Scanning Provia/transparencies with a digital camera: ICC profiling?

[LocalHero1953]

Your 100mm macro might give better resolution than the 24-90mm -- but you've probably already thought of that.

The Leica SL 24-90 zoom is pretty good, but yes, I will try the Leica R 100mm to see what difference it makes.

[LocalHero1953]

I have made some progress, attributable to correcting some user error and understanding some machine error.

First, I realised that the Kaiser light panel rechargeable battery was running down; plugging it in to the mains boosted its brightness considerably, and adjusted its colour. Before plugging it in, the Lightroom white balance settings for the panel alone were around temp = 5800K and tint = -35. After plugging it in they were temp = 5350k and tint = -2 . So still not very close to the specified temp = 5000k but better overall.

A sheet of totally overexposed film (i.e. clear) had a distinct pink colour cast. This could be down to the residual overexposed scene (which is undetectable). Next time I shall properly waste a single sheet to get a test sheet.

I found no difference in the colour and exposure whether I used electronic or mechanical shutter, or pixel-shift multishot or single shot.

I rescanned the images with the light panel on full power. I still had to adjust white balance, but for both images setting temp = 5000k and tint = -25 gave a reasonable match. The match looked even better when, instead of comparing the image on screen with the transparency on the light panel, I held the transparency up against a white background on screen next to the displayed image.

The best tonal gradations were obtained by NOT trying to set white points, black points or otherwise trying to increase contrast. I think this is just one of the things about reversal film - its dynamic range is more limited than negatives and you lose something by trying to 'stretch' the histogram.

The outcome is that although I am still not fully satisfied with the colours, my processed image is close to the original transparency, the tonal gradations match, and I now have a preset I can use as a starting point for future scans.

[Tobias Key]

Are you blocking off absolutely all extraneous light from the LED panel? I have a pixelatr film holder which I place over a light panel. I have found that if I take the bellows from my old monorail and extend them between the lens and the panel that improves contrast, as does shooting in a dark room or draping my dark cloth over the top of everything. The weakness of camera scanning to me is getting rid of any light that isn't directly underneath the negative. I was convinced that my scanning was picking up uneven development that I couldn't see by eye, but was just very subtle reflections from the light panel outside of the negative area.

[xkaes]

What options does your camera have for white balancing?

[Vaidotas]

It’s good to hear about your advance.
Having a comfort to work with continuous tungsten lighting I’m always suspicious about LED, it seems it workable at least in this application (my needs is at least 1 - 2 m2 even illumination).
Scanning transparencies with camera is tempting approach, flatbed Epson 850 which I use frequently for bw is unable to scan Velvia dark tones due to limited Dmax.

[Peter De Smidt]

The white point of your monitor is probably 6500K. Is it calibrated and profiled? 'Calibrated' means adjusting the settings on the monitor to give output within a certain range "Profiling' means have a lut that corrects response to a specific target response. The better you calibrate your monitor, the less extreme the lut has to be.

Note that exposure blending works very well with camera scanning. Usually, it's not needed, but with something like underexposed Velvia it might be.

Getting rid of all stray light is important, as it alignment and freedom from vibration.

[LocalHero1953]

Are you blocking off absolutely all extraneous light from the LED panel? I have a pixelatr film holder which I place over a light panel. I have found that if I take the bellows from my old monorail and extend them between the lens and the panel that improves contrast, as does shooting in a dark room or draping my dark cloth over the top of everything. The weakness of camera scanning to me is getting rid of any light that isn't directly underneath the negative. I was convinced that my scanning was picking up uneven development that I couldn't see by eye, but was just very subtle reflections from the light panel outside of the negative area.

I mask the film sheets with a piece of card with a rectangular cut-out, painted matt black. This keeps out all extraneous light from the panel.
After an embarrassing experience of uneven brightness which I thought might be development problems but which I eventually found were shadows of the tripod legs cast by the room light, I now scan with the room light off. There's still light from outside the door, so I will shut the door next time an see if it helps.

[LocalHero1953]

What options does your camera have for white balancing?

I can set the kelvin temperature. I have set it to 5000K, but as I'm shooting in raw I can adjust the white balance in Lightroom anyway.

[LocalHero1953]

It’s good to hear about your advance.
Having a comfort to work with continuous tungsten lighting I’m always suspicious about LED, it seems it workable at least in this application (my needs is at least 1 - 2 m2 even illumination).
Scanning transparencies with camera is tempting approach, flatbed Epson 850 which I use frequently for bw is unable to scan Velvia dark tones due to limited Dmax.

For the highest quality I would look to a different scanning method. The Kaiser light panel is relatively cheap, and I can tell neither the image brightness nor the colour are precisely even across it. It is good enough for most of what I want it for - certainly as I learn about large format and scanning.

[LocalHero1953]

The white point of your monitor is probably 6500K. Is it calibrated and profiled? 'Calibrated' means adjusting the settings on the monitor to give output within a certain range "Profiling' means have a lut that corrects response to a specific target response. The better you calibrate your monitor, the less extreme the lut has to be.

Note that exposure blending works very well with camera scanning. Usually, it's not needed, but with something like underexposed Velvia it might be.

Getting rid of all stray light is important, as it alignment and freedom from vibration.

Yes, my monitor (Dell 27") is calibrated/profiled, with a XRite i1 Studio. It is noticeably warmer than the light panel - I shall have to think about that!
Thanks for the suggestion about exposure blending - I'll try that.