October 25, 2014, 04:49:10 PM

Author Topic: Lens dilemma for night sky  (Read 6891 times)

CreationHeart

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Re: Lens dilemma for night sky
« Reply #30 on: November 26, 2013, 05:00:33 PM »
I recommend a used canon 15mm f2.8 fisheye
1Dx, 5Dmk3, 15mm fisheye, 16-35L, 35L, 85L, 100L, 135L, 70-200L IS II, 500L and accessories.

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Re: Lens dilemma for night sky
« Reply #30 on: November 26, 2013, 05:00:33 PM »

dswtan

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Re: Lens dilemma for night sky
« Reply #31 on: November 27, 2013, 12:34:23 AM »
I'd be willing to spend $4000 on a lens that has excellent stars stopped down to f/2.0 or so, especially if it is 21mm or 24mm focal length.  That would be a dream.  :)
Wade - have you tried the Samyang/Rokinon/Bower options? For a tenth of the cost, you can live the dream today!  8)

I took the same path as extremeinstability and naively wasted shots on the 24L II. I'm sure Zeiss is nice, but why bother when the Korean lenses are so well-suited to astrophotography. This is one of those rare cases of a true bargain!

BTW, this has a good summary of the coma issue, just to add to the resources already in this thread: http://forums.dpreview.com/forums/post/50949062
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Ruined

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Re: Lens dilemma for night sky
« Reply #32 on: November 27, 2013, 12:49:44 AM »
I have read on astronomy blogs that the 24L II is actually quite good when stopped down to f/2.8 with minimal coma at edges.  If you are trying to shoot it wide open at f/1.4 that is why you had a problem.

wearle

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Re: Lens dilemma for night sky
« Reply #33 on: November 27, 2013, 01:18:01 AM »
Wade - have you tried the Samyang/Rokinon/Bower options? For a tenth of the cost, you can live the dream today!  8)

I haven't tried them yet.  I plan on renting the 14mm and 24mm in the future to see how they compare to the Zeiss. Although the Zeiss 15mm is very expensive, the micro-contrast and look are second to none.  :)  If I were rich, I would go with the Zeiss 15mm, but since I'm not, I'll likely get the Samyang/Rokinon/Bower lens.

Wade

TBiRD

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Re: Lens dilemma for night sky
« Reply #34 on: November 27, 2013, 05:50:21 AM »
I'd be willing to spend $4000 on a lens that has excellent stars stopped down to f/2.0 or so, especially if it is 21mm or 24mm focal length.  That would be a dream.  :)
Wade - have you tried the Samyang/Rokinon/Bower options? For a tenth of the cost, you can live the dream today!  8)

I took the same path as extremeinstability and naively wasted shots on the 24L II. I'm sure Zeiss is nice, but why bother when the Korean lenses are so well-suited to astrophotography. This is one of those rare cases of a true bargain!

BTW, this has a good summary of the coma issue, just to add to the resources already in this thread: http://forums.dpreview.com/forums/post/50949062

Yep I got the Samyang 14mm 2.8 and really love it. Got the correction profile for lightroom too.

JustMeOregon

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Re: Lens dilemma for night sky
« Reply #35 on: November 27, 2013, 05:05:29 PM »
I'd be willing to spend $4000 on a lens that has excellent stars stopped down to f/2.0 or so, especially if it is 21mm or 24mm focal length.  That would be a dream.  :)
Wade - have you tried the Samyang/Rokinon/Bower options? For a tenth of the cost, you can live the dream today!  8)

I took the same path as extremeinstability and naively wasted shots on the 24L II. I'm sure Zeiss is nice, but why bother when the Korean lenses are so well-suited to astrophotography. This is one of those rare cases of a true bargain!

BTW, this has a good summary of the coma issue, just to add to the resources already in this thread: http://forums.dpreview.com/forums/post/50949062

Yep I got the Samyang 14mm 2.8 and really love it. Got the correction profile for lightroom too.

@ TBIRD   I've been thinking about the Samyang 14 for a while, but haven't pulled the trigger because of a  lack of a Lightroom lens correction profile... Where did you get your LR correction profile for the Samy-14? Is it Mac or PC (does it matter)?

wearle

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Re: Lens dilemma for night sky
« Reply #36 on: January 02, 2014, 03:56:56 PM »
To all,

I just rented and star tested the Rokinon 14mm T/3.1.  I'm very impressed.  It can be used wide-open on FF with little, if any, aberrations in the corners.  It is a little bit difficult to focus; otherwise, it is a stellar performer in the world of astrophotography.  I immediately purchased it from LensRentals.com.  This way I know I have an excellent copy since I already tested it.  :)

Although the Zeiss 15mm shows better micro-contrast, it is not as well corrected and for 8X the cost, probably not worth it if only used for taking nighttime photos.

Wade

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Re: Lens dilemma for night sky
« Reply #36 on: January 02, 2014, 03:56:56 PM »

scyrene

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Re: Lens dilemma for night sky
« Reply #37 on: January 02, 2014, 04:52:09 PM »
A few things.

First, if you're not viewing at full size or anything close, problems with coma, chromatic aberration, and astigmatism are less important. Resized to average web viewing can cover a lot of sins.

Second, as Nubu said, you can use tracking mounts with reduced speed if you're shooting foreground/horizon too. I've never used the 1/2x speed on my iOptron SkyTracker, but others have with good results (within reason of course, especially at reduced size).

Third, the Samyang/Rokinon f/2.8 is a wonderful lens for daytime and night ultra wide angle work. You can't get front-mounted filters for it, but I was wondering what kind you meant? If astro filters, the slot-in type (for crop sensor) are good (this is why I use it on the 50D). Other wide angle lenses may take rear-mounted gel filters.

One thing not widely discussed is ability to focus. I would use the 24-105 f/4 for astro work, but it is too dark and the magnification too low (even at Live View x10) to get accurate focus on stars at 24mm, so has never worked for me. You can try different manual focus points through trial and error - I found the Samyang's less loose focus ring easier for this. But with a wider aperture lens, the brighter image can help with focus.

Stopping down isn't always worth the effort. I have experimented with the 85 f/1.2 II at various apertures, and I'm not sure the benefits of less vignetting and distortion at narrower apertures exceeds the loss of light. Do look into flat frames, which are master images taken that can be used to cancel out most of the colour and vignetting problems (but not coma etc; NB it can be hard getting flat frames at the shortest focal lengths).

One last thing. It may be cheaper and easier, depending on where you live, and if you drive, to go to darker locations. Most of what I do in astro work is fighting light pollution. If you can go somewhere dark, any camera will take good wide angle astro images. Good luck in any case!

Below: Milky Way from suburbia, Samyang 14mm (70mins stacked + tracked, no darks/flats).
5D mark III, 50D, 300D, EOS-M; Samyang 14mm f/2.8, 24-105L, MP-E, 85L II, 100L macro, 500L IS II, EF-M 18-55; 1.4xIII, 2x III + 2xII extenders; 600EX-RT; EF-M--EF adaptor.
Former lenses include: 70-200L f/4 non-IS, 200L 2.8, 400L 5.6

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Re: Lens dilemma for night sky
« Reply #37 on: January 02, 2014, 04:52:09 PM »