Star defect

[robindurant]

I have tried imaging with my Celestron 102SLT which is fairly lightweight, the OTA trembles quite easily. I have found that some of the Stars have a white line through them. I think that it may be the initial shutter opening on my Canon Camera making the OTA shake. Would this very small shake cause the white line. The stars look like miniature Saturns. Advice please PS I do use a remote control with a 10 second delay before opening the shutter.

[mikkey99]

Best way to check if it is shutter shake is to try the `hat trick`.

Simply set shutter for say 30 secs and hold a dark cover (card or similar) over aperture of scope, fire shutter, count to 10 and remove card,

so you get a 20 sec exp and first 10 secs lets any shutter vibration die down.

HTH

Mike

[peonic]

I think the 350D has a mirror-lockup function that you can enable?

Chris

[trevboyd]

Yes, the 350D has a mirror lockup - its under a menu titled "Custom Functions" or similar on the last menu page - option 7

HTH

Trev

[robindurant]

Thanks for the info on mirror lock up. Question: how would I use this lock up for imaging ? sorry to be so dense.

[trevboyd]

Hi Robin

Basically, you enable the mirror lockup. Then, when imaging, you press the shutter release once to lock up the mirror and a second time to actually open the shutter. The theory is that you lock up the mirror, wait until any resulting vibration has subsided, then open the shutter (which causes very very little vibration itself). Then at the end of the exposure, both close at once as normal.

One important tip - make sure you set the mirror lockup back to "off" when you're finished for the night - I've got myself very confused trying to take normal photos in daytime when I left it enabled! Wondered why nothing was happening.... Also, you can damage the shutter curtain if used in bright light conditions (since with the mirror gone, the light hits the curtains for a potentially long period)

HTH

Trev

[daz]

Set it to self-timer with the lock-up enabled.

Then hit the button. The mirror locks up at the start of the self-timer count down

And as Trev says, don't forget to reset the mirror lock (you will, though. We all do )

[robindurant]

THANKS TREV & DAZ, VERY USEFULL INFO, WILL GIVE IT A TRY. I AM USING A CANON AUTO TIMER SO I WILL TRY IT AFTER OPENING UP THE MIRROR.