Astrotorilla - Field of View

[Stian]

Hi,

Just started testing astrotortilla and managed to get all the communication up and running. I just have a question related to the field of view inputs based on my setup:

I have the following configurations:

Nexstar 6SE - T-Adapter-S - Canon 100d

FOV:
51.21' x 34.14'
Resolution:
0.59"/pixel
Area:
0.49 sq°
Focal length:
1500mm
Focal ratio:
f/9.9

Nexstar 6SE - Focal Reducer - T-Adapter-S - Canon 100d

FOV:
1.35° x 0.90°
Resolution:
0.94"/pixel
Area:
1.22 sq°
Focal length:
945mm
Focal ratio:
f/6.2

Nexstar 6SE  - T-Adapter-S - 2xBarlow - Canon 100d
FOV:
25.60' x 17.07'
Resolution:
0.30"/pixel
Area:
0.12 sq°
Focal length:
3000mm
Focal ratio:
f/19.7

 

What should I choose as the narrowest and widest field of view? (Looks like I am well below the narrowest option in Astrotortilla? (2-2.8arcmin)

 

br

Stian

[Pompey Monkey]

I don't use AT, but do use other plate solving software.

You want to chose the the indexes that top and tail your maximum and minimum fields of view (FOV) and all the indexes in-between.

Your smallest FOV dimension is approximately 17' and your largest approximately 95', so it looks like you need the range that covers about 15' - 100'.

[ollypenrice]

I don't know how accurate it needs to be but the real focal length you'll get with the reducer may not be the simple F6.3 that it says on the tin. The spacing has a considerable effect. It might be worth plate soving one of your images with reducer to find the real focal length.

Olly

[Pompey Monkey]

2 hours ago, ollypenrice said:

I don't know how accurate it needs to be but the real focal length you'll get with the reducer may not be the simple F6.3 that it says on the tin. The spacing has a considerable effect. It might be worth plate soving one of your images with reducer to find the real focal length.

Olly

That's a good point Olly. One of the plate-solving routines that I've used requires the image size to be defined within +-5%!

The best way I know to find out how to determine the real image size is Astrometry.net. http://nova.astrometry.net/upload

[Stian]

Thanks. I am downloading a huge amount of fits now it seems. Will give it a try tonight.

 

Astrometry.net says: (Based on http://nova.astrometry.net/user_images/958865#annotated)

Size:

72.5 x 48.3 arcmin