FED 2 shutter mod (no more hard slit)

[e_asphyx]

Most soviet cameras have a very annoying feature, a fixed (hard) slit, which (almost, but that's another irrelevant story) doesn't widen as curtains travel across the frame to compensate for an acceleration. This leads to inevitably uneven exposure on speeds above 1/100th of a second. It's done by making the second curtain cam (tab) to catch the first curtain cam. So instead of overrunning the tab the cam bumps into it pushing forward. So effectively the first curtain drags the second one at a fixed distance behind. Why it was done is unknown, presumably to simplify the assembly process by making the shutter virtually insensitive to the second curtain spring tension.

I should admit that the worth of this modification is disputable. Think of it as an experiment.

The old down-faced cam was ground off leaving just a registration pin and the new cam about 1.4 mm in thickness was made from brass and silver-soldered above the old one:



Now the cam passes far above the latch so the new one with an elevated bump (slide) was made. The thick part is 4mm and the thin one is about 1.4mm, almost like the original latch. Again, made from brass and silver soldered to the original axle.



How it looks assembled:




In addition the axle was shortened by about 1mm to make the latch catch the tab more reliably (I discovered that the first curtain gets released slightly before the latch came into plane of the tab so if you press the button slowly enough the shutter may misfire).

As a consequence the 1/500 speed is non functional but all other speeds are pretty close to spec if adjusted properly.

 

[Valkir1987]

This is a very nice modification and the brass latch is very well made. I did a 1 on 1 comparison with a Fed 1f and a Leica IIc a few years ago. Fed started making a hard slit somewhere between the 1f and 1g. The 1f does even exposure, but the highest speed is about 1/300.

The speeds are even engraved in a different spot. Note 1/500 is where the 1/200 is on the Leica with the same speed range. On the Leica the second curtain is activated earlier. You might be able to modify the hook and latch in such a way the curtains will open on the right position. (or you may even build a new speed knob and disc)

 

[e_asphyx]

This is a very nice modification and the brass latch is very well made. I did a 1 on 1 comparison with a Fed 1f and a Leica IIc a few years ago. Fed started making a hard slit somewhere between the 1f and 1g. The 1f does even exposure, but the highest speed is about 1/300.

The speeds are even engraved in a different spot. Note 1/500 is where the 1/200 is on the Leica with the same speed range. On the Leica the second curtain is activated earlier. You might be able to modify the hook and latch in such a way the curtains will open on the right position. (or you may even build a new speed knob and disc)

View attachment 4866272

I just overtightened both springs a bit, so 1/25 became 1/30 and I got 1/200 instead of 1/250, pretty close. I didn't take a measure at 1/500 because while it's supposed to work I screwed it up by glueing the new curtain at incorrect offset (I missed 1-2mm) so it just cuts 1/4th of a frame. It's almost impossible to do it precisely without a sophisticated jig. And on FEDs specifically you can't readjust the drum because the pin and tab unit is a single piece.