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Muse · 10-15-2010, 07:25 AM

What's that green semi-sphere plastic nob thing next to the aperture ring? I assume it's green, I'm actually total green blind, so I'm guessing!

When locked on A mode, the nob is right over the "2" of the 2.8 on the aperture ring.

I just received my used lens from an ebay auction, and it does seem as-new. Obviously, the former owner hardly used it or maybe didn't use it ever! Took a few shots yesterday. It's my first prime (have 4 zooms). I suppose it's best suited to portraiture, head and shoulders shots.

Last edited by Muse; 10-15-2010 at 09:02 AM.

kari · 10-15-2010, 07:48 AM

It's yellow

, or at least mine is. I have no idea what it is there for though.

causey · 10-15-2010, 08:55 AM

It should be yellow... I think it's there to help with dismounting the lens--something to keep your finger on. Is "Pentax A 50mm" written anywhere on the lens? CPC/Cosmicar are exactly like Pentax A, only without SMC.

Muse · 10-15-2010, 09:05 AM

Originally posted by causey

It should be yellow... I think it's there to help with dismounting the lens--something to keep your finger on. Is "Pentax A 50mm" written anywhere on the lens? CPC/Cosmicar are exactly like Pentax A, only without SMC.

OK, I would have guessed yellow-green, but I can never make a positive identification for green, missing the green cones in my eyes, so I always have to guess on that color. They tell me grass is green, so it's a good guess (for grass!).

It says on the lens verbatim:

SMC PENTAX-A 1:1.7 50mm

**pschlute** · 10-15-2010, 09:45 AM

These knobs were put on Pentax lenses so that if you were trying to mount a lens in the dark you aligned the knob with the lens release button.

Modern Pentax cameras don't have the lens release in the same place.

**stevebrot** · 10-15-2010, 10:03 AM

Originally posted by pschlute

These knobs were put on Pentax lenses so that if you were trying to mount a lens in the dark you aligned the knob with the lens release button.

Modern Pentax cameras don't have the lens release in the same place.

What he said...

The color varies by lens series. My FA 77/1.8 Limited is pearlescent green. My K and M lenses are white. My A 50/1.7 is ivory. Interestingly, my Tamron adaptall-2 K-mount adapters have a notch at the edge of the adapter flange that serves the same purpose.

Steve

10-15-2010, 07:25 AM	#1
Muse Senior Member Join Date: Jul 2010 Location: SF Bay Photos: Gallery \| Albums Posts: 211	Pentax-A f1.7 50mm question What's that green semi-sphere plastic nob thing next to the aperture ring? I assume it's green, I'm actually total green blind, so I'm guessing! When locked on A mode, the nob is right over the "2" of the 2.8 on the aperture ring. I just received my used lens from an ebay auction, and it does seem as-new. Obviously, the former owner hardly used it or maybe didn't use it ever! Took a few shots yesterday. It's my first prime (have 4 zooms). I suppose it's best suited to portraiture, head and shoulders shots. Last edited by Muse; 10-15-2010 at 09:02 AM.

10-15-2010, 10:03 AM	#6
stevebrot Site Supporter Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 27,474	Originally posted by pschlute These knobs were put on Pentax lenses so that if you were trying to mount a lens in the dark you aligned the knob with the lens release button. Modern Pentax cameras don't have the lens release in the same place. What he said... The color varies by lens series. My FA 77/1.8 Limited is pearlescent green. My K and M lenses are white. My A 50/1.7 is ivory. Interestingly, my Tamron adaptall-2 K-mount adapters have a notch at the edge of the adapter flange that serves the same purpose. Steve Last edited by stevebrot; 10-15-2010 at 04:03 PM.

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10-15-2010, 07:48 AM	#2
kari Senior Member Join Date: Feb 2010 Photos: Albums Posts: 149	It's yellow , or at least mine is. I have no idea what it is there for though.

10-15-2010, 08:55 AM	#3
causey Veteran Member Join Date: Feb 2009 Location: Arlington, VA Photos: Albums Posts: 3,758	It should be yellow... I think it's there to help with dismounting the lens--something to keep your finger on. Is "Pentax A 50mm" written anywhere on the lens? CPC/Cosmicar are exactly like Pentax A, only without SMC.

10-15-2010, 09:05 AM	#4
Muse Senior Member Join Date: Jul 2010 Location: SF Bay Photos: Gallery \| Albums Posts: 211 Original Poster	Originally posted by causey It should be yellow... I think it's there to help with dismounting the lens--something to keep your finger on. Is "Pentax A 50mm" written anywhere on the lens? CPC/Cosmicar are exactly like Pentax A, only without SMC. OK, I would have guessed yellow-green, but I can never make a positive identification for green, missing the green cones in my eyes, so I always have to guess on that color. They tell me grass is green, so it's a good guess (for grass!). It says on the lens verbatim: SMC PENTAX-A 1:1.7 50mm

10-15-2010, 09:45 AM	#5
pschlute Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 1,240	These knobs were put on Pentax lenses so that if you were trying to mount a lens in the dark you aligned the knob with the lens release button. Modern Pentax cameras don't have the lens release in the same place.

Pentax-A f1.7 50mm question

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