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Old 09-03-2010, 08:52 PM
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Spocky (Glen)
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Integrated guide vs separate

Hello all,

I am a bit new to all this but am looking at getting into astrophotography and just would like to ask some opinion type questions.

What is better for guiding, an integrated CCD (like in the SBIGs) or a separate telescope + separate camera?

I am asking not only on a cost basis but to me an integrated camera would be a better idea because of the resolution axis is the same as the imaging camera and there is no differential movement potential added with a second scope/camera mount.

Does anyone have any issues or problems that I am unaware about?

Cheers Spocky
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  #2  
Old 10-03-2010, 04:25 PM
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I've never used an SBIG, but I understand that when you use filters, especially NB filters, the filter reduces light to such an extent that it may be difficult to pick up a guide star. This wouldn't apply to a OSC camera

You could look at the QSI cameras, which come with an option for a built-in off axis guider, so your imaging scope is also the guide scope (so no flexure issues) and the pick-off prism is in front of the filters, so you get full brightness through to your autoguider.
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Old 10-03-2010, 05:02 PM
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pmrid (Peter)
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Quote:
Originally Posted by Spocky View Post
Does anyone have any issues or problems that I am unaware about?
Have you considered an Off-Axis guider. Do a search in these forums on off-axis guiders and you'll find several threads in which they are discussed extensively. Also, have a look at the site of companies like Orion and ATIK both of whom make good OAGs. I have an Orion, a Celestron radial guider and a Lumicon OAG and I much prefer the Orion Deluxe.

With an OAG you have the advantage of eliminating flexure and you also can still use SBIG cameras with filter wheels because these sit behind the OAG. The newer SBIG's can take what they call a remote head which sits in the OAG in the same place that you would otherwise put a small guide-cam like a QHY5 or an Orion.

Hope that helps.

Peter.
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Old 10-03-2010, 05:08 PM
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Having used both methods, and also OAG's (being a separate guide camera through the imaging telescope) I must say I like the convenience of self guided cameras.. I have used self guiding through a 13nm Ha filter without too much troubles.. I binned the guider 2x2 and ran 2~4 second guide exposures and had no troubles at all..

I love self-guide!
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Old 10-03-2010, 08:07 PM
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strongmanmike (Michael)
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Hi Spocky

People will tell you that Self Guide is great or even indespensable but from where I stand it is simply not necessary. A good quality mount is very helpful though

I have used piggyback guiding pretty much for ever and I cannot see what all the paranoid selfguide hulabaloo is all about

Here are some comparative examples that should belay any fears you may have about passing up on a selfguided camera

http://www.pbase.com/strongmanmike20...94040/original

http://www.pbase.com/strongmanmike20...45498/original

http://www.pbase.com/strongmanmike20...05167/original

NB: Out of about 130 X 10min sub exposures taken over three nights for the full deep version of the above Centaurus A image, only about 3 or 4 were discarded due to guide errors!

Even using 15min sub exposures here is what piggyback guiding, when using narrowband filters so notorious for selfguided images , can do:
http://www.pbase.com/strongmanmike20...18593/original

Think about what these comparisons are demonstraing and make up your own mind

Mike

Last edited by strongmanmike; 10-03-2010 at 08:20 PM.
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Old 10-03-2010, 08:20 PM
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I agree with Mike, in most cases its not necessary, however its sure is convenient... You can achieve just as good results using an external guide scope and guide camera... It sometimes will take a little more time and effort in eliminating any flexture etc. I was plagued with flexture when using my C11 due to its moving mirror... getting a self guided camera eliminated the problems...

My thoughts - Adaptive Optics is -THE- best way to guide... AO surpasses any form of normal guiding, as it reacts much much faster than your usual guiding methods.
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Old 10-03-2010, 08:35 PM
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Bassnut (Fred)
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Quote:
Originally Posted by strongmanmike View Post
Hi Spocky

People will tell you that Self Guide is great or even indespensable but from where I stand it is simply not necessary. A good quality mount is very helpful though

I have used piggyback guiding pretty much for ever and I cannot see what all the paranoid selfguide hulabaloo is all about

Here are some comparative examples that should belay any fears you may have about passing up on a selfguided camera

http://www.pbase.com/strongmanmike20...94040/original

http://www.pbase.com/strongmanmike20...45498/original

http://www.pbase.com/strongmanmike20...05167/original

NB: Out of about 130 X 10min sub exposures taken over three nights for the full deep version of the above Centaurus A image, only about 3 or 4 were discarded due to guide errors!

Even using 15min sub exposures here is what piggyback guiding, when using narrowband filters so notorious for selfguided images , can do:
http://www.pbase.com/strongmanmike20...18593/original

Think about what these comparisons are demonstraing and make up your own mind

Mike
Beware, Mike is low QE, non-AO capable, wide field wooze, FLI sucker freakoid. "even 15min subs" . It gets interesting at 20min plus. Mike doesnt know what 2m plus FL means, he is disabled .

Quote:
Originally Posted by AlexN View Post
I agree with Mike, in most cases its not necessary, however its sure is convenient... You can achieve just as good results using an external guide scope and guide camera... It sometimes will take a little more time and effort in eliminating any flexture etc. I was plagued with flexture when using my C11 due to its moving mirror... getting a self guided camera eliminated the problems...

My thoughts - Adaptive Optics is -THE- best way to guide... AO surpasses any form of normal guiding, as it reacts much much faster than your usual guiding methods.
OH yeah, if you want to "get real" with long FL/exposures, then AO is the ducks guts, yay SBIG
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Old 10-03-2010, 10:02 PM
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strongmanmike (Michael)
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Quote:
"even 15min subs" . It gets interesting at 20min plus. Mike doesnt know what 2m plus FL means, he is disabled .
Actually it is Fred who is dissabled by those unecessarily long focal lengths he insists on using to image tiny postage stamp size pieces of the sky that require long sub exsposures becasue of the large dim focal ratios
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Old 10-03-2010, 10:13 PM
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I am literally lmao at the last few posts.

More biffo, please!

H
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Old 10-03-2010, 10:13 PM
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Fight! Fight! Fight!
Hajime.
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Old 10-03-2010, 10:33 PM
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Take your pick - who do you wanna believe?
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Old 11-03-2010, 12:22 PM
jase (Jason)
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Geez, looking at those mugs...don't think I'd trust either.

More to the point, as Geoff, Peter and Alex have alluded in earlier posts, it depends on the focal length you're operating at. Glen has not indicated this so we are none the wiser in our advice (despite the joyous SBIG/FLI slinging match).
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Old 11-03-2010, 05:32 PM
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Maaaa I dunno..?

It is not the focal length exactly really but more the fact that if the long focal length is provided by a multi mirrored telescope with truss tubes, inadequate focusers, loose mirror mounts or with floppy mirrors, ie Newt, RC or SCT there is potential for differencial movement over time. The significance of this differential movement is a function of the focal length and your image scale sure but the degree of flexure and the time period over which this movement takes place will depend strongly on the class and design of your telescope and guide scope interface.

It is clear from the above comparisons that self guide is simply not necessary just becasue you have a long focal length, the comparisons show rather difinitively that for 10 - 15min exposures at least, the absolute resolution possible without self guide is clearly equal to that with self guide and even rivales AO, atleast for modest exposure times and with a good quality mount.

Due to the limitaions of self guide (poor transmission through filters and faint or no guide stars etc) there are many imagers (most?) both long focal length and short, with selfguide cameras, who are basically forced (happily) to use piggyback guiding and they acheive excellent results!...why worry about having to have the self guide if piggyback works just as well and you must have a guide scope anyway? this is why I think the self guide feature for most situations is just simply overated.

Don't let anyone tell you that darks will always take care of the noise level in your noisey warm subs either, this is not true, excellent cooling does make a difference this is why cameras with poorer cooling cababilities very often have to resort to messy cumbersome water cooling, and others even resort to putting their cameras in a fridge while imaging .

Self guide is a feature for sure but there are other qualities in a good CCD camera that I believe deserve more consideration - namely: overall noise levels, cooling abilities, download speed, method of keeping moistier at bay, build quality and reliability.

Mike
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Old 11-03-2010, 05:51 PM
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Indeed Mike... Self guide is one of many features to consider when buying a CCD, and definitely not the most important... However this thread is only about self guide vs external.. so lets for arguments sake say that the two cameras we are comparing are an SBIG ST10XME (self guide) and ST10XMEi (no self guide)

Everything else is equal except for self guide... for the tiny extra cost of $200, self guide is worth having as an option... Though its not necessary, its nice to have the choice... Its like going to the pub.. whilst there is no need for them to have 10 different beers on tap, it sure is nice to know you can choose what you want...
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Old 11-03-2010, 06:03 PM
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Indeed Mike... Self guide is one of many features to consider when buying a CCD, and definitely not the most important... However this thread is only about self guide vs external.. so lets for arguments sake say that the two cameras we are comparing are an SBIG ST10XME (self guide) and ST10XMEi (no self guide)

Everything else is equal except for self guide... for the tiny extra cost of $200, self guide is worth having as an option... Though its not necessary, its nice to have the choice... Its like going to the pub.. whilst there is no need for them to have 10 different beers on tap, it sure is nice to know you can choose what you want...
But here you are comparing having a selection of one extra beer in two different Sizzlers restaurants when you could be having a choice, all be it one type of beer less, at Doyles by the Sea across the road (but at little extra cost in the CCD analogy)... if you just remember it is there through all the Sizzler hype



Mike
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Old 11-03-2010, 06:46 PM
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hahaha... yea man.. that was good, very indepth analogy.. Loving it!

The question.. Would I forgo self guide for -60c cooling... Bet your backside I would....

If there was a camera offering both self guide and the sensor I want to use with 60c cooling capacity, would I then buy that? you bet your backside I would.... Why? You all know me, I simply can't help myself thats why..
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Old 12-03-2010, 07:25 PM
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Quote:
Originally Posted by strongmanmike View Post
Maaaa I dunno..?

It is not the focal length exactly really but more the fact that if the long focal length is provided by a multi mirrored telescope with truss tubes, inadequate focusers, loose mirror mounts or with floppy mirrors, ie Newt, RC or SCT there is potential for differencial movement over time. The significance of this differential movement is a function of the focal length and your image scale sure but the degree of flexure and the time period over which this movement takes place will depend strongly on the class and design of your telescope and guide scope interface.
Hence OAG

Quote:
Originally Posted by strongmanmike View Post
It is clear from the above comparisons that self guide is simply not necessary just becasue you have a long focal length.... and even rivales AO.
hehe, really ? , rivals AO ?, at long FLs? .

Quote:
Originally Posted by strongmanmike View Post
why worry about having to have the self guide if piggyback works just as well .
Oh really ?

And a quote from Steve Cannistra
......we don't even need cameras that can cool to -25 C. And by imposing more aggressive cooling on these chips, it is possible that we are increasing the likelihood of experiencing other side effects such as residual bulk image (RBI)

Its OK Mike, you can be wrong. I understand, it proves you are human, dont be embarrised, I forgive you . We love you mike, its a momentary lapes of reason thats all.

Quote:
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If there was a camera offering both self guide and the sensor I want to use with 60c cooling capacity, would I then buy that? you bet your backside I would.....
And you too Alex, behave yourself, stop crawling, its silly .
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Old 12-03-2010, 07:33 PM
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Take your pick - who do you wanna believe?
Well, any man who can wear a skirt with as much confidence as Mike, deserves a little respect.
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Old 12-03-2010, 07:37 PM
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Originally Posted by Bassnut
And you too Alex, behave yourself, stop crawling, its silly .

I believe the STX-8300 will be released later in the year. At which point, there will be a camera with the sensor I want, -60c delta cooling and self guide Crawling?? No, just longing to get self guide back
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Old 12-03-2010, 07:38 PM
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Take your pick - who do you wanna believe?
hehe, nice pic Mike. Guad youll scare the natives with that, we look like fruitcakes...........umm yeah, well, one of them is anyway .
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