How to improve

[Rob52]

Hi all
The equipment I have
Scope.... Skywatcher 130/650 Black Diamond Newtonian
Mount ... Skywatcher star discovery alt az goto mount
Camera.. Nikon D3100

I know the mount is my biggest drawback, but at this present time finances do not permit upgrading.

The problem I have is that i'm only able to get 1 sec images before i start to get star trails. I have seen images with the same set up of gear with longer times eg 20 secs.
The question is how is this possible ?
The attached image is Pleiades .. 25 x 1 sec 20 darks and 20 bias stacked in DSS
Any help or constructive critisism greatly accepted.

Thanking you in advance

[raymo]

Provided you have entered the required details of your location etc: properly, done the simple two star alignment process, and switched on sidereal tracking
you should get 10-15 secs before field rotation starts to elongate the stars.
I'm not familiar with the Discoverer's requirements, but if it requires the current date don't forget to enter it in the U.S. order of month/day/year,
not our day/ month/year. Hope this helps.
raymo

[Karlzburg]

What hand controller does your scope have?

I found this in the manual for your mount for set up, I had a mini az gti and I had to set it up so it was facing true north and scope was level before starting alignment, then would do either 2 star or 3 star alignment. I could get anywhere from 30 to 50 sec before star tails.

Hope this helps.

Karl

[RyanJones]

Hi Rob,

As Raymo has stated, making sure that the alignment and tracking mode are right is the first critical step. Given that you can't equatorially align your mount, you're always going to be dealing with star rotation but looking at your image and the movement in the stars, it doesn't actually look like this is your issue. You need to make sure that the mount is super stable, even ad weight to the tripod if need be. I used gym weights on the accessory tray. Make sure you're nowhere near the mount/camera when you're taking the image, remote intervalometer or simple remote trigger.

If you can post a single sub that's maybe 10 second long so we can see the length and direction of the trails, we may be able to help you further ?

Cheers

Ryan

[Ukastronomer]

This is why I don't do imaging, what they have said above is 100%, see image I do this to most of my grab and go setups.

It is a matter of try and try again and learn, imaging has the steepest learning curve and requires masses of time and trial

[Rob52]

Thanks Raymo, yes have done all you said, and was aware of the date difference. will just have to try harder

[Rob52]

Thank you Karlzburg
yes i read that in the manual, that section is if your using the basic hand controller that doesnt have the alignment system. I have the synscan vers 4 controller, but i will set it up using this method then use the 2 star alignment. I also make sure it is level before putting the head onto the tripod, I will face it to true north next time before aligning maybe that will make a difference

[Rob52]

Thanks guys
With all the advise, as soon as i get a clear night I will try everything that has been mentioned and take a 10 sec shot.
I do align my 2 star alignment mainly on Rigel and Canopus, would it be better to use any other stars ?

Thanks again guys

[kens]

Imaging at 650mm FL on an alt-az is always going to be a challenge. Do you have a shorter lens for your camera - say 200mm FL? There are plenty of targets for which that would be an appropriate FL. and you'll be able to expose 3x longer.

[Rob52]

The 650mm is my Skywatcher Newtonian, Yes i do have an 18/250 mm lens for the camera. I was thinking of getting an L
bracket to mount the camera to the alt-az. To do the star alignment would i just use live view on the camera?

[Ukastronomer]

Just a camera on a chair, who needs to track ?

28mm lens, DSLR, chair, pillow :)

[sil]

Yes, just use camera and lens on mount and align through live view. Make sure you are correct with the star you are aligning with. Best to use single bright stars that are easiliy identified . But otherwise the star choice makes little difference. Though stars wide apart across the sky should give a better alignment result. Balancing the gear is important too as front /rear heavy will affect tracking.

Also dont just set the camera to every suggestion you see, you need to test them all and figure out what works best for your equipment. try using slightly longer exposures until you start star trailing, start at a short exposure time first and try several to find where you can photograph and get round stars then increase one increment and test again until the stars start to trail, then you can start increasing ISO similarly until the noise is obvious. Those are the fixed manual settings for your specific equipment.

Experiment and learn.