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DaveB
sage


Reged: 11/21/07

Loc: New England
SBIG ST-8 as a first CCD? new
      #3822728 - 05/22/10 10:43 PM

With the current sale on ST-8 (1/3 off), is this a reasonable first CCD camera? Or, is there a newer generation technology that is more appropriate? The version that is on sale is NABG - is an ABG camera better for a beginner?

I have a used Meade DSI-2 which I use for guiding my DSLR, but the thought of not needing a piggybacked guidescope has some appeal. I may stick with my current setup for a while (I am by far the weak link in my setup...), but I figured that I'd get some more experienced opinions while the sale is going on.

Thanks,
Dave


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elbee
professor emeritus


Reged: 05/02/09

Loc: Arizona
Re: SBIG ST-8 as a first CCD? new [Re: DaveB]
      #3826437 - 05/24/10 06:03 PM

not sure why no one has chimed in here. there are many more experienced than i.

are you talking about the ST-8XME for $3k?? my opinion is that it is far from a starter camera. you will have to spend a chunk more on a filter wheel and filters. NABG, i think will be a challenge limiting exposure time (or dealing with blooming in post). if you want "pretty pictures", i recommend staying away from NABG cameras.

i use a camera now with self guiding and although i like it (vs. guide scope), i could not do it without an application like "The Sky" helping me figure out a guide star. linking my telescope to "the sky" and comparing real time images from the camera vs. where i am relative to a guide star was all new stuff i had to figure out when i went to self guiding (far from newbie as far as i was concerned). guide scope was so simple. finding a guide star without an app like "The Sky" would be a so frustrating.

do you want mono or color? there are some much lower priced mono (and color) options from orion and QHY. also, the new craze for 8300 chips is providing some nice packages.

hope that helps.


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DaveB
sage


Reged: 11/21/07

Loc: New England
Re: SBIG ST-8 as a first CCD? new [Re: elbee]
      #3827103 - 05/25/10 12:24 AM

Thanks Lee. Yes, I am talking about the $3k deal on the ST-8XME, and I would need to add the color wheel (which is also on sale). I realize that it's not a typical entry level camera, but I was wondering if it would be one with long legs for me. I guess the biggest attraction is the self-guiding for a couple of reasons which I didn't articulate in my original post:
- It would (I think) shorten the setup time of the scope for each session (I don't yet have an observatory) but I may be wrong about this.
- I have a 10" newt and a big dob for visual. Currently, I'm using a Meade DSI-Pro 2 on the newt for guiding and imaging with a piggyback camera and telephoto lens. If I switch the DSLR to the newt for imaging, I'll need to purchase a refractor for guiding. Admittedly, an 80mm refractor is an order of magnitude cheaper than an ST-8.

Ultimately, I'm wondering if my best near term solution is to build an observatory. I'm not sure if I'm going to be at our current house for more than a couple years, so that's one hesitation there. So, I was hoping that an ST-8 with its self-guiding capability would make the setup and teardown less painful and eliminate the short term requirement of a guidescope, but perhaps that is wishful thinking. If I remove that aspect (i.e. autoguiding), then I agree with you that the 8300 or the mid-level Orion or equivalent CCDs make more sense for my current abilities or lack thereof.

Anyway, thanks for your insights. Sorry that I didn't articulate more of this in my original post.

Regards,
Dave


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Rick J
Postmaster
*****

Reged: 03/01/08

Loc: Mantrap Lake, MN
Re: SBIG ST-8 as a first CCD? [Re: DaveB]
      #3827296 - 05/25/10 02:40 AM

The main advantage of the ST-8 is also its main disadvantage, namely the omission of an anti blooming gate. This increases its sensitivity quite a bit but you do have blooms to deal with. Shorter sub exposure times lessen them to where software can deal with them better. I started my digital life with an ST-7 on a 6" f/4. It is virtually identical to the ST-8 except for the smaller chip. All other specs are virtually the same. I now use it for my photometric work where blooms aren't an issue as you avoid saturation at all costs when doing that sort of thing. Once in a while some far brighter star will send a bloom across the target but then I just rotate the camera solving that issue. There is software that can debloom an image at a small added cost. I never used it however. I just kept them small by controlling exposure time as my main goal was to learn the ropes after 50 years of film work then move to an ABG camera for serious imaging leaving the ST-7 for photometric work. Mainly I work with an astronomer not at the University of Texas getting photometric measurements of some AGN's he is studying. The ST-7 is great for that with its high sensitivity and linear chip.

If imaging faint fuzzies in reasonable time is your goal then it is a good choice.

The on board guider chip has both good points and bad ones. The bad one is that it can make finding a guide star difficult compared to other systems, especially when doing narrow band imaging. Also a guide star that looked fine in the L, R and G filter may not work with blue in that most fainter stars are red and don't emit a lot of blue light so when that filter gets switched in there goes the guide star. Also the guider chip is red sensitive adding to the problem. Always check blue beforehand to avoid this nasty surprise. Other guiding methods don't look through the filters so avoid this issue.

On the other hand flex from a separate guide scope can be very challenging to solve. I did it for years with film and sometimes it worked great. But then there were those other times! While I rarely guide (I have my Paramount so honed it isn't needed for 10 minutes even at 0.5" pixel size) when I do I've not found finding a guide star difficult at all. I do use The Sky but never used it to help find a guide star! When looking for one I just move the object down 5 minutes in my FOV. Any potential guide star is now seen in a 5 second exposure. If none I move the other way 10 minutes and again look for one on that side. I've never failed to find something usable on one side or the other but then I'm using a 14" scope but at 3650mm FL so my guider chip is small. Also since I don't rotate the camera if the guide star is on the wrong side I just wait and image that object when it is on the right side of the meridian. I have such a long to-do list this isn't an issue. Though my lack of guiding may also be a savior. I normally only guide if subs are longer than 20 minutes which is narrow band only. Mount quality has a lot to do with this. Better the mount and better it is polar aligned the longer you can expose a guide star and thus how faint you can go. I prefer not to guide with less than 10" exposures when I do as this averages seeing and I get a better fix on the star's real position. Many mounts can't do this however. I spent 50 years using such mounts

Some DSLR users find moving to mono a bit challenging, others find it no problem. You might want to get some time on an on line scope using a mono camera and see if it is for you.

ABG makes taking pretty pictures less of a hassle but increases imaging time. Many feel it worth the time others don't.

Matching pixel size to seeing is another issue. A small pixel camera like the 8300 fits a shorter FL scope and is rather ineffective on a 2000mm scope unless you have better than average seeing though binning is an option with a mono camera that preserves the high resolution for those rare nights of super seeing.

An observatory is great but if you're only there 2 years more build one you can move. The next owner will likely make you remove the pier as us amateurs are a rare breed. For now I'd think learning the ropes by moving the DSLR to the 10" (flattener like the one Baader sells will likely be needed) and buying a small refractor with a solid focuser (weak ones will sag even with a light DSI-2) would be a cheap way to go. Save the next move until you move and can build the observatory. In the meantime save for the best you can afford in gear.

All CCDs and DSLRs are a compromise, none is perfect. You will have to decide with compromises you can live with and which you can't, including budget, and dive in. The ST-8 may be an old chip but it still can take some fantastic images, so can most others when properly matched to scope and target.

I should go back and edit this into something that doesn't ramble but this is just how my mind was working tonight.

Rick


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Ted W
Pooh-Bah


Reged: 06/30/05

Loc: 42.13N 71.90W
Re: SBIG ST-8 as a first CCD? new [Re: Rick J]
      #3828086 - 05/25/10 01:51 PM

As far as ABG vs NABG goes, the level of light pollution in your imaging location may factor into the choice. If you have very dark sky then using an ABG camera is preferable because you can use very long exposures without worrying about blooming. Of course this assumes you have a capable mount like say a (cough) Paramount.

If you are in a light polluted area your exposures will be shorter due to fogging from light pollution. In this case the much more sensitive NABG chip can yield more data within the short exposure time.


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DaveB
sage


Reged: 11/21/07

Loc: New England
Re: SBIG ST-8 as a first CCD? new [Re: Ted W]
      #3829633 - 05/26/10 10:52 AM

Thanks everyone for your replies. With your help, I've talked myself out of getting an ST-8. I'll use the money to pick up a refractor as a guidescope/imaging scope and piggyback it on my newt. I'll stick with DSLR imaging for now, as I still have a lot to learn with this setup.

Dave


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fetoma
Carpal Tunnel
*****

Reged: 09/26/06

Loc: Southern New Jersey
Re: SBIG ST-8 as a first CCD? new [Re: DaveB]
      #4059682 - 09/19/10 09:32 PM

Dave,

Rather than the ST-8, why don't you give the Starlight-Xpress H9 a try. You don't need to take dark frames, it's sensitive, and doesn't bloom. Great mono camera to start out with.


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