SMC Pentax-A 50mm f/2 Prime Lens

wildfiremyst · 12-20-2011, 06:52 AM

Bought this lens its on its way. Do I need an adapter to mount it on my K-r.

ducdao · 12-20-2011, 07:06 AM

Nope. It has a K-mount so will mount directly on your K-r

wildfiremyst · 12-20-2011, 07:22 AM

Thank you was hoping that was the case. Having a hard time figuring out all this lens stuff

Adam · 12-20-2011, 07:26 AM

Pentax K-Mount Lenses Explained: The differences between various Pentax lens series

Adam
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ablundon · 12-20-2011, 08:08 AM

Don't forget the M42 lenses as well. A $20 adapter opens up a whole new world of possible vintage lens choices.

There is a good list here:
Pentax Reviews - Pentax Lens Reviews & Lens Database

RioRico · 12-20-2011, 08:09 AM

The main trick of using this lens: Leave the aperture ring set to A. This allows metering and exposing in all Auto modes, and matrix metering, and pTTL flash. If you ever want to physically set the aperture ring to a specific f-stop, be sure that your have set USING APERTURE RING to PERMITTED in the camera's Custom menu. Have fun!

Philoslothical · 12-20-2011, 09:53 AM

Originally posted by RioRico

and matrix metering

~~Hmm, pretty sure no matrix metering with A lenses on the K-r, unsure of other models. I'll check this in a bit, but I'm fairly sure it's limited to spot and center weighted.~~

Last edited by Philoslothical; 12-20-2011 at 01:01 PM.

RioRico · 12-20-2011, 11:24 AM

Originally posted by Philoslothical

Hmm, pretty sure no matrix metering with A lenses on the K-r, unsure of other models. I'll check this in a bit, but I'm fairly sure it's limited to spot and center weighted.

K20D manual, p.98, USING THE MULTI-SEGMENT METERING:

Quote:

The center-weighted metering mode is automatically set even if you select the multi-segment metering mode when using a lens other than a DA, D FA, FA J, FA, or A lens, or when lens aperture ring is set at other than A.

A-type lenses support multi-segment (matrix) metering.

Philoslothical · 12-20-2011, 01:01 PM

Yep, I was very wrong on that. I must have been thinking of older manual lenses.

12-20-2011, 06:52 AM	#1
wildfiremyst New Member Join Date: Oct 2011 Posts: 10	SMC Pentax-A 50mm f/2 Prime Lens Bought this lens its on its way. Do I need an adapter to mount it on my K-r.

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12-20-2011, 07:06 AM	#2
ducdao Pentaxian Join Date: Dec 2009 Location: Montreal/Vermont Posts: 2,160	Nope. It has a K-mount so will mount directly on your K-r

12-20-2011, 07:22 AM	#3
wildfiremyst New Member Join Date: Oct 2011 Posts: 10 Original Poster	Thank you was hoping that was the case. Having a hard time figuring out all this lens stuff

12-20-2011, 07:26 AM	#4
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,597	Pentax K-Mount Lenses Explained: The differences between various Pentax lens series Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

12-20-2011, 08:08 AM	#5
ablundon Senior Member Join Date: Jan 2011 Location: Paradise, NL Photos: Albums Posts: 106	Don't forget the M42 lenses as well. A $20 adapter opens up a whole new world of possible vintage lens choices. There is a good list here: Pentax Reviews - Pentax Lens Reviews & Lens Database

12-20-2011, 08:09 AM	#6
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	The main trick of using this lens: Leave the aperture ring set to A. This allows metering and exposing in all Auto modes, and matrix metering, and pTTL flash. If you ever want to physically set the aperture ring to a specific f-stop, be sure that your have set USING APERTURE RING to PERMITTED in the camera's Custom menu. Have fun!

12-20-2011, 09:53 AM	#7
Philoslothical Veteran Member Join Date: May 2011 Posts: 1,889	Originally posted by RioRico and matrix metering ~~Hmm, pretty sure no matrix metering with A lenses on the K-r, unsure of other models. I'll check this in a bit, but I'm fairly sure it's limited to spot and center weighted.~~ Last edited by Philoslothical; 12-20-2011 at 01:01 PM.

12-20-2011, 11:24 AM	#8
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Originally posted by Philoslothical Hmm, pretty sure no matrix metering with A lenses on the K-r, unsure of other models. I'll check this in a bit, but I'm fairly sure it's limited to spot and center weighted. K20D manual, p.98, USING THE MULTI-SEGMENT METERING: Quote: The center-weighted metering mode is automatically set even if you select the multi-segment metering mode when using a lens other than a DA, D FA, FA J, FA, or A lens, or when lens aperture ring is set at other than A. A-type lenses support multi-segment (matrix) metering.

12-20-2011, 01:01 PM	#9
Philoslothical Veteran Member Join Date: May 2011 Posts: 1,889	Yep, I was very wrong on that. I must have been thinking of older manual lenses.