Well, the clouds moved in after about 30 minutes, but I did get a chance to do some more star testing on the 127ED.
I used Altair because it was in a good area of the sky and the air was pretty steady in that part.
I tried to use a 4mm (285x) but the conditions were not good enough to give me crisp rings. So I ended up using a 5mm (228x) TMB/BO EP and did quite a few runs in and out of focus looking for any changes in the rings.
First thing that I noticed was that the blue separated early on the inside of focus. This was obvious with 2-3 rings but disappeared with 4 rings. Outside of focus did not show this color separation.
The next thing that I noticed was that the rings were basically identical on both sides of focus. There was no sign of any aberration, turned edge, correction or spherical. I am pretty amazed that the scope tests this well. The diffraction rings are as nice as I see with my Zambuto mirrors, minus the central obstruction.
I also found that Altair a .8 mag star showed no color around it when in focus. Nothing like a halo or ring could be seen. Vega, a 0 mag star, did show a slight amount of blue or purple, but no halo or ring, just a slight hazy of color around it. This seemed to almost disappear when focus was perfect.
I also found that when I switched to the Radian EP, the diffraction rings were more sharp and easier to read, which was an interesting find. The difference was fairly large, with much better definition. I did not have a Plossl or Ortho of 5mm to try so these were the only EP used.
Then the clouds moved in and covered all my sky
so I put the scope away again.
I can not wait to get it out on a good night with clear and dark skies. But the forecast for the weekend is not good. :S
I used Altair because it was in a good area of the sky and the air was pretty steady in that part.
I tried to use a 4mm (285x) but the conditions were not good enough to give me crisp rings. So I ended up using a 5mm (228x) TMB/BO EP and did quite a few runs in and out of focus looking for any changes in the rings.
First thing that I noticed was that the blue separated early on the inside of focus. This was obvious with 2-3 rings but disappeared with 4 rings. Outside of focus did not show this color separation.
The next thing that I noticed was that the rings were basically identical on both sides of focus. There was no sign of any aberration, turned edge, correction or spherical. I am pretty amazed that the scope tests this well. The diffraction rings are as nice as I see with my Zambuto mirrors, minus the central obstruction.
I also found that Altair a .8 mag star showed no color around it when in focus. Nothing like a halo or ring could be seen. Vega, a 0 mag star, did show a slight amount of blue or purple, but no halo or ring, just a slight hazy of color around it. This seemed to almost disappear when focus was perfect.
I also found that when I switched to the Radian EP, the diffraction rings were more sharp and easier to read, which was an interesting find. The difference was fairly large, with much better definition. I did not have a Plossl or Ortho of 5mm to try so these were the only EP used.
Then the clouds moved in and covered all my sky
so I put the scope away again.I can not wait to get it out on a good night with clear and dark skies. But the forecast for the weekend is not good. :S
[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue
Amateur Imager
