BBC Focus Magazine

[Jamie]

So, I have a spare old webcam and I'm thinking I might have a go at converting it to use on my telescope. Would be useful to film some .avi's and use registax and such to process the image.

Any tips ?

[M Paul Lloyd]

How do you plan to attach the webcam to the eyepiece Jamie? I had a go at this a while back and ended up having a special adapter made (but then I have access to a machine shop) but no two webcams seem to look the same so you might be better off with something more suited to your needs? A bit of plastic tube and insulating tape usually works well enough though.
If you are feeling technically adventurous removing the infra red filter from the web cam helps improve the amount of visible light the CCD receives, lots of 'how to' sites on line for that.
This U-Tube clip features a webcam similar to mine.
http://www.youtube.com/watch?v=9khTIkwNmW8
And this looks useful.
http://ghonis2.ho8.com/lifecam/lifecam1.html
Otherwise a decent lap top is a good idea, sounds a bit obvious but image processing can take up a lot of processing power.
Clear skies.

[Jamie]

Cheers MPL. I was worried about focussing - do I need to incorporate a lens into the design ? I was thinking of dismantling the camera so I just had the CCD.

[M Paul Lloyd]

Use the scope focus control to get the sharpest image on your laptop screen.
It is a good idea to eliminate as much glass as possible and it all hinges on how confident you are about dismantling the webcam, but they are cheap and plentiful so you can have a few goes at it without breaking the bank.

[Jamie]

I'm good at taking things apart - putting them back together though . . .

Given that it's going to be housed in new structure, that shouldn't be a problem. I will attempt it next week. Results may be posted, depending on the quality.

[M Paul Lloyd]

I look forward to seeing the fruits of your labour Jamie, but if you need any help at all you need only ask.

[Jamie]

Managed to make an adapter with an old 35mm film cannister with a hole drilled in the end. Removed the lens from the camera, and modified the housing so that it would hold the converted cannister. Screwed it all back together, seems to hold ok. Just need to get the h/w drivers sorted now.

[M Paul Lloyd]

Ah yes old film canisters are a fair fit for a 1.25" OD barrel aren't they, brilliant.

It's not a tube size you can get hold very easily for some reason, even though it must be made commercially by someone somewhere..
Anyway sounds as if you are on the right track but be aware that your scope is now operating at its minimal 'magnification' and you may lose a bit of field view unless the CCD is a dead fit to the focus point, although it won't make a huge amount of difference to be honest.

I rather fancy trying the same thing with a hi-Res video camera but I need a decent lap-top to make it all work.

[Jamie]

Well, here is one of the first attempts (the others were flaky to say the least!):



Uploaded with ImageShack.us

I think it's a stack of 5 frames, Registax was complicated.

I need to get the hang of a few things :
- getting the framerate correct so that I have more frames to work with.
- getting the focus correct!
- tracking objects would be useful, so there are more useable frames.
- image was jumpy; not sure if that was the atmosphere or because I'd not cooled the scope down enough.

Oh, and anyone any idea which crater / part of the moon is in the piccy?!

[M Paul Lloyd]

Ah splendid Jamie, good to see this here. Please ignore my comments 'elsewhere'....

So the frame rate is something you will get the hang of with practice I'm sure. Focus wise, that's always a tricky one but again experience will help you judge it more precisely, I read about a technique where someone 'twiddled' the focus back and forth as the frames were taken and simply binned all the ones that were fuzzy. Tracking is indeed most useful, but you need a motorised mount for that, I use one which is actually intended for a bigger scope than the one I have but it makes for a far more stable set-up, which might also help with your final query? Not sure how that will work with your 'go-to' set up though?

The main reason for letting the scope cool is to reduce the air turbulence inside the tube and I usually set my scope up some hours before I plan to do anything with it, I just put a big liner over it just in case it turns to rain unexpectedly. However the image is also prone to atmospheric perturbations especially at higher magnifications.

As for identifying your craters, could you tell me which part of the moon we are looking at and which way round it is orientated please?

[Jamie]

I think it's upside down and back to front, on the terminator to the south. The scope is a go-to, so if I spend time getting it aligned and setup (rather than the 15 minutes I spent on this one) that should solve the tracking issue.

[Jamie]

Another one. Think this is Stevinus Crater.



Uploaded with ImageShack.us

[M Paul Lloyd]

Nice bit of mosaic work there Jamie, you just need to set your contrast levels a bit closer and you have it sorted.

I'm still working on tracking down their respective locations though.

[Thinker]

Loving the pictures Jamie. Have you looked at the two (colliding?) stars that are positioned just below Orions belt. It's two faint stars which appear to have a haze around them. I was just checking on google sky to see if I could find the picture of it again, but I got lost, so I gave up. But I'm sure MPL can shed light on it. It looks amazing!

[M Paul Lloyd]

Do you mean the Orion Nebula Thinker?

[Thinker]

Yeah, that's it!

[M Paul Lloyd]

A long exposure of it is on my 'to do' list.

[M Paul Lloyd]

Think this is Stevinus Crater.

[

You could well be right Jamie, to be honest I'm really struggling to identify anything without an idea of scale and frame of reference of my own.
As it happens Stevinus is a group of craters best viewed on the fourth and seventeenth days of a Lunar cycle as the low Sun will better highlight the surface features.

[Jamie]

I'm pretty sure it Stevinus, I looked on Google Moon, and the Mare in the top right lined up. South it at the bottom of that picture. I know that contrast is a bit out, I just wanted to get the picture done, rather than mess about !! Will try and get them the same and do it again.

Here's an approximate frame of the photo, mapped on Google Moon:



Uploaded with ImageShack.us

Hmmm, actually looks pretty similar - I did take a photo - honest!

The other one, I think it's upside down and back-to-front. A combination of the telescope and web-cam I think. I should be able to mirror and flip the webcam settings so that what's on the laptop screen is actually what you can see in the sky.

Had a go tonight, but it clouded over once I'd setup. I have moved the scope into the garage (all covered up to keep out the dust!) on a permanent basis - that way it should always be the right temp.

I've played with the exposure/shutter/gamma settings on the camera so next lot might be better. Trial and error, for the most part I think. Luckily the moons not going anywhere that fast!

Thanks for the comments Thinker;I will try check Orion - I'm a bit limited to the sky I can see though, due to the house being in the way!!

[M Paul Lloyd]

Yes Stevinus looks like the best bet there Jamie, try to keep a note of what shutter/ISO and speed settings you use as it will help you no end in the future, oh and work out the scopes f-stop (I can supply details on how to do this if needed) otherwise just keep going at your own pace and not worry about any off hand comments from the likes of me about contrast and such. Goodness knows I've been at it for years and still trying to get to grips with it, and yes the weather is probably the biggest problem in the UK. On a good night the viewing can be brilliant but a lot of the time you can't see diddly.