AP Images Taken with Original NexStar
Posted 27 January 2013 - 09:56 PM
Posted 28 January 2013 - 01:22 AM
James, your Jupiter is very good, try with a barlow next time now that you would have grasped gamma / contrast / shutter etc.,
Posted 28 January 2013 - 02:25 PM
Posted 06 February 2013 - 01:51 AM
Posted 19 February 2013 - 11:04 PM
When I was 12, I spent 6 months grinding my own mirror to make an 8" Newtonian. About that same time, Celestron came out with their distinctive orange 8" SCT and I said "one day I'm going to get one of those!” Fast forward over 40 years and I am the proud owner of a new Nexstar 8SE.
I have learned so much from CloudyNights on setup, alignment, tracking, astrophoto techniques. Many posters have commented that M42 is probably not the best first target for an amateur, but how can you resist during winter? Here is my first astrophoto attempt. Prime focus, 6.3FR, 20 sec exposures, ISO 1600, about 140 frames, DSS, then Photoshop.
My question (if this is the wrong thread for it, please forgive me and point me in the right direction) has to do with not being able to photograph anything above 50 deg altitude because the camera hits the base. I have modified my scope with “Ron’s rail” and added extra weight to the back end by putting on my camera flash unit and still cannot balance the scope far enough forward for the camera to miss the base. Numerous posts speak of the best seeing for photography is near the zenith, but I am severely limited in what I can image. How do most of you solve this problem?
Posted 20 February 2013 - 12:03 AM
And that is one great shot of M42! Congrats!
Posted 20 February 2013 - 05:42 AM
A very warm welcome to CN and to this particular, Nexstar forum ! :bow: Also, many congratulations on an excellent image of M42. :bow:
Talking of mirror grinding, I did exactly the same at the same time; (i.e. 40 years ago);with an 8" blank. I've still got it and have it on good authority that, probably more by luck than judgement, I managed to figure it well !
I'll bet though you got further with yours than I did with mine. I never ever did get around to polishing it !
But to your question.
Assuming the addition of "Ron's Rail" indeed allows you, in theory to clear the mount base with your camera assembly if you push the OTA forward enough to achieve this, I further assume that your concern is with front end heaviness produced which, in turn, is likely to cause the OTA to drop. (?)
If this is the case, then if the weight of the added flash unit is insufficient to counter balance, there is a counterweight system available from JMI which might prove more successful. (Link below). This indicates the counterweight placement forward on the rail, but presumably it can also be placed aft; with or without some ingenuity or improvisation.
Also, by the same token, don't be reluctant to make small, tightening adjustments to the altitude axis clutch in order to help support the extra foreward distribution of weight.
As to imaging at the Zenith, and of course this position is likely to be the clearest on any given night, it is however certainly not a good idea to attempt imaging here where Alt.Az. mounts are concerned. Couple the idiosyncrasies of the spur gear drive with the azimuth axis "algorithmic contortions" it needs to perform to keep track of the target directly above this axis, and one can imagine the anomalies which inevitably will arise.
Hoping this helps,
Posted 20 February 2013 - 08:12 AM
Well done on your first attempt James. I'm sure the guys will keep you on the straight and narrow as far as A.P goes.
Thanks for posting.
Posted 20 February 2013 - 07:54 PM
I actually keep a bookmark to a 2011 post you made detailing the alignment process (slight front end heavy, up and right movement etc) that helped me tremendously. I was worried about making it TOO front end heavy. If I go to the full extent of my very short "Ron's rail", I can just clear the base and I am about 1 inch forward of what I had marked as "slightly" front end heavy. (no room for JMI weight) Should I put it that far forward then re-adjust my Anti-backlash settings? Is that what you mean by tightening the altitude axis clutch? Thanks again.
Posted 21 February 2013 - 05:05 AM
I'm pleased and flattered to learn that particular list of instructions of mine helped !
In terms of your above question though:---
No, adjustment of the altitude clutch doesn't refer to backlash adjustment although it's always wise to double check after such.
In this case however, it relates to the amount of friction one imparts to the altitude axis so that its elevation is not causing the altitude motor to labour while, at the same time, the OTA is prevented from slipping or falling under its own weight.
It's a very simple operation which has been detailed by our CN and Nexstar forum colleague, Art Dent, and is featured in the above "Sticky" on this forum page entitled;
"Links and Best of Celestron nexstar Forum".
From this, go into the subtitle; "Useful Forum Threads" and then to "Altitude Nut Adjustment".
Footnote: Don't be too faint-hearted about making the adjustment. Place your OTA as far forward on the dovetail as is necessary to give your camera a minimum but safe amount of mount base clearance and then, with everything secure, elevate the OTA to the Zenith, ensuring that there is no slippage, (i.e. the altitude motor elevates it "tooth for tooth" cleanly).
Next, as Art describes: from the Zenith position, bring the OTA back down under "full steam" (Slew Rate 9) to the horizontal, keeping that other hand hovering, but not touching, beneath it, purely as a safeguard.
At the horizontal, remove your finger smartly from the control button. If the OTA stops dead or almost dead, (and I believe there is a safeguard mechanism in these later 'scopes, as opposed to my older Nexstar 8i, whereby the OTA is not so abruptly [immediately] arrested in order to place less load on the motor/bearings); then that's fine: no adjustment should be necessary.
Any tendency however, to drop under its own weight, i.e. continue downwards towards the base of the mount after the button has been released, will require a little more tightening of the adjustment nut.
Any doubts or problems with this and/or other matters, please let us know. We're all here to help.
Posted 21 February 2013 - 07:28 PM
Thanks to the link to the article on the altitude clutch. Mine seems to be holding the extra front end weight just fine.
Fine tuned anti-backlash too. Now if only I can get clear skies to test it out.
Unfortunately here in south Louisiana the forecast is clouds and rain for the next 2 weeks!
Posted 21 February 2013 - 08:37 PM
Keep the great shots coming!!!!
Posted 22 February 2013 - 04:21 AM
Glad to hear all adjustments seem to have gone OK.
You can of course test the 'scopes' smoothness of operation to a certain extent while waiting for the clouds to clear, by artificially programming the 'scope, "in the comfort of your own home", by literally kidding it into an alignment and then making some pracice slews to this and that called-up object just to see that all is tight and functioning.
BTW. Don't forget though, to let us know how it goes when you do get a break in the clouds and are able to get outside for real ! !
Posted 22 February 2013 - 07:19 PM
When I first started practicing alignment and tracking with my new 8SE, i tried some piggyback shots with it first.
M31 below was shot with the Canon 1D Mark IV, zoom lens at 280mm F4.0, 1250 ISO, piggyback on 8SE,
30 sec exposures, 50 light frames, 25 darks, flats, flat darks, bias, DSS then PS.
Posted 22 February 2013 - 07:58 PM
If you don't mind me asking (sorry if this is a complete newbie question, still getting the hang of things), how did you get such a wide FOV with your 8SE? Was it just because of the camera settings you mentioned, or is there something else helping you with FOV?
Posted 22 February 2013 - 08:40 PM
So, I guess, that photo may be a little out of place for this thread. Sorry for the confusion!
Posted 26 February 2013 - 01:51 AM
Tel's advise is always spot on and helpful isn't it.
Posted 02 March 2013 - 05:40 PM
Stock 8SE, 6.3FR, 20 sec exposures, 1600 ISO, 140 lights, 80 darks, 10 bias, 10 flat, 10 dark flat, DSS, PS3.
Posted 03 March 2013 - 09:32 AM
Nice shot! I think that there is a lot more detail in that shot that could be enhanced with careful processing. You caught a good one.
Posted 03 March 2013 - 03:43 PM
As Grey says though, there is more detail contained within this one, as perhaps this attempt to bring it out, shows ?
Posted 04 March 2013 - 08:14 PM
What's even more amazing, Tel, is that you did that working with a small jpeg file!
Posted 04 March 2013 - 10:01 PM
Posted 05 March 2013 - 03:55 AM
Wonderful remix of the Crab Tel.
Thanks for posting.
Posted 05 March 2013 - 04:11 AM
(Of course there's always the ulterior motive: namely that it provides me with an occasional opportunity to practise my P/Shop et al processing, which is about all I'm doing these days given that we've endured weeks of practically solid cloud cover here in the UK) !
Once again, many thanks and best regards,
Posted 27 March 2013 - 07:34 PM
Exodus, Plato and Cassini