Any hope for this lens?

[Ardpatrick]

Isn't it supposed to be just the front and rear glass cells of the G-Claron lens that are removed from the lens and then screwed into the front and rear of the copal shutter respectively?
Not the whole G-open, and the aperture ring on the front of the G-Claron would be used.

Bingo! ?

Thanks Martie & Dan!

I didn’t realise that the front group just completely screws out of the housing. Now it fits the shutter correctly.

Housing length in shutter 53.44mm

 

[MARTIE]

Sorted!
Now just for the crud and a makeshift aperture scale.

 

[abruzzi]

According to Schneider the G-Claron's were approprate for distance focus (as opposed to macro) when stopped down to ƒ22. Not that plenty of people haven't shot them open wider. If the old aperture scale was for a 210 ƒ4.5 lens then then you may not need to change anything, other than knowing that anything reading wider than ƒ9 won't get you more light. You can get a ballpark estimate on that by doing the folloing:

- open the shutter into focusing mode and open the aperture wide open.
- look through the lens with enough light behind it that you can easily see the opening. At this point the opening will look perfectly circular because it is hiding behind a circular max opening on the lens elements themselves
- while looking through the lens slowly close the aperture down until you see the blades come into view. This will be obvious because these later copal shutters don't have that many blades so the aperture will go from geing perfectly circular to being pentagonal or hexagonal (not sure how many aperture blades)
- move the aperture back and forth a couple times to narrow down to the exact spot where the blades start to become visible
- without accidentally moving the aperture adjuster, take a look at where it is indicating. If it is just higher than ƒ8, i.e. ƒ9, then congrats--the shutter doesn't need an aperture scale, just know that it will never be wider than ƒ9, but any reading above ƒ9 will be close to accurate.

I've transplanted a number of lenses into shutters and made my own aperture scales. The above steps are the second half of that process, and essentially allow you to find the maximum aperture. I've done that on 4 G-Clarons (2 210s, a 270 and a 355) and a bunch of other lenses and frequently spot check my work with calipers to confirm correctness.

If you find that the steps above place the max aperture some other spot than ƒ9, then I can post the easy steps to create the entire aperture scale on a piece of tape. I've posten them in other places, but I'm not sure where, so I can't provide a link. The only work on later shutters (like the one you have) that have stops equidistant on the scale (i.e. 1 stop is always the same distance of movement on the selector whether at the wide end (ƒ5.6-ƒ8) or the narrow end (ƒ45-ƒ64). It takes me 5 minutes to do the whole process.

 

[Ardpatrick]

@MARTIE - thanks again. A potential paperweight has been transformed into a potentially 'new' lens!

@abruzzi - This was obviously my next question (aside from finding a Copal 1 lens board). I followed your direction and I'm already seeing incursion from the aperture blades as I move the aperture lever past f4.5. So I will need to make a new scale. If you have the instructions to hand it would be great. Otherwise I can do a search. Thanks for thinking of this.

 

[Nicholas Lindan]

If the old scale says f4.5 when the lens starts to stop down, and it is an f9.0 lens, you can use the old scale with the numbers doubled. Old f5.6 will be new f11, old f8 will be new f16, and so on.

 

[Ardpatrick]

If the old scale says f4.5 when the lens starts to stop down, and it is an f9.0 lens, you can use the old scale with the numbers doubled. Old f5.6 will be new f11, old f8 will be new f16, and so on.

That would be very simple if it’s the case.

I might be able to rig up a ground glass probe of some sort - using a darkroom tool, the Ilford EM10 for example, to verify light intensity vis another known aperture scale? Or even just shoot a roll of 120 (6x9) at set apertures again alternating between the G-Claron and my App Symmar 210mm? Or maybe I’ll stumble across abruzzi’s methodology online.

 

[reddesert]

Just lay a ruler across the front of the lens and eyeball the aperture diameter as viewed through the front of the lens. When the apparent diameter is 210mm/9 = 23mm, that's f/9, and so on. You can use this to hand label an aperture scale on a sticker, or translate the existing scale into the new effective scale.

You measure the aperture as viewed through the lens, because different lens designs will magnify the physical aperture by slightly different amounts.

 

[abruzzi]

If the old scale says f4.5 when the lens starts to stop down, and it is an f9.0 lens, you can use the old scale with the numbers doubled. Old f5.6 will be new f11, old f8 will be new f16, and so on.

thats a good and simple way to do it.

My "long" way is to lay a piece of tape along existing scale and make tic marks on the tape where ever there are whole stop tic marks on the existing scale. Write your whole stops along those tick marks starting with ƒ11. You might have to guess an exact location for ƒ9, but its going to be 2/3 of the distance from ƒ11 than ƒ11 is from ƒ16. Come to think of it, ƒ4.5 should 2/3 the distance from ƒ5.6 than ƒ5.6 is from ƒ8, so you can use that.

Then you do what I said before, to find exactly where ƒ9 should be, then place the tape with your tic mark for ƒ9 in alignment witht he aperture lever, and the rest of the stops should fall into place correctly.

This only works for shutter where the distance from stop to stop on the lever and the existing scale is the same for every stop. For shutters where the lever distance changes from stop to stop, you need to use the method @reddesert points out.