Wednesday, May 26, 2010

Low budget Astrophotography

Astrophotography may sound to be a huge step for beginners and is only reserved to professionals who spend years and years in this hobby and with quite expensive gadgets. As a matter of fact it needs good experience, but you will educate yourself with trial and error time after time, but to be honest, it's very tricky and maybe impossible to have results like the powerful high-end imaging devices, especially when imaging deep sky objects, but with cheaper equipment you can create decent images if you know how to tweak'em to the limits, now we will see how it's done.
Point and shoot Camera Astrophotography
Your simple compact cam can be quite useful; in fact it does very well in many cases, but first you need to check for some attributes that might be essential in astrophotography, but you can find it in most models.

1. Shutter speed, obviously because you need to gather more light in the single shot, SRL cameras have “bulb” shutter which you can set the shutter as long as you want, but you can't find this in compact non-SRL models. You need a minimum of 15 seconds for bright objects like Orion nebula for example, and longer for dimmer targets. The operation requires more than one shot, then stack them together with any stacking program, we will later talk about stacking and how it’s done.

You can find the shutter speed in the camera specs chart or on the manufacturer’s website, the higher the better of course, and there are some non-slr models which has longer shutter speed like the “Panasonic Lumix DMC-FZ35” that can open it’s shutter for 60 seconds, with a good tracking mount and some stacking and image processing work, you can end up with a satisfying results. There is also the Lumix DMC-ZS7, and the Lumix DMC-FS25 (both are (60 seconds also and has ccd chip).

2. Support movies, with minimum 30fps capturing. There is a small trick you will greatly appreciate for moon and planets imaging, that you can shoot a movie for about 3 minutes, and then you can “decompile” the movie file with a video edit tool, and it will split every frame in this movie in a single image files (for ex: 30fps x 3 minutes=5400 images), then you can stack the images and have wonderful results you will be amazed of. Here is a result of this process captured by "Tim Jensen"(source), stacked from 1200 frames, as you can see, quite impressive result.

3. Aperture control, you will need to have a wide aperture here to collect as much light as you can. Doing it manually will be better but any camera will set it automatically due to the dark frame.

4. ISO limit, any higher number is good, but in most models, the higher the ISO sensitivity the higher the “noise” will be in the shot, so you can figure out your camera limit by trying many settings and see the best highest ISO number and use it.

5. Image stabilizer also is a good feature because you can hardly stabilize you telescope without the effects of wind and accidental shock vibrations that might makes it harder in stacking process.

Now after you’ve got the camera or checking your current for these features, all you need is a “Camera mount” to attach any camera to your telescope eyepiece, find you desired target, set your cam parameters and take the shot, but remember that when you take a single image you will need to steady your hand to prevent the vibration, remote or “flexible” shutter bottom will be needed, but here you can set the self timer for a couple of seconds to eliminate any vibrations and let the scope become steady before the shot.

There are also people use some webcams like Philip's "Toucam", i didn't try it my own because i didn't find this model here in Egypt, but it seems that it bring good results for the price, if you don't mind hanging out with your laptop to use it.

Another tip to consider is you can always use large FL eyepieces (lesser magnification) and then zoom in with your camera’s optical zoom, this will give you more control for the target, or if you haven’t much magnification with your small FL eyepiece, you can use it with the camera zoom to multiply your telescope power, for example your telescope’s magnification with a certain 6mm eyepiece is 100X and you need more power but you don’t have a smaller FL eyepiece, then you can zoom in with your camera to about 3X and the result will be 300X, I know it’s not a professional way to do it, but if you need more power and you don’t have the tool, then why not. Imagine the power of your telescope when combined with a 18X camera like the FZ35, or COOLPIX P100 from Nikon(26X), or even the new Fujifilm HS10 which got a huge 30X zoom, that’s quite a fancy, but again, in curtain circumstances, why not ;-)…

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