Pentax K-x and Pentax-FA lens compatibility

Tylos · 03-26-2012, 07:16 AM

I just purchased a Pentax K-x and I got a stock 18-55mm lens with it. I also have an old Pentax MZ-50 camera with a SMC Pentax-FA 28-200mm lens.

I have attached the Pentax-FA 28-200mm lens to my new Pentax K-x and have found that in Auto Pict mode all the shots are over exposed. To get round the problem, I have to set the camera to -3 with the Av button whenever I use the Pentax-FA 28-200mm lens

Any ideas as to what may be causing the problem

Adam · 03-26-2012, 07:17 AM

Is the aperture ring not in the A position?

Tylos · 03-26-2012, 07:43 AM

Hi Adam,
thanks for your prompt reply. Yes, the lens aperture ring is set to the 'A' position. In fact, the camera will only operate with the lens ring in the 'A' position.
Thanks
Tylos

Parallax · 03-26-2012, 07:52 AM

Originally posted by First Poster

In fact, the camera will only operate with the lens ring in the 'A' position.

The lens ring does not have to be in the 'A' position for the camera to operate. There is a menu option to allow use of the aperture ring.

JinDesu · 03-26-2012, 08:06 AM

Originally posted by Tylos

I just purchased a Pentax K-x and I got a stock 18-55mm lens with it. I also have an old Pentax MZ-50 camera with a SMC Pentax-FA 28-200mm lens.

I have attached the Pentax-FA 28-200mm lens to my new Pentax K-x and have found that in Auto Pict mode all the shots are over exposed. To get round the problem, I have to set the camera to -3 with the Av button whenever I use the Pentax-FA 28-200mm lens

Any ideas as to what may be causing the problem

Is it only in Auto Picture mode? Have you tried using Av mode with both lenses at the same Aperture setting and ISO setting to see if they give the same shutter speed value?

Can you post some pictures from both to this forum so we can judge the settings the camera chose?

**crewl1** · 03-26-2012, 08:14 AM

Do the aperture blades snap back easily or are they possibly a bit sticky?
Contacts clean on both the lens and camera?
How does it behave in manual or av?

Tylos · 03-27-2012, 01:31 AM

Hi All,
Thanks for your responses.
Parallax is correct, I set the camera to enable the camera to be used with the lens aperture ring in use and now when I take shots using the aperture ring the exposure is OK at all aperture settings in the AUTO PIC mode. However, with the lens ring set back to Auto, the shots are still over exposed and I have to compensate by adjusting the AV button to -2 or -3.
I also have an old Pentax FA 28-70 lens that came with my Pentax MZ-50 and this works fine with the camera when the aperture ring is set to Auto. So I guess my FA 28-200 lens has a problem. I did inspected and clean the contacts on both lenses.
Thanks

Docrwm · 03-27-2012, 09:47 AM

Originally posted by Tylos

Hi All,
Thanks for your responses.
Parallax is correct, I set the camera to enable the camera to be used with the lens aperture ring in use and now when I take shots using the aperture ring the exposure is OK at all aperture settings in the AUTO PIC mode. However, with the lens ring set back to Auto, the shots are still over exposed and I have to compensate by adjusting the AV button to -2 or -3.
I also have an old Pentax FA 28-70 lens that came with my Pentax MZ-50 and this works fine with the camera when the aperture ring is set to Auto. So I guess my FA 28-200 lens has a problem. I did inspected and clean the contacts on both lenses.
Thanks

Glad part of it got straightened out. Shine a light down the barrel of the 28-200 and look at the aperture blades - they should look clean and dry. They should move nearly instantly in a sharp fashion from one aperture setting to another. If you see anything that looks wet or sticky, or they move sluggishly, you have found your problem. Good luck.

Tylos · 03-27-2012, 11:48 PM

Hi All,
Just finished shining a light down the lens barrel (Docrwm's suggestion) and sure enough, the aperture blades are sticking. Is it possible for me to fix this myself or is the lens now useless.
Thanks for all your comments and suggestions.
Cheers

unixrevolution · 03-28-2012, 05:29 AM

Originally posted by Tylos

Hi All,
Just finished shining a light down the lens barrel (Docrwm's suggestion) and sure enough, the aperture blades are sticking. Is it possible for me to fix this myself or is the lens now useless.
Thanks for all your comments and suggestions.
Cheers

You may not be able to fix it easily yourself, but most competent camera repair places can probably have your FA 28-200 back in working order for a relatively small fee (under $100 bucks, I'm guessing, but don't quote me!)

Docrwm · 03-28-2012, 09:33 AM

Originally posted by Tylos

Hi All,
Just finished shining a light down the lens barrel (Docrwm's suggestion) and sure enough, the aperture blades are sticking. Is it possible for me to fix this myself or is the lens now useless.
Thanks for all your comments and suggestions.
Cheers

Sorry but it's better to get to the bottom of it so you can make an informed decision about what to do (if anything).

I'd send it to Eric. Who is Eric you ask? Just the most respected Pentax Service Person around, and reasonable too.

https://www.pentaxforums.com/forums/pentax-film-slr-discussion/105296-pentax-...ndrickson.html

Home

unixrevolution · 03-28-2012, 10:41 AM

Originally posted by Docrwm

Sorry but it's better to get to the bottom of it so you can make an informed decision about what to do (if anything).

I'd send it to Eric. Who is Eric you ask? Just the most respected Pentax Service Person around, and reasonable too.

https://www.pentaxforums.com/forums/pentax-film-slr-discussion/105296-pentax-...ndrickson.html

Home

I was under the impression that he only did manual focus lenses.

Docrwm · 03-28-2012, 11:04 AM

Originally posted by unixrevolution

I was under the impression that he only did manual focus lenses.

Wow, you may well be right - I have only sent him older MF lenses and never even thought about AF lenses and that he might not do them. His website only says "Lenses 24mm to 500mm) and nothing about MF or AF. Best to check but if I'm wrong (as it may well be the case) I'm sorry.

unixrevolution · 03-29-2012, 01:46 PM

Originally posted by Docrwm

Wow, you may well be right - I have only sent him older MF lenses and never even thought about AF lenses and that he might not do them. His website only says "Lenses 24mm to 500mm) and nothing about MF or AF. Best to check but if I'm wrong (as it may well be the case) I'm sorry.

It's not a problem. He may still be able to puzzle it out. He did a Sigma 24mm F/2.8 for me. manual focus, but non-pentax.

Marc Sabatella · 03-31-2012, 07:37 AM

Originally posted by Tylos

Hi All,
Thanks for your responses.
Parallax is correct, I set the camera to enable the camera to be used with the lens aperture ring in use and now when I take shots using the aperture ring the exposure is OK at all aperture settings in the AUTO PIC mode.

Actually, while they might be of appropriate brightness, when you use the aperture ring in any mode but M, it is completely ignored, and only shoots wide open. read the sticky note at the front of Beginner's forum for more on how to use manual lenses (which your lens becomes when you use the aperture rong).

So what you are seeing is indeed consistent with sticky blades – shots come out good when shooting wide open, overexposed otherwise.

03-26-2012, 07:16 AM	#1
Tylos Guest	Pentax K-x and Pentax-FA lens compatibility I just purchased a Pentax K-x and I got a stock 18-55mm lens with it. I also have an old Pentax MZ-50 camera with a SMC Pentax-FA 28-200mm lens. I have attached the Pentax-FA 28-200mm lens to my new Pentax K-x and have found that in Auto Pict mode all the shots are over exposed. To get round the problem, I have to set the camera to -3 with the Av button whenever I use the Pentax-FA 28-200mm lens Any ideas as to what may be causing the problem

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03-26-2012, 07:17 AM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,597	Is the aperture ring not in the A position?

03-26-2012, 07:43 AM	#3
Tylos Guest	Hi Adam, thanks for your prompt reply. Yes, the lens aperture ring is set to the 'A' position. In fact, the camera will only operate with the lens ring in the 'A' position. Thanks Tylos

03-26-2012, 07:52 AM	#4
Parallax Senior Moderator Loyal Site Supporter Join Date: Apr 2008 Location: South Dakota Photos: Gallery Posts: 19,332	Originally posted by First Poster In fact, the camera will only operate with the lens ring in the 'A' position. The lens ring does not have to be in the 'A' position for the camera to operate. There is a menu option to allow use of the aperture ring.

03-26-2012, 08:06 AM	#5
JinDesu Veteran Member Join Date: Jun 2011 Location: New York City Photos: Gallery Posts: 5,638	Originally posted by Tylos I just purchased a Pentax K-x and I got a stock 18-55mm lens with it. I also have an old Pentax MZ-50 camera with a SMC Pentax-FA 28-200mm lens. I have attached the Pentax-FA 28-200mm lens to my new Pentax K-x and have found that in Auto Pict mode all the shots are over exposed. To get round the problem, I have to set the camera to -3 with the Av button whenever I use the Pentax-FA 28-200mm lens Any ideas as to what may be causing the problem Is it only in Auto Picture mode? Have you tried using Av mode with both lenses at the same Aperture setting and ISO setting to see if they give the same shutter speed value? Can you post some pictures from both to this forum so we can judge the settings the camera chose?

03-26-2012, 08:14 AM	#6
crewl1 Site Supporter Join Date: Jul 2010 Location: Los Angeles, CA Photos: Gallery \| Albums Posts: 9,807	Do the aperture blades snap back easily or are they possibly a bit sticky? Contacts clean on both the lens and camera? How does it behave in manual or av?

03-27-2012, 01:31 AM	#7
Tylos Guest	Hi All, Thanks for your responses. Parallax is correct, I set the camera to enable the camera to be used with the lens aperture ring in use and now when I take shots using the aperture ring the exposure is OK at all aperture settings in the AUTO PIC mode. However, with the lens ring set back to Auto, the shots are still over exposed and I have to compensate by adjusting the AV button to -2 or -3. I also have an old Pentax FA 28-70 lens that came with my Pentax MZ-50 and this works fine with the camera when the aperture ring is set to Auto. So I guess my FA 28-200 lens has a problem. I did inspected and clean the contacts on both lenses. Thanks

03-27-2012, 09:47 AM	#8
Docrwm Veteran Member Join Date: Sep 2010 Location: Somewhere in the Southern US Photos: Gallery \| Albums Posts: 12,285	Originally posted by Tylos Hi All, Thanks for your responses. Parallax is correct, I set the camera to enable the camera to be used with the lens aperture ring in use and now when I take shots using the aperture ring the exposure is OK at all aperture settings in the AUTO PIC mode. However, with the lens ring set back to Auto, the shots are still over exposed and I have to compensate by adjusting the AV button to -2 or -3. I also have an old Pentax FA 28-70 lens that came with my Pentax MZ-50 and this works fine with the camera when the aperture ring is set to Auto. So I guess my FA 28-200 lens has a problem. I did inspected and clean the contacts on both lenses. Thanks Glad part of it got straightened out. Shine a light down the barrel of the 28-200 and look at the aperture blades - they should look clean and dry. They should move nearly instantly in a sharp fashion from one aperture setting to another. If you see anything that looks wet or sticky, or they move sluggishly, you have found your problem. Good luck.

03-27-2012, 11:48 PM	#9
Tylos New Member Join Date: Mar 2012 Posts: 1	Hi All, Just finished shining a light down the lens barrel (Docrwm's suggestion) and sure enough, the aperture blades are sticking. Is it possible for me to fix this myself or is the lens now useless. Thanks for all your comments and suggestions. Cheers

03-28-2012, 05:29 AM	#10
unixrevolution Veteran Member Join Date: Apr 2009 Location: Waldorf, MD Photos: Gallery \| Albums Posts: 1,861	Originally posted by Tylos Hi All, Just finished shining a light down the lens barrel (Docrwm's suggestion) and sure enough, the aperture blades are sticking. Is it possible for me to fix this myself or is the lens now useless. Thanks for all your comments and suggestions. Cheers You may not be able to fix it easily yourself, but most competent camera repair places can probably have your FA 28-200 back in working order for a relatively small fee (under $100 bucks, I'm guessing, but don't quote me!)

03-28-2012, 09:33 AM	#11
Docrwm Veteran Member Join Date: Sep 2010 Location: Somewhere in the Southern US Photos: Gallery \| Albums Posts: 12,285	Originally posted by Tylos Hi All, Just finished shining a light down the lens barrel (Docrwm's suggestion) and sure enough, the aperture blades are sticking. Is it possible for me to fix this myself or is the lens now useless. Thanks for all your comments and suggestions. Cheers Sorry but it's better to get to the bottom of it so you can make an informed decision about what to do (if anything). I'd send it to Eric. Who is Eric you ask? Just the most respected Pentax Service Person around, and reasonable too. https://www.pentaxforums.com/forums/pentax-film-slr-discussion/105296-pentax-...ndrickson.html Home

03-28-2012, 10:41 AM	#12
unixrevolution Veteran Member Join Date: Apr 2009 Location: Waldorf, MD Photos: Gallery \| Albums Posts: 1,861	Originally posted by Docrwm Sorry but it's better to get to the bottom of it so you can make an informed decision about what to do (if anything). I'd send it to Eric. Who is Eric you ask? Just the most respected Pentax Service Person around, and reasonable too. https://www.pentaxforums.com/forums/pentax-film-slr-discussion/105296-pentax-...ndrickson.html Home I was under the impression that he only did manual focus lenses.

03-28-2012, 11:04 AM	#13
Docrwm Veteran Member Join Date: Sep 2010 Location: Somewhere in the Southern US Photos: Gallery \| Albums Posts: 12,285	Originally posted by unixrevolution I was under the impression that he only did manual focus lenses. Wow, you may well be right - I have only sent him older MF lenses and never even thought about AF lenses and that he might not do them. His website only says "Lenses 24mm to 500mm) and nothing about MF or AF. Best to check but if I'm wrong (as it may well be the case) I'm sorry.

03-29-2012, 01:46 PM	#14
unixrevolution Veteran Member Join Date: Apr 2009 Location: Waldorf, MD Photos: Gallery \| Albums Posts: 1,861	Originally posted by Docrwm Wow, you may well be right - I have only sent him older MF lenses and never even thought about AF lenses and that he might not do them. His website only says "Lenses 24mm to 500mm) and nothing about MF or AF. Best to check but if I'm wrong (as it may well be the case) I'm sorry. It's not a problem. He may still be able to puzzle it out. He did a Sigma 24mm F/2.8 for me. manual focus, but non-pentax.

03-31-2012, 07:37 AM	#15
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	Originally posted by Tylos Hi All, Thanks for your responses. Parallax is correct, I set the camera to enable the camera to be used with the lens aperture ring in use and now when I take shots using the aperture ring the exposure is OK at all aperture settings in the AUTO PIC mode. Actually, while they might be of appropriate brightness, when you use the aperture ring in any mode but M, it is completely ignored, and only shoots wide open. read the sticky note at the front of Beginner's forum for more on how to use manual lenses (which your lens becomes when you use the aperture rong). So what you are seeing is indeed consistent with sticky blades – shots come out good when shooting wide open, overexposed otherwise.