Post by jimcurry on Dec 25, 2013 8:29:50 GMT -5
I've been using my Istar 6" f/12 for a couple of years now. I have a thread on the build in the ATM section. I was out recently observing a rising waxing moon at sunset and had the most incredible viewing I've ever had of planetary objects. The atmosphere had been predicted to be quiet here over the Midwest so I was set up and ready to go as the sun dropped below the horizon. Training my scope on the moon at around 72x it was fully framed in my Zeiss 25mm orthoscopic. The image was rock steady so I began rotating the TEC turret to amp up the magnification. 16mm, 12mm, 10mm (now at 180X) and the image held steady, just plain not moving. This was getting exciting so I rotated once more bringing my 8mm into play. I'm at 225x and the image held perfectly. Viewing more detail than ever before I cruised the terminator region seeing rille and dome detail like I was turning the page of an atlas.
After a an hour and a half of this I realized I still had a suite of shorter orthos to bring into play. Pulling the longer ep's out of the turret I exchanged them for 7mm, 6mm, and 5mm. At 7mm, 257x, there was a slight quivering to the image. I rotated to the 6. Now I'm at 300x. I've never been here before. The image is noticeably dimmer than the sub 200x views but finer details are still being revealed. Clicking over to a 5mm Pentax XO I'm at 360x. The view is dimmer yet but that 60x jump in magnification allowed me to start crawling down the sides of the rilles and looking between central crater peaks. After 15-20 minutes of this the atmosphere started to come back to life and I was soon down to 225x to maintain a great view. I covered the scope and went in the house to warm up for a couple of hours while Jupiter rose high enough in the eastern sky to clear the trees.
By 11pm when I went back out the seeing would not support anything above 150x, really my 16mm at 112x was about the limit for a sharp view. 5-6 bands were seen on Jove but no finer details. I retired that night very satisfied with my earlier views of the moon.
Did I say I was mesmerized? I read about folks with laminar flow conditions where these magnifications are common but I'm not fortunate enough to live in that environment. I was delighted that the image did not break down in this Istar lens. It's pretty cool to run out of atmosphere before I run out of scope...
Jim
After a an hour and a half of this I realized I still had a suite of shorter orthos to bring into play. Pulling the longer ep's out of the turret I exchanged them for 7mm, 6mm, and 5mm. At 7mm, 257x, there was a slight quivering to the image. I rotated to the 6. Now I'm at 300x. I've never been here before. The image is noticeably dimmer than the sub 200x views but finer details are still being revealed. Clicking over to a 5mm Pentax XO I'm at 360x. The view is dimmer yet but that 60x jump in magnification allowed me to start crawling down the sides of the rilles and looking between central crater peaks. After 15-20 minutes of this the atmosphere started to come back to life and I was soon down to 225x to maintain a great view. I covered the scope and went in the house to warm up for a couple of hours while Jupiter rose high enough in the eastern sky to clear the trees.
By 11pm when I went back out the seeing would not support anything above 150x, really my 16mm at 112x was about the limit for a sharp view. 5-6 bands were seen on Jove but no finer details. I retired that night very satisfied with my earlier views of the moon.
Did I say I was mesmerized? I read about folks with laminar flow conditions where these magnifications are common but I'm not fortunate enough to live in that environment. I was delighted that the image did not break down in this Istar lens. It's pretty cool to run out of atmosphere before I run out of scope...
Jim
Memorable nights like that reinvigorate the passion.