Quick-Shift focusing for lenses that lack it.

heliphoto · 10-11-2008, 09:48 PM

Yesterday, I stumbled on a suggestion somewhere over on DPR to use the lens release button to simulate quick shift focusing for lenses which lack this feature. The idea is that since the focusing gear (proper term?) is retracted while the lens release button is depressed, you can manually focus the lens, and when you let the button out, you're back in AF mode... I played with this today with my tamron 90 macro, and it works nicely. I thought I'd post here to spread the knowledge as it's an interesting trick and I'd never heard of it till now.

I don't think this is the thread I read yesterday, but here's a similar post.

marlon · 10-12-2008, 06:11 AM

Sounds like a plan, but not one im comfortable doing, just like I don't like using spanners as hammers.
Maybe someone else could advise on the wear/tear and feasibility of this?

JCSullivan · 10-12-2008, 06:14 AM

Thanks Josh, neat trick. But what is a Quick-shift??

*jmc7104* · 10-12-2008, 06:26 AM

Cannot see what difference it would make as far as mechanical wear is conserned. The feaasibility would have to be determined by the user, hiwever I wouldn't want to unlock a heavy lens like a 200 f2.8 or 500 ect. jim

Spongefingers · 10-12-2008, 06:36 AM

This could be an interesting technique for some people, but I'm not convinced it's really worth doing unless you feel you absolutely have to quick-shift.

The focus driver is retracted when you press the lens release button - so it will almost always be misaligned with the lens focus drive socket after twisting the focus ring manually and releasing the button. So when autofocus is next activated, there will be that unpleasant click and delay.
Also, as the lens mount locking pin is also retracted when the button is pressed, there may be a risk of the lens twisting on the mount when handled (admittedly a remote one.??)

Staying in manual-focus could be just as quick in most circumstances.

heliphoto · 10-12-2008, 08:48 AM

Originally Posted by JCSullivan

Thanks Josh, neat trick. But what is a Quick-shift??

Quick shift is the automatic de-clutching mechanism on most of the new Pentax DA lenses which allows the user to manually turn the focus ring after the camera has auto-focused.

heliphoto · 10-12-2008, 09:46 AM

Originally Posted by marlon

Sounds like a plan, but not one im comfortable doing, just like I don't like using spanners as hammers.
Maybe someone else could advise on the wear/tear and feasibility of this?

Well I don't like it but I've used many objects as hammers, spanners included. I don't think I'll do this often, but it surprised me that I'd never heard of it.

Originally Posted by jmc7104

Cannot see what difference it would make as far as mechanical wear is conserned. The feaasibility would have to be determined by the user, hiwever I wouldn't want to unlock a heavy lens like a 200 f2.8 or 500 ect. jim

I was just thinking that it would be fairly unworkable with my bigma.

Originally Posted by Spongefingers

This could be an interesting technique for some people, but I'm not convinced it's really worth doing unless you feel you absolutely have to quick-shift.

The focus driver is retracted when you press the lens release button - so it will almost always be misaligned with the lens focus drive socket after twisting the focus ring manually and releasing the button. So when autofocus is next activated, there will be that unpleasant click and delay.
Also, as the lens mount locking pin is also retracted when the button is pressed, there may be a risk of the lens twisting on the mount when handled (admittedly a remote one.??)

Staying in manual-focus could be just as quick in most circumstances.

I can see using it once in a while... for instance to fine tune focus on the eyes in a portrait. It's true that leaving the camera in MF would be better if you were doing a series of portraits, or had time, but if you just wanted a quick one off adjustment, and wanted to remain in AF for quicker response in dynamic conditions this might be work well.

With most of my lenses, I can't imagine the lens disengaging from the mount while doing this, as the fit is quite tight.

Marc Sabatella · 10-12-2008, 12:36 PM

I remember when that suggestion was made previously. And my reaction then was the same as it is now - how is that an improvement over simply flipping the AF/MF switch? when you want to focus manually? Mind you, I think both are a drag, which is why I pretty much will not buy an AF lens without quick shift.

deejjjaaaa · 10-12-2008, 05:17 PM

Originally Posted by Marc Sabatella

I remember when that suggestion was made previously. And my reaction then was the same as it is now - how is that an improvement over simply flipping the AF/MF switch? when you want to focus manually? Mind you, I think both are a drag, which is why I pretty much will not buy an AF lens without quick shift.

K20D has such a flimsy AF/MF switch, I am afraid to touch it... plus lens release button will allow you to use trap focus/catch in focus (see my answer to hinman there Questions on Sigma 105mm f/2.8 1:1 Macro Ex (non-DG))

*mithrandir* · 10-12-2008, 06:20 PM

Don't forget to double clutch.

*Canada_Rockies* · 10-12-2008, 10:14 PM

With my middle name, "Klutz", I always try to have the camera and lens above a softly cushioned surface before I press the lens release. I can just see me doing this trick with a lens and seeing pretty pieces of broken glass winking at me before I finish.

deejjjaaaa · 10-12-2008, 10:39 PM

Originally Posted by Canada_Rockies

With my middle name, "Klutz", I always try to have the camera and lens above a softly cushioned surface before I press the lens release. I can just see me doing this trick with a lens and seeing pretty pieces of broken glass winking at me before I finish.

you just rotate the focusing ring w/ the same hand that keeps the button pressed, as your palm is under the lens and your fingers are keeping it over the focusing ring nothing will happen... unless your fingers are real weak.

*Canada_Rockies* · 10-12-2008, 10:40 PM

Originally Posted by deejjjaaaa

you just rotate the focusing ring w/ the same hand that keeps the button pressed, as your palm is under the lens and your fingers are keeping it over the focusing ring nothing will happen... unless your fingers are real weak.

Mine aren't weak. Just clumsy.

*LaRee* · 10-12-2008, 11:34 PM

Originally Posted by Canada_Rockies

Mine aren't weak. Just clumsy.

Yeah me too. I have enough of a challenge using a tripod without doing something clumsy. To each their own, but I don't push on that button unless I am changing a lens.

JCSullivan · 10-13-2008, 04:15 AM

Originally Posted by heliphoto

Quick shift is the automatic de-clutching mechanism on most of the new Pentax DA lenses which allows the user to manually turn the focus ring after the camera has auto-focused.

Ahaaaaaaaaaaaaa!!!! Now I know why my newest addition, the 10-17 DA acts in this manner. I thought it strange at first but now it makes sense.

Thanks.