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10-06-2010, 06:18 PM   #241
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QuoteOriginally posted by dnas Quote
That's why in my earlier point mentioned a "smart" electronic adapter, not the "straight through" adapter tha we currently have from Pany & Oly. We talk about lenses not being "optimised" for CDAF, but what does that mean? It is NOT the glass, it is the lens' communication and focusing electronics.

When I suggested that Pentax use micro 4/3, but have a "smart" adapter(PK-micro 4/3), I was talking about aperture stop down and focusing motors in the adapter(there's around 24mm of space for this). And then I said it should have "smart" adapter that emulates a CDAF compliant lens.

QuoteOriginally posted by Fogel70 Quote
I doubt this is really possible, as CDAF and PDAF works very differently.
CDAF and PDAF are different, but just the fact that Micro 4/3 cameras(with CDAF) support some PDAF lenses WITHOUT smart electronics in the adapter means that it CAN work.
Smart electronics in the converter IS possible and would work.




QuoteOriginally posted by Fogel70 Quote
With PDAF the camera know in what direction and how much the focus must be changed, and then send a command to the lens for doing the movement. With CDAF the camera do not know in what direction or how much it needs to move, so it changes focus in small step and check if focus has improved between movements. And it continue doing this until it has found focus.
The CDAF in the Panasonic & Olympus micro 4/3 does not work in that way. It doesn't do small steps, it does a swing from one end to the other. When it finds that the highest contast point has been passed, it reverses direction.
The Panasonic seems to do 2 direction changes, while Olympus seems to do 3.

10-07-2010, 12:04 AM   #242
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QuoteOriginally posted by dnas Quote
CDAF and PDAF are different, but just the fact that Micro 4/3 cameras(with CDAF) support some PDAF lenses WITHOUT smart electronics in the adapter means that it CAN work.
Smart electronics in the converter IS possible and would work.
DSLR with CDAF in LV it also work with PDAF lenses, but AF do not work very well.
Why would there be any need for "smart electronics" in the adapter when it's already in the camera? If anything, extra electronics will make AF even slower.
The only things needed in the adapter are those things not included in the camera (AF for screw-drive and mechanics for aperture stop-down).
QuoteQuote:
The CDAF in the Panasonic & Olympus micro 4/3 does not work in that way. It doesn't do small steps, it does a swing from one end to the other. When it finds that the highest contast point has been passed, it reverses direction.
The Panasonic seems to do 2 direction changes, while Olympus seems to do 3.
CDAF always do AF in small steps, but on optimized system the steps go so fast that it looks like one motion. On a lens with motor, electronics and software optimized for CDAF the performance can be very fast.
10-07-2010, 12:47 AM - 1 Like   #243
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QuoteOriginally posted by Fogel70 Quote
DSLR with CDAF in LV it also work with PDAF lenses, but AF do not work very well.
But we are not talking about DSLR, we are talking about micro 4/3 optimised for CDAF, as it's sole auto focusing method. The PDAF lenses (e.g. Olympus 14-42mm) work perfectly fine on a Panasonic GF1. It's just slower to focus than the Panasonic CDAF 14-45mm. But the focus DOES work well, and is accurate. Have you actually used one of these cameras?

QuoteOriginally posted by Fogel70 Quote
Why would there be any need for "smart electronics" in the adapter when it's already in the camera? If anything, extra electronics will make AF even slower.
The "smart" electronics would emulate a CDAF lens.
i.e. To the micro 4/3 camera, it sees a CDAF lens. The extra electronics would NOT make AF slower.

QuoteOriginally posted by Fogel70 Quote
CDAF always do AF in small steps, but on optimized system the steps go so fast that it looks like one motion.
No, that's not right. Have you actually watched a micro 4/3 lens focus?
10-07-2010, 05:03 AM   #244
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QuoteOriginally posted by dnas Quote
But we are not talking about DSLR, we are talking about micro 4/3 optimised for CDAF, as it's sole auto focusing method. The PDAF lenses (e.g. Olympus 14-42mm) work perfectly fine on a Panasonic GF1. It's just slower to focus than the Panasonic CDAF 14-45mm. But the focus DOES work well, and is accurate. Have you actually used one of these cameras?
We discuss using PDAF lenses with contrast detection AF in general. I have been saying the whole time that PDAF lens on a CDAF camera will be slower than a CDAF lens. And for me slower AF is not working as well as a faster AF. The principle of using a PDAF lens with CDAF is no different on EVIL or DSLR, but on EVIL it's easy to see how much better a CDAF optimized lens focus.

QuoteQuote:
The "smart" electronics would emulate a CDAF lens.
i.e. To the micro 4/3 camera, it sees a CDAF lens. The extra electronics would NOT make AF slower.
What would the emulation in the adapter do?
Would it not only move the limitation between camera and lens, to between adapter and lens? And by this only add extra delay in communication between camera and lens, as the communication also needs to be processed by the adapter.

QuoteQuote:
No, that's not right. Have you actually watched a micro 4/3 lens focus?
Yes I have watched them many times, but I don't understand what this can tell about the communication between camera and lens?
If I understood the technical details of CDAF on GH2 it process AF 120 times per second, and older m4/3 cameras do it 60 times per second.

10-07-2010, 06:18 AM   #245
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QuoteOriginally posted by Fogel70 Quote
What would the emulation in the adapter do?
Would it not only move the limitation between camera and lens, to between adapter and lens? And by this only add extra delay in communication between camera and lens, as the communication also needs to be processed by the adapter.
The communication between camera and lens will run at something like 30kHz, so any "delay" in the electronic communication is negligible compared to the mechanical movement of lens element required for focusing.


QuoteOriginally posted by Fogel70 Quote
Yes I have watched them many times, but I don't understand what this can tell about the communication between camera and lens?
If I understood the technical details of CDAF on GH2 it process AF 120 times per second, and older m4/3 cameras do it 60 times per second.
This means that processor uses a frame comparison rate of 120 fps((it examines and interprets the whole frame, or portions of it for an increase or decrease in contrast 120 time per second) instead of 60fps. It doesn't mean that the focusing mechanism takes 120 steps per second.
10-07-2010, 07:29 AM   #246
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QuoteOriginally posted by Asahiflex Quote
It does, especially in the case of Pentax. The screwdriven lenses are always faster than the SDM lenses... Give me screwdrive any day, because this cannot be screwed up
LOL yes what i meant (but I thnk you got that) is that screwdrive is no reason to be slower
10-07-2010, 12:26 PM   #247
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QuoteOriginally posted by dnas Quote
This means that processor uses a frame comparison rate of 120 fps((it examines and interprets the whole frame, or portions of it for an increase or decrease in contrast 120 time per second) instead of 60fps. It doesn't mean that the focusing mechanism takes 120 steps per second.
Isn't this just using fancier words saying the same thing? If GH2 can't lock focus within a second it has repeatedly done 120 steps of checking increased/decreased contrast and shifting focus after each check.
10-07-2010, 03:35 PM   #248
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QuoteOriginally posted by Fogel70 Quote
Isn't this just using fancier words saying the same thing? If GH2 can't lock focus within a second it has repeatedly done 120 steps of checking increased/decreased contrast and shifting focus after each check.
No, it does not mean that there is one focus shift(and a stop) of the lens after each frame check. That would be like running a 100m race within your lane, but stopping every second to check that you're in your lane!!!!! You can do both at the same time: Run continuously AND check to make sure you're in your own lane while doing it!!!!

For starters, according to figures, the GH2 can focus lock in 0.1 seconds not ONE second. You have made the mistake of thinking that you need to COMPLETE all 120 frames before it will focus lock. The rate of 120fps vs 60 fps means that the check speed is twice as fast.

It works like this.

It does a contrast check, then moves the lens focus. Let's say it's been moving the lens CONTINUOUSLY for 0.07 sec, in which time it's done 8 frame checks.

It's found that the contrast increased on frames 1,2,3,4,5,7, but decreased on frame 8. So far it has made just one focus "step" but has been monitoring the contrast continuously.
The focusing changes direction (step 2). It finds on frame 9,10,11(with smaller focus movement speed, for more precision) in it increases contrast, but on frame 12, it decreases. Finally(the processor remembering the increases and decreases in contrast), it changes the focus direction again(step 3), and on frame 13 it increases contrast and on frame 14 it locks focus.

The total time for focus lock is 0.117 seconds, with a total of 3 focus steps, and NOT 14 focus steps.
In this case, if both the GH2 & the GH1 need 14 frames to focus lock, then while the GH2 locks in just over 0.1 seconds, the G1 would take more than 0.2 seconds.

I can see that you don't want to believe how it works, and that PDAF lenses can work on CDAF cameras with a suitable adapter. Smart electronics in the adapter can "trick" the camera into thinkng that it has a CDAF lens attached. The electronics then provides a suitable electronic control system to drive the focus motor, and feeds back the appropriate data to the camera to make it appear that it's a CDAF lens.


Last edited by dnas; 10-07-2010 at 03:40 PM.
10-07-2010, 10:51 PM   #249
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Since the big two camera brands (C & N) are so quiet about mirrorless, I can't help but thinking about what kind of strategy they are thinking about right now. Are they waiting each other out? What if Pentax were to join one of the big two in an alliance for a new mount (with shorter registration distance). Wouldn't it be smart to make customers believe that they buy into a system that is more of a standard? My guess is that this is part of the success of the micro43 mount.....not just one brand support it.

Anyway....if a big brand would "give" Pentax some market share of the same mount, I think they would gain even more market share compared to the other big brand that is releasing their new mount alone at the same time. And Pentax could continue in their niche with small rugged designs for both bodies and lenses and not really disturb the market of their mount partner.

Not saying this is how I want things to happen.....just thinking.....wouldn't they fight over Pentax to get them aboard right now? Or could people see it as a sign of weakness if a big brand can't handle their own mount?

/Tommy
10-07-2010, 11:32 PM   #250
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QuoteOriginally posted by dnas Quote
No, it does not mean that there is one focus shift(and a stop) of the lens after each frame check. That would be like running a 100m race within your lane, but stopping every second to check that you're in your lane!!!!! You can do both at the same time: Run continuously AND check to make sure you're in your own lane while doing it!!!!
I think you done the mistake of thinking that a steps need to include a stop or change of direction between each steps.
If you always walk like this and stop or change direction between each step it will look very funny, and not be the most effective way of moving. Steps can be made in a continuous flow of motion without any change of speed or direction between steps.

I never said it will ALWAYS take one second or have to complete 120 steps for GH2 to focus, I just said that IF it takes one second it will do 120 steps. Depending on how long it will take it will do different numbers of steps, and I'm sure in will not ALWAYS take 0.1s for it to focus (one focusing step of CDAF consist of checking contrast and moving or locking focus, but it does not have to include stop och change of direction between steps)

Can you please explain how it will improve AF if you trick the camera to think it has a CDAF lens instead of PDAF lens? The limitation will still be in the lens, and the electronics/software in the lens to be updated for improved AF with CDAF.
10-07-2010, 11:58 PM   #251
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QuoteOriginally posted by Fogel70 Quote
I think you done the mistake of thinking that a steps need to include a stop or change of direction between each steps.
If you always walk like this and stop or change direction between each step it will look very funny, and not be the most effective way of moving. Steps can be made in a continuous flow of motion without any change of speed or direction between steps.

I never said it will ALWAYS take one second or have to complete 120 steps for GH2 to focus, I just said that IF it takes one second it will do 120 steps. Depending on how long it will take it will do different numbers of steps, and I'm sure in will not ALWAYS take 0.1s for it to focus (one focusing step of CDAF consist of checking contrast and moving or locking focus, but it does not have to include stop och change of direction between steps)
You are mistaken about your definition of "steps" then. A step is a discrete change. The CDAF fps measurement is purely that.... it's just a measurement. It's used all the time in digital electronics, where it is called sampling.


You said this:

QuoteOriginally posted by Fogel70 Quote
CDAF always do AF in small steps, but on optimized system the steps go so fast that it looks like one motion.
I'm sure any other person would interpret "CDAF always do AF in small steps" as small but discrete changes in the focusing action of the lens, not a continuous movement.

QuoteOriginally posted by Fogel70 Quote
Can you please explain how it will improve AF if you trick the camera to think it has a CDAF lens instead of PDAF lens? The limitation will still be in the lens, and the electronics/software in the lens to be updated for improved AF with CDAF.
I am talking about ANY Pentax K mount AF lens being used with a Pentax AF -> micro4/3 adapter. Those lenses can't be "updated" because the older ones don't have any firmware!!!! Since these lenses can't communicate intelligently with the camera, the adapter has to have smart electronics to make it so that the lens/adapter combo looks like a lens that a micro 4/3 camera can communicate with. Otherwise, the Pentax lens would NOT autofocus AT ALL, with a micro 4/3 camera!!
10-08-2010, 01:03 AM   #252
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QuoteOriginally posted by dnas Quote
You are mistaken about your definition of "steps" then. A step is a discrete change. The CDAF fps measurement is purely that.... it's just a measurement. It's used all the time in digital electronics, where it is called sampling.
Yea, I don't agree that a step has to be a discrete change of physical motion. It only has to be discrete in change of function so when a step is completed an new one starts.

QuoteQuote:
You said this:

I'm sure any other person would interpret "CDAF always do AF in small steps" as small but discrete changes in the focusing action of the lens, not a continuous movement.
At the time I was describing the function of CDAF, and I would probably had put my words differently if knew you where only interested in the movement of the lens.

QuoteQuote:
I am talking about ANY Pentax K mount AF lens being used with a Pentax AF -> micro4/3 adapter. Those lenses can't be "updated" because the older ones don't have any firmware!!!! Since these lenses can't communicate intelligently with the camera, the adapter has to have smart electronics to make it so that the lens/adapter combo looks like a lens that a micro 4/3 camera can communicate with. Otherwise, the Pentax lens would NOT autofocus AT ALL, with a micro 4/3 camera!!
I really doubt that Pentax ever will be interested in joining MFT camp, and I doubt Olympus/Panasonic is interred in having Pentax joining them. So this happening is very unlikely.

But if Pentax would do a MFT I'm convinced that they put the support for K-mount lenses in the camera instead of the adapter. Doing a two-step conversion would be much more difficult and will probably not work as well as having correct support straight out of the camera.

Edit: And Pentax would not like to make an adapter that can give full support of K-mount lenses on other brand of cameras.

Last edited by Fogel70; 10-08-2010 at 01:33 AM.
10-08-2010, 05:22 AM   #253
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QuoteOriginally posted by Fogel70 Quote
I really doubt that Pentax ever will be interested in joining MFT camp, and I doubt Olympus/Panasonic is interred in having Pentax joining them. So this happening is very unlikely.

But if Pentax would do a MFT I'm convinced that they put the support for K-mount lenses in the camera instead of the adapter. Doing a two-step conversion would be much more difficult and will probably not work as well as having correct support straight out of the camera.


Then it wouldn't be micro 4/3 !!!!!!!!
10-08-2010, 05:40 AM   #254
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It would be, but software and electronics for K-mount lenses would be in camera instead of adapter. The adapter would only have those functions that the camera can't support. Like AF-motor for screw-drive and mechanical aperture control.

Except for K-mount support it would work as any other MFT camera.
10-08-2010, 05:51 AM   #255
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QuoteOriginally posted by Fogel70 Quote
It would be, but software and electronics for K-mount lenses would be in camera instead of adapter. The adapter would only have those functions that the camera can't support. Like AF-motor for screw-drive and mechanical aperture control.

Except for K-mount support it would work as any other MFT camera.
It - would - not - be - micro 4/3

This is why they smart electronics MUST be in the adapter.
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