Just wondering whether maginifaction through a barlow is an accepted method for astrophotography with a dslr? If so, I'd image quality of barlow lens would be very important?
What sort of scope and mount would you be using Heath? Prime focus is the usually preferred technique whereby the DSLR is mounted without a lens such that focus is reached on the DSLR sensor. "Magnification" depends on your scope's focal length.
Its usually preferable to avoid barlows while you're starting out, as the extra length creates a greater moment arm for movement/flexure, more difficult balance, and the longer focal length makes guiding a LOT harder. All this applies a lot less if you're talking a webcam for planetary work - then you really need the extra focal length for resolution and short exposures mean movement in focal train less an issue.
Im using an F7 set up - 105 refractor and canon dslr. I was thinking of increased magnification to capture deep space objects with some more detail.
Thanks Heath
Quote:
Originally Posted by RobF
What sort of scope and mount would you be using Heath? Prime focus is the usually preferred technique whereby the DSLR is mounted without a lens such that focus is reached on the DSLR sensor. "Magnification" depends on your scope's focal length.
Its usually preferable to avoid barlows while you're starting out, as the extra length creates a greater moment arm for movement/flexure, more difficult balance, and the longer focal length makes guiding a LOT harder. All this applies a lot less if you're talking a webcam for planetary work - then you really need the extra focal length for resolution and short exposures mean movement in focal train less an issue.
There's no harm giving it a go, but often you'll find a 200% crop gives as much detail as the barlow because of reasons I mentioned. Depends on quality of gear, mount, fittings etc too of course. I'm sure a Paramount ME wouldn't care if your camera stuck out a few extra inches....
The problem with most Barlows is Chromatic aberration would need to image RGB which cant be done on DSLR easily.
Mine is a 5 element barlow design to reduce CA, I still experience some when capturing planets.
Your scope is middle range, you get some good closer shots without the use of a barlow. Maybe try without first then consider maybe a Powermate instead of a barlow.
