[cwood]

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I know I came here looking for feedback on TC's before buying so I thought I'd post this tidbit for the benefit of others. Unfortunately the Tamron was largely unavailable and the new 1.4 from Pentax won't be out for a while. So I thought I would take a chance on the Kenko MC7. The MC7 was supposed to be better than the MC4.

- Impression is that it is pretty cheap. It's really light, it rattles etc
- Mounted on my K10D with my FA* 300mm F2.8 the AF works but is noticeable slower and louder. Photos look OK. It does not look like it loses a full 2 stops of light (a little more than 1.5) but I don't know for sure why it appears that way
- exif still shows focal length as 300mm
****
****
-IT WILL NOT AF my SDM lenses at all. I tried 16-50 and 50-135. I get a flashing light in the view finder showing MF. I thought that since these lenses had screw drives that they would still AF even if not by SDM.

I may still keep it because it is cheap (< $100) and IQ seems OK from my 300. I'll have to test it a little more before I make my final decision.

[pentaxman]

You might want to take a look at the Promaster 1.7X AF teleconverter:

Promaster 1.7x AF Teleconverter Pentax - Hin's Tech Corner

-IT WILL NOT AF my SDM lenses at all. I tried 16-50 and 50-135. I get a flashing light in the view finder showing MF. I thought that since these lenses had screw drives that they would still AF even if not by SDM.

Hi, i think the AF with 2x TC needs minimum of F2.8 lenses or better to work.

[koper]

Tamron F 1.4X Pz AF MC4 Teleconverter for Pentax 1.4 X - eBay (item 200257802004 end time Oct-26-08 13:13:40 PDT)

you can bay tamron teleconverter now on ebay

[aleonx3]

I know I came here looking for feedback on TC's before buying so I thought I'd post this tidbit for the benefit of others. Unfortunately the Tamron was largely unavailable and the new 1.4 from Pentax won't be out for a while. So I thought I would take a chance on the Kenko MC7. The MC7 was supposed to be better than the MC4.

- Impression is that it is pretty cheap. It's really light, it rattles etc
- Mounted on my K10D with my FA* 300mm F2.8 the AF works but is noticeable slower and louder. Photos look OK. It does not look like it loses a full 2 stops of light (a little more than 1.5) but I don't know for sure why it appears that way
- exif still shows focal length as 300mm
****
****
-IT WILL NOT AF my SDM lenses at all. I tried 16-50 and 50-135. I get a flashing light in the view finder showing MF. I thought that since these lenses had screw drives that they would still AF even if not by SDM.

I may still keep it because it is cheap (< $100) and IQ seems OK from my 300. I'll have to test it a little more before I make my final decision.

I have tried that using the tamron 2x TC on the tamron SP90mm f2.8; it works fine except that in some cases I need to use MF. Apparently AF works only if the aperture is f4 or wider. Correct, the exif still shows the lens focal length (not the effective FL).

[cwood]

I have tried that using the tamron 2x TC on the tamron SP90mm f2.8; it works fine except that in some cases I need to use MF. Apparently AF works only if the aperture is f4 or wider. Correct, the exif still shows the lens focal length (not the effective FL).

Aperture is not the problem in this case. As I stated the two lenses I tried were 16-50 and 50-135 SDM lenses. Both of these lenses are F2.8. The problem is not that it would not lock focus it is that the AF mechanism would not even engage.

The problem, therefore, appears to be that the Kenko MC7 2x is NOT compatible with ANY of the DA* lenses

Tamron F 1.4X Pz AF MC4 Teleconverter for Pentax 1.4 X - eBay (item 200257802004 end time Oct-26-08 13:13:40 PDT)

you can bay tamron teleconverter now on ebay

The Tamron 1.4x has been going on ebay for more than $200 although it sold new for only $130. Now that Pentax has shown their own 1.4x maybe the Tamron's will get cheaper. Still... in the mean time, how could I justify spending that kind of inflated value on used Tamron gear when new Pentax gear is just around the corner

[hinman]

I just purchased the more expensive Pentax F 1.7x from a Canada member. And I have been thinking of selling both of my Tamron 1.4x and Promaster 1.7x TC to cover my cost for my Pentax 1.7x TC. Only the Tamron 1.4x will work with SDM lens.

Tamron 1.4x Pz-AF MC4 Teleconverter - Hin's Tech Corner

Promaster 1.7x AF Teleconverter Pentax - Hin's Tech Corner

I paid Tamron=$140 +$10 shipping for my Tamron and it is near mint condition with original front & rear caps and pouch.

Please let me know if you consider it for $135 + shipping. I will post the sale in about a week when I get my Pentax F 1.7x TC.

Hin

I have sent the above PM to OP. And please PM me if you have interest in the two TC listed. For the Promaster 1.7x TC, I will post it for $65.00 as I really like it. Both TC are in mint conditions. Promaster TC are NIB purchased about 3 months ago. Depending how I do with the Pentax F 1.7x TC, I will have to let both of my TC to go.

[Douglas_of_Sweden]

Aperture is not the problem in this case. As I stated the two lenses I tried were 16-50 and 50-135 SDM lenses. Both of these lenses are F2.8. The problem is not that it would not lock focus it is that the AF mechanism would not even engage.

The problem, therefore, appears to be that the Kenko MC7 2x is NOT compatible with ANY of the DA* lenses

The Tamron 1.4x has been going on ebay for more than $200 although it sold new for only $130. Now that Pentax has shown their own 1.4x maybe the Tamron's will get cheaper. Still... in the mean time, how could I justify spending that kind of inflated value on used Tamron gear when new Pentax gear is just around the corner

I have the same experience with the Kenko 2x on my DA*50-135.
Observations:
1. The converter works well in screw driver mode with my screwdrive-only-lenses, even those slower than f2.8, though in this case with some hunting in dark situations.
2. The converter and the DA*50-135 autofocus with screwdrive on my *istDS and MZ-5 (tough of course in the later case I'm certainly missing the aperture ring!)
3. But when mounting the Kenko 2x converter and the DA*50-135 on the K20D the autofocus is dead! Not a sound, not a motion, not the smalest vibration. Screwdrive and SDM is both stone dead! I have even tried to isolate the SDM contacts with a piece of plastic film in order to try to make the camera/lens believe it is just a screwdrive converter without the SDM contacts, and still it does not work!

Hypothesis: Despite that contacts on the Kenko 2x look identical to the contacts on the Kenko 1.5x and Tamron 1.4x (that have been reported to work with SDM lenses) they are not SDM contacts, but power zoom contacts, which for some reason works differently.

But it is not a good hypothesis since it does not explain all observations.
Though I never had a power zoom, I understand it as the SDM use identical contacts as the contacts used for the power zoom. Right? But it appears it is not as simple, or? If the SDM/powerzoom contacts on the converter is just going straight through, why doesn't the SDM engage? If it is not, why doesn't the screwdrive engage even when I cover those contacts. Way strange. Anyone able to explain this to me?

I'm not going to buy any other over-priced third part converter now when the Pentax is around the corner, but my Kenko converter is on queue for some surgery... I wanna know what's inside, what's there that is not as it should be, and if there is something I could fix.

Anyone who have taken apart their fine working and over-priced Kenko 1.5x or Tamron 1.4x converter so we can compare what's inside?

By the way. I think I have seen converters on ebay claiming to work with SDM lenses which on the photos appear to have the SDM contacts but not the other 7 contacts on the mount. I don't want to try them, since having exposure functions without autofocus is still better than having autofocus with only manual exposure. But if they work with SDM, it could be that there is some combination of the signal in the SDM contacts and the signals in the other contacts that mess things up. Know its a long shot.

[hinman]

I have sent the above PM to OP. And please PM me if you have interest in the two TC listed. For the Promaster 1.7x TC, I will post it for $65.00 as I really like it. Both TC are in mint conditions. Promaster TC are NIB purchased about 3 months ago. Depending how I do with the Pentax F 1.7x TC, I will have to let both of my TC to go.

Thank you to a member of the forum, my Promaster TC is sold. If anyone interested in a mint and tested good copy of Tamron 1.4x Pz-AF MC4 TC for the stated price, please PM me. I will separately open a marketplace thread to list the items in detail.

Thanks,
Hin

[Douglas_of_Sweden]

Partly got this wrong/incomplete when I tried to remember tests I did months ago. Here it is, added info in italic text:

I have the same experience with the Kenko 2x on my DA*50-135.
Observations:

1. The converter works well in screw driver mode with my screwdrive-only-lenses, even those slower than f2.8, though in this case with some hunting in dark situations. It does this on both K20D (has SDM) and *istDS (has not SDM).
2. The converter and the DA*50-135 autofocus with screwdrive on my *istDS and MZ-5 (tough of course in the later case I'm certainly missing the aperture ring!)
3. But when mounting the Kenko 2x converter and the DA*50-135 on the K20D the autofocus is dead! Not a sound, not a motion, not the smalest vibration. Screwdrive and SDM is both stone dead! In the viewfinder "MF" is visible despite that AF is on on both body and lens.
4. I have even tried to isolate the SDM contacts with a piece of plastic film in order to try to make the camera/lens believe it is just a screwdrive converter without the SDM contacts, and still it does not work! However, when doing this, even exposure functions breaks apart. Alternating numbers are flashing for the exposure time and aperture in the viewfinder and "MF" is now flashing, not a constant light as before. This implies that the SDM contacts are somehow involved in transferring information relevant for the exposure and not only providing the SDM engine with power !?

Hypothesis: Despite that contacts on the Kenko 2x look identical to the contacts on the Kenko 1.5x and Tamron 1.4x (that have been reported to work with SDM lenses) they are not SDM contacts, but power zoom contacts, which for some reason works differently.

But it is not a good hypothesis since it does not explain all observations.
Though I never had a power zoom, I understand it as the SDM use identical contacts as the contacts used for the power zoom. Right? But it appears it is not as simple, or? If the SDM/powerzoom contacts on the converter is just going straight through, why doesn't the SDM engage? If it is not, why doesn't the screwdrive engage even when I cover those contacts. Way strange. Anyone able to explain this to me?

I'm not going to buy any other over-priced third part converter now when the Pentax is around the corner, but my Kenko converter is on queue for some surgery... I wanna know what's inside, what's there that is not as it should be, and if there is something I could fix.

Anyone who have taken apart their fine working and over-priced Kenko 1.5x or Tamron 1.4x converter so we can compare what's inside?

By the way. I think I have seen converters on ebay claiming to work with SDM lenses which on the photos appear to have the SDM contacts but not the other 7 contacts on the mount. I don't want to try them, since having exposure functions without autofocus is still better than having autofocus with only manual exposure. But if they work with SDM, it could be that there is some combination of the signal in the SDM contacts and the signals in the other contacts that mess things up. Know its a long shot.

Aperture is not the problem in this case. As I stated the two lenses I tried were 16-50 and 50-135 SDM lenses. Both of these lenses are F2.8. The problem is not that it would not lock focus it is that the AF mechanism would not even engage.

The problem, therefore, appears to be that the Kenko MC7 2x is NOT compatible with ANY of the DA* lenses




The Tamron 1.4x has been going on ebay for more than $200 although it sold new for only $130. Now that Pentax has shown their own 1.4x maybe the Tamron's will get cheaper. Still... in the mean time, how could I justify spending that kind of inflated value on used Tamron gear when new Pentax gear is just around the corner

I have the same experience with the Kenko 2x on my DA*50-135.
Observations:
1. The converter works well in screw driver mode with my screwdrive-only-lenses, even those slower than f2.8, though in this case with some hunting in dark situations.
2. The converter and the DA*50-135 autofocus with screwdrive on my *istDS and MZ-5 (tough of course in the later case I'm certainly missing the aperture ring!)
3. But when mounting the Kenko 2x converter and the DA*50-135 on the K20D the autofocus is dead! Not a sound, not a motion, not the smalest vibration. Screwdrive and SDM is both stone dead! I have even tried to isolate the SDM contacts with a piece of plastic film in order to try to make the camera/lens believe it is just a screwdrive converter without the SDM contacts, and still it does not work!

Hypothesis: Despite that contacts on the Kenko 2x look identical to the contacts on the Kenko 1.5x and Tamron 1.4x (that have been reported to work with SDM lenses) they are not SDM contacts, but power zoom contacts, which for some reason works differently.

But it is not a good hypothesis since it does not explain all observations.
Though I never had a power zoom, I understand it as the SDM use identical contacts as the contacts used for the power zoom. Right? But it appears it is not as simple, or? If the SDM/powerzoom contacts on the converter is just going straight through, why doesn't the SDM engage? If it is not, why doesn't the screwdrive engage even when I cover those contacts. Way strange. Anyone able to explain this to me?

I'm not going to buy any other over-priced third part converter now when the Pentax is around the corner, but my Kenko converter is on queue for some surgery... I wanna know what's inside, what's there that is not as it should be, and if there is something I could fix.

Anyone who have taken apart their fine working and over-priced Kenko 1.5x or Tamron 1.4x converter so we can compare what's inside?

By the way. I think I have seen converters on ebay claiming to work with SDM lenses which on the photos appear to have the SDM contacts but not the other 7 contacts on the mount. I don't want to try them, since having exposure functions without autofocus is still better than having autofocus with only manual exposure. But if they work with SDM, it could be that there is some combination of the signal in the SDM contacts and the signals in the other contacts that mess things up. Know its a long shot.