Capturing Images
Tom's first try with the Nikon 995 and the 8''Dobsonian
Michael's Saturn trail: a beautiful 'gone wrong' shot with the Nikon 995 digital camera; multiple images and a snaking trail showing the disk of the rings and the gap between them and the planet. If Hockney had painted it, it would be worth a fortune!
Toucam Pro at prime focus of an ETX 105
Toucam Pro at the prime focus of an ETX 70
A composite of Jupiter and three of its moons taken at prime focus of an ETX 105 with the Toucam Pro
One of April's star trail photos taken with a Nikon FG20 using Kodak Royal 400
DIGITAL
Cameras
Our original proposal for the project had a digital camera for each telescope. In the end we only bought one. This was a mistake. The camera we did get was a Nikon Coolpix 995. This camera has been used by many amateur astronomers. However it is very complicated and the interface is not intuitive. It's a great camera for an individual who uses it continually but too difficult for students who only get to use it now and then. That said it can produce fantastic results when you get it right. Tom was the first to have success with some great Moon shots. Moon and Sun pictures can be handled by some automatic digitals but you really need one with manual settings. Casio have a much more friendly interface. However we have found that the QV3500 does not have a fixed infinity on its focus. Consequently it can be difficult to focus. For bright objects, the cameras can be hand-held to the eyepiece. We have an adapter to mate the camera to the eyepiece. Once we get into imaging dim, deep sky objects, we'll need it.
Students have a habit of not taking enough shots. The vagaries of seeing, focus, shaking, exposure, etc etc mean that you should fiddle with everything and take lots of shots. Unlike film, it doesn't cost anything to take multiple shots.
Features you need are:
Manual focus and exposure
Variable ISO (sensitivity)
Exposure to 1 minute or bulb (with a hand controller)
Here is a guide that you may find helpful:
The Getting Started Guide to Digital Camera Astrophotography by Gregory Pruden http://velatron.com/dca/Articles/GettingStarted.pdf
The club has a Nikon Coolpix 995. This camera has been used by many amateur astronomers. However it is very complicated and the controls are a bit difficult. That said it can produce fantastic results when you get it right. Tom was the first to have success with some great Moon shots. Moon and Sun pictures can be handled by some automatic digitals but you really need one with manual settings. For bright objects, the cameras can be hand-held to the eyepiece. We have an adapter to mate the camera to the eyepiece and a remote control that allows you to use exposures of up to a minute..
Students have a habit of not taking enough shots. The problems of seeing, focus, shaking, exposure, etc etc mean that you should fiddle with everything and take lots of shots. Unlike film, it doesn't cost anything to take multiple shots.
Web cams
We have recently purchased two Phillips Toucam Pro webcams. Members who have home access to laptops can use these with the telescopes. They can be used with their lens pointing down the eyepiece or, with their lens removed, without the eyepiece. They can also be used without their lens at the rear port of an ETX. The last position allows you to switch between eyepiece and camera using the flip mirror but. Although the image will not both be in focus at the same settings. Be careful at higher elevations as there is not enough clearance for the webcam between the base and the OTA. In both cases we have found the best coupling is composed of a small strip of Sellotape and an elastic band. Feel free to design and make something better.
The CCD chip on the webcam is very small, so it takes a bit of fiddling to get the image on the chip. As usual start on the Moon to give you a big target. Of course trying to operate a laptop, with connecting cables could be courting disaster. If your parents have a Workmate use that to put the laptop on. It's very stable and you can even design and make a special work station to clamp in its jaws.
The webcam can give you exposures of up to 1/25 second and there are lots of adjustments to play with Initial test of the webcams are very promising. Take care with the media setting you choose. TIFF files are very big (3Mb+). JPEGs are much smaller. You can even use the webcams to record a video stream and then stack the images in Astrostack or Registax
There are ways to add electronics to the webcam that will allow longer exposures so that you can capture faint deepsky objects an star fields. We will be having a go at this.
Below is a table showing the effect of resolution settings of a Toucam pro. Still shots of the Moon will probably be best a still shots taken at 640 x 480. Video at that resolution is compressed to stream it over the USB. For video of planets, where the image will tend to only cover the central part of the CCD, use 352 x 288 and 5 frames per second to stop compression of the signal. Binning pools the signal from adjacent pixels and can be used for image
| Resolution | Enhancement | Area of CCD |
| 640 x 480 | none | whole |
| 352 x 288 | none | central |
| 320 x 240 | 2 x 2 binned | whole |
| 240 x 176 | 2 x 2 binned | central |
| 176 x 144 | 2 x 2 binned | central |
| 160 x 120 | 3 x 3 binned | whole |
FILM
Cameras
This is an area where fancy new equipment is the last thing you want. With the long exposures needed, they soon run down their expensive batteries. Instead you want a second-hand manual SLR (single lens reflex) camera. If you want to buy your own there are several local second-hand camera shops. To check that a camera is suitable for long exposure astrophotography batteries out and check it still works, particularly on the bulb setting. A 50mm lens will capture a constellation as big as Orion whilst a 30mm will capture a much bigger chunk of sky. You also need a cable release and a sturdy tripod. With a bit of bartering you may be able to get the lot for less that £50!
For details on how to use a film camera to record star streaks click this button
We have been using a second-hand Nikon FG20. It's a relatively expensive camera (£100 for the body alone) but it is very light which makes it ideal for piggybacking on a telescope. Partnered with its sturdy tripod, it has been used to record star streaks. April was the first student to have success. We have also bought two piggyback camera adapters for the ETX 90s so that you can can polar align and track the stars with the camera. We plan to purchase other cameras, probably another FG20 and a Pentax 1000K.