web cams,can you use hd cams?

[sam mayo]

i have read all the threads i can find on here about using web cams for imaging planetar and dso(optional) and i was wondering if you can use hd cams thanks

sam

[JamesF]

The fundamental question is really "Can you get enough light on the sensor to create a usable image?" and that's actually not an easy one to answer.

Consider, for example, a camera with 6um pixels that creates a good image using your scope in a given configuration. If you now swap to a camera with 3um pixels with the same sensitivity there are now four pixels covering the area that was previously covered by one. That means to get the same signal as before in all those pixels you need four times as much light, which means four times as long an exposure. But four times as long an exposure might be too slow to get a clear image. You might attempt to resolve that by using a scope with a smaller focal length or larger aperture, but those might not be options.

In addition, if the smallest thing you can resolve with your telescope is 12um wide, is there any value in having 3um pixels instead of 6um pixels at all?

In the end the easiest thing to do is probably to try it and see. Many things can be made to work if you're willing to put the effort in, understand the problems and find out how to resolve them. There isn't really a yes or no answer.

James

[sam mayo]

sorry but i really dont get that im stupid as pig **** with this stuff,i have a ssw 250px and want a cheap and easy web cam to use for basic but gratifying images they will be my first any suggestions

sorry for the simplicity and thanks for the patience

sam

[JamesF]

Ok, did you have any particular camera in mind?

James

[sam mayo]

nope not really just not to expensive,thanks

[RikM]

I wouldn't rush into an expensive purchase since your dob is manual, tracking things is not easy. If you put your 10mm eyepiece in with a 2x barlow and have a look at how quickly objects move across the field, that's about what your typical webcam will see. To get a decent image you need to keep, whatever it is you're imaging in the centre of the field for a minute or so, or say 20-30 seconds at least. I think that would be difficult to achieve with a manual 10" dob.

Are you coming to the CAS meeting next Saturday? I can stick my 250px, Phillips SPC880 and lappy in the car and we can have a play with it if you like.

[sam mayo]

yes i will be,that would be great thanks. didn't realize the magnification problem.what mount have you got your on i have been looking at the new neq6 mounts but got penny's to save and more research to do yet.

do people have an obs session after meeting if weather permits its my first so don't know!

thanks

sam

[RikM]

I normally use it on the Dob mount for looking through and on the NEQ6 for imaging. I don't image with it very often, this is my visual scope really.

Yes, if the weather is clear we'll pop outside for a bit of observing after the tea break. We normally have three of four scope available. Look forward to seeing you there.