first attempt - M57 and DSS problems

[Zendrix]

Hello guys!

I have some free time now so i decided to finally try my first attempt at drift alignment with a DSLR (Canon 1000D, prime focus). I know that my setup is lame for DSO pics, but i'm up for the challenge of trying the best i can with what i have for now, so yesterday i started this little quest (and i realized how long i have to go.. hehe.. but that's part of the fun).

The set-up: sky-watcher 130mm F=900mm, EQ2 (lol), 4x speed R.A. motor and Canon 1000D.

To make things short:

After i tried the best out of the polar alignemnt i could, I aimed at m57 and took 120x20 seconds subs, 40 dark and 40 bias. I got from those 120, around 45 without serious startrails (eq2 and polar precision, i guess is gonna be a struggle.. also, i think everytime the wind would hit the scope, would ruin one shot).

In DSS i loaded all this info and left everything in default... at the threshold menu for detecting stars, i got what i predicted was a problematic number: 9 stars at 2%. So the problem is: in DSS, he tells me he can only register one of 45 shots... "you should check the threshold, etc..".

My questions are a lot, but i'll make a few for now:

- wouldn't 20 seconds be enough for it to detect more than 9 stars in every pic? I leave you the example of the processing of DSS with only one light photoframe (in attachment)... I can see more than 8 stars (which i was tols was the minimum for registing the frame).

-Could it be because i was using a baader filter for moon and skyglow in front of the 25x lenses that might have darkened the image to the point of no star recognition? Could it be the light pollution, me being in the center of a city?

-Is there any way i can go around this problem of no star recognition and use the info i have in the 44 pics left ans stack them somehow?

I'm sorry for making it "heavy", please bear with me as i am very new to this!

Thanks in advance!

Cheers,

Rui

[Freddie]

DSS has a problem seeing the stars if they are not round. I think that could be your problem.

[Zendrix]

Is there a way out of it in DSS? Is there any possible way of stacking this info? Could registax do it? Does it work with darks and biad as well?

[Zendrix]

I was using a 25x lense.. Maybe if i do prime focus without any lens between the camera and telescope i will be able to have longer exposures and rounder stars, once they will get smaller?! (and probably less coma effect?) dont know what's the FOV though, if it is too wide for most of nebulaes and galaxies, or not...

[Zakalwe]

"lense" is spelt "lens".

I am a bit confused. You said that you have the camera mounted in prime focus, then later said that you had used a "25x lense" (I assume that you meant an eyepiece??). You need to mount the camera directly to the focuser...no eyepiece is required. Looking at the sub exposure that you posted, it looks like there is loads of chromatic aberration as well as coma. That certainly looks like it was shot through an eyepiece (afocal)

[Freddie]

Just using the camera on the scope should go a long way to helping with your problem. I would try same length of exposure and see how round the stars look.

[Zendrix]

yes, i am sorry... i totally mixed up everything. Yes, i was using an eyepiece... not prime focus. I guess that brings a lot of problems (coma, harder to track stars perfectly, etc). But that means that the data i will have from M57 will be very faint, bearing in mind that the previous shot i showed was using a 25mm eyepiece and still looks far away.. i suppose lots of data will make it possible to crop and zoom in...

I will give it a go at prime focus tonight... i suppose i will have better results.

Thanks you for your patience guys!

Cheers,

Rui

[Zendrix]

By the way, i have this baader filter for skyglow... I suppose it would do me good once im in the center of a city but i dont know where to place it without eyepiece.. i have an extensor but that means my canon wont reach prime focus if i use it, once i already had to "chop" 3 cm to my tube....