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01-26-2012, 03:51 PM   #901
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QuoteOriginally posted by falconeye Quote
This idea is a recurring theme which is why I thought I should explain why it is unfeasible.

1. An AF would have to travel by more than the registration distance allows, and in the wrong direction. E.g., a DFA100WR would have to be shifted 200,000μm!

2. The shifting precision needs to be 30μm or better. Feasible but not very cheap.

3. Many lenses are poor performers if only the focal plane is shifted. They use relative shifting of a few internal lens elements for better performance which is a special case of internal focussing (IF).

4. AF performance would be affected negatively because larger masses need be accelerated as soon as the lens rather than the sensor needs to be shifted due to the limited space in the body.


So, forget sbout this idea sooner than later.


Nevertheless, part of the idea is useful actually: to fine adjust focus during the very last steps of contrast AF. This may be done faster and more accurately using sensor shift than using the focus motor.
In spite of being infeasible, it was done by Contax in 1996 with the AX model.



Not a great success though.

01-26-2012, 03:53 PM   #902
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QuoteOriginally posted by Mistral75 Quote
Not a great success though.
And whole lot more complicated than it would be with digital.
01-26-2012, 04:02 PM   #903
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QuoteOriginally posted by konraDarnok Quote
1. It's already been implemented in the Contax AX? And that was before digital.

2. You'd have to set a focus range first -- like using the 1.7x telecoverter. 5cm should be enough to focus most lenses with ease I'd think.

3. Why would it need to be any more precise than the current focus system?

4. I could certain see how it would less than ideal for some types of lenses -- but a new system would come with its own optimized lenses.

5. You don't think a sensor assembly would weight a whole lot less than hunks of glass?
1. Contax AF is technically like the Pentax 1.7x AF tele converter. A first and early approach to AF, and in no way satisfactory to be THE camera's focus system.

2. But you said you wanted to replace the lens focus mechanism to save money. If it needs to be prefocussed, it is no cost saver and a merket failure for sure. I assumed you ruled that out.

3. I didn't say so. I just highlighted the required relative precision. Normally not doable w/o some kind of gear.

4. It is challenging enough for a lens designer to live with current contraints. You just drive the cost up here. Again.

5. Please read what I wrote.

Moreover, I must say I don't want to discuss this any further. I just wanted to share my opinion why I think this idea may sound greater than it actually is. Which I now did. End of topic for me. Of course, I have no problem whatsoever if you continue to discuss it with the rest of the forum.
01-26-2012, 04:07 PM   #904
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QuoteOriginally posted by audiobomber Quote
I agree with everything above, but unfortunately there will be lots pissing and moaning when the new camera is announced, because it can't possibly satisfy everyone's list. It is annoying to hear that someone is leaving based on a rumour though.
Not only can't it satisfy everyone's list, it is definitely going to be exactly what everyone does NOT want!


I think I'll wait for a review or two.

01-26-2012, 04:08 PM   #905
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This camera may flop, but I applaud Pentax for trying something different stylistically. I think it's silly that photographers are so nostalgic that camera makers are making everything metal and retro, like everyone slobbering over the Fuji X100 because it happens to look like a rangefinder, even though it wasn't one. Fortunately the X100 turned out to be a quality product that was somewhat worth the hype.

Don't get me wrong, retro has a place, but things need to move forward, too. Try not to reject this camera (once it arrives) just because it happens to look different.
01-26-2012, 04:09 PM   #906
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QuoteOriginally posted by Quicksand Quote
Rubber-like material?!? THAT'S TERRIBLE!!! I was totally going to buy the K-01 but now I guess I'll have to buy a Sony.
But are you totally going to buy the Sony??
01-26-2012, 04:13 PM   #907
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QuoteOriginally posted by falconeye Quote
1. Contax AF is technically like the Pentax 1.7x AF tele converter. A first and early approach to AF, and in no way satisfactory to be THE camera's focus system.
I don't understand this reply.

QuoteOriginally posted by falconeye Quote
2. But you said you wanted to replace the lens focus mechanism to save money. If it needs to be prefocussed, it is no cost saver and a merket failure for sure. I assumed you ruled that out.
For legacy lenses not designed for the system, you might need to set a range manually with your hand -- but your example was a macro -- which is not really a typical application. Setting a focus range with a macro is a *feature.* Not a drawback.

QuoteOriginally posted by falconeye Quote
3. I didn't say so. I just highlighted the required relative precision. Normally not doable w/o some kind of gear.
Again I'm losing you.

QuoteOriginally posted by falconeye Quote
4. It is challenging enough for a lens designer to live with current contraints. You just drive the cost up here. Again.
A lens without a motor is not more expensive than one with it.

QuoteOriginally posted by falconeye Quote
5. Please read what I wrote.
I did, and I don't see as how the sensor assemble would weight more.

QuoteOriginally posted by falconeye Quote
Moreover, I must say I don't want to discuss this any further.
*shrugs*
01-26-2012, 04:19 PM   #908
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A rubber skin just might be a good idea, especially if the camera is truely rugged. Weather-sealing would be a big plus. Looks is something, but it really depends upon how the camera performs. I am looking forward in seeing what Pentax has in store for us. It might even show a little in the direction Rich is taking Pentax.

I will love to see how well this new camera performs in the hands of reviewers and actual users. Then if it does what I want I might consider it as a carry with me camera when I don't want to take my K-5.

01-26-2012, 04:20 PM   #909
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QuoteOriginally posted by glanglois Quote
But are you totally going to buy the Sony??
Well, no, not really. I just thought the thread needed more emo trolling!!!!111

In actuality, I'm really intrigued by what we've been hearing. I like the idea. I adore my K-5 (mostly) -- and if we can get similar IQ in a forward-looking package that still allows full legacy lens compatibility, I'm all for it.

My wishes:
* Sensor-based SR.
* A viewfinder of some kind, probably EVF
* Screw-drive AF included
* Good EVF manual focus support (peaking? something else?)
* A hotshoe

It would be hilarious if all these rumors turned out to be unfounded, though, wouldn't it?
01-26-2012, 04:31 PM   #910
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Actually the main rumor that has turned me off of the camera a bit is the lack of a built in viewfinder. But if they manage to make this more videographer friendly I think it would offset that somewhat -- for me anyway. If this truly is a K-r replacement, having a built in mic port is a good upgrade.
01-26-2012, 04:41 PM   #911
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QuoteOriginally posted by Quicksand Quote
Well, no, not really. I just thought the thread needed more emo trolling!!!!111

In actuality, I'm really intrigued by what we've been hearing. I like the idea. I adore my K-5 (mostly) -- and if we can get similar IQ in a forward-looking package that still allows full legacy lens compatibility, I'm all for it.

My wishes:
* Sensor-based SR.
* A viewfinder of some kind, probably EVF
* Screw-drive AF included
* Good EVF manual focus support (peaking? something else?)
* A hotshoe

It would be hilarious if all these rumors turned out to be unfounded, though, wouldn't it?
+1 on this list. I will add the following:
* Built-in flash
* Weather-sealing & rugged
* Good overall performance and handling

Dave
01-26-2012, 05:05 PM   #912
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Never mind weather sealing, from the descriptions so far it sounds like this baby might be waterproof and shockproof, like a w90 with a k mount...
01-26-2012, 05:14 PM   #913
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QuoteOriginally posted by ihasa Quote
Never mind weather sealing, from the descriptions so far it sounds like this baby might be waterproof and shockproof, like a w90 with a k mount...
One can only hope. I always loved my W90.
01-26-2012, 05:33 PM   #914
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"The new 40mm f/2.8 pancake lens is less than 1 centimeter thick and my understanding is that it will work only with the new K-01 body"
-- why old lenses can work on this body but the new 40mm don't wok with older body? hm.... it is can't AF on old body?

what could be the reasons?
01-26-2012, 05:39 PM   #915
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I don't want to discuss it. But of course I'll going to explain points which I may not have expressed in a way easy enough to understand. So, here we go ...

QuoteOriginally posted by konraDarnok Quote
1. I don't understand this reply.

2. Again I'm losing you.

3. I did, and I don't see as how the sensor assemble would weight more.
1. The Contax AX only moved the entire lens (the mirror box actually) by a certain amount. Almost exactly like the Pentax 1.7x AF TC does. The lens needs to be prefocussed, using manual focus.

While this is doable, it is not an acceptable approach to AF for a modern camera. Manual prefocus is not generally accepted anymore. And if you ever worked with the 1.7x AF, then you know that it requires its own kind of skill to work satisfactorily. Moreover, the solution added substantial and unavoidable bulge to the camera.

And this is for any kind of lens (except wide angles), not just a macro lens.

2. A fully functional sensor shift would have to span 400,000Ám with 30Ám precision, or a relative precision of ~10,000:1. This is actually easier to achieve with a focus wheel and a gear box than a linear shift motor. As I said, I don't see a problem with tiny movements as required for AF fine tuning for the last steps of a CDAF. But I consider it to be impractical if it is to replace a full focus system, be it manual or automatic.

3. I wrote "AF performance would be affected negatively because larger masses need be accelerated as soon as the lens rather than the sensor needs to be shifted due to the limited space in the body".

So, why did you reply that the sensor is lighter than the lenses? I said that the lenses need to move as soon as the sensor reaches its maximum travel. The weight of the sensor doesn't matter then.

The entire point I am making is that the sensor cannot shift enough (to make your idea work satisfactorily) and that it isn't generally good enough to only alter the distance to the focal plane. Moreover, such a solution certainly is much more expensive than adding a simple screw to a lens mount.
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