lens tele extenders

I doubt you will get an answer.

Last Login: 14th December 2007 - 04:25

Yes, I did not expect one from the OP but thought someone else might know.

Greg

I am one of the TC junkie's. I have tried various TC to some degree of success. But the lost of light and image quality lead to more bad images than good one. But I still stick to the TC for a few simple reasons -- portability and great bargain for occasional use on that silly birds.

My most favorite TC is the Pentax AFA 1.7x TC as it really work well with MF lenses and turn a MF lens into partial auto focus. I prefer it to use with 'A' capable lens.

There are few other TC's worth noting and I listed here in order of my frequent use
1. Pentax AFA 1.7x TC
- magical in turning MF to partial AF
- I prefer it to work with MF lenses with A setting
- allow you to enter SR focal length
-

2. Tamron Pz-AF 1.4x TC
- this has the least lost of light
- one of the few TC working with SDM lens.
- I see a lot of PF/CA from this TC

3. Promaster 1.7x AF TC
- works with AF, not on DA* 50-135mm f/2.8
- I see some claim it to work with DA* 60-250mm f/4.0
- has less PF/CA when compared to Tamron 1.4x TC


With a 2x AF TC MC7 from Kenko, I can hardly get it to AF with Pentax F* 300mm f/4.5, but the combo is hand-holdable




Thanks,
Hin

I can verify that the Promaster 1.7x Pz-AF TC and the Tamron 1.4x Pz-AF TC will work successfully on a K20D and DA*60-250, I have the Promaster and had a Tamron. I believe they also work with the same lens TC combination on the K-7 and K-x. Reasonable light and subject contrast is neccessary.

I haven't tried them on all SDM lenses, but can verify that they don't work with the DA 17-70, DA*16-50 or DA*50-135.

Only TC's with the designation Pz-AF have the power contacts used by the SDM system.

Some test shots using the Promaster here - Promaster 1.7x test shots

"Only TC's with the designation Pz-AF have the power contacts used by the SDM system."

But not all with the designation Pz-AF work with SDM. Kenko TC's have to be Pz-AF and SHQ, I think. There has been other threads about it, if you want to check.

I believe he means that if the TC had previously autofocussed to either extreme and then been disconnected and connected to a manual camera, then you may find that it affects your minimum focus distance or infinity focus as it won't be able to correct itself since the camera doesn't have AF.

Yes, that makes sense, I wonder how one determines the neutral position of the 1.7AF before mounting it to a manual focus body. I'll have to do some playing around this coming weekend.

Greg

Hi Hin,
That a lovely shot of a pelican in flight, how far was it.

Greg

I would think about 40 to 60 feet but that is a guess on my part. I may have a small crop on that picture. With the 2x mounted, my 600mm can't go AF, and I was using MF for the shot panning the moment I saw the Pelican coming into view. I hand-hold the shot and I got an off focus on 1st shot and the above shot was the 2nd shot in a series in AF.S. I was not using AF.C at the time.



Pentax F* 300mm f/4.5 + Kenko 2x MC7 AF TC

Here is a shot using the Pentax-F 1.7x AF TC on a Soligor 200mm f/2.8 in M42 mount. Darn it, I sold the Soligor due to too-many lenses.




My biggest problems with TC are usually on heavy CA/purple fringing seen in high contrast area such as the tree branches and bird's white feather

Thanks,
Hin