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A9+FE converter + LA-EA3

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marcus-k View Drop Down
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Post Options Post Options   Quote marcus-k Quote  Post ReplyReply Direct Link To This Post Topic: A9+FE converter + LA-EA3
    Posted: 11 September 2017 at 11:22
I know I can not use the LA-EA3 with A-mount tele converters and A-mount tele lenses and get autofocus.

But what about putting an e-mount tele converter on the A9 and then the LA-EA3 adapter? Does this autofocus with A-mount tele lenses? If possible, does anyone know if it affects the focus accuracy and speed. Especially with the 300/2.8 or 500/4 lenses.

Marcus
 



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QuietOC View Drop Down
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Post Options Post Options   Quote QuietOC Quote  Post ReplyReply Direct Link To This Post Posted: 11 September 2017 at 11:37
My Kenko DGX teleconverters work fine with my LA-EA1.
A65 30M 35 50 16-50 16-80 16-105 18-135 18-250 55-200 55-300
A5000 LA-EA1 16 20 16-50 18-55
Maxxum 70: 20 24 28 50 85 100M 135 28-135 35-70 35-105 35-200 70-210 75-300 100-200 100-300D
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marcus-k View Drop Down
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Post Options Post Options   Quote marcus-k Quote  Post ReplyReply Direct Link To This Post Posted: 11 September 2017 at 12:13
Does this mean you get autofocus, and if so is it reliable and fast? I want something at least comparable to the A99.
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Miranda F View Drop Down
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 11 September 2017 at 13:07
Originally posted by marcus-k marcus-k wrote:

Does this mean you get autofocus, and if so is it reliable and fast? I want something at least comparable to the A99.

Doubtless QuietOC will respond, but it surely depends on the aperture. He's had good results with TCs, but I find that anything approaching f5.6 before a TC is added produces slow and unreliable AF with the A58, and the usability is heavily dependent on scene lighting and contrast (so, a waste of time for birding!)

My question is why you are using a TC at all? Very few long tele lenses I've tried (and no zooms) are sharp enough to give much benefit with a TC on a camera with 20+Mp - usually a digital zoom/crop gives better results*. And yes, I appreciate this isn't the case for the expensive wide-aperture tele primes. But *I* use TCs regularly only to fit APS-C lenses on FF, or with film when I don't want to carry another glass bottle around.

*Moonshots are an exception but I need MF focus bracketting to benefit.
A900, A58, 5d, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras . . .
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QuietOC View Drop Down
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Post Options Post Options   Quote QuietOC Quote  Post ReplyReply Direct Link To This Post Posted: 11 September 2017 at 13:34
Originally posted by marcus-k marcus-k wrote:

Does this mean you get autofocus, and if so is it reliable and fast? I want something at least comparable to the A99.

I don't have a PDAF E mount or any experience with the A9, A99, 300/2.8, or 500/4.

My SAM and SSM lenses AF just fine (slow CDAF) with the DGX teleconverters on my A5000 and NEX F3 even stacked. My 55-300 will AF in low light with the 2X stacked with the 1.4X at the long end--effectively 840mm f/16 max aperture. The A65 won't lock focus with that combination even with extremely bright light/contrast, but using the 2X alone at 600mm f/11 the A65 focuses much faster than the CDAF E mount cameras. Maybe that just says CDAF is very reliable.

The on-sensor PDAF might degrade worse than CDAF (or SLT PDAF), but I expect that it should work with the DGX teleconverters.

I wouldn't count on any of the Sony (or Minolta) teleconverters working in this situation. I highly doubt the Sony FE TC's will allow AF to work with the LA-EA3 and any lenses. I wouldn't be surprised if it locked up the camera. It might (should) work mechanically and optically.

Edited by QuietOC - 11 September 2017 at 14:21
A65 30M 35 50 16-50 16-80 16-105 18-135 18-250 55-200 55-300
A5000 LA-EA1 16 20 16-50 18-55
Maxxum 70: 20 24 28 50 85 100M 135 28-135 35-70 35-105 35-200 70-210 75-300 100-200 100-300D
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fritzenm View Drop Down
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Post Options Post Options   Quote fritzenm Quote  Post ReplyReply Direct Link To This Post Posted: 11 September 2017 at 14:32
Well based on Sony/Minolta TCs for A-mount AFAIK those are made especially for the usage with a small set of lenses.

More information you'll also find here in the lenses/converter section.

Now in the case of the new Sony E-mount TCs I suppose it's a very similar situation and that you shouldn't mount "any" E-mount fitting lens or adapter to its lens side.

In the case of the Sony/Minolta A-mount converters there may be even parts of the TC which advance, when mounted, into the barrel of the lens - for which those dedicated lenses are already constructed for. But the construction of common lenses is different and their zooming / focussing move of inside elements could damage those special TCs.

Again it's pretty likely a similar case with the new E-mount TCs. Since they're pretty expensive I'd be very cautious with unusual combinations.
 



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marcus-k View Drop Down
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Post Options Post Options   Quote marcus-k Quote  Post ReplyReply Direct Link To This Post Posted: 11 September 2017 at 15:02
Originally posted by Miranda F Miranda F wrote:




My question is why you are using a TC at all? Very few long tele lenses I've tried (and no zooms) are sharp enough to give much benefit with a TC on a camera with 20+Mp - usually a digital zoom/crop gives better results*. And yes, I appreciate this isn't the case for the expensive wide-aperture tele primes. But *I* use TCs regularly only to fit APS-C lenses on FF, or with film when I don't want to carry another glass bottle around.

*Moonshots are an exception but I need MF focus bracketting to benefit.


I regularly use the Sony 1.4x A-mount converter on the Sony 500/4 with good results on the A99. If upgrading to a A9 I would loose AF for this combination. I was wondering if I could get AF by combining the FE-converter instead of A-mount converter.
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QuietOC View Drop Down
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Post Options Post Options   Quote QuietOC Quote  Post ReplyReply Direct Link To This Post Posted: 11 September 2017 at 15:12
Edit: tried linking to Sony's images, but that didn't work. The FE teleconverters stick out into the lens more than the A mount ones, but I don't think that would be a mechanical issue with the LA-EA3. They would just stick into the LA-EA3.

SEL14TC (FE 1.4X)
[IMG][/IMG]

SEL20TC (FE 2X)
[IMG][/IMG]

SAL14TC (A 1.4X)
[IMG][/IMG]

SAL20TC (A 2X)
[IMG][/IMG]

LA-EA3


The DGX Teleconverters are compatible with nearly every A mount lens I've tried. The chip in them does a good job handling the electronic translations.

Edited by QuietOC - 11 September 2017 at 15:20
A65 30M 35 50 16-50 16-80 16-105 18-135 18-250 55-200 55-300
A5000 LA-EA1 16 20 16-50 18-55
Maxxum 70: 20 24 28 50 85 100M 135 28-135 35-70 35-105 35-200 70-210 75-300 100-200 100-300D
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marcus-k View Drop Down
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Post Options Post Options   Quote marcus-k Quote  Post ReplyReply Direct Link To This Post Posted: 11 September 2017 at 16:37
I agree. It looks like it should be mechanically possible.    But is it also electronically compatible with AF?
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Miranda F View Drop Down
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 12 September 2017 at 11:16
My understanding is that the Sony TCs are recognised individually by the camera which makes decisions based on that, whereas aftermarket TCs like the Kenko simply change some of the data they convey from the lens, and that this is why they are more likely to work in combinations not anticipated (or approved) by Sony.

AF is a different issue and CDAF does seem to promise workable AF in situations where PDAF will not.

I still don't see much value in using them with mass-market zoom lenses though. I agree the Sony 55-300mm is sharp and that a 1.4x TC may give some slight increase in resolution, but my own tests make me surprised to hear that a 2x TC or an effective 2.8x will give you anything to make up for the loss of contrast and speed.
A900, A58, 5d, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras . . .
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