SW 80ED & HEQ5... extra essentials for DSO Astrophotography?

[dmahon]

Consider a Skywatcher Equinox 80 - slightly more expensive, but much faster focal ratio. You can also use a 0.8x reducer (TRF-2008) with it to get down to f/5.

[ollypenrice]

Consider a Skywatcher Equinox 80 - slightly more expensive, but much faster focal ratio. You can also use a 0.8x reducer (TRF-2008) with it to get down to f/5.

But how good is the colour correction if you do that? F5 seems improbably fast for a doublet, at least to my mind. I don't know the answer since I've never seen an Equinox in action.

Olly

[jgs001]

The extention tube I mentioned is to replace the light path taken up by the diagonal. That way you can bring the scope to focus correctly on the camera sensor. 

http://www.firstlightoptics.com/adaptors/two-inch-focus-extension-tubes.html

Acually, http://www.firstlightoptics.com/adaptors/skywatcher-2-inch-t-adapter.html may be better as it looks like it combines an extention tube and t-ring mount, then add http://www.firstlightoptics.com/adaptors/t-rings.html to mount the camera. 

If you go for a reducer, you probably won't need the extention tube.

But, if cost is an issue, then you don't need the reducer, and the tube and t-ring are a much cheaper option.

[dmahon]

Dunno. Have a look at some of my pictures and tell me how bad they are. No doubt blue bloats more than a triplet, but no worse than a larger f/ standard ED80. Mine are done with an Equinox 80 + TRF-2008. No refocusing between parfocal Baader filters.

[ollypenrice]

Dunno. Have a look at some of my pictures and tell me how bad they are. No doubt blue bloats more than a triplet, but no worse than a larger f/ standard ED80. Mine are done with an Equinox 80 + TRF-2008. No refocusing between parfocal Baader filters.

I've no intention whatever of claiming your images are bad! If the Equinox does reduce down to F5 that's great. I simply didn't know, which is why I asked.  I know the normal ED80 is a good 'un. So a doublet at F5? Yes, that's impressive.

Olly

[Peter Drew]

A bit out of my comfort zone when it comes to AP but I think the CA of an objective is relative to its native aperture and focal ratio and does not revert to that of a shorter FR when optically reduced. 

[Fishpaste]

I'm wondering now if instead of buying various filters etc, if I should plough the last of my cash into a camera upgrade...
I have the Canon EOS 400D (no live view -- 10Mpixel)...
Assuming I chose a different EOS which did have live view - would I be better going for  a model with much higher resolution (18 Megapixels) - or a lower resolution Astro Modified camera?
Would an 18 Megapixel camera be better or worse for noise?

(Sorry if this topic is expanding too much!)

[keybaud]

I'm wondering now if instead of buying various filters etc, if I should plough the last of my cash into a camera upgrade...

I have the Canon EOS 400D (no live view -- 10Mpixel)...

Assuming I chose a different EOS which did have live view - would I be better going for  a model with much higher resolution (18 Megapixels) - or a lower resolution Astro Modified camera?

Would an 18 Megapixel camera be better or worse for noise?

(Sorry if this topic is expanding too much!)

Here be a can o' worms.

Modern sensors are usually larger and may have less noise, but the amount of light per pixel is less than a lower resolution, so more pixels isn't always better. There is a value for different types of AO where you calculate the arc seconds per pixel, to see which sensor is best. I have an old EOS 30D and the arc seconds per pixel are better than my new 70D for nebulas, but it will probably have more noise.

[keybaud]

AP (astrophotography) not AO, I don't know what AO stands for!

Post here with a useful chart:

http://stargazerslounge.com/topic/62325-arc-second-per-pixel/