Focal reducer

[g30rg313]

I've been thinking of getting a focal reducer x0.5 will this in effect do the opposite of a X2 Barlow?  My thinking is that since I can't seem to get a 40mm ep then I could perhaps use a focal reducer with a 25mm ep to get similar effect?

[gnomus]

That is correct, but I don't undertand why you cannot find a 40mm eyepiece.  I have two - one by Celestron and one by Meade - or are you not looking for Plossls?

Edited April 7, 2016 by gnomus

[ecuador]

What are you trying to accomplish exactly? If you want to fit a bigger field of view in your eyepiece, then no, an x0.5 reducer (or a 40mm 1.25" eyepiece) will not give you that: the 40mm will have the same true field as a 32mm, while the x0.5 reducer with the 25mm ep will give you pretty much the same field but smaller, so it is a bit like looking through a tunnel. However, the 40mm eyepiece is useful for eyepiece projection photography and the x0.5 reducer for imaging with small sensors - in that case you can say it works like the opposite of a 2x barlow.

[g30rg313]

Eventually I'm getting a Web cam to do planetary imaging and dso imaging so the focal reducer might come on handy then thank you 

[Louis D]

The cheap 0.5X focal reducers aren't exactly flat field.  They tend to introduce quite a bit of field curvature and other aberrations in the outer field.  Stick with buying a dedicated focal reducer/field flattener for photography.

[cloudsweeper]

Yes, focal reducers introduce distortion when used with larger focal length EPs, so your desired effect would probably not turn out very well.