First real light.
Still working out sweet spots for balancing and guiding etc
5 min subs on the Helix and Sculptor
better than what I could do before on these same subjects but i think I can do better still with better guiding and longer subs eventually
anyways, here goes
cheers
frank
Flats will make a big difference too and allow you to stretch the image more.
I know what you mean about processing - I've got a couple from Nambucca that I need to process up, but it's been months since I've processed a deep sky image.
Thanks Dennis,
I still don't know what I should say about the focal length: The C14 is an F11 so when I put the the 6.3 focal reducer on does it make it 6.3 or 7.3 ?
????
anyways,
i've had a quick try of 1 min shots at F11 and cant wait to try that seriously, that'll be a focal length of 3.5 meters and promises to reveal nice stuff a few small and fuzzies I want to image
gotta work out balancing/guiding etc first
i'll keep everyone posted
cheers
frank
Thanks Dennis,
I still don't know what I should say about the focal length: The C14 is an F11 so when I put the the 6.3 focal reducer on does it make it 6.3 or 7.3 ?
????
cheers
frank
Whoops – thanks Frank, I did my calculations based on F10 so at F11, you are closer to 2500mm!
I think an x0.63 reducer will make an F11 system an F6.93 system?
I think an x0.63 reducer will make an F11 system an F6.93 system?
In theory... but I suspect it'd be quite different, depends what's in the image train. My F/6.3 takes my F/10 scope to about F/7.3
Quote:
Originally Posted by spearo
First real light.
Still working out sweet spots for balancing and guiding etc
5 min subs on the Helix and Sculptor
Nice images for a first night. Perhaps a bit high on the contrast for NGC 253 as viewed on my screen, would prefer that backed off a little. Looks like you have quite a nice flat field there, I would've expected a lot more curvature. I only ever tried my 350D on my 12" LX once and had some curvature visible around the corners.
Great work on the 14" Frank. More data will certainly provide pleasing results - @ F11 you'll need longer subs or a higher ISO. A focal reducer would be beneficial if you find it hard to keep stars round when imaging at such long "tear your hair out" focal lengths. Look forward to seeing more.
Thanks everyone,
really appreciate the feedback
Roger, there's a very slight croping done mainly to center the target in the final frame but also to remove some of the stars on the edges which are inevitably suffering from curvature, not much cropping though.
Dennis and Roger, thanks for the info re F ratio, I think I can probably say with clear conscience that the F ratio with the focal reducer and imaging train (focal reducer, 10-1 focusser, Canon) if F/7 ? just never really saw that anywhere else.
Alex and Ric thanks for the encouragement
Jase and Strongmanmike, very pleased with your kind words. On the full res images i notice a very slight elongation in the stars so the guiding isn't perfect yet. I also had to discard 10 min shots which all showed some trailling so I haven't got it licked yet bu i know I'll get to it at some point...just need more time at the scope!
or a self guided SBIG which would reduce overall weight issues, neutralise the issue of differential focal length between the imaging and guiding setups
maybe when the bankbook allows ...the better half is already supportive (what can I say...she's a keeper!)
:]
thanks everyone
it's good to be back!
frank
The exact focal length with the "standard" Meade or Celestron "f.6.3" focal reducers, is 2,370mm. This is taken from using the standard Celestron 1.25" visual back. The resulting f/ratio is f/6.88. However, the FURTHER you are back from the focal reducer, the longer the focal length (and the more coma being introduced) but they are less senstive to distance than the Optec focal reducers and this is why we prefer them. We have run our C14 with filter wheels and flip mirrors using them up to f/7.2, without any problems with CCD chip sizes up to a ST-10.
Trust this helps you.
If you have any Celeston C14 questions, please feel free to ask me - Grove Creek has the 2nd C14 ever made by Celestron and it has undergone a lot of modifications and different configirations. We have a movie on YouTube about our C14. Just go to www.youtube.com and search for "C14 Grove Creek". More details about our C14 is at: www.gco.org.au/scopes/
Our C14 has recently been moved out of our fork mount to a Astro-Physics GTO-1200 mount. The previous fork mount had a Agro Navis and DEC & RA stepping motor tracking system that I built and designed. The fork, motors, controller, Agro Navis and encoders are now all packed away, where we may possibly sell it in the future. The fork only had a PEC of 9.75^sec peak-to-peak, which was very good for its time - 1972.
Steven Williams,
Managing Astronomer
Grove Creek Observatory www.gco.org.au
Quote:
I still don't know what I should say about the focal length: The C14 is an F11 so when I put the the 6.3 focal reducer on does it make it 6.3 or 7.3 ?
????
anyways,
i've had a quick try of 1 min shots at F11 and cant wait to try that seriously, that'll be a focal length of 3.5 meters and promises to reveal nice stuff a few small and fuzzies I want to image
gotta work out balancing/guiding etc first
i'll keep everyone posted
cheers
frank
