Star Adventurer: Many short or few long exposures ?

[Astrofriend (Lars)]

I continue with my Star Adventurer experiments how to get the most out of it.

I can notice when I taking 120 seconds exposures with my Star Adventurer mount and the 150 mm camera lens I sometimes get elonged stars. And with that long exposures also the brighter stars oversaturate.

How will my equipment perform if I take more and shorter exposurers, can my Canon 6D handle that? It has relative low readout noise at higher ISO settings but limited dynamic then.

Here I have done two tests to compare:
http://www.astrofriend.eu/astronomy/...-dynamics.html

At least in this case I feel the camera can handle the shorter exposure and still have good dynamics.

I live close to a big city, but I have found two places out in the east close to the coast where I have a relative dark sky. With my small ST I can easy go out there and doing astrophotographing.

Almost all my earlier AP have been done with a very lightpolluted sky.

/Lars

[blink138 (Pat)]

we have had 2 to 2.5 minutes from our sw sa on many occasions lars with a canon 200mm lens and round stars
polar alignement accuracy is paramount
it does have a guide port too!
pat

[Astrofriend (Lars)]

Hi,
We live at latitude 60 degrees, then the polar telescope is very difficult to look through. I have ordered som stuff to fix that. If it work well I wright a report about that. When I succed with the polar align it looks to be very good tracking. There is one man here in Sweden who have a small 130 mm Newton in his Star Adventurer, but he has added auto guiding. At which latitude do you live?

/Lars

[blink138 (Pat)]

32 south
we don't use a polarscope in ours, my brother has a very accurate compass, once set up we start with a minute exposure on say a 70mm lens, if eggy we adjust the azimuth and do another minute ......... then 2 minute with smaller adjustments
it does not seem to take us that long to get our 2 min exposures and then we are on for the night
going to the 200mm seems to only need the finest of azimuth to get round stars, so we always aim for this and so then we have no problem with the lower f/l lenses doing 2 minutes
pat

[Astrofriend (Lars)]

Hi Pat,
That was a different way to do the polar align, it sounds a bit difficult but maybe not, never tried it. When I polar align my EQ6 I do it by drift align with PHD2.

Another question:
How about your Canon 200 mm, it must be the 2.8 lens I think. I have read a lot of it and it shall be one of the best for astrophotographing. Do you use it at f/2.8 or f/4?

How about vignetting?

/Lars

[Astrofriend (Lars)]

Hi,
I took new photos with different exposure times, and also had two different ISO settings. More control over it in tis test but had some disturbing clouds.

http://www.astrofriend.eu/astronomy/...-dynamics.html

During these circumstanses it's hard to see any difference, or what do you say?

/Lars