Using a webcam on telescope...a beginner's doubt!

[Alberto]

Hi, I am still new in all this and just recently upgraded from a refractor 700mm.60mm to a Skywatcher 130M and decided to buy a webcam from ebay really cheap (7.99) and it is perfectly shaped (cylindrical) to go into the eyepiece and comes with zoom 10x function too, I am pleased so far. I just tried to put it over the eyepiece before making any modifications and on my screen I can see just exactly what the eyepiece is showing, with crispy and clear image so it makes me hesitating if I should take the lenses of the webcam out or not, as now I can get all images using any eyepiece and then all magnifications I have available. My doubt is: if I take the lenses out and leave only the sensor and put it into the focuser (without any eyepiece as suggested by most people in videos and blogs I've seen) I fear that I will be limited to one magnification only (if any) as I will not be using any eyepiece and I don't think the cam sensor only will have the ability to get many images close and far from the objects only using the focuser then ( it will be the only control available), getting the all results as using many eyepieces??? Can someone confirm me this? Will I be able to see the moon at 90x and 180x ,225x and more like I am doing now with eyepieces on and webcam not altered? Also, there's anybody near Southport/Liverpool to meet sometimes whether for sky watching or just exchange of ideas in person, because I just moved into here and apparently nobody is into sky or telescopes? Thanks

[JamesF]

Magnification doesn't really have meaning when you're talking about prime focus (ie no eyepiece) imaging. It's more useful to consider how much of the sky is covered by one pixel or some unit of measurement of the camera sensor because camera sensor sizes and pixel sizes vary.

If you need a larger image then you can add a barlow in front of the camera. A 2x barlow will double the image size on the sensor, a 3x barlow triples it and so on. Adding spacers after the barlow can also be used to increase the image size. The downside is that by doing so you decrease the amount of light per pixel falling on the sensor and have to increase the camera gain and/.or exposure times to compensate.

James

[Alberto]

Thanks, James you made me aware of something that I was not taking in consideration too...but I had the idea that i could take a picture of just what I would be looking at each different magnification i.e: the moon at 200x , and 90x etc, and confused how to achieve that if most seem to not use the eyepieces along with the cam...maybe some experimenting with barlows and cam sensor only will take place soon, when the clouds are gone, hopefully

[JamesF]

It's quite common for people to take images through an eyepiece ("afocal imaging"), though some are better suited than others. There have been images posted on SGL taken that way using webcams, DSLRs, compact cameras and even phone cameras. Most of the usual suppliers sell at least one clamp to allow a camera to be held in place behind the eyepiece, though some eyepieces and barlows actually come fitted with a T thread for fitting a camera. In some respects however you can never take a picture of "what you see" because cameras and eyes don't work the same way and this becomes particularly noticeable at low light levels.

I'd say that prime focus imaging is more flexible and probably a better solution for planetary imaging where you'd want to take thousands of frames to process for an image and I'd always encourage someone to give it a try. I'm not sure it's possible to do so non-destructively when you have a camera with a zoom lens, but if you wanted to keep that one in one piece there's always the Xbox camera which is cheap and easy to modify for prime focus use.

James

[Alberto]

yea...i must agree. as i see there are always some options to try and the xbox's cam , it's another one...that's what makes all this interesting...the multiplicity of ideas and choice. thanks