Orpington Astronomical Society

Astronomy => Technical => Topic started by: Fay on Sep 03, 2013, 08:56:05

Title: Waste of time Last Night, help!
Post by: Fay on Sep 03, 2013, 08:56:05
Spent 3 hours doing M31, it seemed to be going along ok. started to prepare for taking flats, and, as I have to get the scope pointing to the zenith, due to the flat panel, the drawtube with the QSI attached,  slipped about 3" . that was the end of that. so wasted evening.

Has anyone any idea what I can do to stop this happening? I do seem to recall sandpapering a part of the drawtube, to prevent this problem, not sure, obviously did it wrong!
also how can I fix something on my flat panels so they grip the scope tube, so I can take flats at any angle?

Thanks
Title: Re: Waste of time Last Night, help!
Post by: MarkS on Sep 03, 2013, 09:26:22
What a pain - the drawtube slipping!

As for the lightpanel take the "Blue Peter" approach.  Start with one cardboard box and one roll of gaffer tape.  Sandwich the light panel between two sheets of cardboard with a hole cut one side large enough for the scope aperture.  Build a cardboard tube that will fit over the end of the telescope and use gaffer tape to attach it to the flat sandwich you have already made.  Then you just slide the whole contraption over the end of the scope to use it.  It will be lightproof and no-one at Kelling Heath will scream in agony because you've destroyed their night vision.
Title: Re: Waste of time Last Night, help!
Post by: mickw on Sep 03, 2013, 09:40:47
Why not just hold the light panel against the scope ?
Start the Flats sequence then just hold the panel in place, and flats taken before you did that will be obvious so dump them
Title: Re: Waste of time Last Night, help!
Post by: Fay on Sep 03, 2013, 09:45:11
Well Mark, i do have a old light box, that fitted the ED80 & ZS66, i was going to the shed today to see if it still works.

Mick, I thought about holding the panel in place, but QSI subs take tooooo long, 22secs each on top of the exposure time, 20x22sec + exposure time.
Title: Re: Waste of time Last Night, help!
Post by: MarkS on Sep 03, 2013, 09:46:51
Quote from: mickw
Why not just hold the light panel against the scope ?

I can already hear the howls of anguish from the farthest end of field at Kelling Heath!!
Title: Re: Waste of time Last Night, help!
Post by: Fay on Sep 03, 2013, 09:50:02
yes thinking about that, i would have to get inside a bin liner with the panel   
Title: Re: Waste of time Last Night, help!
Post by: mickw on Sep 03, 2013, 09:52:30
 :lol: :lol:
They are far too fussy at Kelling

Sorry Fay, I was thinking flats would be as fast as with the Canon
Title: Re: Waste of time Last Night, help!
Post by: JohnP on Sep 03, 2013, 10:25:01
Fay, I would be more concerned with fixing drawtube. If it drops when you turn scope vertical then it is too loose. Will only get worse as nights get cooler. You may start getting focus issues...
Title: Re: Waste of time Last Night, help!
Post by: mickw on Sep 03, 2013, 10:36:26
Doesn't the drawtube have a locking screw ?
Title: Re: Waste of time Last Night, help!
Post by: Fay on Sep 03, 2013, 11:09:41
Yes i tightened as much as possible, but still slipped
Title: Re: Waste of time Last Night, help!
Post by: Mike on Sep 03, 2013, 11:18:02
Are you sure you are adjusting the locking screw or friction screw? The friction screw is what you need to tighten. This will be on the bottom of the focusser and will either be a small knob or an allen key.
Title: Re: Waste of time Last Night, help!
Post by: Fay on Sep 03, 2013, 11:38:40
just going to look Mike, that is a good point
Title: Re: Waste of time Last Night, help!
Post by: Fay on Sep 03, 2013, 12:43:31
sorted out the old light box, dusted it off & it seems ok. also I think i did not tighten the screw enough on the ED80. it is in a awkward position due to the longer dovetail, but i will pay more attention to it next time
Title: Re: Waste of time Last Night, help!
Post by: mickw on Sep 03, 2013, 13:18:18
Quote from: Fay on Sep 03, 2013, 12:43:31
sorted out the old light box, dusted it off & it seems ok. also I think i did not tighten the screw enough on the ED80. it is in a awkward position due to the longer dovetail, but i will pay more attention to it next time

Rotate the scope in the tube rings slightly so you can get at the screw - or saw a lump off the dovetail.
Title: Re: Waste of time Last Night, help!
Post by: Carole on Sep 03, 2013, 13:27:49
I use something akin to what Mark suggested, lots of carboard, tape and Blue Peter.  

See my equipment page 2/3 of the way down:
https://sites.google.com/site/caroleastroimaging/home/equipment

I did flats looking at M16 (low) on Saturday, though I did have to sellotape the lid onto the box as it fell off.  first time I have tried it at an imaging party so was pleased to see the light didn't leak much and annoy any-one.

What scope are you using Fay that the drawtube should slip?  I am sure there is a "fix" for this, but I know what you mean, I used to have the same problem with my old megrez.

Carole
Title: Re: Waste of time Last Night, help!
Post by: Fay on Sep 03, 2013, 13:39:57
thats a nice slim box Carole. i think, mine needs cutting down it is really big!!!!!!!! cant remember why!! :! i think i will have a go at that

ED80 Pro
Title: Re: Waste of time Last Night, help!
Post by: Carole on Sep 03, 2013, 17:52:33
It you make the hole for the scope a tight fit, it shouldn't fall off plus prevents too much light from escaping.  Be prepared to put some velcro on to stop the body of the box falling off if you're horizontal (ish) as happened to me on Saturday, luckily I don't think I had the EL panel switched on at the time.

It might be a good idea to make the depth of the box just a little deeper than mine too if your EL panel is heavy.

Hope it helps.

Carole
Title: Re: Waste of time Last Night, help!
Post by: Fay on Sep 03, 2013, 18:03:40
thanks Carole, i am wondering why my box is about 2' square!!!!!!!!
Title: Re: Waste of time Last Night, help!
Post by: mickw on Sep 03, 2013, 18:24:56
Quote from: Fay on Sep 03, 2013, 18:03:40
thanks Carole, i am wondering why my box is about 2' square!!!!!!!!

Probably because you were saving up for a 20" RC  :lol:
Title: Re: Waste of time Last Night, help!
Post by: Rocket Pooch on Sep 03, 2013, 19:31:50
Quote from: Fay on Sep 03, 2013, 18:03:40
thanks Carole, i am wondering why my box is about 2' square!!!!!!!!

:o
Title: Re: Waste of time Last Night, help!
Post by: Rocket Pooch on Sep 03, 2013, 19:36:00
Quote from: Fay on Sep 03, 2013, 13:39:57
thats a nice slim box Carole. i think, mine needs cutting down it is really big!!!!!!!! cant remember why!! :! i think i will have a go at that

Double  :o
Title: Re: Waste of time Last Night, help!
Post by: Fay on Sep 03, 2013, 21:13:37
Thinking about it, mine was a bit of a prototype. there were no flat panels around, everyone made a box. i am going to cut it down, i reckon i could get about another 10 out of the panels!! :lol:
Title: Re: Waste of time Last Night, help!
Post by: Fay on Sep 05, 2013, 10:11:34
Know what my draw tube slippage is caused by.

the tightening screw, tightens anti clockwise & loosens clockwise