shawn
Mentor
Working toward trying to convert the Ivanichek 120mm Petzvar from Pentacon 6 to early Bronica mount for the S2/EC series of cameras.
If you remove the trim ring/mount from the Petzvar the remaining portion of the lens has a diameter of 72mm. That will *just* fit inside of the Bronica without its helicoid in place. I have a large bayonet adapter design and printed that recesses the Petzvar a few additional MM into the camera. If I keep it flush with the surface it focuses to about 22 feet. With the recess (about 3mm) the furthest focus point is about 100' away.
The circles on the recess is the location of the 3 mounting screws on the Petzvar.
My current problem to work through is the location of those 3 mounting screws is not ideal as they cross partway into the throat of the adapter.
That might take out too much strength in the throat for this to work. I also might not have enough thickness in the adapter to recess the heads of the screws, I can gain more back by reducing the recess for the lens but then I loose some distance focusing.
The lens does have another section that I think I can remove (about 5mm thick) but it houses the keys for the helicoid so I'd need to see if I can transfer that to the adapter.
Even without the mounting screws this is such a close fit the lens mounts into the adapter and stays in place based on friction itself.
If you remove the trim ring/mount from the Petzvar the remaining portion of the lens has a diameter of 72mm. That will *just* fit inside of the Bronica without its helicoid in place. I have a large bayonet adapter design and printed that recesses the Petzvar a few additional MM into the camera. If I keep it flush with the surface it focuses to about 22 feet. With the recess (about 3mm) the furthest focus point is about 100' away.
The circles on the recess is the location of the 3 mounting screws on the Petzvar.
My current problem to work through is the location of those 3 mounting screws is not ideal as they cross partway into the throat of the adapter.
That might take out too much strength in the throat for this to work. I also might not have enough thickness in the adapter to recess the heads of the screws, I can gain more back by reducing the recess for the lens but then I loose some distance focusing.
The lens does have another section that I think I can remove (about 5mm thick) but it houses the keys for the helicoid so I'd need to see if I can transfer that to the adapter.
Even without the mounting screws this is such a close fit the lens mounts into the adapter and stays in place based on friction itself.
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shawn
Mentor
The big thing I don't know yet is if this is going to clear the mirror(s). The Bronica 100mm on the helicoid recesses about 25mm into the body. I need to measure the Petzvar better but I think it is less than that.
Vince Lupo
Barely Known
Pretty nice job - looking forward to seeing some photos from it.
shawn
Mentor
I could almost shoot it as is but I want to get the lens better held in place so I don't have any issues.
This is just a quick shot of the focus screen to see what distance focus looks like, this is wide open so it is pretty close and it looks better on the screen compared to this snap.
The helicoid in the lens itself might have more movement too. There is a hard infinity stop, if that comes out the lens might screw in further which would help with my mounting. Externally, it looks like there is another 5mm or so before the aperture ring would have interference, don't know if the helicoid has that or not.
This is just a quick shot of the focus screen to see what distance focus looks like, this is wide open so it is pretty close and it looks better on the screen compared to this snap.
The helicoid in the lens itself might have more movement too. There is a hard infinity stop, if that comes out the lens might screw in further which would help with my mounting. Externally, it looks like there is another 5mm or so before the aperture ring would have interference, don't know if the helicoid has that or not.
shawn
Mentor
Removed the infinity stop but there no more movement in the helicoid. I was able to make the throat a bit thicker for more strength and also extended it into the body 10mm to cover the exposed helicoid on the lens. If all works I'll put a cap on it to cover everything but the optics.
Just starting the print, will see if it fits in about half an hour.
Just starting the print, will see if it fits in about half an hour.
shawn
Mentor
It does fit and the screws line up and mount fine. Had to switch to M2 x 4mm to attach the adapter.
and it does protrude less than the 100mm in the helicoid.
I'm making one last tweak and extending the exterior of the adapter to cover the gap at the top of the helicoid. The decorative ring originally covered this space
After that it will be ready to shoot, though the light is going away so it might be a little bit before I had pictures to show.
and it does protrude less than the 100mm in the helicoid.
I'm making one last tweak and extending the exterior of the adapter to cover the gap at the top of the helicoid. The decorative ring originally covered this space
After that it will be ready to shoot, though the light is going away so it might be a little bit before I had pictures to show.
shawn
Mentor
Retro-Grouch
Mentor
You undertake some pretty amazing projects! And, even better, they work! 
shawn
Mentor
Thanks, I was pretty psyched this one panned out. 3d modeling/printing is just so handy. It still blows my mind I can design a part while sitting on the couch, then hit few buttons (still on the couch) to fire up the printer, wait 30 minutes and go down to the basement to retrieve the physical object. Ended up with 14 prototypes on this project.
Next up is converting my Pentacon 6 mount Arsat 30mm fisheye to the Bronica.
Next up is converting my Pentacon 6 mount Arsat 30mm fisheye to the Bronica.