17mm Aperture stop on "22mm" CA Celestron BV's
Posted 27 November 2012 - 10:22 PM
What's up with that?
Posted 28 November 2012 - 12:24 PM
It's nice to have extra aperture at the front end, of course, as this increases the size of the circle of full illumination at the focus. However, this is not as important as suppressing internal reflections, which I suspect that 17mm stop is there for.
In the end, as long as you get full illumination on axis you're doing well. Off-axis fall-off due to the front end stop will almost certainly NOT be detectable, and if reflections are indeed supressed or lessened, so much the better.
Unless you're trying to fit the BV to a faster scope (e.g., f/5), fear not!
Posted 29 November 2012 - 12:59 PM
I was hoping someone would say "Oh, we take that out."
Instead, you have the message that things won't be that bad.
I'm quite disappointed with Celestron. I have no doubt that if Celestron spent the money to put it there, it was needed.
The last thing I need using a binoviewer on a small scope is further reduction of light throughput.
I'm returning them.