p.9 #1 · Samyang AF 18/2.8 FE officially announced
BlueBomberTurbo wrote:
To me, it seems like they're pushing the responsibility of QC onto the customer. Settings like aperture adjustment, where you can adjust the wide open position of the aperture blades, ensuring that none are visible wide open, have never been a thing before. Nor have they ever been needed, since that's certainly a standard QC point.
AF shouldn't be an issue with mirrorless, either. There can't be a misalignment of the AF sensor and imaging sensor like on DSLR, as they're a single part on mirrorless. That's all that AF fine tune/microadjustment changes on a DSLR: the mirror angle that directs the view of the scene to the separate AF sensor. As we've seen with some Sony and Canon lenses, AF inconsistencies are FW issues, not body issues, as one FW update to correct AF serves lenses mounted on all bodies....Show more →
Actually when you use the USB dock with your Samyang lenses, they are AF tuned at the factory. Many lenses are not at base 0, so there is a QC tech that does tune the lenses. It's just sometimes there's still room for improvement.
p.9 #4 · Samyang AF 18/2.8 FE officially announced
I seem to have the worst luck with lenses lately. I picked up a Samyang 18/2.8 on the recent Adorama sale, but it was badly decentered. Visible softness/CA on the LHS even at F8. I've had very good results with all my past Samyang lenses - 12/2, 35/2.8, 35/1.4. 50/1.4. Overall I still believe Samyang has pretty good QA; or no worse than everyone else - including Sony.
p.9 #5 · Samyang AF 18/2.8 FE officially announced
My copy is a bit decentered in the top left corner. But I've used this mostly for street photography, so that's not much of an issue. Overall, the quality is acceptable when shooting Continuous AF with facial recognition. I'd never rely on it where architectural verticals/horizontals are important though. Not surprising, I guess, at the price. Topaz Sharpen AI improves things quite a bit.
p.9 #8 · Samyang AF 18/2.8 FE officially announced
Hello. I want buy these lens for my travel. and I want to understand how works focusing and is it loud. I want to use it for video filming. I have A73.
p.9 #9 · Samyang AF 18/2.8 FE officially announced
kbapk wrote:
Hello. I want buy these lens for my travel. and I want to understand how works focusing and is it loud. I want to use it for video filming.
it's quiet. Biggest flaw is that filming in log, the AF can lose you, even in daylight! Standard modes ok, A7siii it works well, even using a log profile.
p.9 #10 · Samyang AF 18/2.8 FE officially announced
Just got my copy. No decentering and it's a great lens. Can't believe it's this wide, small, and low distortion.
I'm not very good with ultrawide composition, so I rarely bring my 12-24 zoom lens anywhere. With this lens, there's no excuse not to chuck it in the bag. Practice makes perfect, hopefully. Was deciding between this, the Sony G, Batis, and Tamron. Ended up choosing this because of this thread
Jonathan F wrote:
I adjusted my 18mm 2.8 by additional -1 AF adjustment and the wide open performance was noticeably better. I can shoot the 18mm 2.8 wide open all day and be satisfied with the sharpness. Though I'd only get a dock if you plan on buying more Samyang lenses. I currently have 5 lenses and have most my Samyang glass focused adjusted and running current firmware. I actually prefer this method since I've been able to buy cheap Samyang lenses used (due to seller dissatisfaction). Once I receive it, I focus tune the lens, maximizing best results.
BlueBomberTurbo wrote:
To me, it seems like they're pushing the responsibility of QC onto the customer. Settings like aperture adjustment, where you can adjust the wide open position of the aperture blades, ensuring that none are visible wide open, have never been a thing before. Nor have they ever been needed, since that's certainly a standard QC point.
AF shouldn't be an issue with mirrorless, either. There can't be a misalignment of the AF sensor and imaging sensor like on DSLR, as they're a single part on mirrorless. That's all that AF fine tune/microadjustment changes on a DSLR: the mirror angle that directs the view of the scene to the separate AF sensor. As we've seen with some Sony and Canon lenses, AF inconsistencies are FW issues, not body issues, as one FW update to correct AF serves lenses mounted on all bodies....Show more →
Seems that the source of any needed microadjustments are lens decentering/tilting. PDAF samples from opposite sides of the sensor and assumes they are offset from the center's phase. There's some discussion here. Most likely every manufacturer has some of these values in their lenses and just don't make them user adjustable, though of course people to seem to say Samyang has worse QC.
This would seem to imply any large AF Punt values means a lens is more decentered, but according to my recent decentering tests, this isn't true. I have one Samyang lens that is quite decentered and several that are centered, and the decentered one does not have the largest punt value. Though I did not explicitly check focus offsets for all my lenses like Jonathan F.
p.9 #11 · Samyang AF 18/2.8 FE officially announced
Jonathan F wrote:
I adjusted my 18mm 2.8 by additional -1 AF adjustment and the wide open performance was noticeably better. I can shoot the 18mm 2.8 wide open all day and be satisfied with the sharpness. Though I'd only get a dock if you plan on buying more Samyang lenses. I currently have 5 lenses and have most my Samyang glass focused adjusted and running current firmware. I actually prefer this method since I've been able to buy cheap Samyang lenses used (due to seller dissatisfaction). Once I receive it, I focus tune the lens, maximizing best results.
maestrofilms wrote:
Can you elaborate? Do you adjust based on infinity focus, or another method?
For the curious, I tried using infinity but found that the AF Pint setting did not affect infinity focus. My 18/2.8 was very slightly front focused at infinity. I used DMF, 6x focus magnification and high focus peaking. You can autofocus while in 6x focus magnification, and tiny bit more focus peaking highlights showed up when I took the smallest step went towards infinity. When I took pictures though, zoomed in at 400% at 61 MP, I really struggled to tell the difference.
I then tested my Sony G 70-300mm and found a similar behavior, very slight front focusing at infinity.
Then I tried closer focusing the 18/2.8 with a focus calibration chart, like what we used to have to do quite frequently in the DSLR days. Make sure to use AF-C mode to only use PDAF points, as I believe AF-S will do a contrast focus check. Shoot in portrait mode since Sony's PDAF does not have cross-type points. Shooting at more of an angle makes it easier to judge front/back focus, but at some point the focus will jump back and forth, which you don't want. Shoot more straight or maybe add more light and increase contrast. Or print a bigger chart.
Also, shooting too close may result in field curvature having an effect. I believe that's why the chart below gray text printed so you can check near the focus point, and not way out at the sides. But at a certain gray value, the AF system will start to lock onto those, which isn't good. So check to make sure you can't lock AF on any gray text.
My stock AF Pint value of -2 was perfect, and setting it to -3 and -4 resulted in back focus (and as I said before, didn't really affect infinity). My 18/2.8 also doesn't show any decentering using the lensrentals defocusing method, but I'll try the infinity check (Gletscherbruch / Fred Miranda method) maybe at some point.
p.9 #12 · Samyang AF 18/2.8 FE officially announced
For those who have the lens and shoot the occasional video: how is the video AF? What about noise? I owned the 35 and 85mm F1.4 and found video af to be wildly and completely unusable and this is an important consideration. Otherwise I do like the size and FL.
p.9 #13 · Samyang AF 18/2.8 FE officially announced
derKoekje wrote:
For those who have the lens and shoot the occasional video: how is the video AF? What about noise? I owned the 35 and 85mm F1.4 and found video af to be wildly and completely unusable and this is an important consideration. Otherwise I do like the size and FL.
I haven't used video that much yet but so far, it is much better than the Samyang 35/1.4. Much quieter, though still a slight whine, just above the noise floor from the internal recorder that I never notice under my typical video subjects (a kid). I did get it to fail to lock focus for an object too close and it makes a more audible ticking noise constantly. The 35/1.4 on the other hand is quite audible during any video I take.
The 18/2.8 accuracy/smoothness of the video AF seems a lot better as well, with the 35/1.4 somewhat regularly missing and pumping forward/backward. I have not really tested 18/2.8 much on tougher moving subjects, mostly I am walking with the subject.
~~~A7Riv, iso800, f2.8