Infra Red lines with 35f2ASPH on slide film

[lincoln_m]

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I've recently bought VueScan scanner software to work with my Minolta Elite 5400 now that I've upgraded to MAC OS X Lion. When I scan images taken with the 35f2ASPH ( in portrait mode into the light), the light infra red (dust) removal setting causes vertical streaks to appear on the image (that I can't see on the light box & 10x loupe) ! It must be that there is some infra red info on the slide that the scanner and software thinks is dust and needs removing with the built in program.

 

An example on new Velvia 50 (with MP & 35mm F2 ASPH) of a fishing jetty in local park & lake. First with Infra Red removal on and then without.

 

The solution is simple, on the odd occasion it does happen I re-scan with the infra red off so most of the time it does remove the dust.

 

I'm thinking the infra red is bouncing off the wrinkle part of the shutter and reflecting back inside the lens on to the film? No sure why portrait format is worse.

 

I have had issues with muck on the shutter rubber of older Ms but that shows as visible dark lines on shots with fast shutter speeds 1/1000th but this time it's not visible on the light box only enough for an infra red sensor to think it should remove.

 

It is possible that my spray air could be leaving a deposit on the film when I blow it before scanning, but landscape and portrait would be the same issue.

 

I'm wondering just how much infra red gets through and on to the slide film normally and if that affects the exposure or colour balance . I don't use any filters on my lenses anymore to avoid glancing flare from the filter but I do use lens hoods. I guess we can't use IR filters on film because they'll give a colour cast?

 

Regards, Lincoln

[andybarton]

I have never seen anything like that before, Lincoln.

 

I don't use Velvia, nor a Minolta scanner any more, but I do use Vuescan, and I've never come across that.

 

It would be worth emailing these two shots to Ed Hamrick and asking his opinion.

[adan]

Streaky lines like that make me think the infrared-sensitive pixel array (row) used for dust removal may have bits of dirt on it.

 

I.E. your slide isn't dirty, but the scanner is looking at it through dirty glasses, at least in the IR band, and seeing "false" dust on the slide.

 

However, I can also think of several other explanations: incomplete fixing that left a bit of metallic silver in the film (we know how IR dust removal interacts badly with metallic silver), a software bug, etc.

 

One thing it is NOT is IR light having any effect during the exposure in-camera. There's no way IR light in the camera (if any) can hang around to have an affect hours, days, or weeks later when the scan is made. It's like worrying about X-rays fogging film that has already been processed.

 

I second asking Ed Hamrick - he has probably seen every possible artifact from most scanners in doing tech support for his users.