PDAF and m43 lenses on the EM1 - putting a controversy to rest

gryphon1911

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Not only on this forum, but others as well, I keep hearing people decry that the Olympus OMD EM1 does not use the PDAF when a Micro Four Thirds lens is mounted, but only when a legacy 4/3 lens is attached.

I contacted Olympus Support and asked them point blank. Officially - the EM1 determines the best focusing method to use, but it does use the PDAF with micro four thirds lenses. It only uses PDAF when legacy 4/3 lenses are attached.

Here is the correspondence:

My original inquiry to Olympus Support:

Category: Digital Cameras

Model: E-M1

Type of Inquiry: Camera Questions

Question: I just wanted to clarify a question about the focusing system on the OMD EM1.

How does the hybrid AF system work? I see a lot of information out on photo forums that the PDAF system only works when a legacy 4/3 lens is attached. My understanding is that the PDAF system works with micro 4/3 lenses as well, but the camera will determine which focusing system is best to incorporate at the time the shot is taken.

Does that sound accurate?

Olympus response:

Dear Andrew,

Thank you for contacting Olympus Technical Support.

Yes, the Dual FAST AF system can use both the contrast and phase detection elements when a micro 4/3 lens is used, the camera decides when to take advantage of both systems. If a 4/3 lens is used, only the phase detection portion is used. For more information regarding this, please refer to the following web page:

http://asia.olympus-imaging.com/products/dslr/em1/feature/05/

If you require additional assistance please reply to this email leaving the complete history intact.


Best Regards,

Olympus Technical Support
Olympus Imaging America Inc.
Toll Free Technical Support Hotline 1-888-553-4448
 

MarkRyan

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Thanks for digging in. Still pretty vague about when PDAF applies to M43 lenses. Anyone got more specifics? The link Olympus provided doesn't.
 

drd1135

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I recently ordered a Fuji X100s, and it has hybrid CDAF/PDAF on the sensor. Based on exposure conditions, it will use the one it thinks will produce the best combination of speed and accuracy. No control for the user, but according to tests it dopes provide some speed up under good lighting conditions. I would assume something similar would also be effective for mu43 lenses.
 

Ulfric M Douglas

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...If a 4/3 lens is used, only the phase detection portion is used.
Very nice of them to give you a clear reply, but can it be true?
Do you have another modern Olympus m4/3rds body to test focus acurracy alongside and whether the E-M1 is actually using only phase or really using phase plus contrast for final focus tweaking?
 
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I wish that when using 4/3 lenses, the E-M1 would employ CDAF as a backup or when you want to select a focus point outside of the PDAF "diamond".
 

bikerhiker

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Not only on this forum, but others as well, I keep hearing people decry that the Olympus OMD EM1 does not use the PDAF when a Micro Four Thirds lens is mounted, but only when a legacy 4/3 lens is attached.

I contacted Olympus Support and asked them point blank. Officially - the EM1 determines the best focusing method to use, but it does use the PDAF with micro four thirds lenses. It only uses PDAF when legacy 4/3 lenses are attached.

Here is the correspondence:

My original inquiry to Olympus Support:

Category: Digital Cameras

Model: E-M1

Type of Inquiry: Camera Questions

Question: I just wanted to clarify a question about the focusing system on the OMD EM1.

How does the hybrid AF system work? I see a lot of information out on photo forums that the PDAF system only works when a legacy 4/3 lens is attached. My understanding is that the PDAF system works with micro 4/3 lenses as well, but the camera will determine which focusing system is best to incorporate at the time the shot is taken.

Does that sound accurate?

Olympus response:

Dear Andrew,

Thank you for contacting Olympus Technical Support.

Yes, the Dual FAST AF system can use both the contrast and phase detection elements when a micro 4/3 lens is used, the camera decides when to take advantage of both systems. If a 4/3 lens is used, only the phase detection portion is used. For more information regarding this, please refer to the following web page:

http://asia.olympus-imaging.com/products/dslr/em1/feature/05/

If you require additional assistance please reply to this email leaving the complete history intact.


Best Regards,

Olympus Technical Support
Olympus Imaging America Inc.
Toll Free Technical Support Hotline 1-888-553-4448
From what I have read is that..

SAF and CAF with 4/3 lenses will be 37 PDAF sensors only

SAF with m43 lens will be PDAF first for quick target acquisition and then fine tuned with CDAF for accuracy. This makes sense.
SAF wtih m43 lens in low light conditions will be with CDAF only, as PDAF sensors are not very effective in low light. This is the same with Nikon 1 system which has a very fast AF with PDAF+CDAF hybrid system.

C-AF with m43 lens is unknown because the article didn't elaborate that much. But if it works like S-AF, then it would be PDAF first to get the initial quick target acquisition and then CDAF for tracking and finetuning.
 

gryphon1911

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I'm not quite sure what the issue is; you have no control over the mechanism, so AF either works or it doesn't.
The issue is, as stated from the original post - there are people out there posting that the PDAF on the Oly EM1 only works when a legacy 4/3 lens is attached. Trying my best to put some truth out there once and for all.

Responses like that could at the least cause confusion and at the worst turn someone off of getting a camera they want need based on false information. Not saying that one should make a decision on one post, but stranger things have happened.
 

gryphon1911

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I heard back from Olympus regarding more specifics on when the PDAF or CDAF would be employed. I've included my original question as well as the Olympus response. See below.

My Question:
Are there any guidelines regarding when the camera might choose one over the other?

Like, when shooting in bright light, would the S-AF use PDAF, and then shift to CDAF when the light was too dim for PDAF to be effective?

I'm also surmising that the PDAF would be preferred when using the C-AF Tracking. Would the same be said for standard C-AF?

Thanks again!!

Olympus Response:

You are quite welcome. No, we don't have any published guidelines for this available to the public. This is all done automatically in the background by the camera, and there is no way to adjust or control this by the end user. I personally don't think that the camera is using one AF system over the other with these lenses, but both systems at the same time when possible. Please remember that this is proprietary system developed first by Olympus, and this is one of the main reason that a lot of these very specific technical details are kept confidential, to deter copying or "borrowing" of this technology by others.
 

Replytoken

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Olympus Response:

You are quite welcome. No, we don't have any published guidelines for this available to the public. This is all done automatically in the background by the camera, and there is no way to adjust or control this by the end user. I personally don't think that the camera is using one AF system over the other with these lenses, but both systems at the same time when possible. Please remember that this is proprietary system developed first by Olympus, and this is one of the main reason that a lot of these very specific technical details are kept confidential, to deter copying or "borrowing" of this technology by others.
Get the hint - quit asking questions Andrew! Olympus doesn't want you bothering your pretty little mind with such details. Now if I was in your shoes, I would just scrapre off a bit of silicon from the processing chip and inject it ito your D300. Take matters into your own hands, Dr. Frankencamera! :coco:

As if this is how all of the other competitors "borrow" technology. I can understand why they might not want to go into detail about how their products work (which is funny given how they played up their IBIS technology), but do they really believe this lack of tranparency is a deterrent to copying their technology?

--Ken
 

OzRay

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The issue is, as stated from the original post - there are people out there posting that the PDAF on the Oly EM1 only works when a legacy 4/3 lens is attached. Trying my best to put some truth out there once and for all.

Responses like that could at the least cause confusion and at the worst turn someone off of getting a camera they want need based on false information. Not saying that one should make a decision on one post, but stranger things have happened.
I can understand where you're coming from, but from forums like this, people will always find out how effective AF is, or isn't, with various lenses and cameras. In other forums, such as DPR, there are far more negative thing to contend with when it comes to opinions about m4/3 cameras.
 

bikerhiker

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Get the hint - quit asking questions Andrew! Olympus doesn't want you bothering your pretty little mind with such details. Now if I was in your shoes, I would just scrapre off a bit of silicon from the processing chip and inject it ito your D300. Take matters into your own hands, Dr. Frankencamera! :coco:

As if this is how all of the other competitors "borrow" technology. I can understand why they might not want to go into detail about how their products work (which is funny given how they played up their IBIS technology), but do they really believe this lack of tranparency is a deterrent to copying their technology?

--Ken
Panasonic is more upfront with their DFD technology even including graphs and explanation of using Defocus blur data to assist in target acquisition. It's not hard to acquire MTF data and obviously Olympus can "borrow" this DFD like knowledge and have their own Zuiko and M.Zuiko database of their own and incorporate into the new body.
 
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