Night sky images?

Gina · **Posted:** Sat Feb 26, 2011 7:54 am

fractonimbus wrote:

Now that looks interesting... Presumably one would use a timer and a CMOS switch to do the exposing. Ideally software to set the time interval.

DN

Yes, I would think so. I'd probably use a "1-wire" chip to control a CMOS switch. It all needs a lot of thinking about and some research - an interesting project!

mcrossley · **Posted:** Sat Feb 26, 2011 9:06 am

For a similar project I wrote a script that controlled the exposure time, it just calculated the average signal level per pixel on a captured image, and then halved/doubled the exposure until it was within an acceptable range. Once within range it went back to capturing an image once a minute. That was with a software controlled camera though.

Edit: found the script, but it's not much use unless you have the control program - MaximDL - which is expensive and designed for astro-imaging, but does control dSLR cameras too.

Attachment:

AutoImage.vbs.txt

I wrote the script for capturing fisheye all sky images, and it seems to work quite well when I tested it at sunset into darkness.

seabreeze3 · **Posted:** Sat Feb 26, 2011 9:35 pm

Gina wrote:

The first low-lux camera I ordered has arrived - direct from China! This has the 1/3inch SONY Exview HAD CCD which I think was the one someone modified for long exposure.

Hi Gina,

I don't have any experience with dinodirect. Have you done much business with them? I was looking at the various cameras available and some look rather interesting for a great price. They have a waterproof dome which is intriguing. I've got a PTZ indoor wireless IP cam which, if I could weatherproof it, would serve multiple purposes, including night sky.

Gina · **Posted:** Sat Feb 26, 2011 10:28 pm

This is the first time I've used DinoDirect so this camera is my first experience. If you use courier delivery or add insurance to standard delivery they give you a tracking number so you can see how far your package has got. Delivery seems reasonable so far, considering the goods come from China.

Just been trying the camera. It's not quite what I thought. It's colour/mono depending on the light level. The sensitivity seems about that of the non-night adapted human eye - the picture shows random noise rather than going dark. That might be because it's a CCTV camera rather than a webcam. The angle of view seems to be 90 degrees or a bit more, as supplied. Resolution appears good on my 15" monitor.

So far I've only got it connected with a short lead so testing has been limited. The video lead is terminated with a BNC socket/female whereas my other CCTV cameras have plugs/male connectors, so the video connection is a bit of a bodge as I lack the right connector/adaptor. I was hoping to get it outside to see what it made of night-time. I'll see if I can sort things out tomorrow. I may also try it on our HD TV rather than the old 4:3 standard res TV I use as a CCTV monitor.

Gina · **Posted:** Sun Feb 27, 2011 7:04 pm

I've now set up the camera looking out of the lounge window pointing south and covering the same view as my weather webcam (MS Lifecam Cinema). Well about the same horizontal coverage but a lot more vertical (this CCTV camera has a 4:3 image sensor - the Lifecam is 16:9). The CCTV camera shows quite distinct fish-eye distortion of the image. It's also definitely more sensitive. When the Lifecam had gone dark the CCTV camera was still showing daylight. Now the Lifecam is showing about 3 distant street lights whereas the CCTV camera is showing many more streetlights and some lights in houses in a village just over a mile away. I think it would show a lot more if the video frames were to be integrated. There's a hint of more detail but difficult to see for the noise. I'm dying to see how much better the Super HAD sensor will be with 10x the sensitivity of this one (allegedly).

Gina · **Posted:** Sun Feb 27, 2011 8:50 pm

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 · **Posted:** Mon Feb 28, 2011 12:05 am

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 · **Posted:** Mon Feb 28, 2011 2:31 pm

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 · **Posted:** Fri Mar 11, 2011 10:45 pm

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 · **Posted:** Fri Mar 11, 2011 11:04 pm

Gina wrote:

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.

Quote:

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 · **Posted:** Sat Mar 12, 2011 9:25 am

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 · **Posted:** Sat Mar 12, 2011 10:30 am

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 · **Posted:** Sat Mar 12, 2011 10:53 am

mcrossley wrote:

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 · **Posted:** Sat Mar 12, 2011 9:41 pm

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 · **Posted:** Mon Mar 14, 2011 7:39 pm

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 :lol:

) These images have been reduced to 640x400 for posting here.

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Night sky images?

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