Considering Upgrading From CPC800 to CPC1100?

[zakkhogan]

Quite literally as it says, im considering upgrading From CPC800 to CPC1100, will i really benefit from the increase?

I mostly do Planetary and Luna imaging with my ASI120mm and the occasional dabble with DSO with my DSLR

Is it worth the cost to upgrade?

Thanks 

Craig 

[Peter Drew]

For lunar and planetary photography, a definite YES. It's going to be significantly heavier though!. 

[zakkhogan]

Thanks Peter, 

Would it not serve great for DSO, I do have a F/6.3 focal reducer if that helps? 

The weight wouldnt be an issue as it would be pier mounted

Thanks

Craig 

[Peter Drew]

Users do manage good DSO images with DSLR cameras. Even with a F6.3 focal reducer it's still quite a long FL. 

[ollypenrice]

The increase in FL and the sampling rate with small DSLR pixels will make remaining sub-pixel in tracking error pretty darned difficult...

Olly

[zakkhogan]

The increase in FL and the sampling rate with small DSLR pixels will make remaining sub-pixel in tracking error pretty darned difficult...

Olly

i dont follow, what does that mean   ?

[russ.will]

You'll still need very long exposures which at that focal length, will be wobbly?

Just a punt. What I don't know about imaging, is pretty much everything! 

Russell

[zakkhogan]

if it makes a difference it will be permanently pier mounted on a wedge, with guide scope

[ollypenrice]

i dont follow, what does that mean   ?

The fewer arcseconds of sky you sample per pixel the better your guiding has to be. With small pixels and a long FL C11 you are in difficult territory. Given the indifferent performance of the wedge and fork mounts in terms of accuracy you will find that persuading your system to track accurately will not be at all easy. DOn't imagine that an autoguider will 'just work' because it isn't like that. They need to be tuned. If you can't hold the errors down to less than a pixel then you are not gaining anything by shooting at that focal length. You'd get the same resolution by shooting at a shorter focal length.

Assuming focal reducer you would be trying to image at about 0.55 arcseconds per pixel. This is tight. Very tight. You might easily find that your local seeing never allowed that, or anything like it, in which case the excercise is a waste of time. I have never tried to image at less than 0.66 arcseconds per pixel. (ODK14 inch, SXVH36 camera) and this was on an extremely accurate mount, a Mesu 200 roller drive with zero backlash. I was never persuaded that we were really getting everything out of that sampling rate. I think that it would have been faster and easier to have been working at around 1.0 arcsecond per pixel.

So in going from 8 to 11 inches you drop your sampling rate into what is potentially unrealistic territory and you risk not gaining any real resolution for deep sky imaging.

Olly

[knobby]

... What Olly said ... Plus if you get an 11" , I'd need one to keep up

[zakkhogan]

Thanks Olly,  

[jeffmar]

Get the scope and enjoy it. You will still be able to get some nice pictures. 

[ollypenrice]

Get the scope and enjoy it. You will still be able to get some nice pictures. 

Sure, but it's important to understand that for DS imaging bigger is not necessarily better and that matching pixels to focal length does matter, especially when your camera can't bin 2X2 (which OSC cameras can't do.) It's also important to understand why fine pixel scales need better guiding and better seeing. 

Olly