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Author Topic: Pentax K100d  (Read 23989 times)
Kenneth Sky
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« Reply #20 on: May 25, 2006, 08:13:27 AM »
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I've had no problem with a 300mm 2.8 on my K-M 7D. I've even hand held my mirror reflex 500mm but only in bright sunshine. As far as I'm concerned the AS sensor technology works. And as I've said before, the K-M  philosophy of using dials instead of menus inside of menus has allowed me to make the transition from film to digital much easier.
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BJL
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« Reply #21 on: May 25, 2006, 09:24:24 AM »
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Apparently you dial in the focal length in the settings for older pentax lenses ...
[a href=\"index.php?act=findpost&pid=66484\"][{POST_SNAPBACK}][/a]
That  is what I have heard: Pentax seems to be maintaining its excellent attention to backwards compatability. I could even stabilize my old Pentax 50/1.7 K for extreme low light hand held work undreamed of with film.
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BJL
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« Reply #22 on: May 25, 2006, 09:36:30 AM »
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I've had no problem with a 300mm 2.8 on my K-M 7D.
[a href=\"index.php?act=findpost&pid=66537\"][{POST_SNAPBACK}][/a]
Thanks: despite my initial comments favoring the in-lens approach, I am glad to read this experimental refutation of the argument that "AS/SR is inferior at longer focal lengths, just where you need it most". Anything that help to level the "shake cancellation" playing field and so strengthen some of the DSLR industry's smaller players should improve the competitive situation for DSLR buyers.

That argument against AS/SR started wth Phil Askey's 7D review I believe, and as a scientist it sounded like at best a plausable conjecture, worth putting to experimental test, not a theoretically proven fact as some people seem to take it.

Many photographic forum participants put way too much faith in the conclusions of such rough, unquantified, untested theoretical arguments, and should learn a bit of respect for a good balance of theory and experiment!
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tjanik
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« Reply #23 on: May 25, 2006, 01:08:13 PM »
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I wonder how well the “D” digital lenses, with their smaller image circle, will work with Pentax’s CCD-based SR system. I have no idea of the amount of movement involved with the sensor or if it will go outside the image circle.  Any zoom lens, except at its widest setting should have image to spare, but fixed lenses?  If Pentax introduces lens-based SR in its digital lenses at some point, it would be the best of both worlds. Older lenses use the CCD SR and the smaller, lighter “D” lenses uses a lens-based SR.  Of course you would likely have to disable the CCD SR, otherwise you would have a double correction unless a very sophisticated feedback loop was included.
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BJL
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« Reply #24 on: May 25, 2006, 03:05:44 PM »
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I wonder how well the “D” digital lenses, with their smaller image circle, will work with Pentax’s CCD-based SR system.
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1) Konica-Minolta's AS works fine with its "DSLR only" DT lenses, designed for the smaller image circle of its sensors. So the fear that they will not goes with the other bogus theory about AS/SR not working well with longer telephoto lenses.
2) Pentax is not run by complete idiots, and only a bunch of complete idiots would launch this new SR system if it did not work with the numerous Pentax DA (DSLR only) lenses, which probably includes the majority of the lenses being sold and used on Pentax DSLRs.

This is enough to convince me that SR will work with Pentax DA lenses, but just in case, I checked the press release quoted at [a href=\"http://www.dpreview.com/news/0605/06052205pentaxk100d.asp]http://www.dpreview.com/news/0605/06052205pentaxk100d.asp[/url]


"The PENTAX-developed Shake Reduction (SR) system ...can be used with almost all existing PENTAX interchangeable lenses.*

* Lenses compatible with this mechanism are: PENTAX K-, KA-, KAF- and KAF2-mount lenses; screw-mount lenses (with an adapter); and 645- are 67-system lenses (with an adapter). Certain lenses may lose part of their functions."
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tjanik
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« Reply #25 on: May 25, 2006, 06:11:33 PM »
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BJL:

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So the fear that they will not goes with the other bogus theory about AS/SR not working well with longer telephoto lenses.
 
Why so defensive? I did not propose a theory, I simply asked a question.  I don't know how much the sensor moves and if its movement would present difficulties with D lenses. 

2) Pentax is not run by complete idiots, and only a bunch of complete idiots would launch this new SR system if it did not work with the numerous Pentax DA (DSLR only) lenses, which probably includes the majority of the lenses being sold and used on Pentax DSLRs.

I certainly didn't say, nor should my question be cause to construe, that Pentax is run by idiots and am unlikely to do so since I've been buying their cameras for 35 years.  As for rendering old lenses unusable, seems some major camera makers have already done exactly that.

"The PENTAX-developed Shake Reduction (SR) system ...can be used with almost all existing PENTAX interchangeable lenses.*

* Lenses compatible with this mechanism are: PENTAX K-, KA-, KAF- and KAF2-mount lenses; screw-mount lenses (with an adapter); and 645- are 67-system lenses (with an adapter). Certain lenses may lose part of their functions."

I read the announcement as well, my question is what does "almost" mean in this sentence.


[a href=\"index.php?act=findpost&pid=66571\"][{POST_SNAPBACK}][/a]
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BJL
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« Reply #26 on: May 26, 2006, 09:11:14 AM »
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So the fear that they will not goes with the other bogus theory about AS/SR not working well with longer telephoto lenses.

Why so defensive? I did not propose a theory, I simply asked a question.  I don't know how much the sensor moves and if its movement would present difficulties with D lenses. 
[a href=\"index.php?act=findpost&pid=66587\"][{POST_SNAPBACK}][/a]
And yet after I pointed out that the idea was refuted some time ago by the fact that KM's AS with its DT lenses, your response shows that you are not simply asking a question; you clearly seem to be trying to defend the idea that there is a chance of SR not working with DA lenses. (It is interesting too that when you quoted me, you deleted that reference to AS working with DT.)
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2) Pentax is not run by complete idiots, and only a bunch of complete idiots would launch this new SR system if it did not work with the numerous Pentax DA (DSLR only) lenses, which probably includes the majority of the lenses being sold and used on Pentax DSLRs.

I certainly didn't say, nor should my question be cause to construe, that Pentax is run by idiots and am unlikely to do so since I've been buying their cameras for 35 years.  As for rendering old lenses unusable, seems some major camera makers have already done exactly that.
[a href=\"index.php?act=findpost&pid=66587\"][{POST_SNAPBACK}][/a]
You are not talking about making the new SR feature incompatble with some old or old-fashioned (like manual focus) lenses, you are talking about making it incompatable with the great majority of their most recent lenses, ones of central importance to the success of the Pentax DSLR system; the new DA lenses. That sort of incompatability would be unprecedented idiocy, and also massively at odds with Pentax's excellent record of backward compatability.
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"The PENTAX-developed Shake Reduction (SR) system ...can be used with almost all existing PENTAX interchangeable lenses.*

* Lenses compatible with this mechanism are: PENTAX K-, KA-, KAF- and KAF2-mount lenses; screw-mount lenses (with an adapter); and 645- are 67-system lenses (with an adapter). Certain lenses may lose part of their functions."

I read the announcement as well, my question is what does "almost" mean in this sentence.
[a href=\"index.php?act=findpost&pid=66587\"][{POST_SNAPBACK}][/a]
Since a great proportion of Pentax's recent lens sales are surely of the DA lenses, SR working with "almost all existing PENTAX interchangeable lenses" is clearly inconsistent with it not working with the DA lenses.
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Craig Arnold
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« Reply #27 on: May 26, 2006, 10:33:48 AM »
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IS is trying to make sure that it's image circle lands on the same spot.  Meanwhile AS is busy moving that spot all over the place.

Wouldn't work.
[a href=\"index.php?act=findpost&pid=66452\"][{POST_SNAPBACK}][/a]

So are you saying that the IS inside the lens works by getting feedback from the image projected onto the sensor plane? How can that be?

Can you be a bit more specific about why it wouldn't work as a 2-stage stabilisation? (I'm not looking for a fight, it just doesn't seem as obvious to me why it wouldn't work as it does to you!)    

Certainly from the AS side if it's getting a more stable image circle that could hardly be a problem could it?

Any links to how IS/AS works would be very interesting.
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Caer
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« Reply #28 on: May 26, 2006, 02:45:23 PM »
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Regarding sensor-based shake reduction, it's easy to work out how much the sensor needs to move if you just look at how many pixels your typical motion blur covers.

Let's pretend for a moment the shaking is really bad, say 20 pixels' worth.

Now, the sensor in the K100D (and KM 5/7D) is 23.6mm across, and squeezes 3008 pixels into that size.

Therefor a simple bit of maths...
23.6 / 3008 = pixels 0.00785mm wide. 7.85 microns.

Multiply that by 20 and you get a sensor movement of ~0.16mm.

0.16mm sensor movement to cancel out 20 pixels of shaking!

So basically, the sensor doesn't have to move very far at all to cancel out the effects of camera shake, and ought to work fine even on digital lenses with really tight imaging circles.
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tjanik
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« Reply #29 on: May 26, 2006, 08:08:13 PM »
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Caer:     Thanks for the rational analysis.  My concern is based on a near-future lens purchases.  Should I buy a heavier 35mm limited or a lighter digital version, since I have all but abandoned 35mm film?  

Peripatetic:

It is my understanding that both the lens and sensor-based systems respond to camera movement (not image movement in the case of SR). As such, neither would be aware of the other’s correction unless a feedback loop was incorporated.  Interestingly, it seems double correction would yield the same amount of blur, but in the opposite direction.

BJL:

You obviously think my post was meant to be inflammatory; it was not.  I have two closets full of Pentax 35mm, 645 and 67 lenses.  Nevertheless, I considered switching to Canon just for the IS lenses.  I stayed with Pentax and purchased a *ist DS; so I am as pleased with this development as anyone.   You are likely correct, nevertheless, I find your argument that a corporation (in this case Pentax) wouldn’t do something stupid less than compelling
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aaykay
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« Reply #30 on: May 27, 2006, 11:11:38 PM »
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I think the issue with sensor shifting AS (Pentax, KM) is that it will work fine with reduced frame sensors.  All dSLRs from Pentax and KM are reduced-frame sensors (1.5x).

With full-frame sensors you simply cannot shift the sensor to compensate for shake, since the sensor fills the imaging circle and it would fall outside the imaging circle if shifted (up/down/right/left).  Not a problem with 1.6x or 1.5x sensors, since even when shifted to compensate for shake, the smaller sensor will still remain within the imaging circle.
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MrIconoclast
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« Reply #31 on: May 28, 2006, 02:56:53 PM »
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A few random thoughts:

I have a KM A2 and the sensor based Anti-Shake technology works great.  I don't see a difference between it and the VR on my  80-400 zoom.  

Like many people I was dismayed to see KM get out of the photo business and sell it to Sony.   Between the proprietary Sony stick memory and the  the root-kit incident, I have wondered if Sony is really  the way to go.  That whole root-kit thing, even though it didn't involve photography, left me with a bad taste in my mouth.  So far Pentax's partner, Samsung, has not done anything to turn me off.

Pentax has a huge resevoir of K mount lenses out there, most of which will  work with their anti-shake system.  That is a great advantage.  Olympus, had a great system in the OM1 and OM2, but never carried  forward with autofocus and other advances.  That left many of my OM owning friends feeling abandoned.   To the best of my knowlege the OM lenses won't work on the new Olympus digital bodies.  Or am I wrong?

  At least Pentax kept advancing their technology, albeit, late compared to Canon and Nikon.
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gewitterkind
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« Reply #32 on: May 29, 2006, 08:45:35 AM »
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Pentax has a huge resevoir of K mount lenses out there, most of which will  work with their anti-shake system.  That is a great advantage.  Olympus, had a great system in the OM1 and OM2, but never carried  forward with autofocus and other advances.  That left many of my OM owning friends feeling abandoned.   To the best of my knowlege the OM lenses won't work on the new Olympus digital bodies.  Or am I wrong?
There is an OM-adapter.Till the middle of 2005, you could even get it for free if you sent in your e-1 guarantee-card.
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MrIconoclast
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« Reply #33 on: May 30, 2006, 08:31:08 PM »
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There is an OM-adapter.Till the middle of 2005, you could even get it for free if you sent in your e-1 guarantee-card.
[a href=\"index.php?act=findpost&pid=66842\"][{POST_SNAPBACK}][/a]


That's good to hear.  Does the adapter allow the lenses to be fully functional?  Will autofocus lenses still autofocus for example?

( a few days later)  I forgot that Olympus never made autofocus lenses for their OM system.   For me that is a big negative.  I would much rather buy into a system where the manufacturer has a history of upgrading and modernizing the system.
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danag42
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« Reply #34 on: May 30, 2006, 09:24:29 PM »
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I'm tempted to buy long lenses in the pentax or sony mount just to get antishake without having to buy IS on each lens.
[a href=\"index.php?act=findpost&pid=66359\"][{POST_SNAPBACK}][/a]


Pentax has the advantage of compatibility with ANY K mount lens.  You only get what the lens is capable of, but my ancient K 45-125 SMC zoom works fine on the *st D, and it seems Pentax are going to include the cam so you can use the M and K lenses in apeture priority auto mode on the new sooper-dooper whiz bang cameras.

I started in the 1960's when the cream of the crop were Pentax and Zeiss.  I suspect the same is true now, the Pentax Limited series are far beyond anything anyone else makes.  So is their multicoating.
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gewitterkind
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« Reply #35 on: May 31, 2006, 04:13:10 AM »
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That's good to hear.  Does the adapter allow the lenses to be fully functional?  Will autofocus lenses still autofocus for example?
[a href=\"index.php?act=findpost&pid=66960\"][{POST_SNAPBACK}][/a]
well, there are no OM AF lenses ; )
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Ben Rubinstein
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« Reply #36 on: May 31, 2006, 08:55:53 AM »
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I started in the 1960's when the cream of the crop were Pentax and Zeiss. I suspect the same is true now, the Pentax Limited series are far beyond anything anyone else makes. So is their multicoating.

Is this true or is it just what the loyal pentax fans like to say? Are pentax limited primes better than all the other manufacturers pro level primes?

I did see some sample pictures from the K100D, can't remember the link, it was obvious that the new 21mm pancake limited lens was being crippled by the sensor in that camera, it looks capable of far far better and will be interesting to see on the new 10 megapixel version.
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Kenneth Sky
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« Reply #37 on: May 31, 2006, 09:22:16 AM »
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"10 megapixel version"?? I haven't seen the announcement. However the K-M - oops - Sony Alpha definitely does have a 10.2 sensor.
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BJL
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« Reply #38 on: May 31, 2006, 10:38:39 AM »
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I think the issue with sensor shifting AS (Pentax, KM) is that it will work fine with reduced frame sensors.  All dSLRs from Pentax and KM are reduced-frame sensors (1.5x).

With full-frame sensors you simply cannot shift the sensor to compensate for shake, since the sensor fills the imaging circle and it would fall outside the imaging circle if shifted (up/down/right/left).  Not a problem with 1.6x or 1.5x sensors, since even when shifted to compensate for shake, the smaller sensor will still remain within the imaging circle.
[a href=\"index.php?act=findpost&pid=66762\"][{POST_SNAPBACK}][/a]
This is refuted in my post above, #25 in this thread. K.-M. Anti-Shake works fine with DT lenses (and third party "APS-C" lenses) which are designed specifically for the format of the "APS-C" digital sensors, so these sensor-based systems do _not_ need to use a sensor size that imposes a significant crop on the image produces by the lens.
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BJL
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« Reply #39 on: May 31, 2006, 11:36:54 AM »
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Pentax and Olympus seem now to have stripped themselves of the deadwood of some older lens designs for 35mm film cameras that are of far less interest with thier DSLR formats. Pentax has apparently discontinued many of its 35mm format lenses, leaving the list at
http://www.pentaxslr.com/lenses
plus four new DA lenses announced as coming soon. The list of Pentax lenses currently in production (as opposed to ones still available but no longer in production) might be as short as the following:
DA 10-17 Fish Eye
DA 12-24/4
DA 14/2.8
DA 16-45/4
DA 18-55/3.5-5.6
FA 31/1.8 Limited
DA 40/2.8 Limited
FA 43/1.9 Limited
FA 50/1.4
DFA 50/2.8 Macro
DA 50-200/4-5.6
FA 77/1.8 Limited
DFA 100/2.8 Macro
with the following expected soon:
DA 16-50/2.8 (Autumn 2006)
DA 21/3.2 Limited (June 2006)
DA 50-135/2.8 (Autumn 2006)
DA 70/2.4 Limited (Autumn 2006)
If so, about the same size as the Olympus 4/3 lens list, but with more primes at "middle focal lengths" while Olympus has more telephoto extremes and a wider range of zooms.

P. S. I just found another longer and probably definitive list of Pentax lenses currently in production at http://www.digital.pentax.co.jp/en/lens/
It adds the following:
FA-J 18-35 f/4-5.6
FA 20-35 f/4
FA-J 28-80 f/3.5-5.6
FA 28-105 f/3.2-4.5
FA-J 75-300 f/4.5-5.8
FA 35 f/2
FA 135 f/2.8
FA 300 f/2.8
FA 600 f/4
My guess is that these nine extra lenses are being marketed only towards to 35mm film camera users, and so the other site "www.pentaxslr.com" omits them, being entirely oriented to Pentax's digital SLR's.
« Last Edit: May 31, 2006, 12:31:07 PM by BJL » Logged
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