Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-23-2010, 05:04 PM   #1
Inactive Account




Join Date: Dec 2010
Posts: 5
Compatibility issue with Tamron 28-75 ?

Hi everyone !
I bought the K-5 with a Tamron 28-75 lense ( Tamron -28-75mm F/2.8(Model A09) ) and I'm having some problems with those two. Since I'm new to Pentax, I wanted to make sure that I had tried everything before complaining to Tamron . So here I am, asking for help in case I overlooked something.

There are two (likely related) problems :
1) when I switch the camera on (with the Tamron lense mounted), it asks me for the "Input focal length". From what I have understood, it happens when the lense doesn't report focal information to the camera... but I believe that this lense is supposed to do so.
2) I can't autofocus : the camera is stuck in manual focus whatever I do (autofocus switch, autofocus button)

The aperture ring is set to "A" and the lense is mounted properly on the camera (AFAICT). I have another lense from Sigma (Sigma AF 70-200mm f/2.8 EX HSM APO DG macro) which is working fine so I believe the problem comes from the Tamron lense...

I updated the camera's firmware to v1.01, I tried to re-mount the lense several times, but nothing has worked so far.

Has anyone experienced a similar issue or is having some clue about what is going wrong ?
Thanks in advance for your help

12-23-2010, 05:38 PM   #2
Ole
Administrator
Ole's Avatar

Join Date: Sep 2006
Location: Copenhagen, Denmark
Photos: Gallery | Albums
Posts: 3,881
Sure sounds as if you know what you're doing - and the Sigma works. The Tamron must be defective.
12-23-2010, 05:56 PM   #3
Site Supporter
SpecialK's Avatar

Join Date: Dec 2006
Location: So California
Photos: Gallery
Posts: 14,904
If it is a new lens, it sounds like it is the problem. If it is used, perhaps it's just dirty contacts on the back.
12-23-2010, 06:06 PM   #4
Veteran Member
Raybo's Avatar

Join Date: Dec 2007
Posts: 871
It's the contacts (on the lens IMHO)!
Clean the contacts on both the lens AND body just to make sure.

12-23-2010, 10:40 PM   #5
m8o
Veteran Member
m8o's Avatar

Join Date: Jul 2007
Location: 40-55'-44" N / 73-24'-07" W [on LI]
Photos: Gallery | Albums
Posts: 3,102
QuoteOriginally posted by kamui Quote
The aperture ring is set to "A" and the lense is mounted properly on the camera (AFAICT).
Have you tried moving the aperture ring off the "A", thru the whole range, then clicking it back into "A" with authority? I've had many instances where a lens looked like it was in "A", this same Tamron being the one more than once, but I needed to re-seat it to really be in the "A" position.
12-24-2010, 01:27 AM   #6
Inactive Account




Join Date: Dec 2010
Posts: 5
Original Poster
QuoteQuote:
If it is a new lens, it sounds like it is the problem. If it is used, perhaps it's just dirty contacts on the back.
Both the camera and the lens are brand new :/
I cleaned the contacts just to be sure, but still no luck :'(

QuoteQuote:
Have you tried moving the aperture ring off the "A", thru the whole range, then clicking it back into "A" with authority? I've had many instances where a lens looked like it was in "A", this same Tamron being the one more than once, but I needed to re-seat it to really be in the "A" position.
I triple-checked that one too, but didn't work unfortunately...

Seems like i'm going to bring the lense back... That sucks, it was my only mid-range zoom :/
Many thanks for your replies anyway
12-24-2010, 07:08 AM   #7
Inactive Account




Join Date: Aug 2010
Location: Singapura
Posts: 23
I have been using the 28-75 as my workhorse lens everytime. So far used it with K-5 no problem.
12-24-2010, 09:30 AM   #8
Inactive Account




Join Date: Dec 2008
Location: Ames, Iowa, USA
Photos: Albums
Posts: 2,965
It is behaving as if the lens is not set to the A position or the A pin is not making contact with the mount. When the aperture ring is switched to the A position does the A pin protrude? When in the A position there should be electrical continuity between the pin and the lens base; is there continuity? Try twisting the lens in the mount a bit while holding the lens release button down..

12-24-2010, 03:04 PM   #9
Inactive Account




Join Date: Dec 2010
Posts: 5
Original Poster
QuoteOriginally posted by ricsal Quote
I have been using the 28-75 as my workhorse lens everytime. So far used it with K-5 no problem.
You just gave me some hope back ! Can you confirm that you use this lense : Tamron -28-75mm F/2.8(Model A09) on the Pentax K-5 and have no problem at all with the autofocus and the detection of the lense by the camera ? Not that I don't believe you but I need to be 100% sure that this lense is compatible with the K-5 and that I "just" picked a defective one.
Here is the situation : I have (legally) 7 days to bring back the lense and get my money back, after that I'm stuck with it. I don't mind keeping it as long as it can AF with my K-5, even if I need to have it repaired by Tamron. But I don't want to keep it if there is no hope to get the AF working with the K-5.
Perhaps you might tell me if you can see some visible differences between your lense and mine (cf. photos attached) ?

QuoteOriginally posted by newarts Quote
It is behaving as if the lens is not set to the A position or the A pin is not making contact with the mount. When the aperture ring is switched to the A position does the A pin protrude?
Yes it does. More than when it is set to an aperture other than 'A'.


QuoteOriginally posted by newarts Quote
When in the A position there should be electrical continuity between the pin and the lens base; is there continuity? Try twisting the lens in the mount a bit while holding the lens release button down..
I don't understand what you mean by "continuity" and how I could verify it. Here is what the contacts look like on tboth the lense and camera, do you see something wrong ?


Anyway, I tried twisting the lens, but it didn't work either (I don't want to force too much though)


Here is what the K-5 is showing at startup :


And here is what the LCDs are showing when using the Tamron lense (note that the aperture display is blinking, on both LCDs, and I don't think it is normal to have "F--" as aperture on the small LCD :/) The LCD shows "MF" despite the camera is set to AF-S



I spent the day trying to find a kind reseller to test both the camera and the lense, but none of them had the Tamron in stock (not with the Pentax mount). However, I had the chance to try my lense with a K-7 and another K-5 and the result is the same as with mine : no AF. I was also able to try a pentax lense which was working fine, like my Sigma.

Thanks again for helping me troubleshoot this issue, you've already been very helpful. Merry Christmas !
12-24-2010, 03:39 PM   #10
Inactive Account




Join Date: Dec 2008
Location: Ames, Iowa, USA
Photos: Albums
Posts: 2,965
QuoteQuote:
I don't understand what you mean by "continuity" and how I could verify it. Here is what the contacts look like on tboth the lense and camera, do you see something wrong ?
I mean electrical continuity. Use an ohm-meter to measure the resistance between the top of the pin and the lens metal outside the pin.

If the resistance is zero, the pin is ok but it is not protruding far enough or is not aligning with the camera side recess precisely enough to make contact on the camera side of the mount. If the resistance is not zero the pin is not working correctly. In either case the lens is faulty.

Dave
12-24-2010, 03:59 PM   #11
m8o
Veteran Member
m8o's Avatar

Join Date: Jul 2007
Location: 40-55'-44" N / 73-24'-07" W [on LI]
Photos: Gallery | Albums
Posts: 3,102
QuoteOriginally posted by kamui Quote
You just gave me some hope back ! Can you confirm that you use this lense : Tamron -28-75mm F/2.8(Model A09) on the Pentax K-5 and have no problem at all with the autofocus and the detection of the lense by the camera ? Not that I don't believe you but I need to be 100% sure that this lense is compatible with the K-5 and that I "just" picked a defective one.
p.s. I know you wren't asking this above of me, but when I had replied previously I guess I should have mentioned that I used it with the K-5 last. If it's giving you that much trouble, you should return it with haste to meet the 7-day return window.
12-24-2010, 05:13 PM   #12
Inactive Account




Join Date: Dec 2010
Posts: 5
Original Poster
QuoteOriginally posted by newarts Quote
I mean electrical continuity. Use an ohm-meter to measure the resistance between the top of the pin and the lens metal outside the pin.

If the resistance is zero, the pin is ok but it is not protruding far enough or is not aligning with the camera side recess precisely enough to make contact on the camera side of the mount. If the resistance is not zero the pin is not working correctly. In either case the lens is faulty.

Dave
I tested it but without any conviction : my ohm-meter is antique, not sure it's actually working or sensitive enough to actually show something. Besides these tests will only be able to reveal problems that I can't fix by myself. But thanks for this tip, I'll keep it in mind, should another lens fail on me It's always good to know how to troubleshoot


QuoteOriginally posted by m8o Quote
p.s. I know you wren't asking this above of me, but when I had replied previously I guess I should have mentioned that I used it with the K-5 last. If it's giving you that much trouble, you should return it with haste to meet the 7-day return window.
Thanks for your testimony that this lense does work fine with the K-5 !
As for all the "return or not return" thing, my problem is that I'm going on vacation soon and have bought this camera and the lense with the idea to use them during my trip. Without the tamron lense, I'll only have the (full frame) Sigma 70-200 and that doesn't quite fit with the shooting I intended to do over there :/
On the other hand, if I'm sure that the lense is compatible and can be fixed by sending it back to Tamron (which is different of giving it back to the reseller), I can live with no AF for this small amount of time and have it repaired as soon as I am back.
I just wanted to make sure that it was a "defect issue" (fixable) and not a "compatibility issue" (not fixable) And your testimony as well as Ricsal's reassured me.

In the end, I will most likely keep the lense for my trip, and return it to Tamron using the warranty once I come back. In the mean time, I will probably get a true APS-C wide angle lense (I'm thinking Sigma 8-16)

Again, thank you for your quick help and feedback all of you
12-24-2010, 05:34 PM   #13
Forum Member




Join Date: Jan 2009
Location: Berlin, Germany
Posts: 62
I'm also using this lense on a K-5 and it works the way it should. To me it seems although as Tamron is having quality issues with this model. It took them 7 repair attemps and four replacements to eventually hand out a lense w/o flaw. So looking back to two years of expenrience with Tamron support, I am pretty conviced, the lense needs some service. My advice is to look sharply at all features the lense offers, to make sure you gain full functionality once the lense is replaced or repaired, i.e. proper transfer or the focal length into a pic's EXIF, symmetric IQ (same sharpness on either side), all aperture values working (lighting correct?). Maybe I am a bit hysteric about this; hope you get along with less hassle.

k.
12-24-2010, 06:25 PM   #14
Inactive Account




Join Date: Dec 2008
Location: Ames, Iowa, USA
Photos: Albums
Posts: 2,965
Try putting a piece of aluminum foil over the A pin as you mount the lens. It may be sufficient to make contact & the lens will work as it should. It will not harm anything-the lens base & mount are designed to contact metal.

There is a good chance this will work.

Dave
12-25-2010, 09:49 AM   #15
hcc
Pentaxian
hcc's Avatar

Join Date: Nov 2009
Location: Brisbane, Australia
Photos: Gallery | Albums
Posts: 3,531
Could it be a firmware issue with the Tamron lens?

Another Pentaxian reported a similar problem with two Sigma lenses and the K-5:
https://www.pentaxforums.com/forums/pentax-k-5-forum/126924-two-three-sigma-l...focus-all.html

I woud suggest that you send back the Tamron lens for repair / firmware update under the warranty.
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!
autofocus, camera, compatibility issue, dslr, issue with tamron, k-5, k-5 ii, k-5 iis, k5, lense, pentax k-5, sigma, switch, tamron
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Tamron 17-50mm Issue: Overexposure d3zzzz Pentax SLR Lens Discussion 7 09-16-2010 04:42 AM
Sigma EF-530 DG ST compatibility issue with K-x? chaplinlau Flashes, Lighting, and Studio 0 04-24-2010 06:40 AM
Tamron Lens Compatibility jmgacnik Pentax SLR Lens Discussion 2 07-04-2009 05:47 PM
Tamron 28-75 focussing issue charlep Pentax SLR Lens Discussion 0 01-19-2009 02:50 PM
Tamron 28-75mm f/2.8 Focusing Issue Scout Pro Pentax SLR Lens Discussion 3 04-15-2008 07:46 PM



All times are GMT -7. The time now is 01:37 AM. | 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