So initially I just wanted to compare two scans of a slide with different WB settings. One was shot at 5200K (in camera and in the Raleno light panel) and the other at 3200K. Turns out the uneven exposure is a much bigger concern.
Same exposure settings for both scans. So how can it be that one scan is much brighter with burnt highlights? I had to move the negative holder in order to change the color temperature of the light panel, so the positioning of the film wasn’t exactly the same. Could that be the reason? Could it be the metering system of the camera? The camera was set in M mode.
@philip , please share the original RAW captures if you can. Use a sharing platform (e.g. wetransfer.com) if the forum doesn’t accept the files directly.
Other than that: NLP’s adaptive algorithm uses the image properties (colours, tonality, white- and black points etc.) to set conversion parameters. Depending on how your camera is set, conversion results can vary, also depending on many other settings. Whether differences are caused by camera or software doesn’t really matter yet.
Note that NLP 2.3 is fairly old and that newer versions do differently. Version 3.1 (currently in beta) has a positive (slide) mode that could be interesting here.
If I understand you correctly one frame is with the panel set to 5200ºK and 5200ºK in camera and the other with the panel set to 3200ºK and 3200ºK in camera. If you are shooting RAW then the in camera setting doesn’t matter.
A couple of things I don’t understand. Why would the metering system be a factor if you have used the same (manual) exposure for each of the frames, 1/10th sec @f5.6? Presumably the +0.7EV is telling us that this setting was giving 0.7 stop over the meter indicated exposure, but for both of the exposures?
Isn’t it just that the panel is brighter at 5200ºK than it is at 3200ºK,? If you are concerned about the apparent difference in exposures then why not look at the respective histograms of the original exposures before they go through NLP.
I’m using NLP v3.0. No, I have to move the light in order to access the color temp control, the display of the lamp is on the bottom side. It shouldn’t be such a big problem though.
I’m not sure how you’re setting this up. If you are setting the light source tempreature and then manally setting the camera to match? I would not trust the light source to accurately represent the displayed temperature. Also, if your exposure remains the same, the light source intensity could change the exposure at different color temperatures.
I would suggest setting the light level and color temperature of the light source, then set a custom white balance in the camera, based off the lightsource. Notice the exposure settings if you try this with different color temperatures.
And if the original image colors are off, I suggest fixing that in post, not in camera with the light source.
