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05-16-2016, 02:02 PM   #1
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Pentax K-1 + Tamron 28-75 f/2.8 = Front Focusing, halp?

Hello!

I have been enjoying my K-1 for the last two weeks. I've got an array of lenses that are performing incredible well, given the demands of a modern FF DSLR camera, specially the DA 50 F1.8 and the DA* 50-135 F/2.8. I also got a Tamron 28-75 f/2.8 just to go along with my brand new camera. The lens is in good condition and takes sharp pictures when stopped down a little bit and/or with contrast or manual focusing...

BUT

Using phase detection focusing, it just doesn't get tack sharp and front focuses very heavily, so much that even the microfocus adjustment menu is not able to compensate at -10. This is something I've encountered in my K-5 with the DA* 50-135, and was able to fix it by going into debug mode and adjusting to need.

What can I do to fix this issue with the K-1? Is there some debug-mode activation effort being made? Who is responsible for this issue? Tamron or Pentax? Any ideas?

Thank you so much for any ideas that you might hurl this way and I'll make sure to update on this issue.

05-16-2016, 02:16 PM   #2
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QuoteOriginally posted by hectorse Quote
Hello!

I have been enjoying my K-1 for the last two weeks. I've got an array of lenses that are performing incredible well, given the demands of a modern FF DSLR camera, specially the DA 50 F1.8 and the DA* 50-135 F/2.8. I also got a Tamron 28-75 f/2.8 just to go along with my brand new camera. The lens is in good condition and takes sharp pictures when stopped down a little bit and/or with contrast or manual focusing...

BUT

Using phase detection focusing, it just doesn't get tack sharp and front focuses very heavily, so much that even the microfocus adjustment menu is not able to compensate at -10. This is something I've encountered in my K-5 with the DA* 50-135, and was able to fix it by going into debug mode and adjusting to need.

What can I do to fix this issue with the K-1? Is there some debug-mode activation effort being made? Who is responsible for this issue? Tamron or Pentax? Any ideas?

Thank you so much for any ideas that you might hurl this way and I'll make sure to update on this issue.
My copy was front focusing as well, but easily corrected with around -3 microfocus. I would say its Tamron's problem, however, since Pentax can't do anything about how another company's lens acts on their camera.
05-16-2016, 02:30 PM   #3
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QuoteOriginally posted by hectorse Quote
Using phase detection focusing, it just doesn't get tack sharp and front focuses very heavily, so much that even the microfocus adjustment menu is not able to compensate at -10. This is something I've encountered in my K-5 with the DA* 50-135, and was able to fix it by going into debug mode and adjusting to need.
I'm kind of surprised the DA 50-135 was off so much. I've had a couple FA lenses that just wouldn't play with my K3 and ended up selling them.

You can try the repair route if you have a good place locally, but given the value of the lens, I don't know if it's worth the effort. You may just end doing what I did, which was selling it at a discount and picking up another copy that fits within your camera's tolerances.

I have one lens that was probably a -11-ish on my K3, but I held onto it, because it was a pricier piece of FF glass. On my K1, it's a -2. Go figure. Chances are your lens will work great on someone else's K1. Maybe time for it to find a new home.
05-16-2016, 02:40 PM   #4
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You could also possibly make a global adjustment on your camera (that will affect all of your lenses) then dial -10 on the Tamron. You would have to correct all your other lens to compensate for the global adjustment that you made on the camera. Mind you, I'm not sure that this is a viable solution, but I recall it was a possibility. I could be wrong though.

Also, some company offer focus calibration. You could maybe send your lens and preferably your camera body to Tamron for them to mate them properly. I'm pretty sure Sigma offers that service, Tamron, I don't know.

---------- Post added 05-16-16 at 05:41 PM ----------

QuoteOriginally posted by nomadkng Quote
I'm kind of surprised the DA 50-135 was off so much. I've had a couple FA lenses that just wouldn't play with my K3 and ended up selling them.

You can try the repair route if you have a good place locally, but given the value of the lens, I don't know if it's worth the effort. You may just end doing what I did, which was selling it at a discount and picking up another copy that fits within your camera's tolerances.

I have one lens that was probably a -11-ish on my K3, but I held onto it, because it was a pricier piece of FF glass. On my K1, it's a -2. Go figure. Chances are your lens will work great on someone else's K1. Maybe time for it to find a new home.
Note to myself : if I see a lens from you on the marketplace, I must assume something is wrong with it.

05-16-2016, 02:51 PM   #5
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QuoteOriginally posted by kp0c Quote
Note to myself : if I see a lens from you on the marketplace, I must assume something is wrong with it.
fair enough, I understand the attempt at humor. but since my reputation is very important and others aren't quite as willing to put statements in true context, please note a couple of my more recent listings. You will see I go out of my way to disclose faults. The 3 listed working lenses were sold for about half their normal resale value.

https://www.pentaxforums.com/forums/36-sold-items/306751-sale-sold-sigma-100-...carefully.html

https://www.pentaxforums.com/forums/36-sold-items/297730-sale-sold-2-1-deal-d...works-but.html

https://www.pentaxforums.com/forums/36-sold-items/266988-sale-sold-fa28-big-price-drop.html

below are links to 2 transactions after a hiking mishap:

https://www.pentaxforums.com/forums/36-sold-items/60991-sale-sold-sigma-24-70...n-working.html

https://www.pentaxforums.com/forums/36-sold-items/60988-sale-sold-k10d-non-working.html

Last edited by nomadkng; 05-16-2016 at 02:58 PM.
05-16-2016, 04:15 PM   #6
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QuoteOriginally posted by nomadkng Quote
fair enough, I understand the attempt at humor. but since my reputation is very important and others aren't quite as willing to put statements in true context, please note a couple of my more recent listings. You will see I go out of my way to disclose faults. The 3 listed working lenses were sold for about half their normal resale value.

https://www.pentaxforums.com/forums/36-sold-items/306751-sale-sold-sigma-100-...carefully.html

https://www.pentaxforums.com/forums/36-sold-items/297730-sale-sold-2-1-deal-d...works-but.html

https://www.pentaxforums.com/forums/36-sold-items/266988-sale-sold-fa28-big-price-drop.html

below are links to 2 transactions after a hiking mishap:

https://www.pentaxforums.com/forums/36-sold-items/60991-sale-sold-sigma-24-70...n-working.html

https://www.pentaxforums.com/forums/36-sold-items/60988-sale-sold-k10d-non-working.html
Nomadkng-Extend mic...DROP. Exit.
Nice rebuttal. I'd buy from you.
05-16-2016, 04:17 PM   #7
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QuoteOriginally posted by nomadkng Quote
fair enough, I understand the attempt at humor. but since my reputation is very important and others aren't quite as willing to put statements in true context, please note a couple of my more recent listings. You will see I go out of my way to disclose faults. The 3 listed working lenses were sold for about half their normal resale value.

https://www.pentaxforums.com/forums/36-sold-items/306751-sale-sold-sigma-100-...carefully.html

https://www.pentaxforums.com/forums/36-sold-items/297730-sale-sold-2-1-deal-d...works-but.html

https://www.pentaxforums.com/forums/36-sold-items/266988-sale-sold-fa28-big-price-drop.html

below are links to 2 transactions after a hiking mishap:

https://www.pentaxforums.com/forums/36-sold-items/60991-sale-sold-sigma-24-70...n-working.html

https://www.pentaxforums.com/forums/36-sold-items/60988-sale-sold-k10d-non-working.html

I was indeed just trying to be funny and apologize if you thought I implied you were dishonest. I doubt you'd tell us you plan so openly if you were .
05-16-2016, 04:45 PM   #8
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Tamron 28-75 mm

I have the same lens & it's great. I wasn't sure how it would work with the K-1, but I was blown away at how sharp and how fast of a lens it can be.

I was thinking about getting the Pentax 24-70mm f/2.8 but at close to $1,500 I decided to wait until the K-1 got here. I'm glad I did. The lens is over 6 years old, and doesn't have a problem with it at all. Except from 73mm to 75mm it doesn't turn as smooth as the rest of the range. I talked to Tamron and was informed they could get it like new for $140.00. And, if someone is looking for a less expensive lens, they can be had new for under $500.

Sorry to hear about your copy, however you might want to check with Tamron. The price can range from $140 to $250, depending on what the tech finds is the problem. If you don't want to spend the price, they'll send it back to you on their dime.


Last edited by glee46; 05-16-2016 at 04:47 PM. Reason: Left out a word
05-16-2016, 07:08 PM   #9
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QuoteOriginally posted by hectorse Quote
Hello!

I have been enjoying my K-1 for the last two weeks. I've got an array of lenses that are performing incredible well, given the demands of a modern FF DSLR camera, specially the DA 50 F1.8 and the DA* 50-135 F/2.8. I also got a Tamron 28-75 f/2.8 just to go along with my brand new camera. The lens is in good condition and takes sharp pictures when stopped down a little bit and/or with contrast or manual focusing...

BUT

Using phase detection focusing, it just doesn't get tack sharp and front focuses very heavily, so much that even the microfocus adjustment menu is not able to compensate at -10. This is something I've encountered in my K-5 with the DA* 50-135, and was able to fix it by going into debug mode and adjusting to need.

What can I do to fix this issue with the K-1? Is there some debug-mode activation effort being made? Who is responsible for this issue? Tamron or Pentax? Any ideas?

Thank you so much for any ideas that you might hurl this way and I'll make sure to update on this issue.
Are you the original buyer? Tamron has a 6 year (I believe that's right) warranty. The 28-75 unfortunately has been known to have it's share of front/back focus issues. I own one as well. I let mine mostly draw dust because it was just ok after a -10 adjustment in camera unless stopped down. After hearing about the warranty, I called and sent it in. I got it cleaned, factory calibrated and sent back within a month. At no cost!!!! Now it's SO much better!! The dilemma for me is I need to sell some lenses to pay for a K1. It's in the grey area list. The fact that it's been calibrated makes it really hard. I'd like to keep it for the K1, just need $$$. *sigh* At any rate, it could be the lens, not the camera. If so, Tamron can fix it.

Last edited by Kevwaly; 05-16-2016 at 07:13 PM.
05-16-2016, 10:19 PM   #10
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QuoteOriginally posted by kp0c Quote
You could also possibly make a global adjustment on your camera (that will affect all of your lenses) then dial -10 on the Tamron. You would have to correct all your other lens to compensate for the global adjustment that you made on the camera. Mind you, I'm not sure that this is a viable solution, but I recall it was a possibility. I could be wrong though.

Also, some company offer focus calibration. You could maybe send your lens and preferably your camera body to Tamron for them to mate them properly. I'm pretty sure Sigma offers that service, Tamron, I don't know.

---------- Post added 05-16-16 at 05:41 PM ----------



Note to myself : if I see a lens from you on the marketplace, I must assume something is wrong with it.
This did the trick, sort of... I didn't know global and single lens microfocus adjustments were additive. I thought they were an either one or another option. At f2.8 with the calibration chart, the lens is sharp from 0 to +2ish so it is still front focusing, but since this lens is better stopped down a bit, I can live with this until the moment comes when the debug mode is uncovered or if I get Tamron to re-calibrate it some for free.

Thank you all for your kind suggestions
05-17-2016, 03:13 AM   #11
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I owned two of them, both had these issues. First one was withdrawn by the dealer and they called it dead with no chance to adjust it... the one I have now is -10 and sharp from 3.2 on. I can live with that and got it for 100€ but I saw the lens performing on 2.8 in the other thread and you guys inspired me to contact the tamron support and ask for a adjustment of my copy. I am excited what they want for this service? 50-70€ I would easily invest for a readjustment...
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