Thursday, June 29, 2017

Eclipse prep 2

Yesterday, I deforked the ETX90 OTA. I found an old dovetail and adapted it by drilling a couple of new holes in it (the existing holes were about a tenth of an inch too close together for the ETX--Murphy's Law, I guess). I mounted it on the EQ Pro and took a few images--including that below:

The Sun on June 29, 2017. AR 2664 is visible above and to the left of center
I was surprised by the image scale, compared to the ST-80--although an 80mm f/4 scope will obviously give a much bigger FOV than a 90mm f/13.8 scope. It's nice to have the 90 back in use again (I'll try some lunar and planetary images later), but the choice for eclipse scope is pretty clear: the ST-80 will provide a much better platform to image the corona.