Fogging with Hypergon!

ic-racer

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Some background.

The Goerz Hypergon requires two exposures to counteract a severe light falloff at the perimeter of the image.

The first exposure is with the spinning fan, after which a string attached to the lever at the top, releases the fan to allow for the exposure of the center of the image.

My fan has a flaw, the shiny screw holding it in place is reflective and fogs the film in the center (need to fix this).

 
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ic-racer

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The end of the screw is fogging the image while the fan exposure is taking place. Looks like the paint on the inside of the fan did not stick well to the screw. Need to redo this.



 
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ic-racer

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Here is a 20 second exposure with the fan in place the whole exposure. Trying to figure out what is fogging the film. Looks like the end of the screw.

 

Kino

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Maybe some "Black 4.0" paint?

BLACK 4.0 - The blackest black paint in the known universe *NEW*

Black 4.0 is without a doubt the most absolute artists blackest black paint in the known universe. *Note: By adding this product to your cart you confirm that you are not Anish Kapoor, you are in no way affiliated to Anish Kapoor, you are not purchasing this item on behalf of Anish Kapoor or an...
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I would have to wonder if the light isn't bouncing off the shiny surface of the shutter cover (why did they make it glossy?) to the backside of the propeller?
 
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ic-racer

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This is frustrating. I have painted thousands of things in my life, including full size automobiles. But there is some issue where the screw pokes through. The paint is not sticking in that area. Maybe the loctite on the screw.
Now I have multiple coats of three different brands of paint and it is still not right. Time to strip all the paint and start over.
 

abruzzi

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boy...they don't like Anish Kapoor:

 

Kino

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Can you hot glue a black "button" over the screw? One small enough to avoid hitting the spinner, but being removable for maintenance?

B
 
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ic-racer

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Nicholas Lindan said:
You should be able to remove the GG of the camera and peer through into the camera and see what is causing the reflection.

If the film can see it, you can see it - and vice versa.
Click to expand...

The aperture plate has only two tiny holes. So this is not really possible. Best bet was to photograph the fan spinning as I did above and to make an exposure looking at the back of the spinner as I did.

BTW I'm using the lens on my Shen-Hao. Thanks to the front base tilt, I can get the lens as close to the ground glass as I want. It could even touch, so 75mm is no big deal.

 
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ic-racer

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Redoing it. It is hard to smooth the transition to the screw as the screw is so much harder metal.
 

Nicholas Lindan

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If the mountain will not come to Mohamed...

Try shooting a laser pointer from the center of the film plane, through the aperture and onto whatever is causing the problem.

That spot of fog just looks much too well defined to my eye. 75mm/f45 shouldn't be able to image a few mm in front of the lens, but then I have never played around with a Hypergon and stranger things have happened.

There is more than just the spot in the middle that is anomalous - the left side of the image is out of focus and also fogged. Are there other images showing the same problem?
 
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ic-racer

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Don't read too much into the sharpness, that picture of the negative was just a digicam shot of the 8x10 sheet hanging in the drying cabinet.
 

reddesert

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I also am not 100% persuaded that the screw is the only source of the reflection, but Hypergons are unusual.

I would try to glue some thin black felt onto the back of the fan to cover the screw and perhaps as much of the fan as you can, presuming that there is clearance between the glass and the fan for it.
 

pentaxuser

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"Anish Kapoor not letting people have Vantablack" Who is he, what is his business and why does he not let people have Vantablack?

Thanks

pentaxuser
 
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ic-racer

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I tried a little dab of JB Weld (epoxy) over the screw, but that left an irregular border after painting.

 

Kino

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pentaxuser said:
"Anish Kapoor not letting people have Vantablack" Who is he, what is his business and why does he not let people have Vantablack?

Thanks

pentaxuser
Click to expand...

The whole sordid affair is here:

The Vantablack Controversy: Anish Kapoor vs. Stuart Semple | TheCollector

The sculptor and installation artist Anish Kapoor bought exclusive artistic rights to the world’s blackest black in 2016, resulting in widespread controversy and a longstanding feud with Stuart Semple.
www.thecollector.com
 
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ic-racer

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Using a washer of appropriate diameter, some 2 sided tape, and sandpaper, I tried to sand the screw to have the same curvature as the rest of the spinner.

 
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ic-racer

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Here I have stripped all the layers of black paint and will build up some primer at the base of the concavity so I can sand a nice smooth surface.

 
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ic-racer

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BTW this thread is a continuation of information I posted on the "New Hypergon" thread on LF Forum.

My first images (last December) with the lens (and original unpainted, shiny spinner) looked like this on the LEFT. The first attempt at painting the spinner shows on the RIGHT. But there still is a blush in the center. The negative on the RIGHT was taken with the spinner looking like the image in the first post of this thread. You can see the irregularity in the center of the underside of the spinner. Either oil from the bearing or Loctite seeping around the screw.

 

MattKing

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