Click here if you are having trouble logging into the forums
Privacy Policy |
Please read our Terms
of Service | Signup and
Troubleshooting FAQ | Problems? PM a Red or a Green Gu.... uh, User
Mark
super member
Reged: 01/17/04
Posts: 166
Loc: Chicago
|
|
Hi Fred.
I'd like to chip in on two points based on my own experience.
Firstly don't punt too quickly on the idea of observing DSO's from a light polluted site. I live right in the middle of the Chicago light pool and have had a great time over the last year searching out DSO's with my 5" cat. Galaxies are the one thing that I have found to be pretty much trashed. However I have cataloged over 50 DSO's of all other types. Some of them look great, some are barely visible, all would certainly look better from a dark site, but I have never lacked for things to observe from my front yard. Urban observing is challenging, but CAN be very rewarding.
My second comment is about the coma in a fast newt. In addition to my 5" f/10 cat I also have an f/4.7 dob. I find that with moderate field of view eye pieces, like Plossls and Konigs, coma is barely noticable. I really have to be looking specifically for the effects of coma to notice it. From what I have heard, coma will be more noticable as one goes to eye pieces with larger aparent fields of view.
Of course how much coma is bothersome is a personal thing and what does not bother me may drive you nuts.
In any event, have fun choosing a scope. Based on what you are considering you really cannot go wrong, every scope has its strengths and weaknesses.
Mark
--------------------
Celestron C5 on an EQ2
Orion XT10
|
erik
telescope surgeon
Reged: 01/30/04
Posts: 24019
Loc: Hawaii 19 N lat -155 Long.
|
|
yeah, there is no perfect scope. an 8" f/6 is close though (which is why i have one!). 8" gives you nice aperture, it's still portable, and at f/6, coma isn't much of a problem. a 6" f/8 scope is nice too, but you'll have narrower field of views, and the step up in aperture to 8" is pretty noticeable. in fact, i think it's the biggest 2" difference there is. dso's really start to brighten up when you hit 8"....
--------------------
-Erik Wilcox
Homebuilt 16" Truss Dob
SV 80mm ED Nighthawk NG on M1 ALT/AZ
Nikon Prostaff 65mm spotter on Trekpod
Konusvue 20x80 binos/Peterson pipemount
Orion 10x50 binos
Homebuilt 80mm f/5 refractor
Mirador 60mm f/12 1960's refractor
|
Jon Isaacs
Postmaster
Reged: 06/16/04
Posts: 12070
Loc: San Diego, California
|
|
Before you make a decision based on Coma, I suggest finding a club or star party and taking a look through a few scopes so you understand what you are dealing with.
Often I think that eyepiece aberrations are misidentified as "coma." Faster scopes require better eyepieces to have a sharp field of view.
Also, I can't find where you have said whether you are considering an EQ mount or a DOB mount. An 8 incher on a EQ mount is F5 normally, on a DOB mount it is F6. imho, "coma" is not an issue at F6, is a problem at F4 and at F5 is acceptable.
But the main thing here is for you to get out and look through some scopes, depending on my judgement or anyone else's cannot tell you the difference between looking at M42 with a 6 inch F8 scope and an 8 inch f5 or F6 scope...
Jon
|
Anonymous
Unregistered
|
|
I was thinking maybe Orion 8in SVP Eq, because if offers me more flexibility in traveling size and the ability for tracking objects. Plus I could use for astrophotography when the time comes.
|
|
|
Previous
Index
Next
Threaded
[Re: 
Edit
Reply
Quote
