Celestron Astromaster 130eq and Astrophotography...

[LilMissNewb]

Hi All,

Well, I've just posted my welcome post, and I'm straight on here asking questions. Cheeky I know

I've already gotten some great advice from other posts in your forums on how to get my telescope set up with a DSLR. I have a Nikon D3000, and was having trouble getting that to focus using the T-ring and T-adapter. I solved that by adding a 2x Barlow Lens to the T-adapter, and had my first success with photography last night:

http://i.imgur.com/PdNb3.jpg

(Could be better - too much shake and not enough collimation I think - my next two projects before the next bout of photography)

So 'yay!' for that. But my next question is, is my current setup going to work well enough for getting pictures of planets etc? Will I get enough 'zoom' using just my camera and the 2x barlow?

If not, is there any way I can fit a lens between the T-adapter and the barlow, or is there another solution that would work with my DSLR? Ok, that's a few questions, not just one!

I think I've kind of dived straight into astronomy/astrophotography with both feet, and got a little bit ahead of myself, and probably should have done a leeeetle bit more research on telescopes first. Hindsight eh?

Cheers

Joanne

[c3po]

Hi Joanne,

Nothing like diving in with both feet and realising the pool wasn't as deep as you thought eh....i too have a Celestron 130EQ and thought it'd be great for AP...That was until i cam on here and did some proper research!

Sadly, through serious research all over the inter-web and discussions with the very helpful guys & girls on SGL here, it seems not. Firstly, the default CG3 supplied by Celestron only has an RA motor and no DEC control other than manual - as such it cannot be guided for long exposure DSO imaging. Also, as it's just an RA motor, we've no GOTO control possibility. Secondly, the CG3 mount really isn't cut out for proper AP work due to the inexpensive gearing employed. Ultimately this throws up issues you've already noticed with the shaking during rotation with the RA motor as the gears don't quite mesh smoothly, coupled with a bit of backlash from the additional weight from the DLSR. Finally, the lack of a polar scope really does put us 130EQ users with the basic mount at a loss, without this essential item, AP is going to be extremely difficult for long exposure work on the DSOs, Nebulae and such.

It seems, from my research at least, that for a half decent AP set-up you should, at least, consider an EQ5 or better mount complete with polar scope - preferably with the added benefit of a guide-cam or GoTo facility.

As for planetary, most DSLRs won't provide the magnification required for what we're after here unless used with multiple stacked Barlows, and every piece of glass between the DSLR and the 'scope means less light being transmitted through to the sensor. This means longer exposures, meaning more possibility for error. So what do we use for planetary imaging then, well - Webcams! If you check out the forums, you'll find plenty of threads about a whole array of webcams and their use for planetary imaging - from cheap and cheerful £1.50 ASDACam to the specialist ATIK cameras way into the £1000's, webcams are the way to go for planetary!

[JamesF]

As c3po says, at the cheaper end webcams are the way to go for planetary imaging. The "daddy" of all the webcams is the SPC900, but they go for silly money these days. It's probably easiest to start with something like the Xbox Live webcam that can be had from ebay for about £5, plus a suitable nosepiece (the one that fits the SPC900 works fine). An IR filter to fit the nosepiece is useful, but you can live without it if necessary. The Xbox camera does need a little modding, but not much and it's not hard to do (and not expensive if you muck it up Then you need a capture programme such as SharpCap to capture a sequence of images as an avi file, and Registax to "stack" all the images in the avi into one higher-quality image.

The webcam can be combined with barlows to increase the size of the image if you find it's too small at first.

The best (and easiest target at the moment is probably Jupiter, which currently rises somewhere around 2am, but is getting earlier as we head towards autumn, so you have plenty of time for practice.

James

[LilMissNewb]

Thank you both for your replies!

That's a lot of very helpful information. I will certainly look into other mounts, though that's on the backburner until funds allow. No bad thing though - means I can have a good look around without getting too impatient.

I didn't know that about the Xbox webcam. I do have one though, so that's a great start! Do you know if there's a good guide for modding the camera, what needs to be done etc? I'll go have a root around the forum now I think while I have some spare time.

2am is a little bit of a late night for me, having to get up for work at 5:30 hehe. But, as you say, waiting for it to rise earlier just gives me more time to get used to the scope and how to use it. Finding somewhere without light pollution that's within reasonable driving distance is tricky too, but I think that's the same for most people isn't it? I was in the Scottish highlands last week with the scope, and it was typically cloudy every night I was there. D'oh!

Thanks again

Joanne

[JamesF]

The 130EQ should be fine to start planetary imaging with. You'll just need to practice tracking objects using the slow-mo controls, but it's not a big deal if the image moves around a bit because stacking can help sort that out. In fact, it might be easiest at first just to get the planet on one side of the camera image and just let it drift across while capturing.

There are lots of guides to modding the Xbox camera here and elsewhere. I've removed the base and fitted a fan to mine, but there's no need to go that far. As a minimum you need to pop the front cover off which is a bit fiddly because the lens catches on a stop in the "nose", and unscrew the lens. Crush or pick off the four green LEDs on the PCB (this is easier than it sounds and just requires a bit of care, but they do illuminate the camera sensor and give your images a green cast if you don't) and cut down the length of the nose. Once it's reassembled the nosepiece should just screw in and allows you to put the camera into the focuser in place of an eyepiece.

Getting the image of a planet on the sensor is tricky. Sometimes you can't find it because it has to be very well centred to get the image on what is a very small image sensor in the camera. If it's heavily out of focus you often can't see it easily even when it is on the sensor. Turning up the brightness and gain in the capture program can help with that. Practice is everything there.

James