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Pentax ist DL or Canon 350D

 
 
dj_nme@hotmail.com
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      08-14-2005

Nick Fotis wrote:
> http://www.velocityreviews.com/forums/(E-Mail Removed) wrote:
> >
> > I think that Nikon and Canon both have the focus motor in the lens and
> > so with each new lens you get a new motor, but with Pentax K AF lenses
> > the motor (aparently) can't be changed without major surgery on the
> > camera body.

>
> From what I remember, only Canon has a considerable percentage of their
> lens range with USM (Ultrasonic) motors, which are inside the lens.
> Nearly all the other camera makers (Nikon, Pentax, Minolta) with
> autofocus used a motor inside the camera body to move the lens ring.
> Now, the Nikon AF-S lenses use ultrasonic motors inside the lens, but
> this is supported in the bigger cameras.


That is interesting.
It also means that Pentax could do the similar thing to Nikon, such as
putting a motor into their new lenses and (possibly) use the integral
motor (in the camera) to control the one in the lens via the current
mechanical linkage.
Another possibility is that Pentax could add more electrical contacts
to (a new improved) the K AF mount flange to control a motor in the
lens.

 
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frederick
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      08-14-2005
(E-Mail Removed) wrote:
> Nick Fotis wrote:
>
>>(E-Mail Removed) wrote:
>>
>>>I think that Nikon and Canon both have the focus motor in the lens and
>>>so with each new lens you get a new motor, but with Pentax K AF lenses
>>>the motor (aparently) can't be changed without major surgery on the
>>>camera body.

>>
>>From what I remember, only Canon has a considerable percentage of their
>>lens range with USM (Ultrasonic) motors, which are inside the lens.
>>Nearly all the other camera makers (Nikon, Pentax, Minolta) with
>>autofocus used a motor inside the camera body to move the lens ring.
>>Now, the Nikon AF-S lenses use ultrasonic motors inside the lens, but
>>this is supported in the bigger cameras.

>
>
> That is interesting.
> It also means that Pentax could do the similar thing to Nikon, such as
> putting a motor into their new lenses and (possibly) use the integral
> motor (in the camera) to control the one in the lens via the current
> mechanical linkage.
> Another possibility is that Pentax could add more electrical contacts
> to (a new improved) the K AF mount flange to control a motor in the
> lens.
>

Nikon's true AF-S lenses do not use the AF motor in the camera body.
They are "fly by wire" like Canon USM. Apart from quiet and fast
operation, a major advantage of this is that the manual focus ring can
be moved to override AF - so you can use AF to focus on the subject,
then quickly shift focus manually if desired without switching between
AF and MF modes on the lens or body. Unfortunately, this feature is not
on some of Nikon's cheap AF-S DX lenses, which also suffer from slow AF
action.
One day Nikon will release a dslr with no AF motor - to keep cost and
weight down, and the result of this will be howls of discontent.
 
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dj_nme@hotmail.com
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      08-14-2005
frederick wrote:
<snip>
> Nikon's true AF-S lenses do not use the AF motor in the camera body.
> They are "fly by wire" like Canon USM. Apart from quiet and fast
> operation, a major advantage of this is that the manual focus ring can
> be moved to override AF - so you can use AF to focus on the subject,
> then quickly shift focus manually if desired without switching between
> AF and MF modes on the lens or body. Unfortunately, this feature is not
> on some of Nikon's cheap AF-S DX lenses, which also suffer from slow AF
> action.
> One day Nikon will release a dslr with no AF motor - to keep cost and
> weight down, and the result of this will be howls of discontent.


I'm sure the howls will be just as loud as when Canon changed from FD
to EOS mount!

 
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Paul Mitchum
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      08-14-2005
<(E-Mail Removed)> wrote:

> frederick wrote:
> <snip>
> > Nikon's true AF-S lenses do not use the AF motor in the camera body.
> > They are "fly by wire" like Canon USM. Apart from quiet and fast
> > operation, a major advantage of this is that the manual focus ring can
> > be moved to override AF - so you can use AF to focus on the subject,
> > then quickly shift focus manually if desired without switching between
> > AF and MF modes on the lens or body. Unfortunately, this feature is not
> > on some of Nikon's cheap AF-S DX lenses, which also suffer from slow AF
> > action.
> > One day Nikon will release a dslr with no AF motor - to keep cost and
> > weight down, and the result of this will be howls of discontent.

>
> I'm sure the howls will be just as loud as when Canon changed from FD
> to EOS mount!


Pentax K mount: Backwards compatible all the way. Forward compatible,
too, with some exceptions for lenses you don't want to buy anyway.
 
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dj_nme@hotmail.com
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      08-15-2005

Paul Mitchum wrote:
<snip>
>
> Pentax K mount: Backwards compatible all the way. Forward compatible,
> too, with some exceptions for lenses you don't want to buy anyway.


That was precisely the reason why I chose to buy a Pentax ist-Ds!
I was originaly attracted by the ist-D, but the large price asked for
it (compared to an EOS 300D) put me off.

What I meant was that Pentax could (maybe?) add a few more electrical
connections on the lensmount (in their next DSLR?) to make in-lens
motor (USM or HSM or whatever) lenses to AF faster than is possible
with just the current in-camera focus motor.
That mount would still be backwards compatible for all MF K-mount
lenses and still allow the use of current AF K-mount lenses, except as
MF only (assuming that the in-body motor was omitted).

 
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Costas
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      08-16-2005
Isn't it said that you shouldn't just shop for a camera, but a series of
lenses? Compare the lens offerings first to decide on which camera you
want; you'll probably have the lenses longer than you'll have the camera
IMO. Is there anything even comparable to Canon L glass?
 
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