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Celestron CGE 1400 autoguiding


neil B
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Hi Everyone,

I recently upgraded my equipment to a celestron cge 1400, and am in the process of ordering an off axis guider. However, I would like to autoguide this rather than but the reticle eyepiece. I am thinking of going for the celestron nightscape 8300 ccd camera, which is colour and so doesn't need the rgb filters with a monochrome camera. I was also thinking of using this as a standalone camera. Does anyone have any tips or views of this equipment? I also have a canon 100D camera which I was hoping to use.

Thanks for any help,

Neil

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Hi Earl, thanks for the quick reply. I am planning long term wise to have a permanent pier set up in the future, but at the moment just have the tripod and eq mount as supplied. Would I be able to use the ccd for general purposes and autoguiding together?

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I have the original Cge which I used to run with a C11 and image guided at f10 with some success. I used to image with a modded 300d and guiding was hit and miss with an st80 till I hit on using my old 127 mak guiding at f12 and it worked really well. Polar alignment is important at these focal lengths, my cge is now permanent in an observatory, makes life alot easier. The combo of the bolt on polar scope and polar align routine helps when setting up in the field but it still takes up valuable dark sky time.

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Hi, its not my first foray into imaging,  but havnt been able to do as much messing around due to full time work commitments and weather! I have some ability to aquire some decent kit to help out at the moment, but while I can, I thought I'd get the best kit I could to future proof!

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Hi, its not my first foray into imaging,  but havnt been able to do as much messing around due to full time work commitments and weather! I have some ability to aquire some decent kit to help out at the moment, but while I can, I thought I'd get the best kit I could to future proof!

Well, understandable and Id say you should use the strength of the scope and get stuck into some planetary and Luna imaging with a nice ASI 120mm and some RGB and Planet pro filters.

As for DSO imaging even full time pro's like Olly Penrice would agree its very brave and difficult to get consistent results at these focal lenghts im sure he has plenty to input on the subject :)

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  • Thanks Earl, Ive had a play around with some lunar imaging already and its far better than the stuff Id done before, and this was just messing around as opposed to serious attempts as I didn't have that much time!

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To do DS imaging at these focal lengths I wouldn't be itching to use a CGE mount. I've worked at somewhat shorter FL with a Mesu 200 mount at this aperture and that worked but the Mesu is a different class of mount altogether. I would take a big step backwards and think what you are trying to achieve in deep sky imaging. From your post I think you are making some false assumptions. Firstly there is no hope whatever of hand guiding in this day and age with the sensitive cameras now available. They pick up errors just as they pick up details! I would autoguide via an off axis guider. It is the only sane solution.

Is this scope the Edge version? If not, even with the F6.3 flattener reducer, it will not cleanly cover a chip as large as the 8300. With the non Edge I would go far a smaller, cleaner and more sensitive Sony chip which will give better results. With a bigger chip you'll be cropping out the edges anyway.

Under no circumstances whatever would I go for a one shot colour camera at this focal length. These cameras can only work unbinned and the pixels are far too small and don't get enough light. If you go for a monochrome you can bin the pixels 2X2 and then they make a virtual pixel which is more appropriate to your focal length. This will make your capture much faster. Monochrome is faster anyway in the order of at least 6 to 4 and really it is more than that much faster. (This is counter intuitive, perhaps, but I feel it is correct.)

I wouldn't consider using a DSLR at this focal length/sampling rate.

I'm not sure what you mean by using the 8300 camera as a 'standalone.' Could you elaborate?

Deep sky imaging in a C14 is one heck of an undertaking. Sorry, but there it is.

Olly

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Hi, yes its an edge version.

Thanks for the information, that is exactly what I needed. I say standalone but meant multi purpose, ie planetary/ lunar shots as well as Deep sky imaging and auto guiding. (I didn't think using a reticle eyepiece and handguiding was ever in!) So it sounds like you are suggesting a monochrome CCD. It is capable of converting to f2 lengths but this is something for later I think.

Can you suggest a suitable CCD for me to look at?

Cheers

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Lunar/planetary imagers don't use the same cameras as DS imagers but the fast frame cams are not as costly as DS, which is nice! You can't do both with a serious DS camera.

The Edge can cover a large chip which opens up your choices but you need to stick to a reasonable sampling rate. This is a good calculator. http://www.12dstring.me.uk/fov.htm

Some wealthy and very technologically driven and expert imagers will argue that going below 0.5 arcsecs per pixel is worth doing. I tried going down to 0.6 and wasn't convinced that 1.0 wouldn't have been a better idea. Some UK imagers (I'm in SE France) think that 2.0 is optimal for UK sklies. I can't comment on that. 

I would look at binning a mono camera to get a reasonable level of signal in the time from your long FL.

Your problem will almost certainly be guiding.

So far as camera makes go I'm a fan of Atik. I've had six of their cameras here of my own and used three others in collaboration.

If you go to Hyperstar at F2 (ish) you reverse the monstrous aspect of the scope. Instead of a challenging focal length you have a challenging focal ratio, intolerant of optical error. You also run into the problem of filters. One shot colour is highly logical with the Hyperstar but not logical with the native FL.

It's a game of soldiers! Give me a small or medium sized apo any day for DS imaging, honestly. But you can't get into those little galaxies, that's for sure...

Olly

Edited by ollypenrice
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I think guiding will be your number one issue.  I've used the CGE and C14 for a long time and tried astro-photography.  Anything over a slight breeze is difficult to cope with. That doesn't stop me - but it does mean the number of nights you can achieve worthwhile results are relatively few.  But hey that's a challenge.  I use a FR which brings things down to 2.4 metres and also used a Canon 1100D.  Guiding via DMK, ST80 and Ascom through Phd.  Balance is critical - the mount is really maxed out.  On good nights I can get to six minutes or so guided.  But you may have a better CGE - their guiding abilities are quite patchy.

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