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Help!-1Day Old 14mm Samyang
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PostPosted: Fri Aug 16, 2013 7:33 pm    Post subject: Help!-1Day Old 14mm Samyang Reply with quote
hi folks

i bought samyang 14mm prime. Brand new manual lens. I saw great reviews and also on lens review this prime has very solid reputation

but i thought this lens will produce sharp images, maybe i am wrong, please no offense, i went outside and try few shots with my k01. I used m28mm prime pentax old lens, and also this samyang.

f22, tripod, same spot and time. Focus checked with live view.

Here you can see full images directly from camera. In camera settings for sharpness: +1\

is this ok? i mean i though images will be much sharper Sad please i need advice, this is common output or should i return it?

pentax m28mm



samyang 14mm



100%crop pentax



100%crop samyang



samyang left part | pentax right part



thx!


PostPosted: Fri Aug 16, 2013 7:41 pm    Post subject: Reply with quote
edited

Last edited by bernhardas on Thu Apr 28, 2016 1:48 pm; edited 1 time in total


PostPosted: Fri Aug 16, 2013 7:46 pm    Post subject: Reply with quote
I agree with Bernhard, f22 you will have some diffraction for sure. Try f8 and check focus carefully, I strongly suspect your Samyang focuses slightly past infinity and that is the cause of your problem. Many lenses go slightly past infinity so it's not faulty.


PostPosted: Fri Aug 16, 2013 7:46 pm    Post subject: Reply with quote
bernhardas wrote:
At 22 the lens might not be at its sharpest. Also diffraction kicks in. But that should affect both lenses .

I would try at 5.6 and 8.
Also try nearer focus not infinity.
The weather like haze dust or hot air raising from the ground might affect the picture at long distances (air perspective).


thank you! i will do retest with f8. I tried focusing not to infinity, nearer also but best output was with infinity focus for this hills. I will try again

but can you say from this images if this performance is ok for this lens? at f22 for now


PostPosted: Fri Aug 16, 2013 7:47 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
I agree with Bernhard, f22 you will have some diffraction for sure. Try f8 and check focus carefully, I strongly suspect your Samyang focuses slightly past infinity and that is the cause of your problem. Many lenses go slightly past infinity so it's not faulty.


will try it again, but i double checked live view for correct focus, i tried near infinity, not maximum, but this was best i can achieve Sad


PostPosted: Fri Aug 16, 2013 7:51 pm    Post subject: Reply with quote
f22 on APS-C is definitely giving you diffraction. Show us again at f8 and we can give you a better opinion. Smile

If it's not much better, then you have a faulty one and should get it replaced.


PostPosted: Fri Aug 16, 2013 8:18 pm    Post subject: Reply with quote
the samyang is very sharp, mine was going past infinity, I had to use the 3m mark for infinity
if you cannot get any better even with liveview you probably need to adjust infinity
check 2nd page for the method http://forum.mflenses.com/first-walk-with-samyang-142-8-on-5dii-t50565.html


PostPosted: Fri Aug 16, 2013 8:31 pm    Post subject: Reply with quote
thanks people, i will do some tests tomorrow again (11pm here right now) and will post here results, hopefully images will be sharper.


PostPosted: Fri Aug 16, 2013 8:35 pm    Post subject: Reply with quote
Good luck! Smile


PostPosted: Fri Aug 16, 2013 8:55 pm    Post subject: Reply with quote
I have this lens and can confirm it does go over infinity by a bit, I think my infinity is like 10m and F8 is the sweet spot on the Samyang


PostPosted: Fri Aug 16, 2013 9:08 pm    Post subject: Reply with quote
eddieitman wrote:
I have this lens and can confirm it does go over infinity by a bit, I think my infinity is like 10m and F8 is the sweet spot on the Samyang


hopefully i could be able to find this sweet spot too Smile will try again


PostPosted: Fri Aug 16, 2013 10:07 pm    Post subject: Reply with quote
Check your infinity focus with the lens wide open, then stop down.

Here's an article about diffraction, with a calculator to help you determine the point at which stopping down will start reducing sharpness for your body.
http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm


PostPosted: Fri Aug 16, 2013 10:49 pm    Post subject: Reply with quote
fuzzywuzzy wrote:
Check your infinity focus with the lens wide open, then stop down.

Here's an article about diffraction, with a calculator to help you determine the point at which stopping down will start reducing sharpness for your body.
http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm


Reduction in sharpness due to diffraction depends upon the lens f-number and the wavelength of light. It doesn't depend upon the camera body.


PostPosted: Fri Aug 16, 2013 11:10 pm    Post subject: Reply with quote
sichko wrote:
fuzzywuzzy wrote:
Check your infinity focus with the lens wide open, then stop down.

Here's an article about diffraction, with a calculator to help you determine the point at which stopping down will start reducing sharpness for your body.
http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm


Reduction in sharpness due to diffraction depends upon the lens f-number and the wavelength of light. It doesn't depend upon the camera body.


How many megapixels is a factor, crop factor is a factor, smaller pixels = more sensitive to diffraction.


PostPosted: Sat Aug 17, 2013 4:55 pm    Post subject: Reply with quote
fuzzywuzzy wrote:
sichko wrote:
fuzzywuzzy wrote:
Check your infinity focus with the lens wide open, then stop down.

Here's an article about diffraction, with a calculator to help you determine the point at which stopping down will start reducing sharpness for your body.
http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm


Reduction in sharpness due to diffraction depends upon the lens f-number and the wavelength of light. It doesn't depend upon the camera body.


How many megapixels is a factor, crop factor is a factor, smaller pixels = more sensitive to diffraction.


Really ? Then what about this statement ...

Diffraction thus sets a fundamental resolution limit that is independent of the number of megapixels, or the size of the film format. It depends only on the f-number of your lens, and on the wavelength of light being imaged.

These words match my understanding but they are taken directly from the first page of the Cambridge in Colour link you provided. Then McHugh (the CiC owner) goes on to talk about diffraction limited cameras. I haven't a clue what he's talking about. It looks like nonsense to me. Can you - or anyone - help ?


PostPosted: Sat Aug 17, 2013 5:02 pm    Post subject: Reply with quote
sichko wrote:
fuzzywuzzy wrote:
sichko wrote:
fuzzywuzzy wrote:
Check your infinity focus with the lens wide open, then stop down.

Here's an article about diffraction, with a calculator to help you determine the point at which stopping down will start reducing sharpness for your body.
http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm


Reduction in sharpness due to diffraction depends upon the lens f-number and the wavelength of light. It doesn't depend upon the camera body.


How many megapixels is a factor, crop factor is a factor, smaller pixels = more sensitive to diffraction.


Really ? Then what about this statement ...

Diffraction thus sets a fundamental resolution limit that is independent of the number of megapixels, or the size of the film format. It depends only on the f-number of your lens, and on the wavelength of light being imaged.

These words match my understanding but they are taken directly from the first page of the Cambridge in Colour link you provided. Then McHugh (the CiC owner) goes on to talk about diffraction limited cameras. I haven't a clue what he's talking about. It looks like nonsense to me. Can you - or anyone - help ?



I'm not an expert, but what I understood reading that is that diffraction happens according to f number, but this loss of resolution is perceived according to the pixel pitch.


PostPosted: Sat Aug 17, 2013 8:10 pm    Post subject: Reply with quote
diffraction is more noticeable on small formats or higher pixel pitch sensors.


PostPosted: Sat Aug 17, 2013 8:16 pm    Post subject: Reply with quote
Instead of quoting facts and figures, I think it better to rely on practical experience. On an APS-C sensor with a pixel pitch of around 6 then diffraction is not noticeable until f11, and even then, you have to pixel peep and look closely to see it. Always beware the advice of people who don't post pictures.


PostPosted: Sat Aug 17, 2013 8:22 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
Instead of quoting facts and figures, I think it better to rely on practical experience. On an APS-C sensor with a pixel pitch of around 6 then diffraction is not noticeable until f11, and even then, you have to pixel peep and look closely to see it. Always beware the advice of people who don't post pictures.


I've had 3 16 mp apsc cams so far and all of them showes no perceivable signs of loss of resolution at f11.
Something could be noticed at f16, and at f22 usually is quite evident.

That said, and back to the original topic, the lack of sharpness in the pictures posted seem a bit too much, but it's impossible to state anything without more samples at other apertures.


PostPosted: Sat Aug 17, 2013 8:37 pm    Post subject: Reply with quote
I would agree, you see it at f16, at f11, it's hard to see and not always visible.

I made some shots with an I-61 yesterday at F16, I don't see any lack of sharpness at all, I can see very slight diffraction but my usual sharpening completely overcomes it, making it fair to say that shooting at f16 on a 14mp APS-C sensor like the one in my NEX-3 is perfectly possible.

I agree, the lack of sharpness in this Samyang looks far beyond what diffraction would cause.


PostPosted: Sat Aug 17, 2013 11:20 pm    Post subject: Reply with quote
Romans,

I find my Bower version of this lens acceptably sharp. I used Poilu's instructions (brilliant presentation by the way!) to re-set infinity, but I find I usually focus via live view anyway. Here are a few shots with 100% crops from 5D raw files for you. Don't want to hijack your post, but thought you might want a few comparisons. These were taken this evening.

Best,

Paul

Set one:





Set two:





PostPosted: Sun Aug 18, 2013 1:12 am    Post subject: Reply with quote
Wow, that first shot's a stunner Paul!


PostPosted: Sun Aug 18, 2013 1:50 am    Post subject: Reply with quote
Thanks, Ian. I can't take credit for the beauty of Cargil Falls, but the Bower can deliver-even on full frame! The Samyang/Bower images look remarkably similar to those produced by the medium format 30mm Arsat lenses from Arsenal in Russia. I have an almost identical image I made with the Arsat in P6 mount adapted to Pentax 645.

Paul


PostPosted: Sun Aug 18, 2013 3:57 am    Post subject: Reply with quote
I have the Arsat too, you just reminded me I must develop the roll I shot with it!


PostPosted: Sun Aug 18, 2013 8:42 am    Post subject: Reply with quote
yesterday i tested lens again, i think with better results, i used f around 5.6 and live view sharpening. But still, when i am sharpening with liev view i cant see change in sharpness for distant details whenever i used infinity mark or even close but i think its just ok for wide lens.

i will post images today, will see. looking forward to hear your comments. i think i will keep this lens. I though i will change it for some 10-20 sigma or similar but i was happy yesterday with results.
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