I recently did some test scans with my new Lobster Holder. I realized it didn’t come with a diffusor like my Essential Film Holder did. So I wonder if I should place the Lobster Holder on top of the diffusor of the EFH or if it is even necessary because my LED light panel seems pretty diffused already. I just want to avoid a light source that is too soft so that it could affect the sharpness of the scans.
Also I’m not happy yet with the way I’m masking off the stray light. I put a black cardboard with a custom sized hole underneath the film holder, but the light is escaping from underneath and bouncing off the walls. I guess a light box would be the only way to completely get rid of it? Or a black tube connecting my camera lens to the film holder?
Here is the Lobster Holder without the diffusion layer:
Well, certainly experimenting is the only true way to establish what is best for you. Presumably you haven’t put this custom cardboard mask in any of your photos? To me you only want an aperture (i.e opening) in the mask on your light panel just larger than would encroach on your ‘scan’ for the particular format that you are copying. Anything larger than this introduces non-image forming light which as well as bouncing around the room has the potential to degrade your scan by entering the lens directly from outside the image area.
One way to test if diffusion is necessary is to focus on your slide/negative and then remove it and just photograph the panel with a shutter speed chosen to centre the peak of the narrow histogram, with and without the diffuser. Then massively increase the contrast to test for evenness of illumination and any regular pattern from the individual LEDs. If all is well without the diffuser then you don’t need it. Actually anecdotedly some people seem to get problems with the EFH itself, used in the way it is intended, problems which are solved by removing the diffuser. Still he’s sold almost 50,000 so you wouldn’t expect everyone to get perfect results.
If the backlight’s diffusor is well made, there is no need for additional diffusion…unless yo push development really hard with the tone curve and all other means to raise contrast.
Left: backlight in normal settings, right: with extreme contrast settings.
We see the grid-like structure of the panel’s diffusor and some dust.
Note that both crops show exactly the same part of the light panel.
Even though the grid looks disturbing, it’s not visible in the scans.
Yes, you have answered your own question! You need to test and compare. Two problems will show if your diffuser is not working. 1-There will be hotspots from the leds especially if the array is not tight. 2-Patterns and artifacts within the diffuser material can be seen. Best seen without any film in the holder.
Masking the light source is only necessary if you are detecting lens flare. Can you see the light in your viewfinder? Some ambient light reflected off the surroundings will be very weak compared to the direct light source. Some lenses flare more than others. This should be evident if you are capturing the films sprocket holes. Strong flaring will cause disscoloration and loss of contrast. That’s obvious, but small amounts can fool you into thinking the negative is flawed when it’s the light flaring.
I coud be wrong, but I don’t think a softer light source will soften your image. I am using a light source that has diffuser and I have a second difuser with the Essential film holder, that’s only because it’s easier than removing the second one.
PS Diffuser problems may be resolved by increasing the distance between the light source and the difusser and/or the distance between the diffuser and the film.
