Orpington Astronomical Society

Astronomy => Technical => Topic started by: JohnP on Mar 23, 2011, 10:19:35

Title: Fay - Screen Print Problem
Post by: JohnP on Mar 23, 2011, 10:19:35
Below is the scree print Fay was trying to upload....

(http://www.jpastronomy.co.uk/graphics/web/Fay%20Screen%20Print.jpg)
Title: Re: Fay - Screen Print Problem
Post by: Fay on Mar 23, 2011, 10:43:05
Oh thanks John,,,DOH!!!!!!!

Well as you can see I have a box around the star I want to focus, but it does not show up in the focus box.

The FWMX & Y stay as zero, while big figure in focus. I have contacted AA & QSI & they both say it is to do with each other.

I have to go into Nebulosity, at the moment to focus
Title: Re: Fay - Screen Print Problem
Post by: Mike on Mar 23, 2011, 11:18:07
Do you have dark frames enabled or disabled?
Title: Re: Fay - Screen Print Problem
Post by: MarkS on Mar 23, 2011, 11:27:25
I guess the focus box is either empty or is picking up the wrong section of whole image.  You can find out which, by pointing your camera at your garden or a picture or a newspaper.  But that still won't tell you who is to blame.

Mark
Title: Re: Fay - Screen Print Problem
Post by: JohnP on Mar 23, 2011, 11:31:17
Fay - Exactly what I said before - why don't you test in the daylight rather than wait until imaging....
Title: Re: Fay - Screen Print Problem
Post by: mickw on Mar 23, 2011, 11:50:50
You have exposure at 0.3 - Is that 1/3 second ?
Title: Re: Fay - Screen Print Problem
Post by: Rocket Pooch on Mar 23, 2011, 12:01:14
Fay,

It looks like you initia. exposure was 240 seconds 4 minutes and yet your focus is .3 sec, thats approx 960x shorter exposure, I'm not suprised you can't see anything :-)  Correct me if I'm wrong?

I normally do an exposure of 5 seconds, find a brigh star and then focus at 2 second, remembering there's not a lot of point doing it any quicker because the shutter has to rotate out the way.

Also on AA under options turn on Advanced and you will see you can change the histogram.

Chris
Title: Re: Fay - Screen Print Problem
Post by: Fay on Mar 23, 2011, 12:21:44
I was doing 0.3 secs 2x2, do you think that is the problem? Not long enough focus exposure time?

I will be outside tonight, so will test that
Title: Re: Fay - Screen Print Problem
Post by: Fay on Mar 23, 2011, 12:22:35
I did test in daylight John. I focused on a plate in the living room & it was ok, it filled the focus box

Chris, usually I do a sub of around 30 secs, so I can see some stars.I did not used to use AA for focusing, that is why I am not used to it, always done it by sight before.

Will have another go tonight & do longer focus sub

dark frame off, Mike
Title: Re: Fay - Screen Print Problem
Post by: mickw on Mar 23, 2011, 12:37:39
If you're doing 30 secs to see a star, you won't see one at 0.3 sec
Title: Re: Fay - Screen Print Problem
Post by: JohnP on Mar 23, 2011, 12:59:06
It looks like what chris has said is right - The background of the sub shown in your screen print looks quite smooth - so as chris said this is a 4min sub you have then selected a star & only done a .3sec sub so you wont see. You need to loop say 2 or 5 sec subs (background will be a lot noiser I guess) & then pick a star to focus on...
Title: Re: Fay - Screen Print Problem
Post by: Fay on Mar 23, 2011, 13:25:42
thanks, I will have a go tonight
Title: Re: Fay - Screen Print Problem
Post by: MarkS on Mar 24, 2011, 05:27:10

Fay,

I always use my alignment star for focusing since it is very bright and allows for short exposure times (e.g. 1 sec).

Mark
Title: Re: Fay - Screen Print Problem
Post by: Fay on Mar 24, 2011, 08:56:58
Good idea Mark
Title: Re: Fay - Screen Print Problem
Post by: Rocket Pooch on Mar 24, 2011, 09:55:57
Grrrr
Title: Re: Fay - Screen Print Problem
Post by: Fay on Mar 24, 2011, 10:06:26
Well I had a nice visit from John P last night, just in time to do some focusing. Think it is sorted now, I was not doing a reasonable exposure on the focus, as you said Chris.