Hmm… if you are getting orange spots and blotches when “scanning” film with a digital camera, somewhere in your process you have one of the following: a) uneven illumination from your light source, b) lens flare, or c) light reflecting from your lens/camera back onto the film.
Tell me more about your equipment and settings… what light pad are you using? What camera and lens? What film holder?
When users have this issue, I usually go through this checklist first:
1. Be sure to use your lens hood
2. Take of any filters that are on your lens (like UV filters)
3. Shoot the emulsive (matte) side of film facing towards camera (it’s less reflective and less likely to catch the light reflecting back from your camera/lens).
4. Make sure your aperture is at f/8.0 to avoid lens vignetting.
5. Shoot manual and expose with your DSLR so that the negative is just right of center in preview histogram on camera. (If the digitization is extremely under-exposed, it could exacerbate unevenness issues during processing)
So make sure you are following that checklist above before moving on…
After trying that, the first thing I would do is make sure to mask out all the area around your light source that isn’t illuminating the film. (That includes masking out the sprocket holes.) Your mask doesn’t need to be fancy - you can cut out a piece of thick card-stock paper and that should do the trick. But in your case it sounds like you’ve already tried that…
So the second thing I’d try is take a direct shot of your entire light pad with the exact same setup without any negative in it (be sure to shoot around f/8.0)… add a LOT of contrast to that shot in Lightroom and see if you observe the same kind of unevenness you see in your negatives… Here’s an example of a Portra Trace that was giving a user an uneven illumination source (that resulted in orange blobs in conversion)…
If you get something like above, you need to replace your light source. See this page for suggested light sources for digitizing film.
If all that is OK, try taking a shot of the film with the camera and lens further away from the negative… If doing this removes the orange blob, then it is safe to say that the orange blog is either being causes by lens flare or by light reflecting off your lens and back onto the negative. This is one of the reasons I shoot with an 80mm macro lens, because the further distance away from the negative, there is less chance of running into this issue. It’s also worth looking at your camera itself and seeing if there are any highly reflective parts of it that could be causing the issue - for instance, if your camera is silver instead of black, this could cause a higher chance of reflection.
Hope that helps and definitely want to help get this resolved for you and other users who are experiencing something similar!
Creator of Negative Lab Pro