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07-27-2021, 05:43 PM   #1
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Problem focussing Samyang 85mm F1.4

It could be my eyes, but I swear that I am focussing correctly with my Samyang 85mm. However, I am continually finding that the subject I am focussing on is not in focus. I do find that when I use live view and focus peaking that I can get my subject in focus. This lens is manual focus but I am wondering if there is any way of calibrating this lens so that it will focus? I had tried calibrating an auto focus lens and applying that to all, but there are a couple of issues with doing that. One, you apply this calibration to all the lenses you use (not good) and two, I'm not sure it made any difference anyway. Any thoughts on this? More info: I am using a k-1. Any thoughts?

07-27-2021, 06:05 PM   #2
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Do you have the optical view finder diopter adjusted for your eyes? If not and you need to wear glasses, you'll need them on.
07-27-2021, 06:32 PM   #3
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Calibrating the lens using the AF fine tuning only calibrates the AF acknowledgement of an in focus situation. When manually focusing with the viewfinder the diopter is what needs to be adjusted.

Calibrating the Diopter of Your Camera | B&H Explora (bhphotovideo.com)?

Wear Glasses? How to Easily Calibrate Your Camera's Diopter (industrydev.com)
07-27-2021, 06:37 PM   #4
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perhaps some examples of what you're shooting to show us what the trouble is?

07-27-2021, 07:42 PM   #5
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Manual focus through the viewfinder is difficult, especially at f1.4, where your DOF will be very thin. It's possible that you are coming close but not hitting the perfect focus point.

I would recommend trying this:
-use a tripod or set the camera stable on a table
-focus as good as you can on a consistent object (maybe a wall square with the camera, or maybe one small object jutting up into the frame without anything around it) through the viewfinder
-without moving or bumping the camera, switch to liveview
-if you press "ok" in liveview, the camera will zoom in (by default) on the center of the image. you can use the thumb wheel to zoom in closer, all the way to 10x or 16x. you can move the magnified area around with the direction buttons. this (with focus peaking) is the best manual focus aid the camera has.
-you'll be able to tell about how far off you were using the viewfinder by correcting focus zoomed in like this. pay attention to which way you have to turn the focus ring.
-if you repeat that several times, I would expect you will find that sometimes you're focused a bit in front and sometimes you're focused a bit behind where you meant to be, and that it's kind of random each time but your'e always close.


Basically the DSLR viewfinder without any focusing aid isn't extremely accurate. You can really think you've nailed it, but it's more of a good guess. I've added a split prism focusing screen to my K1, and it's still really a challenge. Especially where I'm looking for super critical focus, and especially wide open, and especially with a subject relatively close to the camera for a given lens. A DOF calculator may help understand better what you're up against. Manual focus isn't easy!


Now, if you're having some other problem, like;
-what's in focus in liveview isn't in focus in the file once you've snapped a shot
-if it's happening stopped way down or with distant subjects
-if you're finding you are very consistently off in the same direction by the same amount
well then I'm not sure and that could be more specific to your lens or camera.

BTW I don't have that lens, although I have several wide aperture manual focus lenses and a K1. I wish I had that lens
07-27-2021, 10:52 PM   #6
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Does this lens identify itself and its focal Length to the camera or do you have to setup the ibis to the focal length and it doesnít write a lens id to Exif? Some manual focus lenses still have a lens id and can get af adjustments which impact catch in focus/focus confirmation.

I used an a* 85 f1.4 on a k-50 and a k-3 and found it so difficult to get focused reliably at wide apertures that I eventually sold it. I replaced it with the fa 77 and had enough left to buy my fa 31. I know the k-1 has a brighter viewfinder, but the focusing screens that modern dslr cameras use arenít optimized for manual focus. The screens are actually more optimized for composition, metering, and giving the photographer a good viewing experience. Even focus peaking and magnified live view can be tricky due to the thin depth of field with long and fast lenses.

My story isnít meant to make you give up, your eyes may be more capable and you may develop a skill for this I lacked. I just wanted to share that this frustration with a manual focus 85 f1.4 isnít something you should feel alone in.
07-27-2021, 11:02 PM - 1 Like   #7
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Just want to make sure it is not the too slow shutter speed.

07-28-2021, 01:09 AM - 1 Like   #8
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I may have observed the same problem with my Samyang 85mm. Unlike my 135mm Samyang, I found it very difficult to focus properly with the 85mm. And I think the problem is not just because an 85mm 1.4 has a shallow depth of field. I also thought about whether it might shift focus when stopped down. However, I could not find any further information on this.
07-28-2021, 01:22 AM   #9
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My eyesight is slightly varying so I have to check my diopter adjustment at the beginning of every photo session, when I plan to use manual focus lenses (focus with LV -> switch to OVF and turn diopter adjustment till the same area is in focus). After that I get more accurate focus (for wide apertures) than with the focus confirmation point in the OVF, because the focus confirmation of my K-3 is only accurate for f2.8 lenses (or slower), I don't know for what apertures the PDAF of the K-1 will be accurate though.
07-28-2021, 02:15 AM   #10
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As others have stated, it is extremely difficult to manual focus with a DSLR. That is one of the disappointments I have. Had I known this when I bought my first Pentax based DSLR, I would have chosen something else and sold all my Pentax gear. I think I would have chosen for a superzoom compact. But that is in hindsight. None of the Pentax legacy lenses I own are usable for me to go manual, so I send all my lenses to my personal museum of photographic gear. And just struggle on with APS-C lenses and camera's. But to be honest I enjoy the KP I bought at the beginning of this year very much. Gives a me a feeling of being busy with a camera like the Super A did.
07-28-2021, 02:48 AM   #11
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QuoteOriginally posted by AfterPentax Mark II Quote
As others have stated, it is extremely difficult to manual focus with a DSLR.
I wouldn't go that far (at least not for normal and tele lenses, wide angle lenses are more challenging though).
While I have to check my diopter setting before using MF lenses once per day, I really enjoy using them (otherwise I wouldn't own just 5 AF lenses, whereas I own 15 MF lenses )
07-28-2021, 07:48 AM   #12
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I don't have a problem with any of my drawerful (and then some) of manual lenses and the OVF … I just rely on the "Green Hexagon" for focus confirmation, as I always have done.
Maybe I'm just lucky that none of my bodies are out of calibration
07-28-2021, 08:32 AM   #13
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QuoteOriginally posted by kypfer Quote
I don't have a problem with any of my drawerful (and then some) of manual lenses and the OVF Ö I just rely on the "Green Hexagon" for focus confirmation, as I always have done.
Maybe I'm just lucky that none of my bodies are out of calibration
With an f1.4 85mm? I havenít ever had that work reliably. Given the reality that the focus points are calibrated for f2.8 at the fastest Iím a bit surprised.
07-28-2021, 09:34 AM   #14
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I have problems focusing my Samyang 85/1.4 with the OVF.

It's a different matter when I use Live View, Focus Peaking, and especially the Live View magnification. This doesn't mean that you must be on a tripod all the time. I bought one of those LCD focusing hoods and it works very well indeed. You can not only use LV, FP and magnification with ease, but it also gives one a firm third point of contact, ie., your eye socket. It's also useful for examining your results after. This has increased my focusing accuracy amazingly.

Another alternative is to find an F 1.7x AF converter. These work very well with manual focus lenses, and can focus them much more quickly and accurately than I can. As an older photographer I'm well accustomed to manual focusing, but digital OVF's just don't seem to cut it. I have Samyang 85 and 135 lenses, and several older K, M and A's; they all work great on K-1 II, K-3 II and KS-2 when combined with the converter.

A lot of people say that the Samyang 85/1.4 is soft when it's wide open. I'm not so sure. Like many large aperture lenses, there is some contrast loss when used wide open. Nail the focusing and add some contrast in post, and the lens will surprise you.

Last edited by Derek; 07-28-2021 at 10:25 AM. Reason: avoid confusion
07-28-2021, 09:39 AM   #15
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QuoteOriginally posted by UncleVanya Quote
With an f1.4 85mm? I havenít ever had that work reliably. Given the reality that the focus points are calibrated for f2.8 at the fastest Iím a bit surprised.
With an 85mm f/2, a 35mm f/1.9 and a 50mm f/1.4 I've certainly never experienced issues, I've a couple of 28mm f/2's as well that aren't a problem, most of my other manual lenses are of smaller maximum aperture Ö indeed the only manual lens I get any real trouble with is another Samyang, the 800mm f/8, the focussing on this is so critical and the rotational adjustment so coarse that any success is more by luck than judgement, even on a reasonably rigid tripod
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