CCD vs Film? Lots of time vs no patience? Alright, this is your place to discuss all the astrophotography what's and what's not. You can discuss about techniques, accessories, cameras, whatever....just make sure you also post some nice photos here too!
Skies were clear last night so decided to do a test using my new DSLR to see how well it performs.
Lens: Canon 100-400mm @ 400mm, f/5.6
Exposure: 1 sec x 22 (1 sec to combat the light pollution)
ISO: 12,800
Files were captured as RAW, converted to JPEG, combined with MaxIm DL 4 and resized down. No other noise control performed.
Apologies for the large image size, but I wanted to show the stellar distortions, and color:
[80% Steve, 20% Alfred] ------- Probability of Clear Skies = (Age of newest equipment in days) / [(Number of observers) * (Total Aperture of all telescopes present in mm)]
Gary wrote:Amazing. Which part of the sky/constellation is this?
It's at Sagittarius.
[80% Steve, 20% Alfred] ------- Probability of Clear Skies = (Age of newest equipment in days) / [(Number of observers) * (Total Aperture of all telescopes present in mm)]
croys wrote:This fits with my (limited) experience of some of the longer Canon lenses, though I've not tried any zooms. Coma on axis as well as off, which doesn't get any better with stopping the lens down. A starfield is a pretty extreme test for any lens, never mind a zoom. It looks there's some misalignment as the coma gets worse to the right, but there is little sagittal coma/astigmatism, common for zooms, which is quite impressive.
The 400/5.6L is supposed to be good and I've seen lots of nice photos taken with this. The 500 and 600 L lenses are also supposed to be good. They should be!
Which f/l did you shoot at?
Hi Stuart,
As stated in the first post, it is shot at 400mm. Yes, the coma on axis is a bit surprising - perhaps not considering the low price of the 100-400mm lens. Maybe I'll rent a 500mm or 800mm for testing - the birders love them!
[80% Steve, 20% Alfred] ------- Probability of Clear Skies = (Age of newest equipment in days) / [(Number of observers) * (Total Aperture of all telescopes present in mm)]
There's a Pentax SDUF 100mm f/3.9 on A-Mart right now for $2.4K..
How does that fit into this scheme of things?
This guy Samir Kharusi did some fairly exhaustive tests of the TV140 and Canon 600/4.. and for a 17-element lens, the Canon does quite well against the Televue, only losing on high-mag planetary.
Actually the A-mart scope is an SDUF II. That's pretty fast at f/3.9! I haven't seen a faster refractor actually..
One of my buddies from back home just used his 100-400/4.5-5.6L + Sky Memo to image the ongoing McNaught apparition. His image is too small (and exposure too short, due to weather) to really see what the L lens can do..
