Dust on pinhole negative

[Cybertrash]

I recently tested out my first pinhole camera (made from an Agfa Isola) and when I scanned the negatives I noticed that there were lots of black dust on the image, in "sharp" focus. My theory is that this is from dust that somehow has been present on top of the emulsion during the exposure. Never encountered it before, usually I'd have issues with dust on the negative during printing/scanning, but this clearly shows up as blank spots on the negative image itself. Any idea what I could do to avoid this problem in the future?

 

[AgX]

Use a smaller hole, to keep dust out...

 

[AgX]

Have you cleaned (brushed, blown out) the bellows?

Do the spots occur when you do consecutive exposures (and film transport) without closing the bellows inbetween?

 

[Dr Croubie]

I got dust on the first 4x5s I shot. I scanned it like 5 times and used the blower and wiped the neg and all that, until I held it up to the light and realised it was on the neg when I exposed it, the dust was developed in.

Since then I've made sure I blower out every film holder before I load it, and give it a bit of a blow just after I load it (inside the dark bag, not as easy as it sounds), and I also regularly use the blower inside the bellows when I change lenses or take the graflok off.

Not sure if you've got film-holders or what, but all you can really do is just keep using the blower, or get one of those mini-vacuum-cleaners if you can use it without scratching anything...

 

[AgX]

The Agfa Isolas are type 120 cameras. Thus the fillm is well protected before exposure.

 

[AgX]

Not sure if you've got film-holders or what.

The Agfa Isolas are type 120 cameras. Thus the fillm is quite well protected before exposure.

 

[Cybertrash]

Have you cleaned (brushed, blown out) the bellows?

Do the spots occur when you do consecutive exposures (and film transport) without closing the bellows inbetween?

The Isola does not have bellows, it's of the collapsable lens variety, and I've simply removed the entire lens/shutter assembly and replaced it with a piece of black card with a hole for the pinhole plate. Perhaps you're thinking of the Isolette?

When I look at the negatives it seems as if the ones that suffer from dust the most are the ones where the film has been sitting "unrolled" on the film gate inside the camera for some time before the exposure, the ones were I've made several exposures in "rapid" sucession (as rapid as it can be with a pinhole camera) does not suffer from dust spots to the same extent. I suppose one could come to the conclusion that there is loads of dust inside the camera that settles on the film when it's left, er... exposed... for some time. Maybe I ought to get one of those vacuums Dr. Croubie mentioned.

 

[AgX]

Stupid me... I got several Isolas myself... But at first reading I somehow got one of those Agfa folders in mind, just as those are more poular with Apugers than the Isolas. And when writing about the latter I totally forgot about my remark on those bellows.


Anyway, that makes a source less for that dust. But nevertheless with that retractable barrel you still have got an air exchange (pumping) that may bring in dust.

The Isolas are made from plastic (no Baekelite) and that can built up static and attract dust.
This dust may get onto the emulsion. (I find that issue of dust and static electricity tricky and practice showed me effects contrary to what expected.)

Try to clean that barrel from the outside as well as from the inside. And see if that helps.

 

[ScarletBrown]

I suggest you to apply carefully some farmers reducer to the black sport to lighten them and you really have to figure out the cause of low density area on the negative.