Hyperstar mirror lock trial

[Mike Hawtin]

I have spent what seems like ages doing mods to my C6 Hyperstar to overcome mirror flop and issues with poor star shapes and last night finally got the chance to do a trial run. So here it is, IC5070 taken with what is now a 120mm diameter F/2.4 scope, 193 x 60 sec subs, taken under less than optimal conditions (bright moon, thin haze and starting at low elevation) stacked in DSS with flats and bias applied and no subs dropped plus ABE and auto STF only in Pixinsight. I did not expect too much given the conditions but I think it turned out pretty well all things considered, the image drifted 4 pixels in X and 7 pixels in Y after 3.2 hours.

http://www.astrobin.com/42829/

[JamesF]

Very nice image. Which mod did you do?

James

[Mike Hawtin]

Thanks James, I fitted a mirror lock system and used an aperture mask to improve the star shapes. The scope now operates at F/2.4 geometric and F/3 effective.

Mike

[Gina]

Very nice

[Ewan]

Very nice Mike great detail in that image.

How did you do the mirror lock mod on the C6, i cant say i have noticed flop on my C8, not sure how to check for it either tbh, the one thing i did notice on mine was the 3 screws were quite loose on the focuser knob which i tightened a little & now the image on screen doesn't move about so much.

[Mike Hawtin]

Thanks Ewan, the mirror flop caused trailed stars on exposures longer than about 300 sec. I cut 3 slots in the back of the main casting and attached 3 brackets with lock bolts to them and then attached struts to the primary which exit the scope through the slots and are then clamped to the angle brackets. I can now go to >900 sec without trailing and the clamps do not alter focus or collimation.

Mike

[Lars]

Great job with the mirror locks. The image looks great. /Lars

[TC_Fenua]

Wow, that's a great result you got there Congratulations !