--- Brent Watson <brentjwatson@yahoo.com> wrote:
Chuck,
I have used the Naglers on my 8" doublet refractor (f13.3). I have also used the orhtos. I have never compared the two. I'll do that.
Your 10" is more sensitive to collimation errors. The quarter wave circle for your 10" is only 1/8 inch in diameter, while your 6" quarter wave circle is .358". This means that the six inch has a quarter wave field of almost 26 minutes of arc. The 10" quarter wave field is only 7.5 minutes of arc. This is probably a part of what you are seeing. The 10" has to be aligned much better to see the smaller sweet spot.
I'm aware of that, and also the perils of mis-collimation. I think that diagonal obstruction is more of a culprit in this case- the 10" uses a 2.6" (originally set-up for massive "IN" travel when built, to accomodate various cameras), while the 6" uses only a 1" diagonal. The 6" is also baffled more effectively. C. __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com