Questions about a mystery Balda 6x9 folder in need of care

[jay moussy]

I just got a cheap Balda folder, unmarked.
Unmarked., but it has style attributes speaking "Balda", probably made by Balda for a third-party camera brand (Franka, etc.). It feels like an economy camera, compared to, say, an Isolette - stamped metal parts and such.

Shutter
Pronto, T B 100 50 25
at 1/25 speed, shutter opens and closes slowly, blades forming an almond shape
Maybe a weak spring, and I may just live with it?

Lens
Schneider Kreuznach Radionar f4.5, 10.5 cm
Focus is working, lens has minor dust, a tiny bit of fugus - I can see some on filmside element.

I do not know how this lens is built.
Are all Radionar lenses built the same way, that is, elements are found in same order, so take-apart/cleaning would be the same?

 

[Donald Qualls]

That's almost certainly a 6x9 rather than 6x7...

And yes, all Radionars have the standard triplet design -- positive front element, strong negative middle, and slightly positive rear. The only gotcha is that the front and rear surface of the middle element have very slightly different curves, and it needs to go back with the same side forward.

 

[jay moussy]

That's almost certainly a 6x9 rather than 6x7...

And yes, all Radionars have the standard triplet design -- positive front element, strong negative middle, and slightly positive rear. The only gotcha is that the front and rear surface of the middle element have very slightly different curves, and it needs to go back with the same side forward.

er.. yes, a 6x9.
Pretty compact, actually, and it fooled me!

So, would this be correct?
A - front element screws off, once the focus infinity post is removed
B - then middle element comes off (by means of?), while paying attention to orientation
C- rear element (a single lens?) comes off

 

[Donald Qualls]

Rear element comes out from the back, generally, and you shouldn't need to remove it from the cell.

Front element unscrews, as you note -- be sure to mark the orientation where it comes off, there are (usually) four starts on the focusing thread. Middle element in some is held by a retaining ring, in others by the back end of the front element cell. The front cell stop post isn't for infinity, it's at closest focus. Infinity should be "all the way in."

After you put it back together, you can check that you got it right by seeing that the focus scale matches up when screwed in all the way, then verify with ground glass etc. at the film plane and a loupe (usually the focus scale ring is held by tiny set screws which can be loosened to adjust the scale to match real infinity, though you probably won't need to worry about that).

BTW a Tessar type with front element focus is the same, except the rear group (behind the shutter) is a cemented doublet -- looks and handles like a single element, but actually two pieces of glass (if you have it out of the cell, you can usually see the join on the ground edge, but don't take it out of the cell if you don't need to).

 

[Tel]

Here's the shutter repair manual. Should be good for all the Gauthier shutters (Prontor, Pronto, etc.) I'm thinking maybe gunk on the blades or maybe a dirty escapement rather than a weak spring....

https://learncamerarepair.com/downloads/pdf/PRONTOR-S-SV-SVS1-Repair-Manual.pdf