Shading strip on LS-40

[b4t]

Hello all,

I scan 35mm films with my LS-40, and I get a "shading strip" on the left border on most of my pictures.



It more or less visible depending of the picture (it's exposure?). It happens with B&W and neg color films.
It's not on the film: the strip is not on the pictures I previously scanned with a LS-2000.

I use SA-21, with VueScan on Linux.

A dirty mirror? A light leakage?
Any idea is welcome!

 

[brbo]

Clean the mirror.

 

[b4t]

I will try that. I'm a little afraid of damaging the mirror. I wouldn't want to manipulate it if not needed.

I thought the main consequence of a dirty mirror is getting blurry pictures.

 

[brbo]

Well, you will get that kind of problem when the image area of the negative is not completely masked and the light shining through the unexposed part will bloom into the image area. This will be more pronounced when the mirror is dirty.

Maybe your mirror is perfectly clean and this is a problem with the holder that doesn't position the negative properly so the gate doesn't mask the unexposed area of the negative perfectly. If you have a piece of unexposed slide film, make a tiny hole in it and scan it. See how much flare you get around the hole. Compare your results to what some other people get (a few examples here...).

 

[b4t]

Thanks. I will try that as soon as I find time.

Other ideas:

• Using FH-2 to see if film hidding unexposed border changes anything,
• Switching the scanner off while scanning, to see the film position at this time.

About unmounting the mirror, I saw 2 methods on Youtube: upside up with some paper to receive the mirror when it falls, and upside down with some difficulties to grab it. Any advice?

Can I expect to see the mirror condition without unmounting it? Or is it too hidden to see anything?

 

[brbo]

I'd definitely try using a different holder, putting film the other end first, etc. to see if anything changes.

I don't know how accessible the mirror is in LS-40, but I'd try to find a way without full disassembly and get to the mirror with a bent cotton swab...

 

[b4t]

So, so...

1st step: cleaning the mirror

That's not that difficult. I put the scanner upside down, removed the clip, and and took gently the mirror off.

It was dirty. I used isopropyl alcohol and lens-cleaning Kodak sheets.

It's now cleaner, but, it cannot got it clean. It seems pitted (and has a scratch).



(Not easy to shoot a mirror! )

I tried some scan:



Inverting the film direction:



The problem is roughly the same on the other side.



2nd step: trying another film holder (FH-2)




Once the picture positioned in the holder, the picture border is completely masked by the holder plastic frames.



The picture has no strip.

My conclusion is the shading strip comes from using SA-21 with dirty/pitted mirror.

• The SA-21 gate is larger than the exposed picture (feature to ease positioning with a simple cropping),
• The dirty/pitted mirror spreads the light onto the picture border, which is visible especially when the border is bright (dark on film).

Seems I will try to buy some replacement for my mirror.

 

[Archiloque]

There are relatively cheap mirrors available on aliexpress. Unfortunately it's 5 units per order.

There.

 

[Patrick Robert James]

I'd clean the front of the lens as well when you install the new mirror.

There is a Coolscan group on Facebook if you are on there. Easy enough to ask if anyone has mirror you can get from them. There is one guy who repairs them too so he would have one for sure.