Heliar 75/2.5 - taking it apart and semi-closer focus modification.

Krosya

Konicaze
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Ok, this is something most will not need/want to do, but I did it simply because I wanted to see what can be done. Here is a pic of focus difference - it's not much at all, as I said. So it's more of a excercise in lens hacking than actual beneficial hack. :

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Thats right - hardly any closer, instead of center, 1m mark on the lens is now across a DOF scale mark between 8 and 16. How much closer did I get - sorry, didnt measure, but the way I look at it - every little bit helps. Would I do it again - probably not, but it was a fun process.
If you dont think this is worth the trouble - no ned to read beyond this point.
 
If you are still reading, here is what to do:
1. Take lens hood off.- unscrew it.
2. Unscrew a name plate ring. How - well, there are different tools. I used a couple of chop-sticks, applying even pressure directly opposite while trying to turn the ring. Usung wooden sticks didnt scratch the metal/lettering. Have to be careful to not touch the glass.
3. Using a spanner wrench on the outer retaing ring around the front element of the lens, unscrew the whole front group. What you will have after that will look like this:
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There will be 6 screws visible. 3 silver and 3 black. Unscrew 3 silver ones (longer screws) to remove Apperture ring (apperture unit - blades, etc will still be attached to the lens body, this just removes the ring itself to get access to other things).

It'll look like this:
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Ok, so far so good?
Now, take a close look at the following photo:
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This shows one of the 3 elements that are positioned around the circle of the barrel. Those golden tabs are what comes to a stop at either end of focus range. There "T" looking stops, held by 2 screws that well....stops the turing of the lens.
Here is what they look like:
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And this is where it was attached with 2 screws, long end goig down inside the lens - there is a grove for each one inside the lens. Screws were covered with some red "locktite" substance.:
IMG_0006.jpg


Ok, so we have 3 "T" shaped stoppers. The only way I could figure out to do the close focus fix is to file down a gap in each of the "T" stoppers, so that lens can be turned a bit more. Since they are only so wide as it is, gap cant be made too long. Here is what I did - I didnt want to do more, but maybe it can be done a bit further:
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Thats it - filed the down, re-installed, reveresed my steps and there you have it.
 
Sorry I missed this thread.

Hmmm... looks promising... those 't-stops' are easy to make... so make new ones that allow the minimum focus stop to moved.

I am only looking to get 0.9m out of my 75/2.5 at the moment, since I am using on the Bessa R and its rangefinder only focuses to 0.9m.

I will do better and record my hacking if and when I get around to tackling it.

Thanks!
 
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