[Jie Li]

Pentax 6*7 with MLU ___ high speed exposure issue

Hi friends,

I got a Pentax 6*7 with MLU, camera seems fine except exposure at high speed(1/1000 1/500 1/250 1/125)

At shutter speed of 1/1000 and 1/500 sec, the curtain did not open for >90% of the times
At shutter speed of 1/250 and 1/125 sec, I got uneven exposure from left to right. (see picture)

I already disassemble most of the camera covers, did anybody know how to fix this problem?
tension of the curtains problem? Electromagnet problem? lubrication problem?
I have a shutter speed meter with enough accuracy, also some comment tool and lubricant.

Could anyone give me some suggestion?

Thanks!

Attached Images

 

[pentaxus]

The travel time of the shutter curtains needs to be adjusted which requires proper test equipment. There is no way to guess how long it takes the shutter curtain to go from one side of the frame to the other. This happens when the shutter is left cocked for years. You could try slowing down the second curtain or speed up the first curtain. I don't have a 67 handy to remind myself exactly how the 67 looks. The adjustments are similar to spotmatic/K1000 adjustments. The adjustment toward the rear of the camera is the 2nd curtain. During adjustment the brass gear rotates counter clockwise to lower tension. You loosen the set screw and use the screw that is perpendicular to the brass gear to make adjustments. Take careful notes.

[Jessieben2021]

I have the same issue with mine. Have you fixed the problem Jie Li? Could you please share what you did please and photos of the process would be appreciated. Thanks.

[Jie Li]

I have the same issue with mine. Have you fixed the problem Jie Li? Could you please share what you did please and photos of the process would be appreciated. Thanks.

Yes I fixed these problems with a shutter speed test device, a photodiode and an oscilloscope. I will write an article about that.

[Jessieben2021]

Looking forward to the article.