Exposure times for DSI II

[Ric]

Hi everyone,
I am about to have my first session with my DSI II Pro and was wondering if anyone can advise me on the best exposure times to use. I am using a LX200R 12" in Alt/Az mode and the camera also has a f/3.3 FR. I know that the times have to be kept to a minimum and the general train of thought seems to under 30 seconds per exposure with the average being between 8-15 seconds.
Do these estimates fit with other members findings/experiences, I know the first few sessions will be mainly experimentation but I would like to know if I am in the right area

Thanks in advance

PS. I also noticed the abreviation LOL attached to a lot of messages and being new to all this I cant work out what it means, I know its going to be totally obvious when I read it so apologies in advance for the question

Ric

[EzyStyles (Eric)]

Hi Ric. Exposure times really depends on how long you can go without seeing startrails or over exposured objects. I normally keep at around 84 second - 120 second. I can't comment on your setup but will you be doing any guiding at all?

LOL stands for: laugh out loud. lol

[[1ponders] (Paul)]

Hi Ric. The longer the focal length of your scope the shorter your exposure time until field rotation comes into effect. Eric is working off an EQ mount so he doesn't have that problem so his exposure times are related to how long to burn out the stars (sigma clipping) and how much noise can be dealt with etc. Another thing to take into consideration is chip size. A Canon 300D will show rotation near its outer edges in around 30 - 45 sec at 2000mm fl but with the DSI with it's smaller chip you will have a bit more latitude. At a rough guess I'd say you should be right for exposures of 60 sec. You will be able to get a lot of obects that will come in easily in that time frame with stacking multiple images.


LOL = laugh out loud =
(check the go advanced button for posting replies to see more emoticons and their codes (click on the "more"button when you get there )

[Ric]

Thanks guys for your replys,
that has cleared up a few questions, the guiding will be the tracking that the LX does to keep it in the FOV. Once I get more experience I'll move onto a wedge and get a bit more serious
I think I'll start around the 20 second exposure mark and experiment from there.
Looking forward to posting a few piccy's for members comments and guidance

Cheers

Ric

[alandee]

Hi Ric,
You can also use the Envisage software to reduce field rotation, draw the first box in the DSI preview screen around the primary target, then a second box around a star toward the outside of the view, it aligns them as it stacks them ( and tries to de-rotate ) and if you then also seperately link the laptop to the rs port on the lx you can self autoguide of sorts as the software will drive the LX to try and keep the image centered and de rotated ! .. it works, but it's not perfect. Once you get the wedge, you can do quite a lot with the envisage software ( as I'm slowly learning ! )

[Ric]

Hi Al,
Thanks for the info, I've been slowly working out the software and the camera configurations. I had a test run and experimentation last Saturday and was quite impressed with what I achieved, I was imaging the moon as an easy target to start with, so this weekend armed with more knowledge and confidence I'll be looking to have a more serious play.
Cheers
Ric