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GeneW · 01-14-2007, 05:41 PM

I'm familiar with Pentax M42 lenses but recently have picked up a few K-mount manual lenses and they all have a white button on them. What does it do? What is it for? It doesn't push... Total newb question I'm afraid...

Gene

Arjay Bee · 01-14-2007, 05:53 PM - **1 Like**

It is an aid for the mounting system and a legacy from when pentax switched from the M42 screwmount to the bayonet K mount.
Try closing your eyes and picking up the lens. Locate the button and then fit the lens to your camera. While it is not quite as convenient as on the older cameras when it lined up with the lens lock on the body, it helps you to orient the lens to the bayonet mount.
The colour is like the luminescent plastic found on children's toys. Put the lens under a desk lamp and then take it into a dark cupboard and see if the green/white dot glows.

roy · 01-14-2007, 07:31 PM

Arjay Bee,
100% correct... it's there just in case you need to mount a lens while blind folded

GeneW · 01-14-2007, 10:09 PM

Arjay, Roy, thanks! Okay, I'll quit pushing it now

Gene

Rolly · 01-15-2007, 05:48 AM

Originally posted by roy

Arjay Bee,
100% correct... it's there just in case you need to mount a lens while blind folded

Darned useful for theatre work, street PJ afterdark, surveillance etc.

egarrard · 01-15-2007, 11:25 AM

I think Pentax is the only camera that you don't have to change your grip on the camera to change the lens. It's a safety feature nobody ever mentions.

Alvin · 01-15-2007, 09:39 PM

Originally posted by egarrard

I think Pentax is the only camera that you don't have to change your grip on the camera to change the lens. It's a safety feature nobody ever mentions.

You know, I never thought about that until I was changing lenses today, and then I read your post now. Here I am holding the camera with my right hand, I push the lens release with my "right-ring" finger, twist the barrel and out goes the lens! I did it with my buddy's film based Pentax as well! I could never pull that off with the Nikon D50 or D70/70s. Same goes with the Fuji S2/S3 (based on Nikon bodies). Come to think of it you can't do it with Canon systems either. Brilliant!

Sorry - didn't mean to troll.

JCSullivan · 01-16-2007, 04:19 AM

I miss that "white button". As my vission is deteriorating I find myself looking for that mark since it is becoming difficult for me to see the red marking without having to put on my glasses.

Dana G · 01-16-2007, 08:36 AM

Originally posted by JCSullivan

I miss that "white button". As my vission is deteriorating I find myself looking for that mark since it is becoming difficult for me to see the red marking without having to put on my glasses.

Me too. At least the Limited lenses have a raised dot that you can feel. It makes it easier to change the lens without having to look directly at the lens, you can keep your eye on the action while changing lenses.

01-14-2007, 05:41 PM	#1
GeneW New Member Join Date: Jan 2007 Location: Port Credit, Ontario Posts: 9	What does the white button do on K-lenses I'm familiar with Pentax M42 lenses but recently have picked up a few K-mount manual lenses and they all have a white button on them. What does it do? What is it for? It doesn't push... Total newb question I'm afraid... Gene

01-14-2007, 05:53 PM - 1 Like	#2
Arjay Bee Pentaxian Join Date: Sep 2006 Location: Horn Island, Torres Straits, Q Photos: Gallery Posts: 4,715	It is an aid for the mounting system and a legacy from when pentax switched from the M42 screwmount to the bayonet K mount. Try closing your eyes and picking up the lens. Locate the button and then fit the lens to your camera. While it is not quite as convenient as on the older cameras when it lined up with the lens lock on the body, it helps you to orient the lens to the bayonet mount. The colour is like the luminescent plastic found on children's toys. Put the lens under a desk lamp and then take it into a dark cupboard and see if the green/white dot glows. Last edited by Arjay Bee; 01-14-2007 at 05:54 PM. Reason: explication

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01-14-2007, 07:31 PM	#3
roy Inactive Account Join Date: Sep 2006 Location: D/FW area, Tx. Photos: Gallery Posts: 1,710	Arjay Bee, 100% correct... it's there just in case you need to mount a lens while blind folded

01-14-2007, 10:09 PM	#4
GeneW New Member Join Date: Jan 2007 Location: Port Credit, Ontario Posts: 9 Original Poster	Arjay, Roy, thanks! Okay, I'll quit pushing it now Gene

01-15-2007, 05:48 AM	#5
Rolly Senior Member Join Date: Oct 2006 Location: Perth, Western Australia Posts: 295	Originally posted by roy Arjay Bee, 100% correct... it's there just in case you need to mount a lens while blind folded Darned useful for theatre work, street PJ afterdark, surveillance etc.

01-15-2007, 11:25 AM	#6
egarrard Inactive Account Join Date: Sep 2006 Location: Manchester, TN Photos: Gallery Posts: 51	I think Pentax is the only camera that you don't have to change your grip on the camera to change the lens. It's a safety feature nobody ever mentions.

01-15-2007, 09:39 PM	#7
Alvin Veteran Member Join Date: Dec 2006 Location: Mississauga, Ontario, Canada Photos: Gallery Posts: 2,517	Originally posted by egarrard I think Pentax is the only camera that you don't have to change your grip on the camera to change the lens. It's a safety feature nobody ever mentions. You know, I never thought about that until I was changing lenses today, and then I read your post now. Here I am holding the camera with my right hand, I push the lens release with my "right-ring" finger, twist the barrel and out goes the lens! I did it with my buddy's film based Pentax as well! I could never pull that off with the Nikon D50 or D70/70s. Same goes with the Fuji S2/S3 (based on Nikon bodies). Come to think of it you can't do it with Canon systems either. Brilliant! Sorry - didn't mean to troll.

01-16-2007, 04:19 AM	#8
JCSullivan Veteran Member Join Date: Sep 2006 Location: Windsor, Canada Posts: 3,056	I miss that "white button". As my vission is deteriorating I find myself looking for that mark since it is becoming difficult for me to see the red marking without having to put on my glasses.

01-16-2007, 08:36 AM	#9
Dana G Senior Member Join Date: Oct 2006 Location: Masachusetts Posts: 243	Originally posted by JCSullivan I miss that "white button". As my vission is deteriorating I find myself looking for that mark since it is becoming difficult for me to see the red marking without having to put on my glasses. Me too. At least the Limited lenses have a raised dot that you can feel. It makes it easier to change the lens without having to look directly at the lens, you can keep your eye on the action while changing lenses.

What does the white button do on K-lenses

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