Pentax K10D and Sigma 100-300mm APO EX DG Need help!!!!

[jacques c pelletier]

Hello everyone!

And hopefully Xavier could help with this!

 

 

It,s been a while since I posted here but summer has kept me rather busy.

Nonetheless, I have now a combo: Sigma APO EX DG 100-300 F4 and Sigma APO EX DG 1.4X TC.

(Taking lots of birds photos lately).

 

Here is the problem:

 

Using the lens alone (no TC) is excellent .... fast AF and no problem to focus from near to infinity. All is well.

But !!!

Using the combo lens-TC seems to radically slow the AF system to a point that it just cannot focus at all, the motor

buzzing crazily! Must then use Manual focus! But not all the time.

I also noticed that when the subject is hazy or has little contrast, the TC-lens combo seems to under-perform,

somethimes unable to focus properly or even not able to focus at all in Auto mode.

 

Also, there is a very SLIGHT loose fitting between the lens to the camera and/or the TC ... has anyone encountered

this sort of problem.

At times, the display show F- - - instead of, let's say, F4 or 5.6, ... etc.

Maybe I am doing something wrong?

I have sent the info to the rep here in Canada (Gentec International) and still waiting for any response.

 

So .... I am debating whether I will keep this combo and switch to a Pentax DA*300 F4 but there is no vailable TC for

the SDM lens apparently. Unless I am mistaken, it is still on the Pentax Roadmap.

 

However, one good thing: the results are very satisfying when the focus works.

 

Any sort of answer or comment/opinion/suggestion would be GREATLY appreciated.

[jgredline]

Jacques,

Ny system works perfectly with and with out the TC. In fact, it is my number 1 bird lens. I know exactly what your speaking of when you say ''At times, the display show F- - - instead of, let's say, F4 or 5.6, ... '' the problem is the TC itself. You need to send it back for a replacement. What is happening is that the TC is not going in all the way flush to the body. If it has even a little play it will cause problems through the electrical contacts and the body will not be able to see the aperture..So it will not focus...You may also want to try cleaning the contacts with a pencil eraser. Hope this helps.

[jacques c pelletier]

Oh Great!!!!

Xavier, thanks a million! Really, I thought the camera was faulty or, worse, the lens itself!

Alright, back to the store it goes and I will certainly get bak here to give some feedback.

Again , thanks for the quick response!

Cheers!

P.S.: Have you any idea if a rear TC for SDM Pentax lenses is available anywhere?

JP

[jgredline]

Jacques,

The only TC i have seen that works well with sdm lenses is the Tamron TC 1.4 MC-4 Model...

If you have a few minutes read here...on TC's

http://www.pentaxforums.com/forums/pentax-slr-lens-discussion/19694-tamron-tc-converter-pics.html

[glivingston]

Jacques, I have exactly the same setup and I had exactly the same problem. The lens does a great job

over its entire range---sharp, fast focus, etc. I added the 1.4 TC later and immediately noticed the looseness that you

desscribe, and a disturbing grinding sound when focusing on automatic. I was able to focus manually. I returned the

TC to Adorama as defective and got a refund, no questions asked. However the TC was out-of-stock there and at

B&H. After some Internet searching I found another one at

Sigma4lesss (http://sigma4less.com/). I got one from there and am extremely happy with the setup. The TC/lens

combination now works well--no looseness, no grinding, fast focus and so on. I strongly recommend that you keep

trying to find a good sample of the TC. You will be very pleased with what you get.

[jacques c pelletier]

Javier, again, thanks a bunch!

 

I've checked it out ... will let you know!

 

JP

[jacques c pelletier]

Gary,

 

This is great that you have solved the problem.

 

I was at the marsh this afte. and took tons of pics without the Tc and , of course, the pic turned out great, sharp and in perfect focus.

Back to the TC ... problem happens again!

OK, so I will check this link and will let you know, and Javier, about the results.

Hopefully, the seller will have no problem with the rufund.

 

You guys are great!! Very appreciated!

 

JP