Sure you can use film rated 100 asa! Just go into a building that is not greatly illuminated (church, cool building lobby, etc) and you won’t have a problem using a hat at F32. Or go anywhere outdoors and wait until close to sunset/sunrise. No need for shutters!Originally Posted by amansjeanphilippe
It's been a while since I read about this... what is the exposure time ratio between using the fan and not to get the center filter effect? In other words if at f/32 the exposure time is measured to be 10 seconds what is the amount of time with the fan moving vs. out of the way?
Mine is supposedly out for delivery. (Oops, wrong package, mine is in USA but waiting in Chicago apparently).
What I have read online is that 1/6 of the total exposure time is without the fan and the rest with the fan in the middle.
So for the 10sec exposure make sure you hit the 1.66667 seconds precisely!
Jokes aside, if it really is 1/6 then it seems like one could survive quite easily without bothering to remove the fan. But I've never used one so perhaps the difference is staggering.
More online research on this topic seems to point to keeping the fan in position for at least three-fourths of the time.
https://chestofbooks.com/arts/photog...rgon-Lens.html
by the way the illustration of how wide the lens is, is quite amazing:
https://chestofbooks.com/arts/photog...hy-Part-2.html
and of course don't miss the dare at the bottom:
"Although a special camera is procurable through the Goerz people, anyone handy with tools can, in a few minutes, and with little expense, construct a camera box that will answer the purpose as well as the most expensive instrument."
I've heard the exposure with the fan should be 6 times or 8 times the original exposure. The big variable will be compensating for reciprocity failure, which varies from film to film, at these seconds-long exposures.
"I love my Verito lens, but I always have to sharpen everything in Photoshop..."
That’s what I’m saying too, 6 to 1. However the reference above argues for 3/4 and 1/4, so 3 to 1.
Since reciprocity is not a linear chemical process with time, it is true that dealing with long exposures will be tricky. I wonder however how much fall-off in the corners is left if you always keep the fan.
Also how fast does the fan spin? I can imagine very short exposures may be a problem too as you get only a fractional spin.
Since the fan is blocking light, it seems to follow that just like a CF filter one would need to increase the total exposure time a commensurate amount rather than just spin the fan for a portion of the exposure...?
A fan factor rather than a filter factor?
I am sure that owners of original Hypergons (who have used it) can chime in here with their experience….
Ok just to be clear, what I’m saying is that you expose for the time you think the exposure should nominally be, without the fan. And then you expose an additional time that is 6-8 times the previous, now with the fan spinning. But since 6-8 times will put it in the long exposure regime, some reciprocity will have to be applied, according to the film used.
In practice the two steps were reversed since a second bulb was used to trigger flipping the star out of the way. So you exposed spinning first and then with the star out of the way.
And you have to remove the star because it completely blocks the center of the image. Can’t avoid that step.
This is what I was going to do.
With the fan 'up' and timer ready, place my hat over the lens, pull the dark slide, start spinning the fan while holding the dark slide, and remove the hat and start counting. When the 'edge' exposure is done, flip the fan down and keep counting until the end. Then put my hat over the lens again and insert the dark slide.
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