[just_another_gymbro]

Hi everyone,

I've been playing around with my vintage 50mm f2 lens with my KP, and have noticed that the focus indicator in the OVF, which flashes red when your manual lens is in focus, has been consistently missing focus with this lens.

I've set it up to be spot focus metering, and have changed (I think) the relevant settings for MF lenses, so I'm not really sure what the issue could be. I don't really care since I'm comfortable pulling focus without an indicator, but it is somewhat annoying.

Has anyone else had this issue?

This is when the KP told me I was in focus


Versus when I manually focused


Through the viewfinder they looks pretty similar, but the difference is obviously very clear since I was shooting at f2.

EDIT: I should clarify that the flower was directly in the center of the viewfinder both times and perfectly aligned with the red square indicating focus!

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Last edited by just_another_gymbro; 03-23-2022 at 02:42 AM. Reason: Clarification

[AldaCZ]

As AF lenses can be corrected for front /back focus so the MF can be. It's the same

[shyrsio]

I think you might need focus calibration. try a couple of shots focusing through live view and see if they are on focus, if so you need to make focus calibration.

[AldaCZ]

I think you might need focus calibration. try a couple of shots focusing through live view and see if they are on focus, if so you need to make focus calibration.

Yes I meant this

[MrB1]

I might be mistaken but I think that the red square shows which focus point is being used, but I have always relied on the green hexagon to be the 'in focus' indicator, with an acceptable level of success when using my SMC Pentax K 30 mm manual lens.

Philip

[pschlute]

I should clarify that the flower was directly in the center of the viewfinder both times and perfectly aligned with the red square indicating focus!

The red square in the viewfinder is not actually focus confirmation. They actually indicate which of the focus points is getting a focus lock. In the case of a manual lens only the centre one is in operation. the actual focus confirmation is the green hexagon at the bottom of the viewfinder. Now they may both be illuminating simultaneously, but it is worth checking.

As the previous poster said you can use the AF/FA menu to make a global adjustment to the AF (and the focus confirmation) if there is a slight misalignment.

How do your other lenses focus manually using the same method ?

[Astropaps]

I thought the AF fine tuning adjustment only works on autofocus lenses???? What am I missing?

[mlag]

I might be mistaken but I think that the red square shows which focus point is being used, but I have always relied on the green hexagon to be the 'in focus' indicator, with an acceptable level of success when using my SMC Pentax K 30 mm manual lens.

Philip

Especially in macro where focus accuracy is tight and depth of field is narrow, the slightest movement of camera or focus ring makes a difference. The red dot might light up bit longer if you "passed" focus -showing mainly where it is or rather was focusing- but the green hexagon at bottom of viewfinder is the confirmation you are still in focus, it lights up less long, only while in focus. In normal scenes with larger dof the red dot and green hexagon seem to be more synced, mainly because there is more margin.
The problem is the red dot is central and more visible, so our brains tend to pay more attention to it , ignoring the bottom green hexagon a bit - which might work in easy scenes with larger dof - both pop up simultaneous longer due to the wider in-focus range- but not in difficult scenes needing accurate focus like macro.

[pschlute]

I thought the AF fine tuning adjustment only works on autofocus lenses???? What am I missing?

The green hexacon focus indicator is part of the Autofocus system PDAF when using the viewfinder (not Live View). If you adjust with the AF/FA menu, both the autofocus and the green hexagon change together.

If you rely on the green hexagon to get focus confirmation with a manual lens, adjusting the AF/FA menu changes that too.

With lenses that do not communicate their ID with the camera (K/M/A) lenses, any adjustment can only be Global.

[just_another_gymbro]

The red square in the viewfinder is not actually focus confirmation. They actually indicate which of the focus points is getting a focus lock. In the case of a manual lens only the centre one is in operation. the actual focus confirmation is the green hexagon at the bottom of the viewfinder. Now they may both be illuminating simultaneously, but it is worth checking.

As the previous poster said you can use the AF/FA menu to make a global adjustment to the AF (and the focus confirmation) if there is a slight misalignment.

How do your other lenses focus manually using the same method ?

Ha! Oops I didn't know that it was the green hexagon.

Unfortunately, it still focuses incorrectly.

I did some more tests with this lens + others, and it appears that the AF is pretty consistently front-focusing.

I just adjusted it and it seems to work fine now, but I'll test it more later today. Thank you!

[pschlute]

I just adjusted it and it seems to work fine now, but I'll test it more later today. Thank you!

Excellent. I do the same with my manual lenses.

The thing to remember is that this will affect all lenses you put on the camera. You may find your AF accuracy improves with them all.

[c.a.m]

I thought the AF fine tuning adjustment only works on autofocus lenses???? What am I missing?

Ha! Oops I didn't know that it was the green hexagon.

As others have mentioned, the Green Hexagon may be used to achieve focus with manual-focus lenses.

Here's an article that describes the issues and an approach to calibrating MF lenses.

Achieving Better Manual Focus with the Green Hexagon - PentaxForums.com

- Craig

[just_another_gymbro]

Excellent. I do the same with my manual lenses.

The thing to remember is that this will affect all lenses you put on the camera. You may find your AF accuracy improves with them all.

Yup - so far it has.

I think the degree to which my AF lenses were front-focusing was much less than on manual, but going back and looking at some images I realized that a fair number of them were slightly out of focus. I also noticed slightly less hunting for close-ups, but I'm not sure if I'm making that up.

---------- Post added 03-23-22 at 05:07 AM ----------

As others have mentioned, the Green Hexagon may be used to achieve focus with manual-focus lenses.

Here's an article that describes the issues and an approach to calibrating MF lenses.

Achieving Better Manual Focus with the Green Hexagon - PentaxForums.com

- Craig

Thanks for the link Craig - very helpful

[Not a Number]

Focus confirmation is via the green hexagon. Manual Focus lenses are tricky because the focus can't lock as it can with AF lenses. So the slightest movement can lose confirmation.

You could check the focus by using catch-in-focus with the MF lens and see how it looks.

Otherwise it takes practice and a steady hand to get good at manual focus.

[UncleVanya]

Another factor is that very wide aperture lenses have a lot of difficultly getting focus nailed. The leeway in the PDAF sensor points is larger than you might like. Essentially anything with wider than f2.8 can be a bit sloppy to get perfect focus from - not impossible - just harder.