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Here's mine. This is a first test for the Canon EF 75-300mm lens @ 75mm. I was hoping to, atleast keep 50%, out of 120 exposures but 5, 8 & 15 sec is just too long @ 75mm, on an SLT alt-azi mount. I have to drop back down to 18-"55mm" & max, at 8 sec for M42. Well, 20 sec is possible @ 55mm but the keep rate is too low. I need to be able to keep 50-60%. M42 is tricky, unlike M31, where I can snapoff 20-30 sec exposures and just keep the bulk. I'm not doing that though, with M42. I have to drop back to 55mm & I'm taking:
200 lights x 5 sec, ISO 800 ... keep 50-90%
200 lights x 8 sec, ISO 800 ... keep 50-60%
Stack 'em individually & then stack 'em together
Once it clears, I'm layering a-bit & doing, around 250 exposures @55mm:
50 lights x 3 sec
150 lights x 5 sec
50 lights x 8 sec
25 lights x 10 sec
25 lights x 20 sec
and just keep the good ones. All-in-all, 300-400 frames or so. Below is a 100 stack; 100 lights x 5-15 sec, ISO 800, using a 75-300mm lens @ 75mm. None were keepers. I just wasted 160 exposures, to find the SLT's 75mm limit.
