Webcam query

[DAusten]

Hi,

I am new to astronomy and have been spending time getting used to my new scope, a Skywatcher Explorer 130P.

I would like to start getting into photography (particularly deep sky) and am looking for a bit of advice about the kind of kit I need to get.

At this point I would like to buy a webcam, so, any particular brands to buy? Also, do I need to buy any attachments to fit it to the scope?

Many thanks,

David

[Naz]

I don't think a webcam is any good for deepsky targets, preforms pretty well on the planets and the Moon. Maybe you should think about a Dslr such as one of the Canons. I have also heard that you may have trouble obtaining focus with Explorer.

One of the imaging gurus will be along in a while and be able to give you better advice.

[Merlin66]

david,

A webcam, unless it has been modified, is really no good for deep sky objects.

It will work very well on the moon and planets.

Look out for either a Philips ToUcam or a SPC900nc model.

Any webcam which has a removable lens would do as an alternative; you'll also need a 1.25" nosepiece which replaces the lens and allows you to fit it to your telescope.

To do DSO you either need a DSLR or a dedicated CCD camera.

[DAusten]

Hi Guys,

Thanks for the reply and clearing up the deep sky stuff. I think for the moment I will start with a webcam. I think I will get the Philips SPC900NC as I have seen this handy link explaining how to attach it to the scope.

Just two questions.

1. Re the adapter, where can I get a good one and is there a specific type I should ask for?

2. If this fits directly into the eye-peice tube, then do you not get to use eye-pieces? So how do you get the magnification?

Thanks,

David

[Merlin66]

The nosepiece adaptor is pretty standard.

Adaptors

(near the bottm of the page)

No eyepieces involved.

The "magnification" comes from the focal length of your main mirror.

If you need more "magnification" the you can use a barlow lens to extend the focal length.

[DAusten]

Thanks for your help so far Merlin. Now for the REALLY stupid question.

If a telescopes magnification is calculated from its focal length divided by eyepiece focal length (my scope is 650mm), then how do you calculate the magnification if you are not using an eyepiece.

650 / 0?

[Merlin66]

When imaging the "magnification" is really the plate scale of the image. This is expressed in so many minutes of arc (or seconds) per pixel. The mathemetics are pretty straight forward, think of a long triangle where the longest side is the effective focal length and the shortest the size of the CCD chip in the camera. The apex angle is the angular size of the image projected onto the CCD. So the longer the focal length the smaller the angle, but it's still spread over the same sized chip, this gives more "magnification" ie more seconds arc/ pixel.

Hope this helps.