Much like gothic tales of horror most are
founded in the dark recesses of the human psyche. This true tale is
the story of Franken-lens. Part human, part monster...
Take one of these, and one of those. Hack some
body parts off, rearrange them and you get...
A zombie half-child lens that should never have
been born. (If it really was meant to be, the Russians would have
done this a long time ago.)
through your Jupiter-8 or Jupiter-8M cadavers for a nice body part donor.
Refer to Jupiter-8
lens Dismantle to
see how to dismantle one and reduce it down to this. Throw the left
over remains in the knacker pile.
Take an I61 L/D and remove the lens block by
unscrewing the three grub screws around the body as shown by Blue
lens block from the body. Again, tossing the still warm remains
If you feel
demented you may screw the I61 lens block into the Jupiter-8
body to see how the concept works. This would be a good time to put
on your lab coat and flash the lights on and off while cackling
madly if you choose.
Just a word about the differences between a J-8
and a J-8M. The base is slightly taller on the Jupiter-8 body on the
left versus the Jupiter-8M body on the right. A Jupiter-8 would be
the preferred way to go if you have one as it just tall enough to
overlap the outside collar of the I61 lens block. I you only have a
Jupiter-8M you may need to do some extra steps if neatness is a
I found that if I glued the aperture selector
ring into the Jupiter-8M body securely it would extend enough to
overlap the I61 lens block.
One small detail that may deter most is the
fact that the aperture selector ring will need to have the internal
diameter enlarged to allow the I61 lens to slip inside. If you have
access to a lathe this is but an excuse to spend some enjoyable time
making some metal shavings fly.
Using the methods in Checking
Lens Working Distance. determine roughly the
distance the lens block should be situated in the lens body to
achieve infinity focus. Just keep screwing in the lens block
little by little until you get focus at infinity, then tape it fast.
Use a pair
of vernier callipers to make a reference measurement.
Screw the lens block so that it bottoms out and
make another measurement taking note of the difference. This will be
the size of shim you will need to fabricate.
I went to
the hardware store and got some sort of brass fitting and turned it
on my lathe to make a shim cylinder as a Jupiter-8M body requires a
pretty serious shim.
time to fine tune your shimming distance with other thin shims.
When satisfied put it all together.
You may find that the aperture number will not
line up with the existing markings on the Jupiter-8 so I just marked
a line with an indelible pen to show the selected aperture.
You are now done, go out stalking around taking
pictures with your Franken-lens. So how does it perform compared to
something else? Have a look at this
June 05, 2006