Night sky images?

[Gina]

It's now totally dark, clear sky and millions of stars visible with the naked eye. No moon. Ideal night for star-gazing The camera is showing two or three stars - or more likely planets, plus about a dozen land based light sources. I've got the camera pointing something like 45 degrees skywards with the distant lights across the valley at the bottom of the frame. The lights of aircraft crossing the field of view have also been visible. ATM it's just sat on a box on the window sill looking through the window. When I can arrange a longer video cable I'll try it outside. This camera, in normal operating mode, has just reached the threshold of seeing night sky objects Any image integration, longer exposure or more sensitive CCD is bound to show more.

Because it's a dome camera and designed for ceiling fitting, I had to turn the circuit board round 180 degrees to make the image the right way up when sitting on a horizontal surface. Fortunately, the image sensor and lens are in the centre of the board.

[fractonimbus]

Very interesting information. One of the reasons for my interest in a low light camera is to see the clouds at night. Here in Canberra it's usually not too difficult because the street lights (and moon) illuminate the clouds (although the Lifecam isn't quite up to the task - my "offline image" was made by stacking about 20 Lifecam images using Registax, and tarting up the result in Photoshop). But in a dark site you have to be able to see the sky light (airglow, Milky Way etc) in order to see the clouds silhouetted against them.

DN

[Gina]

I'll give Registax a try, thanks for the recommendation

I too would be interested being able to see the clouds at night (as well as stars and planets, meteor showers etc.). But there isn't much light pollution here to light them up though a good flash light will shine off clouds if they're not to high, so maybe an IR illuminator might work with a sensitive camera.

[Gina]

I've found more info on modifying the ExView camera. Further mods to get better pictures and full details of exactly what to do.
http://jaggedplanet.com/ExViewMod.html

I've always had an interest in astronomy and have been an avid viewer of "The Sky at Night" so I've now decided to treat myself to a telescope - and thus have another use for a low light camera.

BTW, regarding DinoDirect, I'm still waiting for the 0.001lux camera, though I've had some cameras I ordered after that one. I'll probably wait another week and then contact them.

[fractonimbus]

I've found more info on modifying the ExView camera. Further mods to get better pictures and full details of exactly what to do.
http://jaggedplanet.com/ExViewMod.html

Thanks, interesting link.

I've always had an interest in astronomy and have been an avid viewer of "The Sky at Night" so I've now decided to treat myself to a telescope - and thus have another use for a low light camera.

There's a lot you can do with relatively simple equipment, especially planet imaging. In fact it's quite extraordinary what amateur astronomers can do with relatively inexpensive equipment. The most extreme example I know of is the work done by Anthony Wesley http://acquerra.com.au/astro/ But you don't need to go quite that far to get impressive results!

DN

[Gina]

I think the first thing I'll try is my second MS Lifecam Cinema webcam. It should fit nicely in the eyepiece holder. It's the right shape.

[mcrossley]

Gina, you can buy cheap eyepiece adapters for webcams, they have the standard 12.5mm lens thread one end, and 1.25" eyepiece push fit the other, they only cost a few quid, often made of Delrin.

[Gina]

Gina, you can buy cheap eyepiece adapters for webcams, they have the standard 12.5mm lens thread one end, and 1.25" eyepiece push fit the other, they only cost a few quid, often made of Delrin.

Thanks for the info But none of the webcams I've got have a 12.5mm thread. Anyway, I'll bear it in mind.

[Gina]

Found info on modifying a Microsoft Lifecam Cinema for telescope use :- http://ghonis2.ho8.com/lifecam/lifecam1.html

I found this very useful and have successfully completed all the steps mentioned (except mounting in the extension tubes) It's a very clear article. I made up my own mounting - just a matter of increasing the 1" webcam tube to 1.25" for the telescope eyepiece mounting. Can't try it on the night sky tonight due to complete cloud cover. I did try it with a terrestrial view though this afternoon. That wasn't too good either due to mist. Removing the webcam's lens also removed an IR cut filter and this resulted in a pinkish cast on the image. I'm not sure yet if I'll remove it from the lens and mount it in front of the sensor. It might be useful to collect infra-red for night sky objects to increase the sensitivity. OTOH IR will focus at a different point from visible light and might cause blurring.

One thing I noticed in removing the webcam lens was that it's quite a small aperture. Using a 1.2mm "board lens" instead should increase the sensitivity as well as increase the angle of view to something like 120 degrees. This might make the modified webcam suitable as an almost whole sky night cam. Testing indoors at night with the 1.2 mm board lens, showed a significant increase in sensitivity and an estimated 120 degrees coverage as compared with the unmodified camera coverage of about 45 degrees. A webcam is easier to connect to a computer but unfortunately, nobody as yet seems to have found any way of increasing the exposure time.

[Gina]

I now have my modified MS Lifecam webcam reasonably securely mounted on my telescope (Celestron Astromaster EQ130-MD) and have been trying it out using Cheese as the webcam software. Today the visibility was alright and in a break in the clouds I was able to see the moon. It was daylight so the contrast is a bit lacking but it gives an idea of what can be achieved. With the IR filter removed from the camera (it's attached to the webcam lens which I removed) there was a strong pinkish cast to the image. This can't be totally removed by colour balance correction. I've applied some correction in the magenta-green balance in the following images. I think for moon photos it really wants an IR filter. This image sensor is quite small though runs at 1280x800 resolution and with a 3 micron pixel size, gives a large magnification - I think a 1/3 inch CCD sensor would probably be better. (I also need to clear some debris off the image sensor before I capture any more pics ) These images have been reduced to 640x400 for posting here.

2011-03-14-174145.jpg

2011-03-14-174229.jpg

2011-03-14-174300.jpg

2011-03-14-174334.jpg

[Gina]

One of the images above after "enhancement" using GIMP to change to monochrome and increase contrast by changing the gamma curve.

2011-03-14-174300a.jpg

Or a different gamma curve to bring out the craters on the terminator :- And I've left this image full size.

2011-03-14-174300b.jpg

[Gina]

Another GIMP doctored image - full resolution but cropped to remove uninteresting bits :-

2011-03-14-174334a.jpg

[fractonimbus]

Excellent start The SLR camera people seem to prefer a manual blower ball to clean stuff off the sensor. Can't remember the brand but it looks like a rocket (appropriate in this context!!)

DN

(added: the brand is "Giottos")
and Jessops seems to have one that's nearly identical:

[mcrossley]

Gina, a small IR blocking filter would be a good idea - you can get them in 1.25" eyepiece screw mounts for just this purpose. As an alternative for the Moon you may want to try a red filter. This has the advantage of 'calming' the seeing too (longer wavelengths are less affected by atmospheric turbulence than short).

Also you want to try Registax on your captured videos, it will bring out tons more detail.

As for sensor cleaning, I use Scotch Magic Tape - the opaque stuff that is semi-sticky - much to the horror of many folks, on all my sensors, even my expensive APS sized sensor astro cam. I got the tip from a camera manufacturer and it works a treat, far cheaper than all the expensive cleaning kits you can buy At your own risk of course!

[Gina]

Thanks very much for the tips Mark

I've found the MS Lifecam body needs to be beyond the end of the focus tube so I could put a filter between the focus tube and the webcam body. I want to make up an improved mounting anyway. The Celestron T-Adapter, Universal 1-1/4" would be too long unfortunately so it's Blue Peter time again

Oh, and yes, I'll be try Registrax shortly.