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Antenox
super member
Reged: 10/10/08
Posts: 104
Loc: Los Angeles, CA
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Ok, these three types of scopes seem to fall into more or less the same total price range (as OTA-only with a decent GoTo EQ mount purchased separately, or as an OTA-mount combo). Their OTAs also are all reasonably portable.
What kinds of astrophotography suits each type best? And is there one type that you would consider to be a good "all-around" AP telescope?
I'm mostly interested in (eventually) taking photos of DSOs with a DSLR, but I may branch out. I'm not considering anything larger than 6" nor am I considering a Newtonian because I at least want the OTA to be portable (i.e. can fit into a carry-on suitcase onto a plane).
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Haves
10" SkyWatcher Collapsible Dobsonian
15x70 Celestron Skymaster Binoculars
35mm Parks Gold Series
8-24mm Baader-Hyperion Clickstop Zoom Eyepiece
TeleVue 3x Barlow Lens
76mm Celeston FirstScope mini-Dobsonian
Wants
Astrophotography/travel telescope (80-100mm APO or 5-6" SCT/MCT)
Ultra-wide angle eyepieces
Hads
114mm SkyWatcher GreatStart Reflector
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orenabah
sage
Reged: 05/21/08
Posts: 292
Loc: Connecticut
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The 80mm APO will be good pretty much just for DSO work, and wide angle moon shots.
The 127mm Maksutov has a pretty long focal length. I have one, and it's great for the planets. I would never use it for deep sky though. MCTs are well built, and Orion's is advertised as "never having to adjust the collimation" so that's a plus for portability.
The 150mm SCT is probably your best bet. It's focal length can be bumped up for planetary work, and it can be likewise bumped down for deep sky. Of course, you can do the same with the Maksutov, although I've never seen anyone using an MCT for anything besides the planets.
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Paul S.
SLT alt-az mount & EQ4
Orion 8" OTA
Orion Apex 127mm Mak-Cass
Coronado PST
DMK21AU.04
Meade DSI pro
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Antenox
super member
Reged: 10/10/08
Posts: 104
Loc: Los Angeles, CA
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Quote:
The 80mm APO will be good pretty much just for DSO work, and wide angle moon shots.
The 127mm Maksutov has a pretty long focal length. I have one, and it's great for the planets. I would never use it for deep sky though. MCTs are well built, and Orion's is advertised as "never having to adjust the collimation" so that's a plus for portability.
The 150mm SCT is probably your best bet. It's focal length can be bumped up for planetary work, and it can be likewise bumped down for deep sky. Of course, you can do the same with the Maksutov, although I've never seen anyone using an MCT for anything besides the planets.
I thought APOs were supposed to be good with planets, particularly planetary details? Couldn't I just increase the magnification with a Barlow?
EDIT: On the other hand, I think I'm missing some fundamental difference between visual observing and astrophotography. 
Any good online "beginner's guides" I take take a look at? 
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Haves
10" SkyWatcher Collapsible Dobsonian
15x70 Celestron Skymaster Binoculars
35mm Parks Gold Series
8-24mm Baader-Hyperion Clickstop Zoom Eyepiece
TeleVue 3x Barlow Lens
76mm Celeston FirstScope mini-Dobsonian
Wants
Astrophotography/travel telescope (80-100mm APO or 5-6" SCT/MCT)
Ultra-wide angle eyepieces
Hads
114mm SkyWatcher GreatStart Reflector
Edited by Antenox (09/20/09 11:38 PM)
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orenabah
sage
Reged: 05/21/08
Posts: 292
Loc: Connecticut
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Sure, you can, but the small aperture and short focal length means things are going to get fuzzy and dim very quickly. Since MCTs are very similar in optical quality to an APO of an inch less in aperture (e.g. a 5" MCT is close in quality to a 4" APO), and cost a lot less, they are a choice option for planetary photography. Their long focal length means that you don't need strong, light robbing Barlows.
SCTs are commonly used in both fields, mostly because MCTs get cost prohibitive above apertures of 7". I might be wrong but they may also have a slightly faster focal ratio than a typical MCT, making it easier for DSO work.
I personally love my 127mm MCT/DMK21 combo.
http://farm3.static.flickr.com/2538/3755012663_416328648a_o.png is a good example of what that combo can put out.
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Paul S.
SLT alt-az mount & EQ4
Orion 8" OTA
Orion Apex 127mm Mak-Cass
Coronado PST
DMK21AU.04
Meade DSI pro
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Antenox
super member
Reged: 10/10/08
Posts: 104
Loc: Los Angeles, CA
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What effect would using a focal reducer have on the image quality?
Right now I'm thinking of a NexStar 6SE plus a separate CG-5 mount so I can double up and pair the OTA with the NexStar mount as a travel scope or with the CG-5 as an AP scope. But since my primary interest right now are DSOs, and wide field is necessary for those, I gotta know how a focal reducer would affect the picture.
Maybe further in the future I'll also invest in an 80mm triplet to make this question moot, but that's a ways away.
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Haves
10" SkyWatcher Collapsible Dobsonian
15x70 Celestron Skymaster Binoculars
35mm Parks Gold Series
8-24mm Baader-Hyperion Clickstop Zoom Eyepiece
TeleVue 3x Barlow Lens
76mm Celeston FirstScope mini-Dobsonian
Wants
Astrophotography/travel telescope (80-100mm APO or 5-6" SCT/MCT)
Ultra-wide angle eyepieces
Hads
114mm SkyWatcher GreatStart Reflector
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jsigone
super member
Reged: 12/27/08
Posts: 131
Loc: Escondido--> San Diego, CA
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funny topic because for the past month I pondered the same thing. I ended up finding a C80ED onyx from OPT and then scored a C6 w/ ASGT setup off craigslist for a great deal. So now I can image both wider field objects with the 80ED and faint fuzzys will fill the chip better with the C6 SCT. Total investment for the two scopes, mount, WO .8FF & diag is under $1300. Bonus items that came with the C6 deal was the GPS unit, the Celestron 1.25" EP/filter kit and solor filter.
I haven't tried the SCT yet, been using the 80mm to image M31, M8 w/ M20 in same field. I might use the SCT tonight to try and image the Eagle.
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Celstron C6 SCT
Celestron C80ED Onyx
Celestron ASGT mount
Celestron Omni 150 newt CG4 EQ
Canon XS 1000D (stock)
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orenabah
sage
Reged: 05/21/08
Posts: 292
Loc: Connecticut
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Quote:
What effect would using a focal reducer have on the image quality?
Right now I'm thinking of a NexStar 6SE plus a separate CG-5 mount so I can double up and pair the OTA with the NexStar mount as a travel scope or with the CG-5 as an AP scope. But since my primary interest right now are DSOs, and wide field is necessary for those, I gotta know how a focal reducer would affect the picture.
Maybe further in the future I'll also invest in an 80mm triplet to make this question moot, but that's a ways away.
Focal reducers will cause vignetting, the amount of this varies among them and of course the imaging chip you will be using. This is very easy to fix with a standard calibration frame called flats which you apply during processing. Since you are shooting with a DSLR, I would hold off on purchasing one until you take a few test shots and see how satisfied you are with the FOV. You may change your mind.
Also sounds like you have a good setup idea going. I use my 5" MCT in combination with my NexStar SLT mount, which is a lighter version of the SE. Just remember that the SE will limit your exposure times unless you make it a wedge.
At home I use my 8" Newt and EQ4 (although the poor mount is constantly struggling). I'm a little better off, since I'm recording video the mounts' errors are not a big deal.
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Paul S.
SLT alt-az mount & EQ4
Orion 8" OTA
Orion Apex 127mm Mak-Cass
Coronado PST
DMK21AU.04
Meade DSI pro
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Antenox
super member
Reged: 10/10/08
Posts: 104
Loc: Los Angeles, CA
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Quote:
Also sounds like you have a good setup idea going. I use my 5" MCT in combination with my NexStar SLT mount, which is a lighter version of the SE. Just remember that the SE will limit your exposure times unless you make it a wedge.
Well, I did say that I planned on getting a separate CG-5 mount that I could use the NexStar 6SE's OTA on for longer exposures. 
Actually, I've also heard of something called the Hyperstar? I heard it reduces the focal ratios of the SCTs that are compatible with it to f/2 by basically replacing the secondary with a set of lenses and an adapter for a DSLR or CCD. Collimation is supposed to be very difficult with it, but it reduces exposure time drastically. Have you heard of this, and do you recommend it?
--------------------
Haves
10" SkyWatcher Collapsible Dobsonian
15x70 Celestron Skymaster Binoculars
35mm Parks Gold Series
8-24mm Baader-Hyperion Clickstop Zoom Eyepiece
TeleVue 3x Barlow Lens
76mm Celeston FirstScope mini-Dobsonian
Wants
Astrophotography/travel telescope (80-100mm APO or 5-6" SCT/MCT)
Ultra-wide angle eyepieces
Hads
114mm SkyWatcher GreatStart Reflector
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orenabah
sage
Reged: 05/21/08
Posts: 292
Loc: Connecticut
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|
Quote:
Well, I did say that I planned on getting a separate CG-5 mount that I could use the NexStar 6SE's OTA on for longer exposures.
Actually, I've also heard of something called the Hyperstar? I heard it reduces the focal ratios of the SCTs that are compatible with it to f/2 by basically replacing the secondary with a set of lenses and an adapter for a DSLR or CCD. Collimation is supposed to be very difficult with it, but it reduces exposure time drastically. Have you heard of this, and do you recommend it?
I've heard the name, but I'm not familiar with it, sorry.
Also, only reason I suggested the wedge was so if you took it to a dark sky, you could take full advantage of that...
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Paul S.
SLT alt-az mount & EQ4
Orion 8" OTA
Orion Apex 127mm Mak-Cass
Coronado PST
DMK21AU.04
Meade DSI pro
|
|
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