A-Mount Teleconverters Guide

Miranda F wrote: QuietOC wrote: It doesn't adjust the reported apertures or focal lengths--the later is an issue for proper SteadyShot operation. Odd. I've only seen that on Tcs without a chip (or which have been de-chipped). I'd expect a recent one to report the changes as my older model does.

Yes, it is just wired straight through. Oh, well. At least it works.

Ahoy!

I haven't waded through 25 pages on this thread, but unless it's already been posted or discussed, I've come across the Kenko TC compatibility chart on their website, so if you're after the Kenko DGX model to fit the A-Mount, you might want to check first:

Kenko

Whilst on the subject, you can also see the Sigma TC compatibility chart below:

Sigma

So, I hope this info will be of use, but if not, then no harm done.

TTFN.

Edited by Pirate - 24 February 2016 at 20:07

Initial compatibility report for the Kenko α-AF 1.4X TELEPLUS MC4 DGX and Sony SLT-A58.

AF works, focal length & aperture corrected:

DT 55-200 SAM
Sigma 24 F2.8
DT 30 F2.8 SAM Macro
DT 35 F1.8 SAM
DT 50 F1.8 SAM
Tamron 60 F2 Macro
AF 85 F2.8 SAM
DT 16-105
AF 35-70 F4
AF 35-105 F3.5-4.5
AF 70-210 F4

AF works, focal length & aperture uncorrected:

DT 55-300 SAM
DT 18-135 SAM

AF disabled, focal length & aperture corrected:

DT 18-55 SAM I
DT 18-55 SAM II

Some better compatibility than the straight-pass-through 1.5X DG model, but no better compatibility with the 55-300 SAM. The 18-55s would AF on the 1.5X DG, and attempt to AF on the older Mx-AF 2X TELEPLUS MC7. There might be a lens age/firmware issue.

It came with a sheet from Kenko that states:

"(1)TELEPLUS converters are compatible with SSM/SAM Lenses.
(2)TELEPLUS converters are compatible with image stabilization.
(3)Depending on the combination of DIGITAL-SLR and primary lens, the focal length information of EXIF data may not be the same."

"If Lens element has as fixed aperture, TELEPLUS converters cannot be used with lenses faster than F1.8. If it set F1.2, the photo is taken at F1.8. You can't obtain a correct exposure."

Date on the sheet: "2011.12"

The 55-300 and 18-135 were released in 2012. The 18-55 SAM II was released in 2013. All the other lenses were released before 2011.12. There might be newer versions of the DGX with firmware to support the later lenses.

Edited by QuietOC - 25 February 2016 at 00:34

Miranda F wrote: Well, thanks very much for that, QuietOC. I'm quite surprised by the results - it seems Kenko still haven't got their firmware quite right, or else there's something in the way the data is communicated which makes it impossible to get right for all lens camera combinations and they have to make a choice. * * Maybe that's why Kenko no longer list Sony A-mount TCs - they've given up trying to follow all the comms changes!

That seems likely. As far as correcting the reported aperture and focal length, the DGX behaves identically to the older Mx-AF 2X MC7 TCs. Those also don't adjust the 55-300 and 18-135, but do adjust those values on the other lenses including the SAM lenses. So that part of the firmware doesn't seem to have changed much.

An example with the Sony SLT-A58 + Kenko α-AF 1.4X TELEPLUS MC4 DGX + Sony DT 55-300 SAM


ISO 160 1/500 s f/7.8 420 mm

It seems to be pretty decent in the center part of the frame, but the edges looks a little funky. This was the sharpest image in a sequence of six, and it is a bit back focused. AF worked okay, not much worse than the 55-300 acts normally.

Mmm, fairly consistant with your results for the other TC then, given the increased f no.
I did some tests with the Koren 2003 chart to check the relative resolution and contrast with various lenses and either 2x TC or 2x CIZ. On most of my lenses the TC didn't give very much improvement in resolution and lost contrast, and the CIZ didn't give any improvement but didn't lose contrast, so neither seemed worth much (all jpegs in camera). I was tempted to conclude that the MC4 just isn't as good as the MC7, but then . . .

EDIT: Correction: The 55-300mm *does* show some benefit with the 2x Kenko TC though it won't AF and doesn't update the fl or aperture. I suspect the CIZ would give more benefit if standard quality jpegs are used.

The only lens I tried which really shone with the 2x teleplus MC4 TC was the Tamron 90mm f2.8 di (not the USD) and this made a pretty good 180mm macro lens! I could see some slight loss of res and contrast compared with no TC and standing closer, but when the lenses were tested at a given distance (which is relevant for birding/etc) the TC helped signficantly and the results were very good. Clearly this lens out-resolves the A58 sensor a lot (at f5.6-8, at least; res at f2.8 was noticeably worse, though that may have been affected by DOF/Focussing issues, despite the multiple shots I took).

At a fixed distance (around 5m), the best resolution/contrast I obtained was actually the Tamron 500mm mirror, which narrowly beat the 55-300mm, though when measured the normal way (at different distances) it doesn't. Not a compeltely fair test since the mirror was MF and adjusted with focus peaking while I used AF on the AF lenses which usually loses a bit (no AF adjust on the A58!), but this represents how the lenses would be used - if you choose to use an AF lens because of its AF, then you should compare IQ/etc with it functioning IMHO, if the tests are to be reprsentative of use. And I appreciate that being 'representative' may demand a different test setup to being 'fair'.

Edited by Miranda F - 25 March 2016 at 22:10