Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
11-07-2012, 08:01 AM   #1
New Member




Join Date: Nov 2012
Posts: 9
SMC Pentax-A 50mm F1.7 Problem

First post - so apologies if in wrong forum. Currently using a Samsung GX20 with a Pentax DA 16-45 - all working well (and in my defence the GX20 was preceded by an SF7 and an ME Super). Then I got this Pentax-A 50mm F1.7 - but when on the GX20, its aperture is shown as F-.-. and I can't take any pics regardless of camera settings (and I have used menu to select 'Aperture Ring' - but made no difference). The mechanics of the lens appear to work fine but I'm suspecting it has been fiddled with - should there be an open hole in the contact group area of the mount? - between 2 and 3 o'clock in the attached picture.

Any advice on cause of problem or ways to fix very welcome.

Attached Images
View Picture EXIF
DMC-TZ10  Photo 
11-07-2012, 08:08 AM   #2
Senior Member




Join Date: Jul 2012
Location: SW Florida
Posts: 234
You have a contact pin missing.You should be able to use the lens as a M type
11-07-2012, 08:28 AM   #3
New Member




Join Date: Nov 2012
Posts: 9
Original Poster
Thanks very much - you are quite right - it will take pictures with the camera set on aperture priority. Is there likely to be any sensible way of repairing it?
11-07-2012, 08:32 AM   #4
Senior Member




Join Date: Jul 2012
Location: SW Florida
Posts: 234
Think it will stay wide open in Av mode but will work properly in M

11-07-2012, 08:44 AM - 1 Like   #5
Pentaxian
Just1MoreDave's Avatar

Join Date: Feb 2007
Location: Aurora, CO
Photos: Gallery | Albums
Posts: 4,862
This article shows what's missing: https://www.pentaxforums.com/forums/maintenance-repair-articles/88051-pentax-...ng-repair.html

I've read about using different things to replace the contact. It needs to be spring-loaded or the lens won't mount. That's the tricky part.
11-07-2012, 09:06 AM   #6
New Member




Join Date: Nov 2012
Posts: 9
Original Poster
Again you are right about Av mode - the camera always takes the picture at f1.7 - but in M mode I get no indication of aperture so no indication of over/under exposure - so not a lot of use! Unless the lens can be fixed I'll dump it & get one that works.

thanks again
11-07-2012, 09:09 AM   #7
New Member




Join Date: Nov 2012
Posts: 9
Original Poster
@ Just1MoreDave - thanks very much - article spot-on
11-07-2012, 01:58 PM   #8
Site Supporter
JimJohnson's Avatar

Join Date: Jan 2012
Location: Lake Superior - Michigan
Photos: Gallery
Posts: 2,271
QuoteOriginally posted by bluemarvin Quote
Any advice on cause of problem or ways to fix very welcome.
Ideally you will repair the lens. The missing contact is the pin that extends itself when the aperture ring is locked in the 'A' position. There IS a fix you can apply in only a few minutes time that will restore full functionality to this lens.
https://www.pentaxforums.com/forums/pentax-k-r/178928-kr-short-contacts-chang...ml#post1867401

Once you short the contact as described, simply lock the aperture ring in the 'A' position and you will have full functionality with the camera and lens until (if) you decide to repair it.

11-07-2012, 02:52 PM   #9
New Member




Join Date: Nov 2012
Posts: 9
Original Poster
QuoteOriginally posted by JimJohnson Quote
Ideally you will repair the lens. The missing contact is the pin that extends itself when the aperture ring is locked in the 'A' position. There IS a fix you can apply in only a few minutes time that will restore full functionality to this lens.
https://www.pentaxforums.com/forums/pentax-k-r/178928-kr-short-contacts-chang...ml#post1867401

Once you short the contact as described, simply lock the aperture ring in the 'A' position and you will have full functionality with the camera and lens until (if) you decide to repair it.
Thanks for that - I'm a little bit wary of modifying the camera as it works fine with my other lenses. I'll try to fix this lens if I can find the bits.
11-07-2012, 04:16 PM   #10
Veteran Member
hks_kansei's Avatar

Join Date: Jun 2012
Posts: 795
If you need parts you may be able to buy the relatively cheap A series F2 lens.

I'm not cure if the parts are interchangable, but I imagine they would be.
11-07-2012, 04:37 PM   #11
Site Supporter
JimJohnson's Avatar

Join Date: Jan 2012
Location: Lake Superior - Michigan
Photos: Gallery
Posts: 2,271
QuoteOriginally posted by bluemarvin Quote
Thanks for that - I'm a little bit wary of modifying the camera as it works fine with my other lenses.
Obviously it is your choice. That said, shorting out the A pin on the body is easily, quickly and 100% reversible if you don't like it; further it will work just fine with any lens you can mount on your camera. The only difference is your camera will think all your lens are 'A' capable ... if a lens is 'A' capable, absolutely NO difference in performance. If the lens is a non-A, manual lens you use it exactly the same as you always did, only now you will see an aperture value and won't see "F - - -".

I have two Pentax A-series lenses, one F-series, three DA-series, a Sigma F-series equivalent lens. I frequently mount my A-50mm f/1.7 on a manual macro-converter giving me the equivalent of an M-series lens, and I have a Pentax K-mount bellows unit. Everything works perfectly, and I've never found a need to undo this modification. In another post in this forum I proved that I could even successfully do P-TTL flash photography using a borrowed M-50mm f/1.2 lens.
11-08-2012, 01:22 AM   #12
New Member




Join Date: Nov 2012
Posts: 9
Original Poster
Thanks to everyone for help/advice. Not at home for next 2 weeks so can't try repairs/mods - but will report on progress when I get back.

cheers
11-08-2012, 08:24 PM   #13
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by bluemarvin Quote
Again you are right about Av mode - the camera always takes the picture at f1.7 - but in M mode I get no indication of aperture so no indication of over/under exposure - so not a lot of use!
Not sure if you've already figured this out or not, but the above is *not* true. I mean, yes, it's true that you don't get an indication of aperture, but that doesn't meant you can't get an indication of over/underexposure. You just need to get the camera to stop down the lens for you, by doing DOF preview. Or simply hit the Green button so the camera will automatically stop the lens down, take a meter reading, and set an appropriate shutter speed for you. Do a search and you should be able to find any number of articles explaining more about how to use manual lenses. Some of us use them a lot! With the Green button and DOF preview, it's really not much less convenient than using an "A" lens.
11-08-2012, 09:33 PM   #14
Site Supporter




Join Date: Jul 2008
Location: Detroit MI, USA
Posts: 503
The contact pin is in the wrong hole. I can tell by looking at the screws and lens retainer someone took this lens apart before and when they put it back together things gut ugly. Take a look at all Pentax A only primes as yours. What you are missing is the little white cap that goes where the contact is now. You can try to move the contact over by removing the back cover very carefully. Have a magnet pickup tool ready. A small steel ball will come out and perhaps a spring or two. Thats what happened last time. But just remove the cover slow and aperture ring slow. The steel ball you don't see that I am talking about provided the clicks as you move the aperture ring.

I see others give you links to repair. But just know its in the wrong hole!
11-08-2012, 09:53 PM   #15
Senior Member




Join Date: Jul 2012
Location: SW Florida
Posts: 234
QuoteOriginally posted by jamesm007 Quote
The contact pin is in the wrong hole. I can tell by looking at the screws and lens retainer someone took this lens apart before and when they put it back together things gut ugly. Take a look at all Pentax A only primes as yours. What you are missing is the little white cap that goes where the contact is now. You can try to move the contact over by removing the back cover very carefully. Have a magnet pickup tool ready. A small steel ball will come out and perhaps a spring or two. Thats what happened last time. But just remove the cover slow and aperture ring slow. The steel ball you don't see that I am talking about provided the clicks as you move the aperture ring.

I see others give you links to repair. But just know its in the wrong hole!
Good catch,you are absolutely right
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
50mm, f1.7, gx20, pentax help, pentax-a, pentax-a 50mm f1.7, smc pentax-a 50mm
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
SMC Pentax A 50mm F1.7 Samples alan_smithee_photos Lens Sample Photo Archive 9 02-24-2015 11:36 PM
SMC Pentax-M 50mm F1.7 focus problem? Deano1969 Pentax SLR Lens Discussion 9 06-17-2011 12:04 PM
For Sale - Sold: SMC Pentax-A 50mm F1.7 occhicone98 Sold Items 3 02-19-2011 11:42 AM
My Poor smc Pentax-M 50mm f1.7 (Aperture Blade Problem...) AaronBHicks Pentax SLR Lens Discussion 7 01-30-2011 11:00 AM



All times are GMT -7. The time now is 09:04 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top