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
diggy
sage
Reged: 05/09/04
Posts: 303
Loc: Vancouver Island, Canada
|
How big is a star..in pixels??
08/09/08 07:22 PM
|
|
|
I've been stumbling on the black art of focusing a DSLR at prime focus without the recommended computer connected tools. One question is how big would a star be in pixels, if the image is "ideally" focused. I realize the question is probably over-simplified: I'm sure it depends on a bunch of factors. So, for an example:
I shot the double cluster (12 subs 25" ISO 400) with a Nikon D70s (3008x2000 pixels) through a 110mm refractor with a 0.8 focal reducer/field flattener. The "largest" star in any of the raw images measured 12 pixels across; the smallest about 4 pixels wide. After processing through DSS the largest was reduced to 9 pixels. So, is there any info I can gather from that about focus: should stars be smaller?
Thanks in advance for any guidance here.
Diggy
--------------------
WO 110mm Megrez doublet on an HEQ-5 mount
Nikon 10x50 binocs
"Beyond here be there"
|
|
1 registered and 4 anonymous users are browsing this forum.
Moderator: Charlie Hein, knuklhdastnmr
|
Forum Permissions
You cannot start new topics
You cannot reply to topics
HTML is disabled
UBBCode is enabled
|
Rating:
Thread views: 382
|
|
|
|
|
|
|
Previous
Index
Next
Flat
Edit
Reply
Quote
