What causes this?

[Mr Perceptive]

I've been a bit tardy in getting rolls processed, and just got one back from last Oct/Nov

This was shot with a Fuji GA645 using in date (fridge stored) Portra400 - Frames 1 to 3 and frames 10 to 16 are all fine, but frames 4 to 9 all have a horrendus cast on on them. This is on the negative (and is not incorrect scanning, etc). The GA645 puts the exposure details on the bottom of the frame, and for the day in question, the exposure time recorded by the GA645 pretty much matches that of digital images I took on the same day, so I'm happy that the expsoure is all ok. It was a warm day (for UK October) and the camera was carried (along with the digital equipment in backpack - and not left unattended heating up in a car!)

So a simple Epson Scan (using Epson Scanning software - default WB) of a cut of 4 shots, shows Frame 7 with the effect.

And a shot of the Negatives on a lightbox, shows frames 1-3 and frames 10-12 being OK, but frames 4 and 9 are not (and the intervening frames 5-8 are similar) - there is a definite cast on the negative.

Any ideas what causes this?? as I'm keen if its possible to prevent it happening in the future.

All subsequent rolls through the camera have been fine.

 

[trypdal]

The cast is not affecting the film rebate so it's presumably not a chemistry problem during processing.

Are the colour casts chromatically coherent? If so, might it be you absent-mindedly had a filter on/off the lens?

I find sometimes that on my GA645i my yellow filter comes off with the hood when I take the hood off. Could it be you had the hood on for some, but not all, pictures, and a filter was there paired with the lens hood? You wouldn't have seen the effect through the viewfinder for obvious reasons. You would have seen a difference in exposure however that might have easily been compensated by metering area differences.

 

[Mr Perceptive]

The casts are not affecting the film rebates so it's presumably not a chemistry problem during processing.

Are the colour casts chromatically coherent? If so, might it be you absent-mindedly had a filter on/off the lens?

I find sometimes that on my GA645i my yellow filter comes off with the hood when I take the hood off. Could it be you had the hood on for some, but not all, pictures, and a filter was there paired witg the lens hood? You wouldn't have seen the effect through the viewfinder for obvious reasons. You would have seen a difference in exposure however that might have easily been compensated by metering area differences.

UV filter only, one that has been on the camera for all shots - no hood

 

[dmb]

In dip and dunk processing the central frames of a 120 roll are often at the top and a fault in the liquid levels or movement of the arms can affect those frames rather than others. If in Dev tank then under development, if in the bleach tank colour casts or bleach bypass effect. The rinse before fixing being low could also cause colour casts and low fixer would leave silver that can degrade negative. Would though expect to see effect in film rebates and imprint too.

Can watch process here

View: https://youtu.be/3ooD7EJx02w

 

[Mr Perceptive]

The casts are not affecting the film rebates so it's presumably not a chemistry problem during processing.

If so, might it be you absent-mindedly had a filter on/off the lens?

yellow filter

Now I've slept on this, there is a (very) remote possibility that I used a yellow filter on the camera thinking that it was loaded with HP5+, the previous film in the camera was HP5+. This might explain the effects as its obviously not designed to be used on Portra400 !!!!

Would though expect to see effect in film rebates and imprint too.

Might be explained by the above. So for the moment I'm going to put this down as user error (and in future make sure I put the film type in the slot on the back of the camera)

:banghead:

 

[Nod]

With it being so clearly defined and restricted to just the image(s) with no "bleed" into the next, I think you're almost certainly right.

I've NEVER stuck a red filter on for darker skies and wondered why those prints were odd and had dreaded oval stickers on them...