Help with Kodak Retina helicoid dimensions

[jaroslav_ilnytskyi]

I am working on super-wide-angle 6x7 camera which involves mounting

47mm lens with appropriate coverage on older 6x9 folder (I've got

Ensign Ranger II). I did the similar combo before, with 65mm Angulon

and Baldalux camera and am very pleased with the results. The lens is

already mounted in Prontor shutter (from some 6x6 folder). The only

missing link is the helicoid which I hope to strip off some other

camera.

 

I just thought that many of our forum members are owning different

Kodak Retinas and I might try to ask a favour to measure the helicoid

dimensions. Some of the models (especially not working ones) are

quite cheap on eBay.

 

I am interested in knowing the internal diameter of the rear side of

the helicoid (whether my the rear element will go there or not) and

the depth of the helicoid (measured from the rear lens element to the

edge of the helicoid's cylinder). Unlike Super-Angulon the rear group

of my lens is cylindrical so that the chances are it may just fit. I

know it will go into Kodak duo helicoid but these are more rare and

expensive to get.

 

I would really appreciate a great help very much!

 

Regards,

Jaroslav

[jaroslav_ilnytskyi]

The models I've seen on sale are Retina 1b and retina 3 with selenium meter.

[connealy]

I have a Retina IIa body, but I'm not real clear on which parts of the focusing mechanism you want the dimensions for. When I put my calipers inside the opening where the lens would go, it measures 25mm. The length of the moving helicoid is about 8mm, exclusive of the front and rear plates. On my IIa, the rear lens element protrudes clear past the helicoid into the camera body. Perhaps it is different on other models.

<br>   

I think you will get a much better answer from Rick Oleson on this if he happens to have some Retinas opened up. If not, I could take a picture of mine if that would be of any use.

[jaroslav_ilnytskyi]

<p>

Thanks very much, Mike, that is really helpful!

</p>

 

<p>

<i>

On my IIa, the rear lens element protrudes clear past the helicoid into the camera body. Perhaps it is different on other models.

</i>

</p>

 

<p>

The helicoids I've seen so far (on Kodak duo and Balda 35mm) got a flat front with the central opening to mount Compur/Prontor. The rear side is in the form of cylinder with the threads. The rear lens elements of the lens are within the cylinder and move forward/backward when you focus (together with the shutter). Now, here the problem is. When using another lens either the rear element can be too large to get inside the helicoid cylinder or the cylinder is too long and will cause the light fall-off in the corners (my lens are wide-angle for 6x7). So, that, effectively, I need to bother with only two specified dimensions - the internal diameter of the helicoid cylinder and it's depth from where the shutter is mounted to the end of the cylinder.

</p>

 

<p>

From your description, Mike, looks like that in your Retina the helicoid is on the front and the rear of it is flat (hence, the rear lens element is protruding far inside the camera) if I understood that correctly. It might be even better for my purpose in case the shutter will go into the front.

</p>

 

<p>

<i>

I think you will get a much better answer from Rick Oleson on this if he happens to have some Retinas opened up. If not, I could take a picture of mine if that would be of any use.

</i>

</p>

 

<p>

Rick, do you happen to have any opened?

</p>

 

<p>

Thanks for the reply!

</p>

[richard_oleson]

i don't have one open, and mine has film in it at the moment... there's a real good discussion and set of photos here (no dimensions though):

 

http://retina.topcities.com/retinafocusmechanism.html

 

:)=

[jaroslav_ilnytskyi]

Thanks, Rick, that's a very good link indeed. By a naked eye it looks like it might just go, will know for sure when the camera arrive (won one ob eBay yesterday).