Judy-A
Posts: 525
Location: Edmonton, Canada
Registered: 20 Jan 2010
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Samyang 8mm wide aperture tests
Posted: 2 Oct 2011 at 23:52 GMT
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In my quest to get some useable images for low-light panoramas, I did some focus tests today with my Samyang 8mm lens at wider apertures. I was not pleased with the results.
All images were shot from the same position. The 100% crops are from about halfway between the center and corner of the images. They show the deteriorating sharpness with apertures at f/5.6 and f/3.5.
I tested with various focus distances. This is the best focus I could achieve at each aperture.
For star photography, the wide aperture results are unacceptable.
For my Nikon D5000 (DX format) I’ve been looking at specs for these two lenses:
Nikon AF 10.5mm f/2.8 G IF-ED DX
Tokina AF 11-16mm f/2.8 Pro DX
Any opinions and advice welcome.
Judy
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John Willetts
Posts: 259
Location: Bath, United Kingdom
Registered: 13 Mar 2008
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Re: Samyang 8mm wide aperture tests
Posted: 3 Oct 2011 at 17:27 GMT
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Hi Judy,
1/. Fixed focal length lenses are sharper than zoom lenses.
2/. Ask the manufacturers what the optimum aperture is.
3/. European glass is sharpest. Try a second hand Zeiss (you get what you pay for).
4/. I see you've published RAW images. Try a knat's whiskeners of pre-sharpening -it makes life a lot easier in PT Gui.
5/. Concentrate on the centre of the image. Double or treble the numbers of pics you take and work on the layers.
John
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Judy-A
Posts: 525
Location: Edmonton, Canada
Registered: 20 Jan 2010
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Re: Samyang 8mm wide aperture tests
Posted: 4 Oct 2011 at 6:01 GMT
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Thanks for the tips, John.
I did some more tests today with the Samyang 8mm lens. There’s good sharpness over the whole image at f/8 and f/11 which I use for shooting daytime landscapes.
The characteristics of the blur at f/3.5 look like astigmatism as described here.
www.cambridgeincolour.com/tutorials/lens-quality-...
I’d prefer not to crop images because I’d like to be able to shoot aurora borealis which moves quickly and changes constantly. For that I need the whole image.
Judy
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DennisS
Posts: 1292
Location: Los Anglels, United States
Registered: 1 Sep 2007
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Re: Samyang 8mm wide aperture tests
Posted: 4 Oct 2011 at 6:31 GMT
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Judy,
Maybe what you need is one of those very expensive f2.8 or lower prime lenses. I hear that they are very good wide open. Since I have no experience with them, I cannot say for sure.
Dennis
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No One
Posts: 501
Location: Sri Lanka
Registered: 14 May 2004
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Re: Samyang 8mm wide aperture tests
Posted: 4 Oct 2011 at 6:50 GMT
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Hi Judy,
gut response is:
Nikon AF 10.5mm f/2.8 G IF-ED DX
Still the go to lens in my bag after using the Samyang "8", Sigma 8mm 3.5, Tokina 10-17mm, and others. This is on a DX format, Canon or Nikon. It's on par with a Canon 5D2 with a Canon 15mm 2.8, perhaps even a bit better - it's a close call.
But, given your, and mine, budgets at this point I would upgrade your camera, not lens. The Samyang is a good lens. Just not wide open. At around F7 s/b pretty good. Below or beyond that, not so much.
But a Nikon D7000 is a whole lot better ISO pushed up 4 or more stops than a D5000 or for that matter much else.
So, if you have the budget, get both. Your stars (and cowgirls by the fire -  will never look better.
Cheers,
Robert
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hindenhaag
Posts: 729
Location: Netherlands
Registered: 7 Mar 2010
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Re: Samyang 8mm wide aperture tests
Posted: 4 Oct 2011 at 7:17 GMT
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Hi Judy,
My choice comes down from 10.5, Samyang 8mm, Sigma 8mm f3.5.
To get an overview about lenses you could look for Zeiss, Leica, Leitz and Voigtlaender. Near the quality of Leica but much cheaper.
cameraquest.com/index.htm to get an overview and US dealer for "rare lenses"
Cheers,
Heinz
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jannefoo
Posts: 59
Location: Finland
Registered: 3 Jun 2009
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Re: Samyang 8mm wide aperture tests
Posted: 4 Oct 2011 at 16:53 GMT
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Judy Mentioned Tokina 11-16mm f2.8. I have one of those and I just shot series of images at different apertures.
Here's the lower left corner (well not the extreme corner since there was nothing there worth seeing, but close):
100% crop from the center, I can't tell the images apart sharpness-wise:
Here's the corner again, now remapped to same angular resolution as the image center as is the case with spherical panoramas:
Chromatic aberration (RawTherapee's automagic correction) and vignetting (with flat field image) were both corrected and exposure was equalized between images (there's slight tendency for overexposure wide open, about one third of a stop). Of course this lens is no fisheye, so lot images are needed if spherical panorama is the goal of shooting, but in low light the IQ is peerless.
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Judy-A
Posts: 525
Location: Edmonton, Canada
Registered: 20 Jan 2010
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Re: Samyang 8mm wide aperture tests
Posted: 4 Oct 2011 at 20:38 GMT
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jannefoo said: Judy Mentioned Tokina 11-16mm f2.8. I have one of those and I just shot series of images at different apertures.
Thanks for doing this Janne.
I had done my tests with a higher contrast subject matter to try to simulate bright stars against a night sky.
These were taken at an aperture of f/3.5. Look at the light bleeding into the branches of the trees. It comes from the bottom in the upper part of images and from the top in the lower parts of the images.
Capture NX2 has several CA correction and sharpening options, but none that worked on this kind of blur.
At f/8 with the same lens there is no bleeding and no discernable difference among the corresponding image crops.
Judy
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Judy-A
Posts: 525
Location: Edmonton, Canada
Registered: 20 Jan 2010
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Re: Samyang 8mm wide aperture tests
Posted: 4 Oct 2011 at 20:43 GMT
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Robert Harshman said: But, given your, and mine, budgets at this point I would upgrade your camera, not lens. The Samyang is a good lens. Just not wide open. At around F7 s/b pretty good. Below or beyond that, not so much.
But a Nikon D7000 is a whole lot better ISO pushed up 4 or more stops than a D5000 or for that matter much else.
Robert Harshman, this is all your fault! Your suggestion to shoot some starry sky panoramas got me going on this pursuit. I hold you responsible for all the time I’ve laboured in vain over blurry starry images.
You’re off the hook, though. Your suggestion to look at putting my money towards a better camera is a very good one. The aim is lower noise, which can be had with a better sensor.
Having a second Nikon DX camera would solve another problem I have.
When we were in Jasper Park this summer we saw a mother bear and her two cubs feeding by the road. So cute! My camera was lying on the back seat with fisheye lens, NN3 and tripod all hooked up and ready to go for the next panorama. Telephoto lens was somewhere out of reach in the camera bag.
We enjoyed looking at the bears and moved on.
A while later we saw a beautiful bull elk. Still not ready with a camera! After that I disassembled my pano rig, put on the telephoto lens and held the camera in my lap, ready for action.
We didn’t see another animal all day.
Judy
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DennisS
Posts: 1292
Location: Los Anglels, United States
Registered: 1 Sep 2007
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Re: Samyang 8mm wide aperture tests
Posted: 4 Oct 2011 at 21:08 GMT
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Telephoto lens was somewhere out of reach in the camera bag This is why I let my wife take the stills while I take the panoramas. I would not want to be swapping out lenses out on the dirty trail. A second camera is definately in order here. Early Merry Christmas, Judy.
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John Willetts
Posts: 259
Location: Bath, United Kingdom
Registered: 13 Mar 2008
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Re: Samyang 8mm wide aperture tests
Posted: 5 Oct 2011 at 11:43 GMT
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Judy, I've got no sympathy at all. I took a look at your website. You have awesome locations on your patch, while we have to make the most of pocket-sized countryside and grey skies for most of the year. And you're still complaining about not shooting (photographically) bears - all I get is aggressive cows.
Seriously, get a second hand NEX3 (unless you need full HDTV) which you can keep in your pocket. I always make a Photobook whenever we go on holiday (vacation) and this camera produces Hassleblad quality A4 prints.
John
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Judy-A
Posts: 525
Location: Edmonton, Canada
Registered: 20 Jan 2010
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Re: Samyang 8mm wide aperture tests
Posted: 6 Oct 2011 at 2:02 GMT
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John Willetts said: And you're still complaining about not shooting (photographically) bears - all I get is aggressive cows.
Don’t you have ferocious hounds on the moors and trolls under bridges?
We don’t have much human history to photograph, but there’s lots of geological history if you like rocks. We also have clear dark skies not too distant from home. We get snow, but last winter we had so much that the roads were near impassible for months. There was no place to safely park and I’d have needed skis or snowshoes to get to a decent pano location. More gear needed!
I’ve been following Smooth’s and Dennis’ adventures with their NEX cameras. Those cameras solve the weight and bulk problems, but wouldn’t be any improvement over my Nikon D5000 for night photography.
I guess it’s time to get my priorities sorted out.
Judy
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DemonDuck
Posts: 312
Location:
Registered: 10 Mar 2011
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Re: Samyang 8mm wide aperture tests
Posted: 6 Oct 2011 at 3:51 GMT
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Judy-A said: but last winter we had so much that the roads were near impassible for months. There was no place to safely park and I’d have needed skis or snowshoes to get to a decent pano location. More gear needed!
I guess it’s time to get my priorities sorted out.
Judy
Snowshoes! A definite must have. Big floaty kind that lets you mush through the new stuff with a pack. Nothing like untracked snow and trees and blue sky .....
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No One
Posts: 501
Location: Sri Lanka
Registered: 14 May 2004
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Re: Samyang 8mm wide aperture tests
Posted: 6 Oct 2011 at 3:52 GMT
updated: 6 Oct 2011 at 4:20 GMT
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I have to moo in at this point , yet again, sorry.
Judy,
Work what you have, no excuses. I like rocks, clear night sky's, even the small spider watching me from the room corner I'm sitting next to has potential with a macro lens and proper lighting.
Make history on those rocks. Add yourself or others as appropriate. You are part of history, tomorrow.
And it does not really matter if you use a NEX or Nikon or ... whatever.
Make the shot with what you have, in general better equipment will only make a very small improvement on what you can already do if you know what you're doing.
Work on skills until you've exceeded your equipment and vision.
Robert
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