laptoprob
back to basics
Hi everyone,
It's a sunny morning in Holland so I decided to do the shutter burn test with a dismantled Zorki 6. That was the first russian camera I got years ago and sadly I ruined it trying to open ut the top.
Afterwards I descovered viewfinder alignment does not require removal of the top part.
Anyway, the shell is still used occasionally for screw mount focusing testing.
The results of this burning test are alarming. First I figured out that the 2 to 2,5mm distance between shutter curtain and film is about the same distance of focus between resp. minimal and infinity focus. In other words, at minimum focus the sun is projected sharply on the curtain. That means highest energy. The sun is projested in a 1,5mm diametre circle at minimum focus, against a 3mm diameter circle at infinity. This means 4 times higher surface, 4 times higher energy, I guess 4 times faster burning.
With my Canon 50mm f1,2 mounted the shutter burns instantly. Really, directly. At f2 it burns within a second, at f4 there is smoke within 10 seconds. Very alarming!
I could not mount my 90mm collapsible Elmar M on the Zorki, but handheld at focus distance the shutter burned at f4 within a second. At 5,6 it took only a few seconds.
Stopping completely down does help though! Then it takes minutes.
All this under bright sun, EV15.
It's a sunny morning in Holland so I decided to do the shutter burn test with a dismantled Zorki 6. That was the first russian camera I got years ago and sadly I ruined it trying to open ut the top.
Afterwards I descovered viewfinder alignment does not require removal of the top part.
Anyway, the shell is still used occasionally for screw mount focusing testing.
The results of this burning test are alarming. First I figured out that the 2 to 2,5mm distance between shutter curtain and film is about the same distance of focus between resp. minimal and infinity focus. In other words, at minimum focus the sun is projected sharply on the curtain. That means highest energy. The sun is projested in a 1,5mm diametre circle at minimum focus, against a 3mm diameter circle at infinity. This means 4 times higher surface, 4 times higher energy, I guess 4 times faster burning.
With my Canon 50mm f1,2 mounted the shutter burns instantly. Really, directly. At f2 it burns within a second, at f4 there is smoke within 10 seconds. Very alarming!
I could not mount my 90mm collapsible Elmar M on the Zorki, but handheld at focus distance the shutter burned at f4 within a second. At 5,6 it took only a few seconds.
Stopping completely down does help though! Then it takes minutes.
All this under bright sun, EV15.
Last edited:
