-=FAQ=- Teleconverter/T-Con Tele extender Discussion

Mark K wrote in post #16607301
I have just come across this great produce, one made by X pro claiming about 1.7x with two component. By removing the central optical part, the adapter becomes a 25mm ext tube. Optically it is amazingly sharp...it cheats the camera by having a 1.4x TC and I have no problem using it on 100-400L with autofocus on 5D3. Here is one taken by 70-200

Sorry mate. I am lost. What is it you are saying?

Cheers.

RAW-Shooter wrote in post #16607328
Sorry mate. I am lost. What is it you are saying?

Cheers.

Sorry I did not make that clear
I found a 1.7x TC from another maker X Pro http://www.lt-oe.com/ who has been making a lot of close up adapters/extension tubes
This one looks very like the Canon original TCs

Well, I brought this teleconverter out today to test against my Kenko 1.4..their focal length extending power is the same..

Canon 70D, 70-300L and Kenko Telepro 300 1.4x?

Has anyone tried this combination using the live-view function of the 70D? Theoretically, it should autofocus, as the 70D is supposed to autofocus down to f/11. And, how about the Kenko 2x converter?

Added 2/15/2014

I bought the Kenko 1.4x Telepro 300 and tried it with my 70-300L and 70D. Here is what I found:

Image quality - pretty good even at 300mm (420mm). But when I cropped a 300mm shot without the converter to match the image size of the same subject with the converter, the image quality was nearly identical.

Autofocus - erratic but usually OK, but needed a high-contrast subject even in daylight. In bright room light the lens still autofocused given a high contrast subject. (I can make the same statement about the lens without the teleconverter.)

Image Stabilization - worked well. One of my indoor shots was at 1/4 second and reasonably good, although not perfect.

Live View - did not help autofocus much. I find that autofocus is slow in this mode, even without the teleconverter and with all of my lenses.

EXIF Image Information - accurately reported - aperture showed as f/8, the actual effective aperture at 300mm using the teleconverter.

My Overall Conclusion - Although the converter worked better than I expected, I decided not to keep it. As I could get the same image quality without the teleconverter by cropping the image, I could not see the value.

RodneyCyr wrote in post #16634659
Has anyone tried this combination using the live-view function of the 70D? Theoretically, it should autofocus, as the 70D is supposed to autofocus down to f/11. And, how about the Kenko 2x converter?

Only 1D bodies and the 5dIII can AF at f/8. The 70D has the same AF system as the 7D, they just added another different AF system for video. Other than that the 70D AF system is limited to f/5.6

Cheers.

RAW-Shooter wrote in post #16634674
Only 1D bodies and the 5dIII can AF at f/8. The 70D has the same AF system as the 7D, they just added another different AF system for video. Other than that the 70D AF system is limited to f/5.6

Cheers.

The dual pixel live view phase AF on the 70D can be used for stills though surely? Not sure how fast it would be with a small aperture, but I understand it'll work beyond f/5.6.

sploo wrote in post #16635209
The dual pixel live view phase AF on the 70D can be used for stills though surely? Not sure how fast it would be with a small aperture, but I understand it'll work beyond f/5.6.

Yes, indeed. Actually, the LiveView AF on bodies like the 7D will work at f8 and beyond. Just not very fast. I gather the 70D dual-pixel magic is faster, but that it slows down quite a bit past f11.

hollis_f wrote in post #16635367
Yes, indeed. Actually, the LiveView AF on bodies like the 7D will work at f8 and beyond. Just not very fast. I gather the 70D dual-pixel magic is faster, but that it slows down quite a bit past f11.

Thanks.

I suppose the live view AF on DSLRs other than the 70D are using contrast detection, so it's more about having enough light and/or detail than specifically the fstop.

If I understand phase AF correctly, at a larger fstop there isn't enough distance/phase between readings for the AF sensor to work, but the 70D's dual pixel AF is more forgiving.

Disclaimer: I rarely use Live View or video.

There are not many lenses with a max aperture of f/8, let alone slower. You only get into that pinch if your lens is a f/5.6 and you add a reporting TC. Then you are at f/8 or slower. Canon cameras always use the max aperture for metering and AF and then stop down when you take the picture. Except for 1D and 5DmkIII no other camera will work in these circumstances.

I have no idea how this works in Live View / video and then snapping a still during that condition. Maybe I will try that later today.

Cheers.

RAW-Shooter wrote in post #16635571
Disclaimer: I rarely use Live View or video.

There are not many lenses with a max aperture of f/8, let alone slower. You only get into that pinch if your lens is a f/5.6 and you add a reporting TC. Then you are at f/8 or slower. Canon cameras always use the max aperture for metering and AF and then stop down when you take the picture. Except for 1D and 5DmkIII no other camera will work in these circumstances.

I have no idea how this works in Live View / video and then snapping a still during that condition. Maybe I will try that later today.

Cheers.

I guess AF during video recording would have to use the shooting aperture. There are also people discussing stills with a 2x TC on f/5.6 lenses, which is probably asking for trouble, but it would be interesting to see if it would work on a 70D.

From time to time, I read references made to a white Tamron teleconverter, as a quality t-con, yet, I can't find it anywhere on the web to buy. Is that an old/discountinued Tamron teleconverter? If so, is there a newer model with the same quality? Link?
TIA

"Kenko 1.4X Teleplus DG Pro 300 TC with Canon 70-300 IS USM"

I use that combo and it works for me.

Ok so been wading thru the thread and just need to ask....

What TC would you recommend for this setup so I can get reach for some birds and sports.
Probably a 1.4x used with 7D and Sigma 70-200mm f/2.8 EX DG OS HSM.
Will everything function properly..ie AF, IA servo, shoot at least at f4?

I've been shooting college baseball and birds with a white Tamron 1.4x on a 7D with a Canon 70-200 2.8 with no problem and been very happy with the results.

lauderdalems wrote in post #16744010
I've been shooting college baseball and birds with a white Tamron 1.4x on a 7D with a Canon 70-200 2.8 with no problem and been very happy with the results.

Thanks I was looking at the Sigma version and Kenko version as well, I may go Sigma since that's the lens I will be using it on or are the others just as good or better?