Pentax AF Fine Adjustments

[@nuttick]

Perfect timing. I was just thinking I should calibrate the new 150-450. I go to yewtoobm, and before I can look it up there you is, waiting with the info in my subscriptions. Perfect!

[@KobieMC]

Oh wow! That's awesome! You'll have to give yourself some space to calibrate the 150-450 though.

[@nuttick]

@@KobieMC I recall someone saying ... 10x the focal length? Which sounds about right with more than a few duck pond shots being off by inches. (On the other hand... uncooperative subjects and hand-held long barrel shots!)

[@KobieMC]

@@nuttick That is the general consensus. The focal length in mm x10. I've found you don't absolutely need to do that. What I do are some test shots to make sure everything is good. If not, then I go back and mimic the distance and re-calibrate.

[@nuttick]

@@KobieMC Well that was an interesting test. I was expecting the adjustment tool to move the focus point further, but -10 to +10 settings only moved the focus an inch or two further and closer. Anyroads, that's what I found with my combination of full frame body and the 150-450. I suppose it'll range further with shorter focal length lenses? Oh, and the lens, at the 450mm end, seems to be pretty well-centered at zero fine adjustment, which is good!! Catch you next video. Wash your hands!

[@SPetersonImages]

Great video, thanks for sharing! I'll be doing this to my lenses with my K1ii over Christmas break.

[@malekianalireza]

Thanks. Very useful. I have a question. Does Pentax also support focus adjustments on manual lenses? Do manual lenses on manual focus even need adjustments?

[@KobieMC]

Manual focus lenses don't need focus adjustment since they don't use the AF sensor of the camera to drive the lens (there's no electronic connection to the lens for focus). The focus is solely done by hand, so, in another way to look at it, you are the focus adjustment.

[@malekianalireza]

@@KobieMC Thank you for the answer. :)

[@peterlundgren8867]

Nice video! I do very similar to you! Two questions though. 1. Can you elaborate a little about the optimal distance From the lens to the ruler? 2. You aimed to have the “6 and 9” on the ruler equally blurry. Referring to the rule of thirds when it comes to where to put focus to optimize depth of field, would it not make more sense to aim for one third in front should be equally blurry as two thirds behind?

[@KobieMC]

Technically you're correct about the rule of thirds. I haven't had any issues though at least that I've been able to spot. I do a lot of birds in flight and prefer to have an equal balance of fore and aft area. The general rule for distance is the focal length x10. So if it's a 70 mm lens, it should be 700 mm from the target. I've never actually done that though. But I do test shots both up close and at infinity with a good amount of distance just to make sure everything is good.

[@Sertao2013]

If the 9 is sharper than the 6 then isn't it front focusing ? You said it was back focusing at 4:15 in the video . Are you saying that if its sharper on the 9 than the 6 its back focusing ? Also the camera has to be perfectly level you have a built in level in the camera and you didn't show or say that it needed to be level . If the camera is even tilted a little it can make the distance longer on the top or bottom depending on how you are off . Another thing . You should be at the right distance for example you should be 5 to 10 times the focal length . On a 50 mm lens that 25 cm to 50 cm so 40 cm would be a good distance to calibrate the lens.

[@KobieMC]

Oh man, my bad, you're correct. It's front focusing. In my head I was thinking behind and back came out instead of front. Sorry for the confusion. Can't believe I missed that ☹️

[@duncanknifton6613]

Hi gang... can you simplify something for me.. If my lens is focusing past the subject, do I adjust the Fine Tuning with a + or a - number... ( eg +7 or -7 ) Thanks

[@KobieMC]

If it's "back focusing" (focusing past the subject) you'll want to minus it - to pull it towards the front of the subject. Think of this diagram where "|" is the subject - is in front (front focus) and + is back focus and | is smack in the middle... ---|+++

[@duncanknifton6613]

@@KobieMC ..thank you mate...much apricated..

[@PentaxLife]

Thank Kobie good info how about doing it for the 55-300 PLM thank yo.

[@KobieMC]

It would be the same thing. All lenses are adjusted the same.

[@ninjashinobi2413]

I'm confused, what angle exactly did you have the tape measure at? I know on a flat plane, the depth of field is 1/3 in front & 2/3 behind, how much does different angles [of the tape] effect that rule?

[@KobieMC]

It was a 45 degree angle. The focus was on the flat plane (box). And yes, it should be 1/3 in front and 2/3 rear. It also comes down to your acceptance level of that rule.

[@markdonoghue9077]

After you calibrate each lens will the camera remember or do you have to set it every time you change lens.

[@KobieMC]

There's 2 settings. "Set for 1" is for that individual lens. I believe you can set 12 lenses individually and the camera will remember each one when you mount them. The other option is to "Set for all" which will apply that adjustment to every lens you attach (I wouldn't recommend using Set for all).

[@markdonoghue9077]

Do you use the same setup for zoom lens?

[@KobieMC]

@@markdonoghue9077 Yes. Just have to add more distance between the lens and the shooting target.

[@TL-vt8uk]

Just for my clarity, your lens was originally "front focusing" and you had to shift the focus back to a -6, correct? You indicated that your lens was back focusing. Just trying to make sure I have the terminology correct? I am newer to Pentax, can one save the focus adjustments in the camera? thx.

[@KobieMC]

Welcome to Pentax! The terminology is if the lens is focusing PAST the subject, it's BACK focusing (focusing BEHIND) the subject. If the lens is focusing BEFORE the subject, it's FRONT focusing since it's in front of the subject. You can save the focus setting by lens and the camera will remember. You don't want to set it to all because if you have one lens that's perfect, another that's front focusing and another that's back focusing, setting one lens and saving "to all" will make that new adjustment across every lens you attach even if the lens doesn't need to be adjusted. I always set it by lens instead (it's in the AF Fine adjustment setting). Hope that helps 🙂

[@TL-vt8uk]

@@KobieMC Ok, so since your 9 on your ruler was in better focus than the 6, your camera was "front focusing"?

[@KobieMC]

Yes so you need to use + to push the focus further - to pull it in closer.

[@bansheep1]

What if +10 is not enough? Like in my sigma 24mm 1.8 exdg

[@bansheep1]

It only goes up to +10 and still lacking

[@KobieMC]

Then you'll have to send it in to be calibrated

[@bansheep1]

@@KobieMC Fixed! there is a small piece of lint on the autofocus sensor. Picked it up with a tweezer. Man that lint caused alot of headache..

[@KobieMC]

@@bansheep1 That would definitely do it! Glad it's all fixed now 🙂

[@FlyFishFairwx]

hahahaha excellent video, you are doing a great job, I thank you for your content and effort..

[@KobieMC]

Thank you!

[@djerfiyoucef4066]

شكرا صديقي ⁦👍🏻⁩😷

[@SW1911ES]

Did you do it at 17mm, 35mm or 70mm?

[@KobieMC]

It was at 70 mm

[@pixelpusher3589]

Hi everyone! does anybody have a copy of pk tether?

[@KobieMC]

I might actually. I'll have to check when I get home.