Astronomy and Astrophotography

[Gina]

As I've indicated in the night sky thread in the Homebuilt forum, I've started to get serious interested in astronomy and astrophotography. I've always had an interest and watched The Sky at Night avidly but really never done anything about it (other than looking at the stars, moon and occasional meteor trails with binoculars). I've now bought a telescope - Celestron Astromaster 130 EQ MD - plus a 4mm eyepiece, Barlow lens and some other accessories. I've also bought a Sony A200 DSLR (second hand) with a view to astrophotography as well as general photography.

I'm also looking into CCD imaging and have several image sensors I'm looking at. These include the Sony SuperHAD 0.001 lux 1/3" CCD CCTV camera sensor and the Philips Vesta 675 webcam. There are details for modifying the latter for long exposure on the web. I've also been trying the image sensor from a MS Lifecam HD Cinema webcam, though this is a CMOS sensor I believe. I've taken some moon shots with this and posted some in the other thread. In due course I plan to use Registax software to collect multiple images and stack and process them.

Recently the weather has been against night sky viewing and also this is one of my many projects I have on the go (in addition to housework etc.), but the last couple of nights have been fairly clear. There is no moon visible at night and I've been trying to locate Saturn amongst the stars. I have not been having much success! But I'll do it in time I've been taking star photos (with the DSLR) in the region where I think Saturn is and trying to match up with start charts.

The telescope as supplied only has a simple star finder. A pair of graticules and a red LED to line up on. This is pretty useless at night - you can't see the graticules (except when viewing the moon) and I've bought a cheap telescopic finder scope. The mounting for it was rubbish so I've made my own. Now I do have something to line up the telescope with. Wish I could afford a "goto mount"

This is all by way of introduction and I'll post the results and progress as I make it.

[Gina]

The moon pics are on my weather website under Astrophotography from my Home page. Please excuse the dust spots.
Or here is a direct link :- http://ginad.org.uk/weathergd/Astrophotography.html

[mcrossley]

Gina, rather than a 'traditional' telescopic finder, I would suggest a simple 'red dot' finder. This has a single clear 'screen' that projects the red dot at infinity. You don't have to squint through the screen and because the dot is at infinity there is no parallax so you can use both eye's - it's much easier to use, and accurate enough for me to put things in the eyepiece of my C14 with a 4 metre focal length. The cheaper ones are a little fiddly, but the ones like this (v. similar to mine) are much better - personally I would never go back to a finder scope. I have some spare ones in a cupboard!

If you are starting imaging, or interested in astronomy in general then you could do no better than join Star Gazers Lounge which is largely UK based, but with many internal members too.

[Gina]

Ah, maybe I've been trying to use the star finder the wrong way. I've been closing one eye and lining up the red dot on the object, using the circles on the spaced reticles to line my eye up with the telescope axis. Your method relies on the eyes being perfectly muscle balanced but unfortunately I have a slight disability in that area - muscle imbalance - so my eyes aren't up to that, I'm afraid. I can use the red dot finder to get the object well enough lined up to be able to use the finder scope though And I can improve it by fitting a "spy hole" near the opposite end of the telescope from the red dot finder.

Thank you for the link to the Star Gazers Lounge - I'll check that out

[Gina]

The Stargazers Lounge is good Been following links yo hints and tips for beginners and gaining a lot of useful info. What with this and several books I've bought, I'm beginning to get the hang of it. Lately, everything has been based on reading and learning and daytime viewing of trees etc. Nights have either been overcast or very cold. As recommended, I have bought myself a decent pair of binoculars - Olympus 10x50 - which came today. These are the best bins I've ever owned. Only tried on terrestrial objects so far but they look good. Reviews of them are good too.

Generally I think I have been trying to rush into astronomy too fast and getting frustrated. This seems to be a common thing with beginners and I've taken the advice to take things slowly and calmly. I'm a "hands on" person and like to get on with it generally but this hobby needs a more relaxed attitude. So... more studying and I quite expect to make a few mistakes in what I buy. I don't think I've wasted too much money yet though

This is a good quote :-

"Lose your ego. Astronomy teaches patience and humility -- and you'd better be prepared to learn them. There's nothing you can do about the clouds blocking your view, the extreme distance and faintness of the objects you desire most, or the timing of the long-anticipated event for which you got all set up one minute late. The universe will not bend to your wishes; you must take it on its own terms."

[Gina]

Been spending some money (while I've got it to spend above my reserve). After much thought I decided to buy me some help with finding night sky objects having tried with planisphere and sky maps etc. I've bought this http://www.amazon.co.uk/gp/product/B000 ... ss_product the Celestron SkyScout GPS Star Locater. It came today and I've been trying it out as far as I can in daylight. The moon is in a visible position but covered ATM by some wispy cloud - I was able to choose the moon from the menu and locate it. It's just far enough from the sun to look for it even though the sun is in clear sky. There are thousands of astronomical objects in it's database and it should save me a lot of time finding what I want to see or to tell me what I'm looking at.

I've also been trying it next to the Celestron 130EQ telescope with the thought of piggybacking it onto the scope. It doesn't like being near metal or magnetic fields. The scope main tube isn't metal but most of the fittings are - like the focussing mechanism and red dot finder. It shows a magnet symbol when it's upset by magnetism or metal so it's easy to see where it's happy. It has a tripod bush but doesn't like the metal in the screw on the scope. The straps that hold the tube which I thought were metal don't affect the SkyScout but the clamping screws do. There is a place just above the EQ mount quite near the tube where it seems OK, so I'm going to see if I can make up a plastic mounting for it making it into a manual GOTO system. Problem is avoiding metal fixings though it has a tripod bush - but I haven't tried it on a tripod yet.

I'll report how I get on

[Gina]

OK on a tripod - guess the mount is non-magnetic eg. aluminium. And my tripod bush extenders are fine too. So a plastic or aluminium framework plus tripod screw should do for a bracket.

[Gina]

We have a clear sky tonight and I was able to do some viewing and photography. Early on it was A200 DSLR shots of the crescent moon, which fitted very nicely in the frame. Then later I pointed the scope the other way - to the east - and lined up on Saturn. I homed in using more and more magnification. 20mm, 10mm, 4mm and finally 4mm with 2x Barlow. I could see the rings quite clearly, particularly @2mm or 325x magnification though even at this magnification the image was quite small. With motor drive off the image moved across the field of view in seconds. I found my axial mount alignment was a little bit off the pole.

I eventually had problems with dew and misting up but the seeing was excellent. I had the scope set up on the lawn and for Saturn the grass continued for hundreds of metres across fields, so nothing to produce warm air currents. I'd also had the equipment in position since the afternoon - so much easier setting up in daylight! So the scope had time to cool down after being indoors.

A very pleasing evenings viewing and photography I'll post one or two of the better moon shots tomorrow. I feel quite pleased with my first efforts with the A200. The SkyScout performed nicely and put me straight onto Saturn. In fact it was where I thought it was from looking at the planosphere, but nice to have it confirmed. I also used it to identify some of the brighter stars though with a very clear night it was quite easy to identify the main constellations.

This has also been the first night I have tested my new starfinder scope - that was bang on and a very useful intermediary between the red dot finder and the scope, either with camera or 20mm eyepiece. I estimate the FOV on the camera CCD to be about 0.6x0.4 degrees - the horizontal being just a bit wider than the moon. I read that the moon is about 0.5 degrees of arc.

EDIT :- that is using the Barlow x2 between camera and scope (needed to extend the back focus). That gives a prime focal length of 1300mm.

[Gina]

Another session tonight but much shorter - the dew was soaking everything. Took a few more moon shots though and viewed Saturn again. Tried the motor drive but although the motor was running (quite noisy) the RA did not seem to change. Will check it tomorrow indoors. Can't do much without a decent motor drive.

[mcrossley]

Keep at it Gina, it's worth it. Do you have a clutch between the motor and mount to allow the use of manual slow motion knobs?

I battled last night with trying to set up for imaging and autoguiding at prime focus of my C14 - not easy at nearly 4 metres focal length and f/11. I need to expose for a minimum of 10 minutes at f/11 with a light pollution filter in the mix.

[Gina]

Keep at it Gina, it's worth it.

I certainly will

Do you have a clutch between the motor and mount to allow the use of manual slow motion knobs?

No, it doesn't have a clutch To disconnect the drive so that you can use the manual slow motion, you have to undo a knurled screw on the flexible coupling that connects the drive shaft to the worm drive shaft - other end from hand-wheel. I thought this was tight when it was outdoors and I was testing it but maybe not tight enough. I don't consider this at all satisfactory and lowers my faith in Celestron considerably. I've read a number of reviews of Celestron equipment and they seem good. The telescope, mount, tripod, lenses and adapters all seem of high quality and precision and the telescope performance seems very good - though I haven't any other scope to compare it with, I'm just going by reports of others. Seems to me that the motor drive is a bit of an afterthought and I shall be replacing it with my own construction. I have the motor and gear train sussed out and mostly mounted into a plastic box. I have yet to sort out a clutch mechanism.

I battled last night with trying to set up for imaging and autoguiding at prime focus of my C14 - not easy at nearly 4 metres focal length and f/11. I need to expose for a minimum of 10 minutes at f/11 with a light pollution filter in the mix.

Sounds difficult and something I expect to tackle in time. Hopefully not with light pollution unless I'm pointing south west, over the town of Honiton. I shall have to look into how to use autoguiding I expect - I think it will be very difficult to get an accurate enough motor drive without.

BTW.... Which celestial object are you trying to capture?

Just received the Baader AstroSolar Safety Film (A4 size), from Rother Valley Optics and hoping to image the sun - extremely carefully. This film goes over the open end of the scope and anything else used for the sun. I don't intend looking directly at the sun even with the safety film!

[Gina]

Followed the instructions that came with the foil and have made a cardboard filter for the scope. Now to try it...

[mcrossley]

I made one of those some time ago for my refractor - it works well, about as good as you can get for white light. Which density did you get? There are two, one for visual use, and a higher transmission version for imaging. I used a couple of off-cuts to put over a pair of 8x30 binoculars for 'quick looks'.

[geoffw]

Sun with sunspot using a home made Baader Filter.

[Gina]

I made one of those some time ago for my refractor - it works well, about as good as you can get for white light. Which density did you get? There are two, one for visual use, and a higher transmission version for imaging. I used a couple of off-cuts to put over a pair of 8x30 binoculars for 'quick looks'.

Think it's the lower transmission one.

I'll post an image or two tomorrow.