Purple corners when "scanning" B/W film negative

[Veganist Falafel]

Hello everybody!

I'm completely new to this and I've started developing/scanning 35mm film just for personal use.

I have two developed Ilford SFX200 B/W film rolls. One of them was developed at a professional lab and the other one I developed myself. However, when trying to scan the film I run into an issue with BOTH films, so I don't think that the problem lies in the developing process.

I use an LED light board and a Canon EOS 550D DSLR Camera with a Canon macro lens.
When "scanning", the film slides have purple edges that turn green when inverting the negative in Photoshop. It almost looks like an RGB glitch or something like this.

Does anyone know what could cause this issue? I've tried all kinds of different settings on my camera but nothing seems to fix it. I have no idea if it's the film, the camera, the lightboard... ??


Thanks already for your ideas and help!

 

[Derrel]

Looks like lateral chromatic aberration to me...a product of a lens typically.

 

[Veganist Falafel]

Looks like lateral chromatic aberration to me...a product of a lens typically.

Wow!! I think this is the exact issue! So the problem lies in the macro lens of my DSLR which I'm using for scanning the film negatives? Would you recommend getting another macro lens in that case? (It's a Canon EF 70-210mm F/4 Lens)

 

[Derrel]

I would look at The Canon 50mm f/2.5 "Compact Macro", or the Canon 100mm F/2.8 IF macro ;not the uber-expensive 100mm-L macro with IS, but the much older 100mm Internal Focus.

 

[Veganist Falafel]

I would look at The Canon 50mm f/2.5 "Compact Macro", or the Canon 100mm F/2.8 IF macro ;not the uber-expensive 100mm-L macro with IS, but the much older 100mm Internal Focus.

Thank you Derrel! Unfortunately, these are over my budget right now. Do you think it's ok to fix the problem in post-edit by adjusting the saturation of blues/greens OR would I lose too much quality?

 

[Derrel]

Some software apps have dedicated controls designed to eliminate chromatic aberration. Depending on what software you are using it might be easier and better to specifically eliminate chromatic aberration through a dedicated control which offers easy and repeatable settings and is specifically designed to eliminate CA.

 

[compur]

Can't you just convert to grayscale?

 

[Veganist Falafel]

Some software apps have dedicated controls designed to eliminate chromatic aberration. Depending on what software you are using it might be easier and better to specifically eliminate chromatic aberration through a dedicated control which offers easy and repeatable settings and is specifically designed to eliminate CA.

Thank you, Derrel! I'll look further into that!!

 

[Veganist Falafel]

Can't you just convert to grayscale?

That's actually what I tried today and it basically solved the problem, but I was afraid that I'd lose too much quality or photo information ‍ Would I?

 

[Derrel]

You could buy a Nikon 55mm pre-AI;micro nikkor in ugly condition from KEH for probably $35. the front element is about dime-sized and is deeply recessed; the front elements are usually in quite good condition but the barrel of a lens graded out as ugly would probably be well-worn. You could use the Nikon m2 non coupled extension tube and a Nikon F to Canon EF lens adapter. the entire set up would probably set you back about $55.

 

[Veganist Falafel]

You could buy a Nikon 55mm pre-AI;micro nikkor in ugly condition from KEH for probably $35. the front element is about dime-sized and is deeply recessed; the front elements are usually in quite good condition but the barrel of a lens graded out as ugly would probably be well-worn. You could use the Nikon m2 non coupled extension tube and a Nikon F to Canon EF lens adapter. the entire set up would probably set you back about $55.

Sounds kind of complicated! Would it be better than keeping my lens and converting the negatives to greyscale?

 

[Derrel]

Chromatic aberration can be removed, but it's better to use an actual flat-field macro lens. Your 70 to 200 mm is not a genuine macro lens, but rather a 70 to 200 millimeter lens which has a close focusing range. A true macro lens will give outstanding performance with a flat field of focus, with no focus curvature and negligible to no chromatic aberration. Your current zoom lens does not give that good a performance. For copying negatives you need to have optical quality of a fairly high order.... Otherwise your images are severely compromised.

Your current scan images do not look that good, and in fact you might be able to do even better with something like a cell phone and accessory close-up lens.

 

[Derrel]

Converting to grayscale will still show the "fringing". You need a high-quality lens to copy a 35mm negative.

 

[compur]

Can't you just convert to grayscale?

That's actually what I tried today and it basically solved the problem, but I was afraid that I'd lose too much quality or photo information ‍ Would I?

You're the best judge of that.

I believe your camera has a monochrome mode so you could also try that.

But, Derrel is right about lens choice. Long zooms may have close focusing capabilities but they really don't give very good results when used as a macro lens. They're sort of a better-than-nothing proposition.

 

[Derrel]

A real macro lens would help tremendously...since you use a Canon crop sensor camera, a 50-70mm macro prime would likely be about right. Canon ef-s cameras adapt to 7 legacy 35mm brands-- with a glass free lens adapter which will give you infinity focus. Since you are going to be photographing your negatives from 1 to 4 in from the front of the lens I think you might be able to use 25 or 30 different brands of lens with an extension tube and an inexpensive lens adapter. I have myself used four different brands of 1970s and 1980s lenses on my Canon cameras.

to copy a 35 mm negative which measures 24 by 36 mm, you need a lens which will focus fairly close.