Affiliation
Astronomical Society of South Australia (ASSAU)
Mon, 05/18/2015 - 12:16
Hi all,
I have also recently taken the DSLR course and have been doing some work with my Canon 600D and 50mm f/1.4 lens. This combination only gets me down to about 6th magnitude. To take this further should my next step be a longer lens or a tracking mount?
Michael.
Hi Michael,
I'd recommend both, but if it has to be one I'd suggest a longer fast lens. One of the following would allow reasonably long exposures and fainter targets.
EF 100mm f/2 USM
EF 135mm f/2 L USM
With a tracking mount you could go to longer lenses and longer exposures as well as time series photometry. Cheers,
Mark
Hi Michael, Mark
I'm making good use of my EF 100mm f/2 USM and Canon 1100D; thanks to Mark for the suggestion! I'm still following R Car to minimum, piggy backing on my Meade LX-90 (alt-az!) for tracking. The combination of wide-field imaging and the defocus required for DSLR photometry makes this feasible. I'm still happy to use a tripod for short exposures, but the LX-90 permits longer exposures (I've only gone to 30 seconds with stacking so far, but I'm sure I can go longer) with modest equipment that I already had available. That's a Good Thing given that I don't have much in the way of spare funds.
David
One step at a time for me. The 100mm f/2.0 looks more like my price range. I see there is also a new Samyang 135mm f/2 that is at a good price and seems to get good reviews. Has anyone had their hands on one and tried it?
Michael
Hi Michael,
I just read a review of this lens, looks interesting. Being designed for full frame sensors I expect vignetting on the APS-C sensor in your Canon 600D would be reasonable.
My only concern would be that it is a manual focus lens so no easy option for computer controlled focussing which I find really useful. Third party belt driven focussers are available but expensive. But being a manual lens you might find it has finer focus control than auto-focus lenses used manually. So it may be easier to set the required amount of defocus.
If you do end up buying a Samyang 135mm f/2 lens post a quick review on this forum to let us know how it performs for photometry. Cheers,
Mark