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Stuck between webcam and afocal!


virtualpilot45
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I'm a newbie on quite a tight budget, around the £30 mark, and I've decided I want to spend it on some kind of imaging equipment. I think I've narrowed it down to a couple of 'gadgets'.

(My telescope is a Skywatcher Explorer 150P with a 25mm and 10mm EP and a 2x Barlow)

1. Phillips SPC880 webcam (flashed to SPC900)

Advantages: Good magnification, up to 250x with my 2x Barlow, easily controllable with my laptop, good results on planets

Disadvantages: Deep sky out of the question, may have limited use once I've photographed all the planets/moon.

2. Universal Digital Camera Adaptor

Advantages: My compact camera can do up to 60s exposures and I've previously taken decent planetary pictures with it just against the lens, held with a camera tripod.

Disadvantages: Can only get to 150x magnification when I have my 2x Barlow and 10mm EP in. So far the deep sky stuff hasn't looked that great, with M42 looking like a purple star. Also, I don't have a motor drive.

Here's some stuff I've taken afocally so far:

5440219670_b833e71eca.jpg

5401025612_b8764756a2_m.jpg

Venus

5395875931_af16abffb9.jpg

Jupiter

5397137525_8cc5b4038b.jpg

Saturn

:) Any advice on what I should buy?

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I started out with afocal a few years ago, however, it was always a fiddle, and I reached the limit very quickly. Just got a SPC900NC, and have only had a quick play so far, but it already looks more practical that afocal. (also have a modded webcam for LX, but I need to sort out my alignment for that!).

Cheers

Alun

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  • 2 weeks later...

Hi Virtual, those pics are great and something i would like to do, im pondering what scope to get and the 150p is on the top of my list.

Are they the sizes of the objects from viewing or only from the cameras?

And would you mind explaining how you got the shots, im looking for a good scope but wouldnt mind having a dable with getting some pics like you have done, i too am on a shoe string budget! (sort of)

Thanks

Jay

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Yep, the size is virtually the same, the moon is clearer visually, and the planets are generally brighter. The picture of the moon was with the lowest powered magnification, as I couldn't fit the entire disc in with the higher ones. Only saw the end of Jupiter's opposition, as it started to get further and closer to the sunset, so I hope I'll get some better pictures next time. I haven't really bought anything since getting the telescope (apart from a moon filter bought with it, definitely necessary).

For the shots I used my compact camera on my camera tripod, I think good tripods ones can be bought for ~£15. My camera was aligned to the eyepiece, this is called afocal and means the camera sees what you would see. You can change the EV or ISO setting on your camera to make the image brighter or darker. With Saturn it's necessary to turn the brightness up a little, while with Venus it's a matter of cutting out as much light as possible, it's too darn bright!

I'm probably going to buy the webcam tonight, which will apparently give more magnification, which should be useful, but the afocal I will continue to use for easy deep sky (Pleiades etc).

A disadvantage to the tripod-camera-eyepiece-telescope method is the fiddling around necessary when the object moves out of view. If you were using the telescope visually, you'd just turn the RA knob until it came back into view, and automatically align your eye to see it. However, with afocal you need to realign the tripod to face the eyepiece, and this can get annoying, especially at high magnification when you can spend up to 30s realigning and then find the object's gone again!

Anyway, the telescope's great and my only wishes would be

*I lived in an area with no cloud whatsoever at any time

*I had better eyesight (for comfort I take mine off when I look at the eyepiece)

*There was no light pollution

*I had a limitless amount of money :)

Anyway, afocal is good fun and you really have to learn it for yourself with your equipment. If your camera has a manual mode, use it and fiddle around with different sensitivities, shutter speeds and f-stops until you find your preffered one. Or alternatively, take a movie of your object and put it through Registax. Oh, and set focus to ∞, unless your camera has a setting for 250,000 miles (I would be very impressed!).

Hope I helped!

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Thank you for your reply, i think im sold on the 150p, was going for the 150pl, but dont think the wife will be happy with the size of it!

I just want to do stuff like you are doing, visual only to begin with then looking into taking some pics without spending loads of cash, as i have a young family etc..

Im very impressed at the images you have taken and explaining how you have done it, keep us updated with the webcam you are getting and the results.

Thanks again

Jay

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No, I haven't got it but, there is one on FLO's site. If you've got an SLR/DSLR it's probably worth getting it to do prime focus (attaching telescope directly to SLR without eyepiece, it still magnifies though!) and long exposures for galaxies and nebulae.

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Yep, the Orion Nebula (shapes visible), the Andromeda Galaxy and quite a few open star clusters (pleiades, m41, beehive etc). I got this of the Orion Nebula:

5480441960_47e25fbc3c_m.jpg

Note that you will only see white/greenish light from M42 with your eye, a camera can pick up more colours. Star clusters are great, but again, they're better with the eye than the lens.

If you want to get lots of good deep sky images, I hear DSLRs are a very good (and expensive!) option, but being cash limited, I have stuck to varying my afocal techniques.

One thing I forgot to mention before - you might have to re-adjust the focus when you put the lens to the eyepiece, for reasons I have not been able to fathom!

Anyway, for the DSOs I generally take 10 or 20 pictures, depending on the magnitude of the object, and put them together on GIMP. I align all the layers manually, then set the layer transparency to lighten. In this way, the virtual exposure time is increased. So if I have 15 3s exposures it's roughly the same as a single 45s exposure. Remember that stars trail at least 30x quicker with the lowest magnification on the scope, so anything much longer than 3s will cause noticeable trails. When you've added all the exposures, you can go to the Colour - Levels toolbox where you can remove The Dreaded Noise and Light Pollution, simply click on the pen tool to the right of Auto and click on a seemingly blank area of sky, and that hue is removed from the image. If you need help just post here, I'm happy to help, just remember I'm still on the learning curve myself!

Edited by virtualpilot45
wrong picture!
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Casio Exilim EX-Z850 Digital Camera: Amazon.co.uk: Electronics

Great camera, my dad bought it for Christmas and completely coincidently got the compact camera with the best exposure range I've ever heard of in my limited experience of compacts - 1/6000s to 60s! Wouldn't swap it for anything, even though it's getting on a bit now!

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I align all the layers manually, then set the layer transparency to lighten. In this way, the virtual exposure time is increased.
Although this works after a fashion, it is not the best way of combining in Gimp, as it will always pick up hot pixels etc etc and put them in the final images. The better way is to use 'normal' combine mode and alter the transparency of each layer in the ratio 1/(1+n). So 100%, 50%, 33%, 25%, 20%, 16.66% etc etc. Mathematically this is an average combine.

NigelM

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Afocal imaging is not as bad as some people make out. There is no reason why a modern point&shoot digital camera cannot do DSOs nearly as well as a DSLR. It is some times not appreciated that they have to have very low read noise in order to work well as daytime cameras (I have seen measurements suggesting some models have lower read noise than DSLRs).

The main disadvantage is that you have extra glass in the way from the eyepiece and camera lens, so lose some light. You also tend to have rather weird astrometric distortions, which can make combining data from different nights rather tricky.

On the plus side, you can, within reason, chose any pixel scale you like, by changing the eyepiece or zooming the camera.

NigelM

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Although this works after a fashion, it is not the best way of combining in Gimp, as it will always pick up hot pixels etc etc and put them in the final images. The better way is to use 'normal' combine mode and alter the transparency of each layer in the ratio 1/(1+n). So 100%, 50%, 33%, 25%, 20%, 16.66% etc etc. Mathematically this is an average combine.

NigelM

Thanks, I'll try my M42 image again with this!

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