Teleconverter 2x with LA-EA4 adapter and A7II and Sigma a-mount lens

[Chrislaglisse]

Hi guys,

 

Well, pretty much everything is in the title. I was wondering if anyone tried such a combo? Not necessarily with a Sigma lens and it can be with any A7 series camera of course. The Vivitar one seems good and not too expensive.

I know we loose speed but considering the extra reach and price (and weight and volume saved in the bag), that's fair. I guess it's the trade-off.

My only concern is the image quality. The sharpness will be impacted, but is it really a problem? What about chromatic aberrations?

I'd like to have this extra reach with my Sigma 150mm f2.8 APO so that it'd be a 300mm.

 

Any thoughts or feed back on this kind of combos and how it performs?

 

Thank you very much!

Chris

[Michael_j]

I have tried an A7 with a Sigma 70-300mm OS (the newer version of the 70-300mm), a Kenko Teleplus 1.5x extender and LE-EA4 adaptor. I have also tried with Sigma 105 macro.

 

The 70-300mm will autofocus sometimes with the extender but is unreliable above 200mm lens zoom. OS doesn't work properly with the extender. Image quality on a specified close crop is about the same or slightly less with the extender despite the increased pixel count of the crop with the extender.

 

The 105 macro will not focus with the extender. Image quality is degraded with the extender.

 

The extender has the same effect on field of view as using a crop sensor A6000. Both lenses work correctly on my A6000 and the image quality is good. The 70-300mm IQ is about the same on both cameras for a given tight crop, (about 800-1000 pixels), the 105mm macro is possibly slightly more detailed on the A6000 because the very sharp lens makes good use of the extra pixels.

 

These results are subjective, maybe I'll try it under controlled conditions but at present I find the extender to be of no practical value. Perhaps if I were to look at modest sized prints of uncropped pictures my conclusions would be different.

 

Here are some test shots. Tripod mounted, manually focused. OS off.

 

Sigma at 300mm

 

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Crop on date - just under the flagpole

 

 

Same picture and crop with Kenko 1.5x extender

 

 

and just for interest this is a Leica T with Olympus OMx2 extender and Zuilo 500mm mirror lens

 

 

 

 

[Lefty]

From the LAEA4 manual "Do not attach anything (teleconverter etc.) between this unit and the lens."

 

My experience with LAEA4 (and 2) is that auto focus varies depending on which teleconverter is used. 3rd party UNCHIPPED converters are the trick, but will report un-converted lens length. Generally, lower magnification works more often/better than higher. Some discussion here: http://www.dyxum.com/dforum/problem-use-of-laea4-sony-14x-extender-dont_topic111080.html

 

FWIW my 2x 7 element Kenko teleconverter won't AF on LAEA4 and Tokina 400mm f5.6 lens, but another branded thinner 2x (likely 4 element) will. That and many other 3rd party teleconverters, appear to come off the same Kenko assembly line. I expect the current Vivitar teleconverters are rebranded Kenko. The body ridges and release buttons of the Kenkos are pretty distinctive

 

The 7 element Kenko works on larger aperture (but also shorter) lenses, so it may be running afoul of the minimum AF aperture requirements when using the Tokina. That might also be the 70-300mm issue reported by Michael_i. It's really aperture rather than focal length that interferes with teleconverted AF. 1.4 and 1.7x teleconverters work just fine with LAEA4 and the Tokina. Sony requires a minimum aperture of f6.3 to AF, with the exception of the 500mm f8 AF cat.

[Golem]

I put a Kenko 2X between a Maxxum 135/2.8

and a LA-E2 on a Nex 7. It focuses slowly in

very low light, cuz it's operating at f/5.6. The

xif data showed the effective FL and f-stop of

the combination, IOW 180mm and f/5.6. AF

performance is entirely adapter-dependent

with these adapters. Camera is not involved.

 

IIRC it really did say 180mm, tho it seems it

should be 170mm, but 10mm is no big deal.

 

AFAIK the LA-E4 is identical to the LA-E2

except that the E2 vignets on a FF camera.

 

I wouldn't comment on the IQ. While it has

to be less than the lens alone, the amount

of loss is unpredictable from lens to lens.

Some lenses are more agreeable to certain

TCs. Has to do with exit pupil, convergence,

etc. It's not like a filter factor or some other

totally constant effect. IOW TC "X" may

seem less lossy than TC "Y", but only on

a certain lens. Change to another lens the

TC "Y" might outperform TC "X".

[ViRuS X]

I have tried Sony A7R + LA-EA4 + Minolta 1.4x teleconverter + Minolta 600mm f/4

 

AF didn't work at all although AF worked well on my A99 don't know why

[Chrislaglisse]

Thank you very much for your help and sharing your experience. I'll try to gather some more "testimonies" but I guess I'll have to see it by myself. It seems pretty unpredictable.

 

I haven't found any Sony e-mount teleconverter, have you?

 

Thanks again!

[Michael_j]

 

I haven't found any Sony e-mount teleconverter, have you?

 

 

I don't think that there is such an item. 

 

For best quality you probably need to used matched lens and teleconverter. Sigma EX lenses and extenders work well but you need to be careful about compatibility. Wrongly paired units can cause glass to glass contact and physical damage to one or both