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Archive 2013 · 20mm 2.8 astrophotography?
  
 
lighthawk
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p.1 #1 · p.1 #1 · 20mm 2.8 astrophotography?


I've been getting into night time photos and want something wide and fast.
I've looked at the Samyang 14mm, and it is reported to be sharp, but it's MF, which I think could be limiting.

The deciding point for me was star trails at 30s exposures using 24-105 on my 6D.


I can push ISO much more with this body, but fast glass is really what does the trick. I have an old 35mm f2 (lil buzzy), that is great, but not wide enough. My other choice is a Sigma 12-24 which only gets to 4.5 aperture. The Canon 14 is out of my budget

Do other users here have the Canon 20mm, and what's their experience? Is it wide enough for Milky Way photos, landscapes, etc? Do you find it is a useful FL for street, indoor shots, etc?
Feedback appreciated.



Aug 02, 2013 at 05:46 PM
cameron12x
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p.1 #2 · p.1 #2 · 20mm 2.8 astrophotography?


Have you considered the very fast and sharp 20mm f/1.8 from Sigma?


Aug 02, 2013 at 05:51 PM
dgdg
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p.1 #3 · p.1 #3 · 20mm 2.8 astrophotography?


I would first review all lenses in your price range at lenstip.com.
Some have bad coma wide open, and some even if you stop it down.
I find for night landscapes the MF lenses are just fine. The samyang is very sharp and fast.



Aug 02, 2013 at 10:28 PM
lighthawk
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p.1 #4 · p.1 #4 · 20mm 2.8 astrophotography?


Thanks for the input. I sort of jumped the gun on a Canon 20 on Ebay today. I'm in at a price I can give it a test and keep it or move on to the Samyang or Sigma options.

Thanks dgdg, I'll check out lenstip in any case.




Aug 03, 2013 at 04:12 AM
dgdg
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p.1 #5 · p.1 #5 · 20mm 2.8 astrophotography?


I had a moment to look at your new lens on lenstip.com
Looks like you'll be ok wide open depending on how much you demand of the lens. Stopped down to f4 (ie with tracker) it will clean up the center quite nicely with some minor issues on the edges/corners that probably won't matter.

Except for the short star trails, pretty cool shot. You could always stack more and just do a photo with trails.....



Aug 03, 2013 at 05:31 PM
lighthawk
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p.1 #6 · p.1 #6 · 20mm 2.8 astrophotography?


The Canon 20 will show up on the 6th, just in time for me to take it with me for our annual trip to Desolation Wilderness. I'll be shooting star tracks (for stacking), as well as shorter exposures with minimal tails. There's a new moon, so it should be pretty dark. Persied meteor shower (up to 60/hr) will also be happening. Should be a good trip for a wide & fast lens.


Aug 03, 2013 at 07:36 PM
niktnowy
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p.1 #7 · p.1 #7 · 20mm 2.8 astrophotography?


What type of Star Tracker do you use with 6D?



Aug 04, 2013 at 01:17 PM
dgdg
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p.1 #8 · p.1 #8 · 20mm 2.8 astrophotography?


Well, they are not camera/lens specific.
Popular ones include vixen polarie, ioptron skytracker, and astrotrac. They all have their pros/cons. A large astrotrac thread in the landscape forum touches on all three of these.

good luck on the meteor shower. Here we are seeing a lot of thunderstorms and rain. Hard to find a clear day. I have a spot picked out myself for the shower this weekend. If things look good, I'm grabbing my tent



Aug 04, 2013 at 02:11 PM
lighthawk
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p.1 #9 · p.1 #9 · 20mm 2.8 astrophotography?


Good luck with the Tstorms. Maybe you'll get lucky and catch some lightning shots.

niktnowy: I am using a fixed mount, without tracking.



Aug 04, 2013 at 09:25 PM
StarNut
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p.1 #10 · p.1 #10 · 20mm 2.8 astrophotography?


You have to manually focus to get critical focus of the sky at night, so I see no disadvantage to a MF lens.


Aug 05, 2013 at 05:13 AM
 

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niktnowy
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p.1 #11 · p.1 #11 · 20mm 2.8 astrophotography?


lighthawk wrote:
Good luck with the Tstorms. Maybe you'll get lucky and catch some lightning shots.

niktnowy: I am using a fixed mount, without tracking.


Sorry for bothering again but would you point me in direction where I could learn more about achieving that wonderful effect without star tracker.

Thank You again
Nik



Aug 05, 2013 at 07:30 PM
coppertop
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p.1 #12 · p.1 #12 · 20mm 2.8 astrophotography?


Question... between the 20mm and 24-105mm was it an issue between the one stop, 4mm in width or both?


Aug 07, 2013 at 12:12 AM
nburwell
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p.1 #13 · p.1 #13 · 20mm 2.8 astrophotography?


StarNut wrote:
You have to manually focus to get critical focus of the sky at night, so I see no disadvantage to a MF lens.


StarNut is right. When it comes to astrophotography, I always manually focus my lens using live view. I have the Rokinon 14mm, and I see no drawback to it being a fully manual lens. Then again, I never use AF to be quite honest.

Best of luck with the 20mm though!

-Nick



Aug 07, 2013 at 03:05 PM
molson
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p.1 #14 · p.1 #14 · 20mm 2.8 astrophotography?


From what I remember from owning the EF 20mm f2.8, it has pretty substantial field curvature, so you'll need to stop down to f8 or so to get the edges of the frame sharp... assuming you want or need sharpness outside the middle of the frame for your astrophotography.


Aug 07, 2013 at 04:12 PM
dgdg
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p.1 #15 · p.1 #15 · 20mm 2.8 astrophotography?


nburwell wrote:
I have the Rokinon 14mm, and I see no drawback to it being a fully manual lens. Then again, I never use AF to be quite honest.

-Nick


I certainly agree. Sometimes if the moon is out, I will 'cheat', focusing on it with AF, then flip the manual focus switch. Depending how long you are out, you will probably want to confirm you are still in focus from time to time. So if the moon has set or you don't want to change composition - live view manual focus.



Aug 07, 2013 at 06:52 PM
AbramG
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p.1 #16 · p.1 #16 · 20mm 2.8 astrophotography?


I've been a proponent for the 20mm for the past year or so. I think it's a highly underrated lens and its actually a lot better than it gets credit for. No it's not perfect but it works very well for many topics.

I dd a review of the Sigma 20mm and I wouldn't even touch that lens personally. Perhaps it was an old faulty copy but that lens wasn't as sharp at f/4 as my Canon 20 is wide open. Not only that, the AF motor completely failed in the desert heat.

My sigma 35/85 lenses are far superior to the 20mm.

Give the Canon 20 a shot, it's a very usable lens on full frame



Aug 08, 2013 at 03:51 AM
AbramG
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p.1 #17 · p.1 #17 · 20mm 2.8 astrophotography?


molson wrote:
From what I remember from owning the EF 20mm f2.8, it has pretty substantial field curvature, so you'll need to stop down to f8 or so to get the edges of the frame sharp... assuming you want or need sharpness outside the middle of the frame for your astrophotography.


This is true. The 20 does have a pretty noticeable field curvature but with live view it's easy to mitigate. Focus closer to the edges of the frame and you'll get more of a broad focus.

It's definitely not a "flat-field" lens though.



Aug 08, 2013 at 03:57 AM
lighthawk
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p.1 #18 · p.1 #18 · 20mm 2.8 astrophotography?


coppertop wrote:
Question... between the 20mm and 24-105mm was it an issue between the one stop, 4mm in width or both?


It was both. My main priority was a faster lens, to shorten star trails, and/or iso requirements. The extra width is helpful, but I fear it may not be enough after trying it out last weekend.



Aug 13, 2013 at 06:14 AM
matanuska
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p.1 #19 · p.1 #19 · 20mm 2.8 astrophotography?


I use the Rokinon (Samyang) 14mm f/2.8 and 8mm f/3.5 (on my crop) for astro and Aurora photography. Quite honestly, both produce start images wide open at the edge of the field better than my Canon 24mm f/1.4L, and on par with my Zeiss 21mm f/2.8 Distagon.


Aug 13, 2013 at 06:39 AM
lighthawk
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p.1 #20 · p.1 #20 · 20mm 2.8 astrophotography?


We returned from our trip last weekend and I have a few shots to share using the 6D, 20mm 2.8 combo.

The first is a stack, using StarStax.

Perseid over Loon Lake






The second shot is a result of some research into iridium flares

It was truly amazing to gaze up and spot the satellite with naked eye, when suddenly it flashes like a burnished mirror in the sun for just a few seconds.




Aug 13, 2013 at 06:45 AM
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