G11/Gemini-2/OPWB Canon 60D (unmodified) with 18/55mm kit lens and "nifty fifty" lens Assorted M42 screw mount lenses (28mm thru 300mm) Celestron 102GT refractor (Costco special) 8/10 inch astrograph someday. DeepSkyStacker 3.3.2 StarTools 1.3 http://www.astrobin.com/users/StarGale/ http://everettastro.org/
Cliff Hipsher ICC USN (Ret.) '03 883 XLH Meade 2080/LXD75 (Big Blue) Meade DSI Color Meade DSI Pro TEC Cooled Celestron Neximage Celestron Radial Guider Star Guider Filter Wheel Vixen Flip Mirror Some Eyepieces Swift 7x50's Empty Wallet I.A.M.B.K. I ride. There fore I am...
Quote:Or in other words what's the maximum exposure time I can go before the star drifts....I'm willing to hear everything....
1987 Meade LX3 2120 10" SCT on hypertuned EQ6 Pro Baader Self-Mod Canon XS_CLS Clip Filter DSI color_Orion ST80 Coulter 10" Compact Odessey Dob http://www.astrobin.com/users/shawnhar
Quote: 90- to 300-second exposures in my opinion won't get you anything with an H-a filter. 600 seconds minimum..
LX850 blog: www.LX-850.com
personal website: www.wadsworthobservatory.com
Quote: Like stated above... use a short fast lens like a 50/1.8 or 100/2 (the fast focal ratio will mean you can shoot shorter exposures, and the short focal length will mask tracking errors). I was able to do 2-minute unguided exposures with a 50mm lens, and results weren't too bad. Now these are not H-a (just plain unfiltered) but with a good polar alignment I don't see how you can't do 4-5 minutes.
Quote:i want to do the 200-300 second exposures so what mount would do that for me?