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09-23-2009, 04:19 PM   #1
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Tokina 80-200mm f2.8 AT-X Pro question

Just got this lens used, and while AF works fine on my K200D, the body asks me what the focal length is when I turn on the camera - did this lens predate whatever lens-body communication now occurs with more recent lenses? (This is the first time I've seen it on an AF lens on my K200D, and thought it only only occurred on older manual focus lenses.)

09-23-2009, 08:19 PM   #2
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QuoteOriginally posted by nater Quote
Just got this lens used, and while AF works fine on my K200D, the body asks me what the focal length is when I turn on the camera - did this lens predate whatever lens-body communication now occurs with more recent lenses? (This is the first time I've seen it on an AF lens on my K200D, and thought it only only occurred on older manual focus lenses.)
I will check on the obvious with loose AF contacts, your AF/MF switch on body. If the obvious are checked, it is darn weird that it prompts you for focal length. It is as if you have the manual focus lens, I had my copy and sold it here last week. How about the MF toggle on your lens.

Tokina AT-X SD 80-200mm f/2.8 manual focus with 'A' aperture.

Can I ask how much ball park figure to expect about a used copy of this AF version. I sold my manual copy for $225.0 + shipping, and I bought mine at $250 + shipping.

Thanks,
Hin
09-24-2009, 05:51 AM   #3
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QuoteOriginally posted by hinman Quote
I will check on the obvious with loose AF contacts, your AF/MF switch on body. If the obvious are checked, it is darn weird that it prompts you for focal length. It is as if you have the manual focus lens, I had my copy and sold it here last week. How about the MF toggle on your lens.

Tokina AT-X SD 80-200mm f/2.8 manual focus with 'A' aperture.

Can I ask how much ball park figure to expect about a used copy of this AF version. I sold my manual copy for $225.0 + shipping, and I bought mine at $250 + shipping.

Thanks,
Hin
Hmm... first thing I did when I tried the lens and the camera asked about the focal length was to take it off and clean the contacts with a bit of rubbing alcohol (they already looked clean). Looking at the contacts in the lens in profile (from the side) they are not all quite the same height - is that something to be concerned about?

The only switch on the lens for MF/AF is a clutch system involving the focus ring. The lens is 828AF, as described here:

PentaxForums.com Third-Party Pentax Lens Review Database - AT-X 828AF PRO 80-200mm F2.8

I paid about $400 for it, and while it is in great condition, I am now wondering if there is something wrong...
09-24-2009, 07:32 AM   #4
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I thought I recalled reading that Pentax F lenses (not FA) required the focal length to be manually entered. So if that is true then it may be a similar situation. The lens may pre-date the system that transmits the focal length info to the camera.

As far as what setting to use. I have heard people say they enter the longest focal length and I have heard others say they enter the middle middle focal length. I guess you would have to test that out.

09-24-2009, 08:03 AM   #5
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QuoteOriginally posted by StephenMerola Quote
I thought I recalled reading that Pentax F lenses (not FA) required the focal length to be manually entered. So if that is true then it may be a similar situation. The lens may pre-date the system that transmits the focal length info to the camera.

As far as what setting to use. I have heard people say they enter the longest focal length and I have heard others say they enter the middle middle focal length. I guess you would have to test that out.
Hmm I don't have any F lenses to test. According to:

Pentax Lens/Camera Compatibility - Mark Roberts Photography

"FA = Autofocus lenses with digital data chip in the lens"

That page says that chip transmits MTF data, so the "F" series lacks MTF data, then further down that page it says this about "F" series lenses:

"All lenses from the 'F' Series onward transmit focal length data to the camera body. This data is used for flash metering and for the Shake Reduction system in the latest DSLR's. With zoom lenses the focal length data changes as you zoom the lens in or out."

Which indicates that at least for Pentax "F" lenses, focal length is transmitted (and I've always seen it transmitted for recent third-party AF lenses from Sigma and Tamron).

I am pretty baffled... searching the web isn't turning up any instances of Tokina AF lenses behaving this way on Pentax bodies... I've emailed Tokina, and I think I'll email the person I bought this from as well.

Regarding manually putting in the focal length, I can't see how it would work properly with a zoom lens, if the shake-reduction works anything like I expect it does... i.e. it would need to know the *current* focal length at a given point in time in order to estimate the amount of shake happening and properly compensate. If the focal length data it has is incorrect (too high or too low), the shake-reduction system will either under or over-compensate at any given point in time. (Someone please correct me if I'm wrong in this assumption, or if they have any specific experiences which demonstrate my concerns regarding the relationship of focal length data to shake reduction are not as significant as I think they are.)
09-24-2009, 09:16 AM   #6
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Tokina AT-X PRO 80-200

Mine does transmit data to my K10D body, even in manual position. #5701593
09-24-2009, 09:26 AM   #7
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Haven't noticed that issue on my copy; as mentioned above, check the contacts possibly?
09-24-2009, 09:56 AM   #8
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QuoteOriginally posted by Chip Quote
Mine does transmit data to my K10D body, even in manual position. #5701593
Thanks for the info... looks like the lens I have indeed has a problem.

I'll post a photo of the contacts when I get home (I've already tried cleaning them to no avail).

So the possibilities are:

1) electrical contact issue
2) internal lens electronic issue (regarding transmission of focal length)

If it's #1 and cleaning the contacts hasn't fixed it, is there something else I can do? Could it be that some contacts have lost their "springiness" resulting in the symptoms I'm seeing? If so, is this easy to fix, or should I just not even attempt it and just try to return this lens to the seller?

If #2, I assume there's little that could be done and I should just try to return it to to the seller.

09-24-2009, 10:21 AM   #9
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QuoteOriginally posted by nater Quote
Thanks for the info... looks like the lens I have indeed has a problem.

I'll post a photo of the contacts when I get home (I've already tried cleaning them to no avail).

So the possibilities are:

1) electrical contact issue
2) internal lens electronic issue (regarding transmission of focal length)

If it's #1 and cleaning the contacts hasn't fixed it, is there something else I can do? Could it be that some contacts have lost their "springiness" resulting in the symptoms I'm seeing? If so, is this easy to fix, or should I just not even attempt it and just try to return this lens to the seller?

If #2, I assume there's little that could be done and I should just try to return it to to the seller.
First thing in Communication & and clear deadline
I would set a deadline before you can return. Communicate the problems you have with your seller before it is too late for return.

While you started the needed communication, check the contacts with a good copy of a AF lens and compare the contact one by one and examine on lost of spring by pushing the contact in and out to feel the presence.

Good price you have
What you paid is a good price and please re-read your sale and note down any disclosures from seller such as known faults and disclosed accident.


SR focal length in MF lens
As far as the correct SR focal length, the middle should work well but I like to choose the closest but the lower one. Say I am going to shoot in the next hour from 150mm to 200mm, I will likely set for 180mm as in the middle. Say, I have no idea but likely over 100 to 200mm, set for the lower of the two in 100mm. If your zoom is at 175 and SR only have 150mm, 180mm and 200mm, I always use the lower one next to the closest one which is the lower one of 180mm, I pick 150mm SR focal for 175mm focal position. That is how I use it but not sure if that is right. My logic is to have SR NOT to overcompensate. An middle average will serve me close enough if I know the rough range what I am shooting. If the range is too wide for a predicted guess, I would set for every freaking photo that I shoot but at the lower SR focal length allowed to the actual focal length. That way, I won't overcompensate the SR feature while a good value is provided to help stabilize the shot -- a compromise for Manual focus lens.

Thanks,
Hin
Thanks,
Hin

Last edited by hinman; 09-24-2009 at 11:55 AM.
09-24-2009, 10:41 AM   #10
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Let me just say Tokina has seriously impressed me by already replying to my email, and the response is very interesting, and here's the relevant bit:

"The lens may be in need of a chip upgrade... Include a note explaining the problem, along with any and all contact information. We will contact you with a repair estimate before any work has begun."

They gave me an address to send it to. I've asked them if they can at least give me a ballpark estimate of the chip upgrade service, since I have no idea how much it will cost... anyone here ever had a lens chip upgrade done?
09-24-2009, 11:21 AM   #11
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I have heard of it, but not so much with Pentax mount lenses. For example, I have heard stories about old Sigma lenses needing chip upgrades for Canon mounts and maybe Minolta mounts, and other stories about flashes needing chip upgrades. Good luck.
09-24-2009, 07:53 PM   #12
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QuoteOriginally posted by StephenMerola Quote
I have heard of it, but not so much with Pentax mount lenses. For example, I have heard stories about old Sigma lenses needing chip upgrades for Canon mounts and maybe Minolta mounts, and other stories about flashes needing chip upgrades. Good luck.
I'm not sure I need a new chip... tonight I've gotten the lens to intermittently work communicating focal length.

Sometimes I just need to turn the camera body on and off 3 or 4 times, and then it works without asking, and focal length is recorded correctly with each photo taken. Then I can turn it off and turn it on, and it asks. It's pretty random, and not correlated to lens mounts/dismounts.

I've done some comparisons to my other lenses, and it looks like the contacts are worn/low and must not be making good contact.

I've attached three photos, first is 3/4 view of the Tokina, then profile of the Tokina, then profile of my Tamron lens. The difference in the contacts is striking.
Attached Images
     
09-25-2009, 10:19 AM   #13
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This is not a good suggestion but I like to throw it out on the discussion for you to give that a try. For you people who have a better idea, please don't Lol with what I am going to suggest as this may not work at all.

I have an old Photosniper Tair-3 Phs 300mm f/4.5 and when I put on the magical Pentax F-1.7x AF TC that will turns a manual focus lens in K mount to have partial AF, I used a well-talked about trick to get the two working to have partial AF where the TC will engage in AF on behalf of the MF lens when the focal point is close to target on your focusing point.

For most of the M42 lens, there is probably the mount material and paint around the lens rear mount that prevent the transmission of what-ever signals in the electric contacts that many authoritative places documented such as Bjoir and Mark Roberts (will update with correct spelling and hyper-links to the mount documentation).

I used a small piece of aluminum foil to slip in between the lens and the K-mount socket in my Pentax F-1.7x AFA I hope this picture give you a rough idea on what to try -- no promise if this is going to do you any good


please noted the aluminum foil
between adapter and lens rear mount





Precautions to consider:
  • only use a small piece of foil to cover only the outer rim of lens mount
  • pay close attention to contact position, don't use too much foil
  • upon mounting with insertion from RED dot and the small clockwise turn to LOCKING position, there is a slight twist in the foil, make sure the foil is not broken into pieces
  • try your best in NOT re-using the foil as you are more likely to have a foil torn with usage
  • be warned on excess or broken pieces of foil that may fall into your mirror housing
  • don't fold the foil, only use a single piece to begin the trial as a two-fold thicker may leave room in the mount
  • disclaimer: use common sense -- this is a safe operation and many people have adopted this trick plus other more complicated alterations to get manual focus lens to work with focus trap, work with F-1.7x AF TC, and other too-good-to-be-true claims with matrix metering and pttl with internal flash

The simple idea behind the suggestion is that if your contacts are indeed recessed with intermittent connection problem, perhaps an added foil will help you leverage the added thickness for transmission of signal related to focal length and possibly related to AF and MF lens distinction.

If you do the MF/AF switch on body without the lens mounted, you will note a extra pin, away from the electrical contacts, that pushes up from the K mount socket from the body to the lens, check not only the contacts but also the mf/af receiving end on your lens. I don't have an illustrative pictures, I hope you use your lens mount and your K body to examine the mf/af clutching details. The mf/af receiving end is located at top at about 11:45am position


not-so-good picture of Pentax F-1.7x AFA adapter
mf/af clutching contact at about 11:45am at top



Thanks,
Hin

Last edited by hinman; 09-26-2009 at 05:51 AM.
09-26-2009, 05:03 AM   #14
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Looks like an easy repair.

I would have to agree on your assessment, I don't think it would be too hard to remove the base plate and replace the bearings. IANLRP

NOTE: I am not a lens repair professional.
09-26-2009, 11:48 AM   #15
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QuoteOriginally posted by omega leader Quote
I would have to agree on your assessment, I don't think it would be too hard to remove the base plate and replace the bearings. IANLRP

NOTE: I am not a lens repair professional.
Since I have no experience repairing lenses, I figured best to have Tokina take a look at it and see what they can do. It's on it's way to them.
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