly).

I use a white LED light box. Its advertised color temperature is 5500K. Before scanning I take a couple shots of the "empty" light box with various exposure times and use this as a white point reference for RAW conversion of the scanned images.

I have a relatively cheap 5500K LED light box that I will use to camera scan B&W film. But its CRI is only in the mid 80s, and I'm sure it has a spiky spectrum, with gaps. So I have not used it to camera scan color film. For that, right now, I use a flash as a light source (not very convenient). Do you have a recommendation for an LED that works well for color film? (They are very convenient to use, for sure.)

 

[Adrian Bacon]

I have an Epson v550 that I got on the cheap for $50, but I've been considering getting a macro lens for doing DSLR scanning. Some people claim the scans are better but is this true?

I also want to do 120 scans...lots of question marks on the setup which has been delaying me from doing it.

Also some people claim it's faster, but I've talked to some that say they don't like the workflow. Inverting the colors and removing the color cast was too tedious for them.

What do you all thing? Do you prefer it and is the effort worth a vastly increased IQ with DSLR scanning (I've got a full frame camera but no macro lens at the moment) or is this a myth?

DSLR scanning is generally better in terms of optical performance and speed of capture, and given the right workflow/software can provide incredible results. It's all personal preference.

My personal preference is currently the Sigma 70mm macro prime, shot at f/8 paired with a 24MP APS-C dslr, for a total raw resolution of 24MP for 35mm or 120 roll film using a custom copy stand setup. For 95%+ of images I've scanned with it, that is more than enough resolution. I can do stitching if I need to, however, that's not necessary the vast majority of the time. I'm currently evaluating moving to the new 32MP+ Canon APS-C DSLR as the shutter count on my current rig is way over it's rated count (I scan a ridiculous amount of film, a side effect of owning a running a film processing lab).

If you go the DSLR route, there's a couple of things to watch out for, some of which have already been mentioned in this thread. I'm personally not an advocate of shooting as wide open as possible as the film is rarely flat enough make that worth it. The goal should be to reach a balance where you have enough depth of field that most alignment and film flatness issues aren't really an issue without eating a bunch of sharpness via diffraction. At the 24MP mark, f/8 is a reasonable tradeoff. f/5.6 could work with a shorter focal length. Another thing is auto focus. Here, Canon's dual pixel auto focus in live view makes getting things in focus stupid level easy, as long as you have the film illuminated enough that it can focus, I'm personally pretty hard pressed to get better focus than what it does. Combined with stopping down to f/8, you can focus once at the start and just run the film through.

The other thing to pay attention to is your light source. Here, quality of light, power output, control, and consistency is key. I personally use a strobe. It's very high CRI, I have control over the output power in 1/10 f-stop increments, and it's extremely consistent. More importantly, it has enough power that I can shoot at ISO 100, f/8, and still have a 1/200 shutter speed, effectively eliminating any light contamination from the room and not really having to worry about motion blur or other vibration induced blur.

 

[Mainecoonmaniac]

I don't know much about LEDs. I don't think LEDs are a constant source because if they are dimmed, the electronics turn them off an on to create an illusion of dimming with the duty cycle. The longer the cycle, the brighter the light.

 

[Chan Tran]

I don't know much about LEDs. I don't think LEDs are a constant source because if they are dimmed, the electronics turn them off an on to create an illusion of dimming with the duty cycle. The longer the cycle, the brighter the light.

Don't dim the LED and they are constant. Their spectrum isn't all that great though. I would use flash or quart lamp.

 

[etn]

Do you have a recommendation for an LED that works well for color film? (They are very convenient to use, for sure.)

I don't know much about LEDs. I don't think LEDs are a constant source because if they are dimmed, the electronics turn them off an on to create an illusion of dimming with the duty cycle. The longer the cycle, the brighter the light.

I use a cheap Kaiser Slimlite LED which does not seem to be in production anymore (I could not find it on their website).
The thing is easy: power comes from 2 AA batteries, there's no electronics or dimmer apart from a low-tech on/off switch.

I agree with you Mainecoon that dimming electronics can turn off the led (or any light source) with pulse width modulation to achieve dimming. All depends at which frequency it happens - it can be done at 50/60 Hz (synchronizing to the mains) or at a much higher frequency (in the 10's of kHz.) Choosing a long enough exposure time generally alleviates any problem here.

 

[David A. Goldfarb]

Isn't this how macro is done anyway? set the magnification ratio on the lens and focus with the distance to the object?

Ideally, yes.

 

[etn]

Don't dim the LED and they are constant. Their spectrum isn't all that great though. I would use flash or quart lamp.

Absolutely true. A flash is much closer to daylight!

With quartz lamp, do you mean halogen lamp?

 

[Mainecoonmaniac]

I don't think the color temperature doesn't matter because digital sensors are white balanced for the light source.

 

[runswithsizzers]

I'm curious as to how the backlight chosen to illuminate your film (prior to photographing with the dslr) affects your picture? Obviously it could colour your image. Sometimes I've also noted that fluorescent bulbs and digital cameras don't play well together resulting in a dark banding. Do people run into this with dslr scanning? I used to have this issue with my xray viewer and phone camera not playing well together.

The author of the Negative Lab Pro plugin has a page discussing the merits and defects of various light sources for dslr scanning <click here>

 

[markjwyatt]

The author of the Negative Lab Pro plugin has a page discussing the merits and defects of various light sources for dslr scanning <click here>

He recommends daylight. The Durst slide copier is halogen, and I believe it uses a 3400 K EFP tungsten/halogen/bulb. He recommended 4700K for a daylight halogen. Maybe I could "dial in" daylight (may be tough), or the Durst also has a slide out filter drawer for color corrections. So far I seem to be ok with camera WB, but am not checking critically. I imagine the Durst was designed properly (maybe for tungsten film originally?).

 

[MattKing]

A tungsten source is more likely to have a continuous spectrum, and as such likely to be usable with white balance adjustment.

 

[runswithsizzers]

He recommends daylight. The Durst slide copier is halogen, and I believe it uses a 3400 K EFP tungsten/halogen/bulb. He recommended 4700K for a daylight halogen. Maybe I could "dial in" daylight (may be tough), or the Durst also has a slide out filter drawer for color corrections. So far I seem to be ok with camera WB, but am not checking critically. I imagine the Durst was designed properly (maybe for tungsten film originally?).

The way I read it, Nate seems to emphasizing the importance of a high CRI, over color temperature.

 

[Adrian Bacon]

I don't think the color temperature doesn't matter because digital sensors are white balanced for the light source.

Digital sensors actually have a native white balance where there doesn't need to be multipliers applied to each channel to get to white. This varies from camera to camera. Most modern cameras usually are natively around 5000K-5500K.

Also, white balance happens on two axis: green/magenta, and Amber/Blue (or Yellow/Blue, the depends on the implementation).

 

[Mainecoonmaniac]

Digital sensors actually have a native white balance where there doesn't need to be multipliers applied to each channel to get to white. This varies from camera to camera. Most modern cameras usually are natively around 5000K-5500K.

Also, white balance happens on two axis: green/magenta, and Amber/Blue (or Yellow/Blue, the depends on the implementation).

Great info. I didn't know there was a native white balance. Makes sense because there's also native speed of sensors too. The bump in speed from my understanding is through signal amplification. My question is it better to shoot or in this scan in this case at the native white balance or not? Is it similar to digital zooms where there's digital trickery?

 

[Adrian Bacon]

Great info. I didn't know there was a native white balance. Makes sense because there's also native speed of sensors too. The bump in speed from my understanding is through signal amplification. My question is it better to shoot or in this scan in this case at the native white balance or not? Is it similar to digital zooms where there's digital trickery?

If you’re shooting raw it doesn’t matter unless your light source is way out of whack. That being said, if the native white balance is 5000K, and you’re using a 3200K source to scan C-41, that’s not very desirable because you’re unnecessarily having to white balance the orange mask out with a very amber light, which causes a very large digital gain on the blue channel. All white balance is done digitally after the fact. I can’t think of a single modern camera that changes the analog gain for individual channels for the purposes of white balance. It’s nearly impossible to exactly have a light hit the native white balance of a given sensor, so there’s always some amount of digital gain going on for white balance, so as long as you’re approximately daylight with a high CRI light, and you’re shooting raw, you’ll be fine.

 

[Ces1um]

The author of the Negative Lab Pro plugin has a page discussing the merits and defects of various light sources for dslr scanning <click here>

Lots of information there. Thanks for posting.

 

[markjwyatt]

The way I read it, Nate seems to emphasizing the importance of a high CRI, over color temperature.

I probably need to read it again more carefully, but it seemed that high CRI was also tied to having an appropriate color temperature.

 

[MattKing]

I probably need to read it again more carefully, but it seemed that high CRI was also tied to having an appropriate color temperature.

One thing I came to understand recently as a result of one of the recent Photrio threads on DSLR scanning is that this is actually incorrect.
If your source is a full continuous spectrum source, the colour temperature isn't particularly important to CRI numbers - a very red tungsten source can have a high CRI, as long as its spectrum has appropriate amounts of all the other colours.
The colour temperature may, however, be relevant to how digital sensors respond to a high CRI source.

 

[GLS]

Lots of information there. Thanks for posting.

Yes, a useful link. I had been meaning to upgrade my LED lightpad anyway, as it is just a cheap one which probably doesn't have a good CRI, and also some time back it developed a dimmer illumination in one corner. I went ahead an ordered the large size Kaiser Slimlite Plano (which has a CRI of 95), so it will be interesting to see what noticeable difference (if any) it makes to digitising colour films.

 

[Chan Tran]

Absolutely true. A flash is much closer to daylight!

With quartz lamp, do you mean halogen lamp?

Yes. The color temp of quartz halogen light is lower than daylight but can be corrected in the RAW converter or using filter because its spectrum is of a black body radiation.

 

[Mainecoonmaniac]

I work at a university where I’m responsible for gear in a film making program . The students are shying away from hot lights and are prefers LED panels. Hot lights have issues of heat and power. From the footage I've seen, the colors are really good. I've seen HMIs 30 years ago and they're way too expensive. If you want a slide scanning rig, go on Ebay and get a strobe slide duper or if your like tungsten, you can rig up a setup with a set of macros bellows and an old dichroic color head.