[falconeye]

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Ok, so I did the test now.

IT WORKS!!

Disabling pin marked as #6 in the graphics above (denoted "Digital contact") brings up the SR enter focal length menu!

We now can use TCs in conjunction with full shake reduction, making some landscape subjects feasible w/o tripod which weren't before.

Did nobody find this out beforehand?


There are two caveats, though:

- AF is not working. But AF indicator is working just like with a manual lens.

- With a DA lens, you cannot stop down the lens and you may get a wrong exposure (I got 3 full steps overexposure! (*)). So, you probably have to use manual mode.

[(*) something like the camera thinks exposure is taken at f/1.0 but that the lens has fixed aperture at f/4.0.]

I tried this with the DA 50-200mm. I guess, the following is hapenning: The DA 50-200mm transmits the aperture info thru the masked (digital) contact rather than the 6 other contacts of the KA mount (it actually has pretty few contacts anyway). In my EXIF info I see f/4 all the time. But the DA50-200 is f/4-5.6 with f/5.6 at 200mm which I used. Also, the lens cannot be stopped down, the f reading in the display says "--" and cannot be changed.

Therefore, for this to be really useful, an FA lens rather than a DA lens should be used. It either uses the KA pins or at least has the aperture ring to stop down ...

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Last edited by falconeye; 05-15-2008 at 05:01 PM.

[jgredline]

I must admit, this Pentax 1.7tc is pretty good. Well worth the $440.00 I paid for it. I hooked it to my newly arrived 500 f/4.5 and was sharp as a tack. I will post some images Monday after my bird hunt this weekend.

I do have a question if anybody here can answer it. The lens is a f/4.5 and yet the camera sees it as F/2.8 with the TC. With out the TC it sees it as f/4.5..This was true of all the lenses I tested it on. The images are coming out well exposed and so I am perplexed by this.

[falconeye]

The lens is a f/4.5 and yet the camera sees it as F/2.8 with the TC.

Well, I don't know the answer. But disabling the digital pin in the KAF mount (cf. above) meant to study the KAF mount spec a bit.

So, let me speculate... I guess that the 1.7x TC is a KAF mount on the body side (with the 7th digital pin) but KA mount only on the lens side (6 pins, no AF screw).

Then, the TC will report data through the digital pin while the lens doesn't. And because the TC doesn't contain a processor, only a rom, it statically reports f/2.8. The body will operate the aperture lever relative relative to the aperture where the exposure was taken and you still get correct exposure. But the program curves don't map and I would switch the body into Av mode (and enter an aperture corrected by the wrong opening aperture, i.e., f/2.8 for fully open).

[jgredline]

Here is a TC on eekbay. It does NOT look like the MC-4 model, so if your looking for one, check first.
Tamron F 1.4X AF teleconverter for Pentax AF - eBay (item 250248842928 end time May-25-08 18:00:00 PDT)

[borno]

Hey Javier, Try cleaning the contacts maybe, the 1.7afa will report the f-stop of the lens plus tc factor i.e. f 6.7 on an f4 lens

[Mike.P®]

Taken with a K10D, Tamron 28-300mm XR Di lens and a 1.4X Tamron Teleconverter.

[AML]

Great action shots Mike. P . Love how you captured the wave in number 6. Mr Gull looks good too! The last one is a very nice action shot, nice angle on that one.

[AML]

Here's some flower shots i got on my first day out with the M 50/1.7 and the Tamron 1.4x TC 3 days ago.




Loved the lighting on the back side of the flowers.




Bird of Paradise.







and here's a few shots of what looks like an old water pipe system.

[jgredline]

Wow, amazing shots...I love it...

[Marc Langille]

Snagged a new in box unit several weeks ago... I was curious as to how the Tamron 1.4x TC (MC4 model) does with a really high quality lens, such as the FA* 300/2.8. Generally the TC will always be the weakest link, especially with high quality glass. However, it's quite interesting... almost surprising...

Still testing under harsh wildlife photography conditions, and sometimes it really shines with that lens... but I am being selective on it's use with the FA* 300/2.8.

Cheers,
Marc

[jgredline]

Snagged a new in box unit several weeks ago... I was curious as to how the Tamron 1.4x TC (MC4 model) does with a really high quality lens, such as the FA* 300/2.8. Generally the TC will always be the weakest link, especially with high quality glass. However, it's quite interesting... almost surprising...

Still testing under harsh wildlife photography conditions, and sometimes it really shines with that lens... but I am being selective on it's use with the FA* 300/2.8.

Cheers,
Marc

Great going Marc...So what are your first impressions and when can we see some images?

[Marc Langille]

Great going Marc...So what are your first impressions and when can we see some images?

Very soon on the images - have to wait until the competition ends though. I can post a test shot with/without the TC to show you - cable release and tripod in use, to ensure the images are accurately taken.

Believe it or not, almost as good, sometimes better than my 1.7X AF TC... sometimes I had trouble telling that a TC was attached, even at 100%...

Granted, it's been used sparely, since shaded areas are difficult at best to get a decent shutter speed, even harder if overcast and it's evening (when a lot of activity occurs). Therefore I cannot afford to use it if the shutter speed drops too much. Also, the EXIF doesn't show the TC being attached- still reads at 300mm, not 420mm... did that diagram in a previous post in this thread explain how to overcome this? I only briefly read it and bookmarked the page... haven't read it in detail yet.

However, with poor lighting conditions, you can tell a TC is attached, which is always par for the course, and a consistent problem with any TC I've used. I shoot under much less than optimal conditions, so it's nothing new there. It does flex a lot on my camera body, compared to the Pentax TC's I own. I am glad I have a tripod collar on the lens - it would be a little unsettling otherwise if a heavier lens with no tripod collar was attached.

Perhaps I got an exceptional copy in terms of optics?

Regards,
Marc

[jgredline]

Very soon on the images - have to wait until the competition ends though. I can post a test shot with/without the TC to show you - cable release and tripod in use, to ensure the images are accurately taken.

Believe it or not, almost as good, sometimes better than my 1.7X AF TC... sometimes I had trouble telling that a TC was attached, even at 100%...

Granted, it's been used sparely, since shaded areas are difficult at best to get a decent shutter speed, even harder if overcast and it's evening (when a lot of activity occurs). Therefore I cannot afford to use it if the shutter speed drops too much. Also, the EXIF doesn't show the TC being attached- still reads at 300mm, not 420mm... did that diagram in a previous post in this thread explain how to overcome this? I only briefly read it and bookmarked the page... haven't read it in detail yet.

However, with poor lighting conditions, you can tell a TC is attached, which is always par for the course, and a consistent problem with any TC I've used. I shoot under much less than optimal conditions, so it's nothing new there. It does flex a lot on my camera body, compared to the Pentax TC's I own. I am glad I have a tripod collar on the lens - it would be a little unsettling otherwise if a heavier lens with no tripod collar was attached.

Perhaps I got an exceptional copy in terms of optics?

Regards,
Marc

Marc,
Actually your finding are in the majority. I am glad it is working out. I agree with the Low light stuff and it is true, there are times when I forget it is even being used. The trick is that it really has to be the MC-4 model.

What competition are you referring to?

[Marc Langille]

I am too - it's a nice alternative in AF format to my 1.4X-L, which is a stellar TC, but MF only.

Competition: South Texas Shootout - Wildlife Photography Contest - Valley Land Fund

Some preliminary images from the competition:

https://www.pentaxforums.com/forums/p...ite-egret.html

https://www.pentaxforums.com/forums/p...4x36-hung.html

The images in the second post may not be eligible - possibly "Exotics" in the mammals division - awaiting confirmation from folks running the competition. They're not simply from Mexico or something similar - I'm in an area where sub-tropicals species exist - deep south Texas. A decent portion of Mexico is north of my location!

[falconeye]

Here is a TC on eekbay. It does NOT look like the MC-4 model, so if your looking for one, check first.
Tamron F 1.4X AF teleconverter for Pentax AF - eBay (item 250248842928 end time May-25-08 18:00:00 PDT)

Sold for USD 335,- !!

Buyer is from the States.