Manual Focus Lever - Needed?

Lord Lucan · 08-11-2021, 02:45 AM

I was using a manual focus lens (a M100 macro) on my K-1, taking pictures, and realised I had forgotten to switch the camera from AF to MF with the lever on the mirror box. No harm seems to have been done, the camera was not making any fuss, and the pictures were fine. Is changing this lever necessary? What does it do?

MarkJerling · 08-11-2021, 03:25 AM - **2 Likes**

The lever retracts the screw drive. The screw drive in the body is spring loaded anyway, so provided there's no indent on your manual lens in that same location to engage the screw drive, there should not be any damage.

**UncleVanya** · 08-11-2021, 04:59 AM - **2 Likes**

Catch in focus requires at switch to be in af position and either a manual focus lens or a lens with a switch itself set to manual focus. There shouldn’t be any problem.

Lord Lucan · 08-11-2021, 09:32 AM

I see it now: moving the MF/AF lever with no lens mounted, the screw drive shaft moves In/Out respectively and is sprung. My M100 macro lens has a plain area on its mount where the screw drive will press when mounted*, so it's not going to try chewing up a screw or anything

. In fact my DFA 24-70, being focussed electrically, also has a plain area where the screw drive shaft must be pressing against, so it is obviously an acceptable scenario.

* But not necessarily every legacy lens I guess.

pschlute · 08-11-2021, 11:40 AM

Originally posted by Lord Lucan

Is changing this lever necessary? What does it do?

If you have your camera set up to the default AF setting regarding shutter release, and the AF/MF switch is in AF, the camera will not take a picture unless AF confirmation is attained. So you can have a problem using a MF lens if your subject is off centre. The centre AF point may not get a lock, and the shutter will not trigger.

So best to use the MF/AF switch.

**fs999** · 08-12-2021, 08:19 AM

Originally posted by pschlute

If you have your camera set up to the default AF setting regarding shutter release, and the AF/MF switch is in AF, the camera will not take a picture unless AF confirmation is attained. So you can have a problem using a MF lens if your subject is off centre. The centre AF point may not get a lock, and the shutter will not trigger.

I don't think so. You can trigger at any moment with a manual lens in AF position and also with an AF lens in MF position on the lens...

**UncleVanya** · 08-13-2021, 06:50 PM

Originally posted by fs999

I don't think so. You can trigger at any moment with a manual lens in AF position and also with an AF lens in MF position on the lens...

Catch-in-Focus Tutorial - Articles and Tips | PentaxForums.com

If catch in focus is setup - I don't think you can.

**fs999** · 08-14-2021, 09:46 AM

Originally posted by UncleVanya

Catch-in-Focus Tutorial - Articles and Tips | PentaxForums.com

If catch in focus is setup - I don't think you can.

There was no mention of catch in focus in pschlute's post nor in op's...

**UncleVanya** · 08-14-2021, 05:50 PM

Originally posted by fs999

There was no mention of catch in focus in pschlute's post nor in op's...

True but I’ll bet pschlute has it set.

kypfer · 08-15-2021, 01:10 AM - **1 Like**

Originally posted by Lord Lucan

Is changing this lever necessary? What does it do?

Some a/f lenses (not necessarily Pentax) are very much a/f OR m/f.
If you want to manually focus one of these lenses for whatever reason, with the camera set in a/f, you'll be also forcing the camera focus drive mechanism, which is probably not recommended

The lever effectively operates a dog clutch which disconnects the camera's a/f drive from the lens.
As others have noted, having this switch in the a/f position is necessary for the catch-in-focus feature, so there may be circumstances where the two functions are not practical.

**fs999** · 08-15-2021, 03:33 AM

Originally posted by UncleVanya

True but I’ll bet pschlute has it set.

Ok sorry, I thought he was answering the op

08-11-2021, 02:45 AM	#1
Lord Lucan Pentaxian Join Date: Sep 2017 Location: South Wales Photos: Gallery Posts: 2,977	Manual Focus Lever - Needed? I was using a manual focus lens (a M100 macro) on my K-1, taking pictures, and realised I had forgotten to switch the camera from AF to MF with the lever on the mirror box. No harm seems to have been done, the camera was not making any fuss, and the pictures were fine. Is changing this lever necessary? What does it do?

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08-11-2021, 03:25 AM - 2 Likes	#2
MarkJerling Moderator Site Supporter Join Date: May 2012 Location: Wairarapa, New Zealand Photos: Gallery \| Albums Posts: 20,421	The lever retracts the screw drive. The screw drive in the body is spring loaded anyway, so provided there's no indent on your manual lens in that same location to engage the screw drive, there should not be any damage.

08-11-2021, 04:59 AM - 2 Likes	#3
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,452	Catch in focus requires at switch to be in af position and either a manual focus lens or a lens with a switch itself set to manual focus. There shouldn’t be any problem.

08-11-2021, 09:32 AM	#4
Lord Lucan Pentaxian Join Date: Sep 2017 Location: South Wales Photos: Gallery Posts: 2,977 Original Poster	I see it now: moving the MF/AF lever with no lens mounted, the screw drive shaft moves In/Out respectively and is sprung. My M100 macro lens has a plain area on its mount where the screw drive will press when mounted, so it's not going to try chewing up a screw or anything . In fact my DFA 24-70, being focussed electrically, also has a plain area where the screw drive shaft must be pressing against, so it is obviously an acceptable scenario. But not necessarily every legacy lens I guess.

08-11-2021, 11:40 AM	#5
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,215	Originally posted by Lord Lucan Is changing this lever necessary? What does it do? If you have your camera set up to the default AF setting regarding shutter release, and the AF/MF switch is in AF, the camera will not take a picture unless AF confirmation is attained. So you can have a problem using a MF lens if your subject is off centre. The centre AF point may not get a lock, and the shutter will not trigger. So best to use the MF/AF switch.

08-12-2021, 08:19 AM	#6
fs999 Loyal Site Supporter Join Date: Jul 2008 Location: Luxembourg Photos: Gallery Posts: 8,646	Originally posted by pschlute If you have your camera set up to the default AF setting regarding shutter release, and the AF/MF switch is in AF, the camera will not take a picture unless AF confirmation is attained. So you can have a problem using a MF lens if your subject is off centre. The centre AF point may not get a lock, and the shutter will not trigger. I don't think so. You can trigger at any moment with a manual lens in AF position and also with an AF lens in MF position on the lens...

08-13-2021, 06:50 PM	#7
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,452	Originally posted by fs999 I don't think so. You can trigger at any moment with a manual lens in AF position and also with an AF lens in MF position on the lens... Catch-in-Focus Tutorial - Articles and Tips \| PentaxForums.com If catch in focus is setup - I don't think you can.

08-14-2021, 09:46 AM	#8
fs999 Loyal Site Supporter Join Date: Jul 2008 Location: Luxembourg Photos: Gallery Posts: 8,646	Originally posted by UncleVanya Catch-in-Focus Tutorial - Articles and Tips \| PentaxForums.com If catch in focus is setup - I don't think you can. There was no mention of catch in focus in pschlute's post nor in op's...

08-14-2021, 05:50 PM	#9
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,452	Originally posted by fs999 There was no mention of catch in focus in pschlute's post nor in op's... True but I’ll bet pschlute has it set.

08-15-2021, 01:10 AM - 1 Like	#10
kypfer Pentaxian Join Date: Jan 2018 Location: Jersey C.I. Posts: 3,596	Originally posted by Lord Lucan Is changing this lever necessary? What does it do? Some a/f lenses (not necessarily Pentax) are very much a/f OR m/f. If you want to manually focus one of these lenses for whatever reason, with the camera set in a/f, you'll be also forcing the camera focus drive mechanism, which is probably not recommended The lever effectively operates a dog clutch which disconnects the camera's a/f drive from the lens. As others have noted, having this switch in the a/f position is necessary for the catch-in-focus feature, so there may be circumstances where the two functions are not practical.

08-15-2021, 03:33 AM	#11
fs999 Loyal Site Supporter Join Date: Jul 2008 Location: Luxembourg Photos: Gallery Posts: 8,646	Originally posted by UncleVanya True but I’ll bet pschlute has it set. Ok sorry, I thought he was answering the op