Internal Bellows Reflections

[ic-racer]

I believe I'm getting internal bellows reflections. My photocopy stand is not setup right now, but I'll post some examples shortly.

I wonder if others that had this issue and solved it could chime in.

I do have a bag bellows that may focus with my 300mm lens. I don't have a compendium shade. I use the darkslide to shade the lens. But the pictures in question seemed to cause the internal reflections from a big semi-overcast sky. Perhaps I need to be more diligent to in these cases (where the sun is not actually hitting the lens) and still shade the lens with the darkslide from above.

[rfesk]

Yes, it is possible. Depends at lot on the bellows material and how close it is to the light going through the lens. Even film reflects some light back towards the bellows and lens so it can't be 100 percent eliminated. A bag bellows is the best option.

[Bernice Loui]

Flare from stray light inside the bellows is a given. In the past, there have been "miracle" bellows materials that claim to reduce stray light inside the bellows.. skeptical at best.

~Use a lens with a smaller image circe at a given reproduction ratio to limit the amount of stray light hitting the inside walls of the bellows.

~Use an adjustable lens shade to effectively limit the image size projected to the film recorder and stray light hitting the inside walls of the bellows.

The amount of internal flare thus contrast reduction due this stray light bouncing around inside the bellows can be more than most suspect.
This is one of the reasons why always trying for a lens with the largest possible image circle is not always wise.


Bernice

[neil poulsen]

With what camera?

[Alan9940]

I have found that you need to provide some sort of shading above the lens, especially on overcast days. I use the darkslide.

[Kiwi7475]

We just need bellows made with this stuff:


http://sitn.hms.harvard.edu/flash/20...kest-material/

[ic-racer]

I see "Black 3.0" on the internet, but it seems a little shady. I's expect 'the blackest paint' to come from 3M or some chemical company, not "Kickstarter," so I'm skeptical that "Black 3.0" is just black paint packaged in 'internet hype.'

If "Black 3.0" does what it indicates on the internet, I'd need to just paint the inner parts of the fold with a line of paint. It is the inner fold of each pleat from which the light reflects. I can see it clearly when I remove the ground glass.

By the way camera is a Shen-Hao 8x10 with its original bellows. Lens is a 300mm W 5.6 80 degree lens used with no compendium shade.

Currently I use the darkslide and I shade the lens standing in front of the camera. This works when direct sunlight shows on the lens because I can see the shadow of the darkslide.
Problem is the negatives in question were exposed with "Bright Overcast" that does not cast a shadow. It might be hard to know when the darkslide is in the angle of view.

Maybe some flexible arm with single barn-door on top, that I can set in place before the exposure, might be easier than adjusting a complete compendium shade.

[ic-racer]

I took a photograph of the negative but it does not show well. It shows better on the print. On some other negatives it is more of a box but it is fainter. This print shows it most prominently.

[Balazs Szabo]

Hi there,

I'm having similar issues and wondering if (and how) you managed to sort out yours.

Please see an example below.



Many thanks,

Balazs

[ic-racer]

I made this, but due to COVID surge, had very little time for photography this last summer to use it. The few times I went out I was working in a wooded area.
https://www.largeformatphotography.i...=1#post1580047