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
mtngoat62
sage
Reged: 12/04/06
Posts: 205
Loc: USA
|
|
What kind of eyepiece magnification range do you use for viewing close-ups of DSOs? I have a 10" Dob f/4.7. Thanks!
--------------------
Laurie
Orion 10XTi f/4.7 w/padded case
Pentax XWs 7mm,10mm
TV Ethos 13mm, 21mm
TV Paracorr
DGM NPB filter
Orion O-III filter
Baader Moon & Skyglow Filter
Telrad Finder w/riser
Astro Chair
Howie Glatter Collimator w/Barlow
Telegizmo Dob Cover
|
David Knisely
Postmaster
Reged: 04/19/04
Posts: 8803
Loc: Beatrice, Nebraska
|
|
Quote:
What kind of eyepiece magnification range do you use for viewing close-ups of DSOs? I have a 10" Dob f/4.7. Thanks!
For large diffuse nebulae, I tend to stay under 100x (my favorite powers for nebulae are between 40x and 60x), although there are a few exceptions. For open clusters, again, it will depend on the object, as larger ones require lower power. I have used over 200x on some of the smaller more distant ones, but much of the time, I tend to stay below 100x for them. For planetary nebulae, it will depend a little on the object, but I have used from 220x to as high as 720x on some of the brighter targets. For globular clusters, to get good resolution, I start at 100x and go up from there, although I generally won't go much over 350x on them. Galaxies also will require a variety of powers depending on the size of the object and the type of detail I am after, although much of the time, I stay under about 220x on them. For viewing the spiral structure of smaller galaxies, I often like from 100x to 150x, as it tends to enlarge the detail without spreading the light out too much. Clear skies to you.
--------------------
David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org
|
stevecoe
"Astronomical Tourist"
Reged: 04/24/04
Posts: 2862
Loc: Arizona, USA
|
|
I agree with David, if you have a set of eyepieces that will take you from 50X to 300X in four or five steps you have a lot of the observing situations covered very well. The need to go below 50X or above 300X is rare with 10 inches of aperture.
Enjoy;
Steve Coe
--------------------
TeleVue 102 refractor on CGEM mount
9.25 inch Celestron SCT
Author "Deep Sky Observing" Springer-Verlag
Author "Nebulae and How to Observe Them" Springer
Canon Xt astrocamera with Hutech modification
|
Thunderhead
professor emeritus
Reged: 08/27/05
Posts: 562
Loc: Melbourne, Australia
|
|
I own a 10" dob aswell and this is how I do it:
Open clusters
I'll stay in the 50-100x range, maybe up to 150x for the small or faint ones.
Globular Clusters
I find that many globulars look best at 250-350x, however in very good seeing I go up to 500-625x.
Large emission nebulae
For larger, extended nebulae (both low and high surface brightness), I find myself using powers of 50-150x but if
the nebula is bright and there is good structure and detail to be seen, like in M42 or NGC2070, I may push 250-500x in my scope. If the nebula is really large and faint, use powers below 100x.
Small Nebulae
Such as Hubble's Variable Nebula and NGC1999. I use powers above 150x to get a good image size and darken the sky background.
Planetaries
For large and faint ones, I'll use mags around 100-200x but with the small, high surface brightness examples, such as NGC 1535, I have gone to 625x to bring out detail. But most often, I'm using 250-500x on planetary nebulae, depending on size, surface brightness and seeing conditions.
Galaxies
large ones require lower powers, maybe around 100x, smaller objects I find best at around 150-250x.
--------------------
SAB - Melbourne, Australia
GSO 10" F5 Dob with flocking & dewshield
12" (304mm) F4.6 truss dob with premium optics
|
Silicon Owl
scholastic sledgehammer
Reged: 11/25/05
Posts: 982
Loc: Waimea, Hawaii 20N
|
|
The above recommendations are pretty good. You need to change power to respond to the object and conditions. The seeing will limit the use of high power often enough and powers above 200x or so will just make the blur bigger if the air is too unsteady.
Most of the time I use the same eyepiece for finding and first observations of an object, I my case usually a 12mm that gives 175x and almost exactly a 1/2degree field (28 arcminutes). After finding the object I will change if necessary to properly appreciate the object. The use of the same eyepiece for finding helps me star hop and confirm I am looking at the right object. If I need to move 1 degree east I just move two eyepiece fields. If I know I am looking for a 10 arcminute galaxy I know it will be 1/3 of my field across. You get used to that telescope/eyepiece combination.
--------------------
Andrew Cooper
Personal Website and CN Gallery
Handmade 18" Dob / NS11GPS / 6" RFT / 90mm APO / TV-76 ...and a twin 10m
"I have loved the stars too fondly to be fearful of the night." --Sarah Williams
|
Achernar
Postmaster
Reged: 02/25/06
Posts: 5212
Loc: Mobile, Alabama, USA
|
|
On rare occasions I've gone as high as 375X to see the structure of bright but very small planetary nebulae and globular clusters. A good 10-inch can achieve much higher magnifications than that if the optics and collimation are up to snuff, but seeing usually makes 250 or 300X the maximum magnification you'll be able to use without the view blurring from turbulence in the atmosphere. There's plenty to see at 250X on deep sky objects that respond well to high magnifications. Usually for most deep sky objects I use low or medium power eyepieces due to normally bad seeing in my area.
Taras
--------------------
15-inch F/4.5 Dob under construction
10-inch F/4.5 Discovery Dob
6-inch F/8 Homebuilt Dob
4 1/4-inch F/4 Homebuilt reflector
A whole bunch of eyepieces, filters and other accessories....
One curious cat
|
mtngoat62
sage
Reged: 12/04/06
Posts: 205
Loc: USA
|
|
Thanks for all the information on viewing the DSOs - this has really helped me out - I appreciate it very much! 
--------------------
Laurie
Orion 10XTi f/4.7 w/padded case
Pentax XWs 7mm,10mm
TV Ethos 13mm, 21mm
TV Paracorr
DGM NPB filter
Orion O-III filter
Baader Moon & Skyglow Filter
Telrad Finder w/riser
Astro Chair
Howie Glatter Collimator w/Barlow
Telegizmo Dob Cover
|
helpwanted
Carpal Tunnel
Reged: 07/04/07
Posts: 2878
Loc: Phoenix, AZ
|
|
this is a great thread... thank you to all the posters!
--------------------
|
PhilHoyle
super member
Reged: 09/02/06
Posts: 141
|
|
Normally, you should always start with a low power eyepiece to get a large field of view, if, for no other reason, than to make it easire to find. Once you have found it in a low power field of view, increase the magnification to what your eyes percieve as the best.
Phil
|
Ptarmigan
Carpal Tunnel
Reged: 09/23/04
Posts: 2704
Loc: Arctic
|
|
I rarely use high power for DSOs. Only time I do is for planetary nebulas.
--------------------
Ptarmigans=Cute and Cuddly
Meade Starfinder 8
Nikon 10x50
Rebel XT
|
|
7 registered and 4 anonymous users are browsing this forum.
Moderator: Dave Mitsky, Olivier Biot
Print Thread
|
Forum Permissions
You cannot start new topics
You cannot reply to topics
HTML is disabled
UBBCode is enabled
|
Thread views: 432
|
|
|
|
|
|
|
Previous
Index
Next
Threaded
Edit
Reply
Quote
