Quote:
Originally Posted by OzEclipse
You'll need to have a pretty good worm drive to do unguided exposures with a 200mm lens.
6.4 micron pixels @200mm is 6 arc sec/pixel
What drive do you have on your home made mount? You can get away with much bigger drive errors with shorter lenses.
Joe
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I have roller drives on my mount so no PE.
Quote:
Originally Posted by gregbradley
Here's an example from the Nikon 180 F2.8 ED at F4:
http://www.pbase.com/gregbradley/image/152449036/large
Round stars to the corner of a FLI Proline 16803. Very few lenses can do that. There is a tad amount of tilt here as the adapter needs to be unscrewed a little bit from the filter wheel otherwise it catches the filters and stops them from turning. But its minor.
I did notice minor chromatic aberration in some other images I used it for but again its minor compared to most lenses. It often goes for less than US$450 from places like keh.com.
There are a few versions of the lens. The crinkled paint finish version goes for more. I have had both and they both are very good and I think the differences are more cosmetic and to do with autofocus which is not needed.
Plus it has an aperture ring which not all lenses these days have which is also sometimes a pain.
On Canon APSc with 1.6 crop factor that is 288mm. On a Fuji it is 270mm (Fuji APSc is 1.5 crop).
Even with Polarie you would be limited to a couple of minutes tops without a proper mount or autoguiding. I don't think Polarie will handle that long a focal length for several minutes.
Greg. |
you've sure convinced me Greg
I'm gonna get one
I did some maths and worked out that with the 350d FOV is 7.072 by 4.71 degrees, 7.37 arcsec/px.
It looks like it will suit my needs very well, so thanks everyone for your comments
and I hope to be able to show you some results once I get my camera going.
Cheers
Jo