Extension tube?

[northcanadian]

Hello:

Just wondering ...if you place an extension tube between the scope and barlow, will this increase the image scale considerably?

Thank you

[mark7331]

I would have though that the most likely effect is that you wouldn't be able to achieve focus. The barlow itself will increase the image scale by increasing the focal length and thus reducing the field of view. If it's not enough then perhaps a higher power barlow.

To clarify: Image scale is a function of the focal length relative to the pixel size of your CCD. An extension tube won't change that.

Mark

[davew]

I could be wrong but I think you have things back to front.

To increase mag we would put an extension tube after the barlow not before.

Now to put some figures on it from my gear. Barlow = 1.6 x. Put a 40mm extension on and it becomes 2.1 x. Put a further 40mm it becomes 2.6x.

Does that help ?

Dave.

[Whippy]

To clarify: Image scale is a function of the focal length relative to the pixel size of your CCD. An extension tube won't change that.

That's about the size of it. All an extension tube does is extend the length of the focuser. All of my scopes use one to bring my camera to focus.

Tony..