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View Full Version here: : Blue and Pretty - but what is the problem?


2020BC
23-04-2006, 05:54 PM
While imaging the Running Chicken I got this optical artifact that, while pretty, is going to be a nuisance if I can't find out how to get rid of it.

My setup consists of a Meade LXD-75 Schmidt Newtonian 8" with MPCC Coma Corrector. Camera was Canon 350D (unmodded). Exposure was 100 seconds, ISO 1600 and Noise Reduction On. Dew Shield was on the front of the scope and no extraneous light sources shining in.

Is it lens flare - from the Coma Corrector or the SN corrector plate?

leon
23-04-2006, 11:00 PM
Thats a great shot, and i was going to say CA, but i'm not sure now.

I too have diffficulty with my Digital Shots, and am still waiting for the specially ordered lens from Pentax, it is.......

Well, I better explain this lens

It is only 15 cm long, yea that's true, and is an f/2.8 40mm, which will be 63mm on the old terms, and is specifaclly designed for the Pentax IstD, to meet the Sensor Size problem, so at 520.00 Dollars there should be no CA.

Well this is what they tell me, however if it dosn't work i'm lucky enough to give it back to my friend at the camera shop.

I'm lucky enough to be able to star test any lens before i buy, so how good is that. :)

Vermin
24-04-2006, 12:00 AM
Really looks like an internal reflection of the bright star. Bit difficult to say off which glass surface though. I'd start by trying a test shot without the coma corrector.

ballaratdragons
12-07-2006, 11:50 PM
Is this the ONLY pic it is in, or does it show up in others too?

Shawn
13-07-2006, 03:13 AM
I think its a bizarre thing that you get an internal reflection or whatever it is that looks just like a question mark in a black box, by the way whats the blue fuzzy nebula called, ???:P :lol:






seriously tho
Hope you work it out

acropolite
13-07-2006, 08:08 AM
As Tom says it's lens flare caused by internal reflections of the bright star at middle bottom.

RB
13-07-2006, 08:25 AM
Yes it looks like flare caused by internal reflection of the C.C from the bright star.
I wonder if you try and centre it more, it might change the angle of reflection and make it dissapear.
:shrug:

JohnG
13-07-2006, 12:07 PM
This is a cropped part of an image I took showing the same area of sky, at the 1 o'clock position is the same type of reflection, this was with the Tak at f/5.9 and using the Tak focal reducer and an umodded Canon 350D, it is definately an internal reflection and it only happens to me when the FR is fitted and when near a bright star.

JohnG