[benny2nd]

Hello from a new member

I'm seeking some advice. Bought a used Samyang 14mm 2.8 mainly for som night sky photography.

To my best abilities I've tried to focus to infinty, and whatever I do I'm not able do better than the attached F2.8 photo. This actual shot is taken with the help of focus peaking in live view, which is about the same result I get if I try to do it fully manually. The camera is on a weighed down tripod (shortest legs), shake reduction off, 2 sec timer (not remote though).

The images are 100% crop from the centre of the RAW image (no post processing other than default sharpening in Capture One, i.e the images are identical except for the aperture).

Is this what is expected from this lens at F2.8?

Only stepping down a little dramatically increases the IQ, the second attached picture is F5.6.

The yellow house is approx. 160m (525 feet) away, and the ridge is approx. 10km (6.2 miles).

Edit: The camera is K-S2

F2.8

F5.6

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Last edited by benny2nd; 08-19-2016 at 03:10 PM.

[Driline]

Wow that's really bad

[CDW]

I owned a Samyang 14mm 2.8 a few years ago that I shot on a K3 with similar results. I picked up the Rokinon version when I purchased a K1 and it's sharp wide open with no coma at 2.8 on night sky shots. I think there is tremendous variability with this lens under various names (Rokinon, Samyang, Vivitar). Based on my experience I would not recommend buying a used or refurb. I'd go for a new copy from a reputable vendor that will allow a return. I can't condone it but one friend sometimes will order 4-5 copies of a lens from Amazon, keep the sharpest and return the rest.

[MJSfoto1956]

I had a Samyang 14mm on my Nikon D800 and it was sharp wide open -- slightly sharper stopped down. The f/2.8 image you posted doesn't look right to me.

Michael

[Outis]

Yeah, my 14mm Rokinon is really sharp, even at f/2.8. You must have a bad copy. I had to go through, I think, 4 copies before I finally got one that was good.

[Driline]

I can't condone it but one friend sometimes will order 4-5 copies of a lens from Amazon, keep the sharpest and return the rest.

Wow. Imagine ordering 5 $2,000 lenses

[DeadJohn]

Here's my Samyang 14mm from a recent outing. Granted, it's a very different scene than what you shot, but my foreground and background are reasonably sharp at f2.8.

The Samyang/Rokinon/Bower 14mm has a reputation for miscalibrated focus ring. In my case I could focus way too far past infinity. Maybe your lens is wrong in the other direction and can't focus on far objects. It's pretty easy to adjust but in your case I don't recommend doing any work to a lens you just bought, and the problem doesn't look like simple misfocusing. Return it if you bought via a dealer, the marketplace here, or anywhere else that allows returns.

[benny2nd]

Seems like all of you think the same as me, that it does not look good and something is wrong.

Unfortunately it is bought used, so I cannot return it.

Anyway, there is no use in crying over spilled milk, and I'm a curious engineer, so does anyone have any idea what might cause this kind of softness? Is it something that maybe can be fixed with some clever home engineering (taking the lens apart to fix), or is it simply other factors, like e.g. "glass quality" or something else, which cannot be fixed?

[Dlanor Sekao]

Do a little research on here and you will see what to do to correct it as these lenses are notorious for being incorrectly calibrated on the infinity hardstop......nothing unusual at all.

[Alnjpn]

This is exactly the characteristics of the lens. My images look the same at these settings. Very soft at 2.8, usable from f4, great at 5.6 and brutally sharp at f8. I replaced my first copy, the second was the same. If your using it for stars it is fine at 2.8. I have had the best results 2.8, ISO3200 and 25secs. I don't think there is anything wrong with your lens. Stick with it - it is a lens worth getting to know.

[benny2nd]

Do a little research on here and you will see what to do to correct it as these lenses are notorious for being incorrectly calibrated on the infinity hardstop......nothing unusual at all.

I've done my research (or at least tried to ), and adjusted it before these pictures were taken. Now it's adjusted so I can focus just a tiny bit past infinity so I know when to back up a little. At first I suspected the hardstop to be before infinity was reached, but the quality is the same before and after the adjustment, so didn't help. Might just be me and subpar manual focusing skills, I don't know.

This is exactly the characteristics of the lens. My images look the same at these settings. Very soft at 2.8, usable from f4, great at 5.6 and brutally sharp at f8. I replaced my first copy, the second was the same. If your using it for stars it is fine at 2.8. I have had the best results 2.8, ISO3200 and 25secs. I don't think there is anything wrong with your lens. Stick with it - it is a lens worth getting to know.

Thank you, you just lifted my spirits a little at least I'll definately stick with it a little more as I haven't had the opportunity to shoot starry skies with it yet, so I don't actually know the result.

[Na Horuk]

Hello from a new member

Hello, welcome!

To my best abilities I've tried to focus to infinty, and whatever I do I'm not able do better than the attached F2.8 photo. This actual shot is taken with the help of focus peaking in live view, which is about the same result I get if I try to do it fully manually. The camera is on a weighed down tripod (shortest legs), shake reduction off, 2 sec timer (not remote though).

So this might be the first problem. The focus ring is usually miscalibrated on this lens, so the numbers are unreliable. Secondly, live view often stops down the lens, so you are not really focusing at f2.8. And focus peaking with this lens is unreliable because it shows a massive DoF, which is too generous at f2.8.

How to focus Samyang 14mm: take test photos. Select M mode on camera, f2.8, lowest ISO, 2 sec timer, put it on tripod, aim it at something that is near the horizon and take test photos, then remember where each one was focused and look at them on computer at 100% zoom. This was how I figured out where my Samyang 14mm is actually focused to infinity (around the 3m mark). This alone will fix most of the problems. There are some videos online on blogs and youtube about how to manually calibrate the focus ring on this lens (because it is such a common problem). You can check them out, it is not too difficult. I never bothered with mine, even though I should do it eventually.

How to find optical problems: Ok, your first photo is either completely misfocused (focused past infinity, most likely, as this lens allows you to focus past infinity and make literally everything OoF) or the lens has some problems. Most common problem with this lens is decentering. This is often a problem for fast ultrawide lenses and can usually be diagnosed by the edges of the photo. One part of the photo will be in focus, but another will be soft, and the CA will be different on different sides of the frame. Often the DoF will be diagonal, instead of parallel. Most people who notice this, send the lens back and get another copy. And possibly send that one back, as well. I know a couple of forum members here had to return multiple Samyang 14mm to get a good one. My first copy was decentered. My second copy is slightly less decentered, so I kept it. I don't know if a shop can fix this for you or not.

However! I would recommend you first check the lens. Make sure the front glass element and especially the back are both clean. Don't wipe them with a harsh cloth - check online for instructions on how to clean a lens. Make sure there is no filter or teleconverter or anything like that mounted. After you clean it, check the focus calibration. Maybe you can reach infinity by 2m, and the lens is fine. Finally, take photos of something parallel (wall, newspaper, things like that) to the lens at f2.8 and check the edges. Remember, the DoF is always curved, but the edges should still all look relatively similar, even if they are different from the centre. But if one half of the photo, or one edge of the photo looks noticeably worse than another, then there is probably decentering. I recommend you do this test near the minimum focus distance of the lens, as it is more easy to detect problems and set up the whole rig. You can try using Catch in focus, but I would generally only recommend focus peaking with this lens when you are really near the minimum focus distance. Even 1m and further the FP is almost useless.

Tl;dr: My Samyang 14mm is much sharper at f2.8, it is very sharp. Either you misfocused or your lens is dirty or your lens has some sort of damage. Clean it, calibrate the focusing, do some tests, then have it sent to a repair shop or return it to seller (or have seller pay part of the repair costs). Good luck.

There is a Samyang lens club thread on these forums, and possibly you can find an f2.8 photo on my 500px gallery (but I usually shoot this lens at f8, where it is super sharp and has huge DoF). You will see they are sharp. But note that I do add some digital sharpening.

[benny2nd]

^^

Thank you for the feedback and advice, I will definately try more test photos while fine adjusting focus.

[ScooterMaxi Jim]

I don't have any idea whether or not this is a tight crop, but it appears to be so. Pretty much all fast UWA lenses have significantly low contrast and marginal sharpness wide open - and are a challenge to focus precisely. Any reasonably priced UWA lens that shows good sharpness across the frame by f/5.6 is performing at a strong level. Generally, issues with field curvature and other plane of focus challenges are not eliminated until around f/11. That's where you will find a lot of landscape shooters landing.

What you should look out for if the lens is off will usually involve decentering such that one side or the other is considerably softer at a particular focus point. Usually, if considerably decentered, you'll get significant CA. I'm not seeing that on these sample images.

A 14mm FF lens is a far cry from 17-18mm designed for crop. It is a specialty lens designed to be used in specific ways that requires more thought than shooting in the middle focal length range. Yes, you can try to shoot it at f/2.8 in low light situations where you have no other good choice, but that isn't its strength.

[Wingincamera]

I have the Bower version of this lens. Pay attention to what Na Horuk wrote above. I brought mine new from B&H and the first copy had a de-centered lens and was exchanged for another which was a very good copy, with the exception of the focus/distance markings were not even close. Mine is very sharp at 2.8.
Like Na Horuk stated, there are plenty of videos explaining how to correctly move the markings to be more accurate, but I didn't bother with that. I placed a piece of painters tape over the markings and made my own. What I did was set up the camera on a tripod and took lots of using live view starting at the minimal focus distance, then six feet, ten feet and then infinity. Used two second timer when taking photos and keeping accurate record of where each shot was taken at. What I ended up with is markings on the tape that I can just line up knowing that it is accurate for the given distance. For photos where infinity is needed, there is no guessing, even in the middle of the night. If I want everything in focus I can just set it at six feet, F8 and everything from a little less than three feet to infinity is in focus.