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Dob views vers. A APO

Started by boatclocks, 06/21/2005 01:13AM
Posted 06/21/2005 01:13AM Opening Post
I have a 8" and 10" Orion f5 Dobs. I have NP101, and have been comparing the dobs against the APO on Jupiter. Both Dobs are a litte fuzzier than the APO. The moons are not nice and tight like the APO. The question I have is this way it is on all reflectors? Is it maybe my mirrors. I have though about sending the 10" mirror off to Swayze to be test or refigured. Any one have any ideas.

Posted 06/21/2005 01:27AM | Edited 06/21/2005 01:28AM #1
Carl Gall said:

I have a 8" and 10" Orion f5 Dobs. I have NP101, and have been comparing the dobs against the APO on Jupiter. Both Dobs are a litte fuzzier than the APO. The moons are not nice and tight like the APO. The question I have is this way it is on all reflectors? Is it maybe my mirrors. I have though about sending the 10" mirror off to Swayze to be test or refigured. Any one have any ideas.

Well Carl, I can't answer the 10-inch question but I can give you comment on the 8-inch. And BTW you've got a very fine NP101 indeed!

I have an 8-inch Discovery f/6 PDHQ Dob with enhanced mirror and small secondary (19%). I think it has a pretty good mirror (I've got a Ronchi eyepiece to test it ;-). When seeing permits, the view of Jupiter is extremely sharp (except the 4 rays ;-) emanating out from the planet of course due to the 4 vane secondary). The swirls and the ovals were well edged. Of course, the view from my 4-inch TV-102 APO is very sharp too but never as detailed as in the 8-incher (unless the seeing is bad). You can get some idea of what I saw here.
http://www.cloudynights.com/observe/ronbee/Jupiter/Jupiter-050804-PDHQ.html
http://www.cloudynights.com/observe/ronbee/Jupiter/Jupiter-050904.html

So if you're seeing fuzzy image, the possibilities are:
A) The culprit seeing :-(
B) The scope has not cooldown completely, or not collimated (f/5 is sensitive to collimation). I usually let mind cooldown at least 1 hour to be safe or put the house fan to the mirror ;-).
C) Dew? You never know ;-)
D) Not such a good eyepiece?
E) Dirty mirror - I got a good taste of this earlier this year :-( and will result in fuzzy image.
F) Lastly but hopefully not, it could be bad optics :-(.

Ron B[ee]