GSO RC images 21 May 2009

[bluescope]

Originally Posted by EzyStyles

Hi Steve, the twin spikes in 5128, theres 2 bright stars next to each other. nothing got to do with focusing .

Thanks for pointing that out Eric ... it did baffle me as to why ... I didn't realize there were two close stars there.

[Paul Haese]

Originally Posted by strongmanmike

Three very excellent images Paul after some initial frustrations I bet you are pretty happy sitting at your computer looking at these



Mike

Yeah only minor frustrations though Mike really in the scheme of things. I reckon I could go deeper on the 5128 though. What do you think? I was thinking of doing a deep field centaurus A. I reckon I read where someone else did the same thing.

In all seriousness though, very happy thus far with the results. More work to do though to get that perfect image, but this is a very good start. Looking at monochrome cameras now again. More research and more thinking. I am thinking of front illuminated but not sure which company to go with. I can only use and APS size chip though as full frame will be vignetted too much I think. At the moment it is a toss up between the QSI583 or the STL6303e. I cannot afford an FLI or an Apogee, not keen on separate filter wheels either. Also like the idea of using a camera with self guiding too, but affordability is the main issue.

[Craig_L]

Hi Paul,

Great images - scope and camera working very well as everyone has commented. What length extender tube did you use to get focus with the Canon? And I wonder whether this would be the same for the 6 inch which I'm thinking about?

[Paul Haese]

Craig, I used the 2" extension behind the focusor and in front of the focusor I used Takahashi CA35. This has given me the correct length for focus. The long CA35 is used so that I can use the Taka flattener.

[Craig_L]

Thanks for that Paul. I have a Tak flattener but for my Sky 90 but I mightn't need it for the 6inch which I understand is pretty flat to the edges. My only worry now is whether I have to use dew heaters.

[AlexN]

Craig, I think I'll be making a dew heater for the secondary.. As on a dewy night, the secondary fogs up pretty quick.. The primary seems well protected. But I'll make a dew shield first to see if that keeps it at bay, if not, secondary heating setup will be built..

[TrevorW]

Dew whats dew

[Craig_L]

Must be that mild Western Australian weather Trevor. Thanks Alex. Hmm. Dew heaters, collimation, internal reflections...my feet are getting cold.

[TrevorW]

Hi Craig

Don't generally need dew heaters here until Sept/Oct when it gets below zero at night

All these issues you mentioned are indicitive of RC, Schmidt Cassegrains and Newts, dew can hit anyone so don't be put off by that and collimation as all reflector type scopes need this done regularly.

Th reflection artifact may be something simple to fix and we are working on that.

Cheers

[AlexN]

hah.. If all it takes to cool your feet is collimation, dew and a reflection that may be easy enough to fix, you best stay away from telescopes...

Newtonians - Require collimation, require secondary dew heaters
Refractors - require heaters, can get reflections
SCT/Mak Newt/MCT/SN - can get reflections, require collimation and dew control.

No matter what scope you buy in this price bracket, there are going to be extras to buy, there are going to be modifications to be made and issues to rectify... If a bit of dew control, careful collimation, a focuser and an internal reflection is all this scope needs to be as good as it can be, I say its awesome.

Alex.

[leinad (Dan)]

That internal reflection would drive me insane!!; I don't know about you guys?

Hope the supplier provides some fast answers. Does the Astrotech model have the same problem; possibly email Astrotech directly ?

Could this be possibly off-axis aberration? I'm suprised you've all been hit by this same problem. Sounds like a defect to me.

Hope you sort it out soon

[AlexN]

I emailed astrotech 3 days ago with regards to their announced 0.75x reducer/flattener, and also asked about the internal reflection... I am yet to get a reply.. Waiting, waiting waiting...

I highly doubt its an aberration, more likely light shining off something inside the OTA.. My current thoughts are secondary baffle, the end of the primary baffle tube and possibly the mirror edge... An aperture mask made for the two mirrors will either identify that as the problem, or rule them out.. then I'd be looking at the other options... At the end of the day I would imagine that this wont be something thats extremely hard to fix.

[leinad (Dan)]

Out of curiosity; how does the reflection look when the camera is slightly out of focus?

[AlexN]

softer.

[TrevorW]

As I stated on the other thread I got no reflection in 6 minute subs of Cent A

I'm betting on the primary baffle being the issue

Cheers

[leinad (Dan)]

Originally Posted by TrevorW

As I stated on the other thread I got no reflection in 6 minute subs of Cent A

I'm betting on the primary baffle being the issue

Cheers

Just saw something similar here:
http://www.narrowbandimaging.com/mar...egrain_hex.htm

Perhaps it is the tubes focuser baffle tube..

[dpastern (Dave Pastern)]

What's the primary baffle?

Dave

[TrevorW]

Dave

It baffles me too

see the short and long black thingies in the middle of the scope in the images from the link posted by Leinad they are the baffles

Cheers

[leinad (Dan)]

Originally Posted by dpastern

What's the primary baffle?

Dave

Meant to say the focuser baffle tube.

[AlexN]

Daniel, That link you posted does show a VERY similar reflection, and apparently flocking the baffle tube fixed it (as seen in the image)