Techchart AF adapter for M-mount

[YYV_146]

Yes, the title is spelled correctly...

http://www.sonyalpharumors.com/hot-worlds-first-techart-m-mount-to-e-mount-autofocus-adapter/


More information (Chinese):
http://forum.xitek.com/thread-1535183-1-1-2.html

Notes (from xitek, the SAR translations have a few errors):

1. Requires PDAF E-mount bodies (A7, A7II, A7rII, A7SII, A6000). Works best with the A7rII and A7II
2. Maximum lens weight is 1kg if you hold the lens. Maximum weight without hand-holding is 300g
3. Comes with an app for lens information in EXIF - although I'm not sure how they deal with aperture
4. Supports tracking (but presumably no eye AF)

 

[Corran]

How silly.

Probably can't focus through the whole range for longer lenses. It says 4.5mm travel, so you could figure out the focus range for a given lens based on that. Of course you can focus closer manually and let it do the final adjustments.

Worse, if you've got a newer lens with elements that move independently based on focus distance to maximize performance, this throws that all out the window.

Well, whatever floats peoples boats I guess.

 

[YYV_146]

How silly.

Probably can't focus through the whole range for longer lenses. It says 4.5mm travel, so you could figure out the focus range for a given lens based on that. Of course you can focus closer manually and let it do the final adjustments.

Worse, if you've got a newer lens with elements that move independently based on focus distance to maximize performance, this throws that all out the window.

Well, whatever floats peoples boats I guess.

Right, but how many M mount lenses (of all brands) are FLE? Most still use traditional focus methods. As for the focus range, some rough calculations suggest that most lenses can get auto between 2m and close to infinity - which is sufficient for, say, street photography.

I know I'll get one. I use AF occasionally - and this would allow me to sell some of my E-mount lenses.

 

[CK Dexter Haven]

Silly? Pretty freakin fantastic.
If they can develop it so that it's accurate, and then quick, it might push me into the Sony from the 5D range. An autofocus Jupiter-3! Noctilux AF.... If it focuses as quickly as something like a Contax G2, I'm in.

 

[ferider]

4.5mm travel means 60cm min. focus for a 50mm lens, and even shorter for a wider lens.

That's pretty cool. Might have to get an A7* as second M body after all ....

Roland.

PS: even a 75mm should focus down to 1.3m, a 90 down to 1.9m.

 

[f16sunshine]

Man that's cool!

 

[YYV_146]

Silly? Pretty freakin fantastic.
If they can develop it so that it's accurate, and then quick, it might push me into the Sony from the 5D range. An autofocus Jupiter-3! Noctilux AF.... If it focuses as quickly as something like a Contax G2, I'm in.

Accuracy won't be an issue - the focus is on-sensor, so it will be as accurate as native E-mount lenses with PDAF. Speed is probably going to be an issue, though...and the designer mentioned that battery life may drop sharply with heavy lenses.

Still fascinating, of course.

 

[Harry Caul]

The idea of using z-shift sensor movement to autofocus manual lenses has been discussed many times in the past. So I guess I'm surprised this thread doesn't have a million posts by now!

To me this would be most interesting if they had a limited movement range "focus refine" setting. Meaning you pre focus to get close, then this adapter uses the camera face/eye detect to nail it.

Regardless, this is a pretty cool product!

https://www.youtube.com/watch?v=zEwpHChOkC0

 

[dcsang]

This should be pretty interesting... may be completely useless or something that will be ultimately very useful. Time will tell once it's tested 🙂

Cheers,
Dave

 

[sevo]

1. Requires PDAF E-mount bodies

The adapter cannot avoid hunting for focus, as it can neither know the focal length of the mounted lens, nor whether its own helical is set to some offset. What benefit is there in limiting the adapter to PDAF?

 

[YYV_146]

The adapter cannot avoid hunting for focus, as it can neither know the focal length of the mounted lens, nor whether its own helical is set to some offset. What benefit is there in limiting the adapter to PDAF?

I couldn't find any information about that from the original post. Maybe it's just software issues that will be worked out in the final product.

To be specific, the designer mentions that AF might not work "properly" with non-PDAF bodies. Perhaps the adapter takes advantage of the dual AF of the newer E-mount cameras, and relies on both to function...but may also work slowly with CDAF?

 

[YYV_146]

The idea of using z-shift sensor movement to autofocus manual lenses has been discussed many times in the past. So I guess I'm surprised this thread doesn't have a million posts by now!

To me this would be most interesting if they had a limited movement range "focus refine" setting. Meaning you pre focus to get close, then this adapter uses the camera face/eye detect to nail it.

Regardless, this is a pretty cool product!

Eye AF is limited to native lenses on A7 series cameras - this is well documented and with no apparent work-around. Face detection should work - I've used face detection with adapted AF Canon lenses.

 

[Pherdinand]

To me this would be most interesting if they had a limited movement range "focus refine" setting. Meaning you pre focus to get close, then this adapter uses the camera face/eye detect to nail it.

isn't that the idea anyway? You still have the focus helical on that lens so you CAN also manual-focus -maybe not in the correct range but within SOME range-

 

[MIkhail]

Can I get that in M mount?
/sarcazm.

 

[Harry Caul]

isn't that the idea anyway? You still have the focus helical on that lens so you CAN also manual-focus -maybe not in the correct range but within SOME range-

From my understanding the focus range would be quite large for something like a 35 or 50mm lens. I just wouldn't want to get close to perfect focus manually and then have it hunt all over the range when I hit the shutter.

 

[Pherdinand]

im not sure how the focusing mechanism on these cameras work. Does it see that from a defocused image the movement is in the "wrong" direction (i.e. if it gets even more defocused he will switch direction immediately) or does it need to hit the end stop before it reverses?

What other issue i see here is the manual aperture. If you close down the aperture the focus speed/accuracy/chance will also degrade a lot.

 

[MikeL]

What other issue i see here is the manual aperture. If you close down the aperture the focus speed/accuracy/chance will also degrade a lot.

yeah, FLE shouldn't matter since it is working off the sensor and not changing the aperture. But it seems like accuracy would get squishier with stopping down. But maybe it wouldn't matter if it gets you in the range of acceptible sharpness.

 

[YYV_146]

im not sure how the focusing mechanism on these cameras work. Does it see that from a defocused image the movement is in the "wrong" direction (i.e. if it gets even more defocused he will switch direction immediately) or does it need to hit the end stop before it reverses?

What other issue i see here is the manual aperture. If you close down the aperture the focus speed/accuracy/chance will also degrade a lot.

That's basically how CDAF works. If the A7S native lens CDAF is any indication, it will hunt in low light but when the light is good lock-on is achieved fairly quickly. The advantage is that focus is very accurate, but usually not as fast as PDAF.

 

[bmattock]

Interesting. Reminds me of the old SMC Pentax-F 1.7x AF Adapter, which supposedly permitted non-AF Pentax lenses to autofocus on Pentax AF bodies. With, however, the 1.7 multiplier and loss of lens speed. Seems like this works in a similar fashion, only without glass in-between, taking advantage of the space available with the Sony 7. Cool.

 

[splitimageview]

The Techart adapter for Contax G lenses works very well. The 45/2 and 90/2.8 on an A7R-II feels native-fast...

The entire mass of a G lens is not being moved, however...

I weighed a 50/2 Summitar (209 grams.) A 40/2 M-Rokkor or Summicron-C would be good options at about 125g.

I'm not sure what the 1kg reference means, "if you hold the lens." How is that supposed to work?