Evostar 80ED Orion nebula FOV?

[willcastle]

Hello everyone,

I just had a go, on stellarium, at trying to see the FOV of a skywatcher evostar 80ED, with an APS-C sensor attached to the scope. Does this look about right? or did I do something wrong? It seems very zoomed in (which I actually quite like).

 

[geordie85]

Looks about right. 

[vlaiv]

That FOV seems to be too small.

Ah, I get it - you are looking at ED80 FOV without flattener / reducer. With x0.85 FF/FR it is wider - here is comparison:

[celestron8g8]

Just curious , is your camera a 1.6x or 1.3x  ? I don’t have my picture available now but i imaged M42 over 10 yrs ago with my XSi (1.6x) with my AT1010 which was a 80mm 480f/l , F/6 and i don't think mine was that large in the frame or FOV but I didn’t keep records very good to compare here . Like i said just curious . 

[willcastle]

2 hours ago, geordie85 said:

Looks about right. 

Great. Thanks for confirming. It’s a nice, tight view of the two nebulas. Cant wait to get out there imaging 

[willcastle]

2 hours ago, vlaiv said:

That FOV seems to be too small.

Ah, I get it - you are looking at ED80 FOV without flattener / reducer. With x0.85 FF/FR it is wider - here is comparison:

Excellent. Thanks a lot. Yes you are totally correct, I am not going to use a field flattener just yet; I have run out of funds 😃

[willcastle]

2 hours ago, celestron8g8 said:

Just curious , is your camera a 1.6x or 1.3x  ? I don’t have my picture available now but i imaged M42 over 10 yrs ago with my XSi (1.6x) with my AT1010 which was a 80mm 480f/l , F/6 and i don't think mine was that large in the frame or FOV but I didn’t keep records very good to compare here . Like i said just curious . 

APS-C cameras have a 1.6x crop factor. So they are more zoomed in. Additionally, the focal length of the evostar 80ED is 600mm, which again, gives you a more narrow field of view than the 80mm you were using  

[celestron8g8]

2 hours ago, willcastle said:

APS-C cameras have a 1.6x crop factor. So they are more zoomed in. Additionally, the focal length of the evostar 80ED is 600mm, which again, gives you a more narrow field of view than the 80mm you were using  

Well that makes sense . I’m not familiar with the Evostar . Mine is a Stellarvue and about 15 yrs old approx. and it’s an achromatic so mainly i deal with CA but other than that it’s a fine scope   !

[ollypenrice]

As this is in the 'getting started' section I think it would be appropriate to say, here, that the term 'crop factor' should be dispensed with in astrophotography.  It offers a means of comparison between the field of view of 'chip x' and a traditional 35mm film-sized sensor. This is not a useful comparison in astrophotography and leads to confusion with regards to being 'zoomed in.' (This is another phrase which we should abandon.)

'Crop factor' implies 'zooming in' which in turn implies an increase in captured detail. In reality more detail requires an increase in focal length or a decrease in pixel size or both. Detail and sensor size are entirely unrelated.

We should stick to focal length, chip size and pixel size in this kind of discussion and describe resolution of detail in terms of arcseconds of sky per pixel. That way we can avoid confusion.

Olly

[Skipper Billy]

18 minutes ago, ollypenrice said:

As this is in the 'getting started' section I think it would be appropriate to say, here, that the term 'crop factor' should be dispensed with in astrophotography.  It offers a means of comparison between the field of view of 'chip x' and a traditional 35mm film-sized sensor. This is not a useful comparison in astrophotography and leads to confusion with regards to being 'zoomed in.' (This is another phrase which we should abandon.)

'Crop factor' implies 'zooming in' which in turn implies an increase in captured detail. In reality more detail requires an increase in focal length or a decrease in pixel size or both. Detail and sensor size are entirely unrelated.

We should stick to focal length, chip size and pixel size in this kind of discussion and describe resolution of detail in terms of arcseconds of sky per pixel. That way we can avoid confusion.

Olly

Here here. I guess that many people are arriving here are from daylight photography with a DSLR and the change of terms used is a tough one to get used to.

[willcastle]

Fair enough. Those particular terms don’t confuse me but I guess for the sake of someone who would find those concepts confusing then it’s good to clarify. Perhaps you are confused with the fact that I never mentioned “resolution of detail” however? My post was about FOV and therefore framing of image. 

But yes generally speaking “zooming in” is a horribly imprecise term. 

I don’t see the harm in “crop factor” however. In my opinion it is a very simple and unambiguous concept. I can’t see how anyone would think that allows for the capture of more detail but I guess they might...? 

[alacant]

18 hours ago, willcastle said:

21 hours ago, geordie85 said:

 

Great. Thanks for confirming. It’s a nice, tight view of the two nebulas

Maybe turn the camera 90°? IIRC, both clumps of nebulosity extend beyond what's seen on a planetarium preview.

Cheers