I’m trying to get a bit into astro and my first target would be the moon. I have a Celestron adapter and a T-ring for the DSLR (Nikon D7500).
To avoid the frustration of trying out things in the dark, I decided to practice in daylight. So I picked a target half a mile away, made sure that I can focus on it visually through an eyepiece. Then I removed the visual back, attached the adapter and the camera body to the adapter. The c8 is 2032 mm f/10. I shot manually and by trial and error I got the exposure right. However, it was very hard, and in practice impossible, to get a good focus. I used Live View and zoomed in. I’m not talking about reaching focus, I can defocus in either direction, but I don’t seem to be able to get a pin sharp image. I took a comparable image with a Nikon p900 and the latter was much sharper, even though I took it hand held. I can get decent images of the moon with the p900, but I was expecting to get much better results with a DSLR and the C8. Now it seems that I can’t even get a sharp image of a terrestrial subject.
I don’t think thermal equilibrium is the problem, the C8 had stayed at the same temperature for more than six hours. I also don’t think this is an issue with atmospheric seeing, as in this case the distance was rather short and in any case the P900 should encounter the same conditions. And I don’t think it’s vibration, the Evolution mount is quite good and I used exposure delay of 10 sec. The collimation is OK. I get sharp images when using the scope visually.
Am I expecting too much? Is the C8 not really sharp? Will I always get better images with a P900 (with a really small sensor) than with a DSLR through the telescope?