OneOfOne
28-09-2006, 07:04 AM
Hi guys,
As we all know, the skies lately have been less than impressive and so I have not had very many chances to try out my new XW's and Powermate. Anyway, I have now had a chance to try them several times and it has raised a question about the Powermate.
I have tried it on a number of occasions with the 7, 10 and 14 XW. The fields without it are clear, stars are sharp, sky is...well....about what you can expect in the 'burbs where you can read the printing on the eyepiece at 10pm without a torch. If I focus either side of centre, the stars turn to disks, nice and clear as expected. I put the Powermate in, and for want of a better word, the image "falls apart". I find it virtually impossible to get a sharp focus, the image goes from almost there with a little more movement in, to almost in focus with a little more movement out! In some cases, bright stars have the normal pair of spikes without it, put it in, and some of them scatter light everywhere. I cannot get a "clear" out of focus image of a bright star at all, the image is just bad. If I use the 2x Celestron Barlow from my eyepiece kit, I see the four spikes, a bit of chromatic aberation (not a high quality barlow) but the out of focus image is a nice clear circle, similar to when it is not there.
The other night I tried Jupiter. Without the Powermate, I could see the belts clearly in the 7 and 10. Put in the Powermate and I just can't focus it. I put in my old 2x Barlow, and the image was better.
Then I turned to the Moon, couple of days old. Nice sharp image. In the Powermate it is as if someone has been eating burgers and put their greasy fingers over the lenses, just slightly out of focus.
I have been checking the optics of the scope too to see if this is a possible cause, but that is another thread. But the fact that I can get quite clear stars, the diffraction rings are "almost" concentric (see other thread, but I haven't done that one yet!) seems to indicate that I should get a similar result with the Powermate in.
Am I missing something? The guff on the TeleView site implies that the Powermate should be suitable for any eyepiece and better than a Barlow.
As we all know, the skies lately have been less than impressive and so I have not had very many chances to try out my new XW's and Powermate. Anyway, I have now had a chance to try them several times and it has raised a question about the Powermate.
I have tried it on a number of occasions with the 7, 10 and 14 XW. The fields without it are clear, stars are sharp, sky is...well....about what you can expect in the 'burbs where you can read the printing on the eyepiece at 10pm without a torch. If I focus either side of centre, the stars turn to disks, nice and clear as expected. I put the Powermate in, and for want of a better word, the image "falls apart". I find it virtually impossible to get a sharp focus, the image goes from almost there with a little more movement in, to almost in focus with a little more movement out! In some cases, bright stars have the normal pair of spikes without it, put it in, and some of them scatter light everywhere. I cannot get a "clear" out of focus image of a bright star at all, the image is just bad. If I use the 2x Celestron Barlow from my eyepiece kit, I see the four spikes, a bit of chromatic aberation (not a high quality barlow) but the out of focus image is a nice clear circle, similar to when it is not there.
The other night I tried Jupiter. Without the Powermate, I could see the belts clearly in the 7 and 10. Put in the Powermate and I just can't focus it. I put in my old 2x Barlow, and the image was better.
Then I turned to the Moon, couple of days old. Nice sharp image. In the Powermate it is as if someone has been eating burgers and put their greasy fingers over the lenses, just slightly out of focus.
I have been checking the optics of the scope too to see if this is a possible cause, but that is another thread. But the fact that I can get quite clear stars, the diffraction rings are "almost" concentric (see other thread, but I haven't done that one yet!) seems to indicate that I should get a similar result with the Powermate in.
Am I missing something? The guff on the TeleView site implies that the Powermate should be suitable for any eyepiece and better than a Barlow.