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sdzsdz
8-Sep-2017, 02:46
Hey folks!

I need a short hint how to do this. I whant to Mount a Rodenstock APO Ronar 300mm/9 into a Prontor Prof. 1S shutter. The shutters aperture scale starts from 5,6 onwards. But the Prontors have clicks in 1/3 f-stops. Normaly I would think that I start at 9 and count onwards to 11, 16...but is this really correct? It is annoying me that the first step from 9 to 11 is only a 2/3 step!

Any suggestions are welcome!

Sebastian

sdzsdz
8-Sep-2017, 03:27
Now I found the information that the stops (and clicks???) are adjusted by two screws on the back of the shutter. So unfortunately it wont't be as easy as I hoped. At least I found a photograph of exact this lens in this shutter and it seems if the same number of stops is done in nearly the same overall stoppig-distance

https://grossformatfotografie.de/thread/14326-rodenstock-apo-ronar-1-9-300-mm-mc/

Bob Salomon
8-Sep-2017, 05:33
Why not call Rodenstock and ask them if they still have scales left?

john.l.barford
22-Sep-2017, 07:32
I have had similar problems when using old shutters from 120 bellows cameras with homemade lenses on a 4x5 camera. The aperture readings of the shutters bears no resemblance to the amount of light entering the camera. The solution i devised is written up in another blog on this site entitled "through the lens metering"

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Pere Casals
22-Sep-2017, 07:52
Hey folks!

I need a short hint how to do this. I whant to Mount a Rodenstock APO Ronar 300mm/9 into a Prontor Prof. 1S shutter. The shutters aperture scale starts from 5,6 onwards. But the Prontors have clicks in 1/3 f-stops. Normaly I would think that I start at 9 and count onwards to 11, 16...but is this really correct? It is annoying me that the first step from 9 to 11 is only a 2/3 step!

Any suggestions are welcome!

Sebastian

I solved same by printing a vynil sticker, if IIRC cost was 1€.

Brook Martin
26-Sep-2017, 20:19
300mm is close enough for rock and roll (assuming b&w) to 12". Use a caliper to measure the aperture, setting it to open one inch. This is f12. Work out the offsets.

Paul Ewins
27-Sep-2017, 05:15
If you still have the original shutter (or barrel) for the APO Ronar the all you need to do is measure the diameter of the aperture at each marked f stop. This measurement will be the same for the new shutter at the same f stop.

consummate_fritterer
27-Sep-2017, 09:15
Paul, that makes sense except the shutter aperture has fewer blades so measurement won't be precise (irregular hole). However, that may not matter enough to be concerned with. 'Close enough' is often close enough... just not something we OCD folks are comfortable with.