Barlow in Optical Train.

[astro mick]

Hi.

I image with a 80mm f7.5 refractor,which is fine for nebulae,star clusters and such,but the image size of Galaxies is very small.I was wondering if i could introduce a Barlow before the filter wheel,in order to increase magnification.

Would this work,or is there a better way.

Regards.

mick.

[jgs001]

Mick, you can, but that introduces more problems. As you double the focal ratio, you then require 4x the exposure to capture the same amount of light, which puts more pressure on the mount and guiding, along with working at double the focal length. If you're guiding is up to it, then give it a try... I face a similar issue with an identical spec scope and my SLR... I did use a 2x TC on a glob and it can work.

[Shibby]

Sure, as John says, if your guiding is good enough for double length exposures there's no reason why not. I used to image with a barlow and Alt-Az mount!! Bad example, the results were poor but it was possible

[astro mick]

Thanks guys.

I think it needs a bit more thought,the relationship between Focal Length and guiding,is obviously an important issue,and my set up may not be able to handle it.

Best regards.

Mick.

[jgs001]

What have you got it mounted on Mick ? I have done 20 minutes guided with a 2x in place, I don't normally it was a test. Thats mounted my c80ed and konus (st80) on my heq5.