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05-16-2013, 04:58 PM   #76
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QuoteOriginally posted by monochrome Quote
I don'expect you to understand. .
To comprehend and to concur are two separate things.

05-16-2013, 11:58 PM   #77
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I would love to see Pentax make both a full-frame DSLR and a full-frame medium-format camera. (Those would be my 'dream-cameras.' The 645 isn't full-frame either when compared to medium-format film, if memory serves me correct. Although it is still awesome!) But if Pentax wants to keep up with the big-two, they are either going to need to go to a full-frame sensor format or wait for the pixel-density of smaller sensors to catch up. But then they will always be lagging behind.

And as far as their crop-sensor line of lenses go, keep their midlevel cameras on the APS-C format. That way those buyers can still use them. But for the higher-end market, a.k.a. current K-5 users, it would be better to put them out of one generation of lenses now than wait and eventually put them out of the market for multiple generations of lenses later. (I don't think the 'DA' line of lenses really killed the demand for, or abundance of, legacy- even manual- lenses. There is still a lot of lens options out there. That's part of the beauty of Pentax.)

Plus, as a middle-aged guy into photography, there is the reflex connotation that if a camera's image sensor is smaller than it's film counterpart- it just seems like it will yield a lower quality image. Pixel-density of the sensor and human logic be damned.

Of course, that's just my opinion. But, hint, hint- Pentax!
05-25-2013, 05:38 AM   #78
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Lens selection

Lens selection would not stop Pentax from going full frame. Even if they dont launch a single new lens they still have a wider selection of lenses for the new full frame camera then Fuji X-system, Sony NEX, Panalympic mFT, Sigma and Samsung NX had at their launch dates. Still, im pretty shure Pentax would launch at least a few extra full frame lenses simoultanously. It would make a great lens selection from day one and only grow.
05-25-2013, 02:12 PM   #79
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QuoteOriginally posted by Simen1 Quote
Lens selection would not stop Pentax from going full frame. Even if they dont launch a single new lens they still have a wider selection of lenses for the new full frame camera then Fuji X-system, Sony NEX, Panalympic mFT, Sigma and Samsung NX had at their launch dates. Still, im pretty shure Pentax would launch at least a few extra full frame lenses simoultanously. It would make a great lens selection from day one and only grow.
I agree, I have a myriad of Pentax PK mount full frame lenses that I use on my full frame Sony NEX-VG900 like the 24mm F1.4 .

05-27-2013, 02:13 AM   #80
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QuoteOriginally posted by jogiba Quote
I agree, I have a myriad of Pentax PK mount full frame lenses that I use on my full frame Sony NEX-VG900 like the 24mm F1.4 .
Does that Sony NEX-VG900 have SR? Or does that sensor remain static like a the 135mm film? (Comparably: There is a very good reason why the image circle of DA-lenses is considerably larger then the image circle required by an APS-C sensor: the sensor moves around. Making lots of DA lenses 135mm-film compatible.)

Worst case scenario is that not a single currently known Pentax lens is 135mm+SR compatible. Which would explain Pentax being so reluctant to go FF better then any other reason.
05-27-2013, 05:37 AM   #81
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The Sony NEX-VG900 uses Sony OSS E mount lenses instead of sensor based SR just like the NEX-3N etc.
05-27-2013, 05:48 AM   #82
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The question was retorical. The fact that a K-mount lens shows no vignetting when used on an film FF SLR, or on an FF digital camcorder, doesn't indicate they will also work on a Pentax FF DSLR with SR. The difference being the required image circle being considerably bigger for lenses to be used on SR cameras. The APS-C sensor in Pentax DSLRs with SR moves a whopping 3mm in every direction! I don't recall 135mm film doing that.
05-27-2013, 06:22 AM   #83
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QuoteOriginally posted by Clavius Quote
The APS-C sensor in Pentax DSLRs with SR moves a whopping 3mm in every direction! I don't recall 135mm film doing that.
But the whole movement of 3mm is not used for SR. For 4 stops of SR on a APS-C camera it's probably closer to +-0.3mm movements needed. The larger movement is needed for acceleration of the sensor (which can be done outside the image circle), and is used for other features (video, composition adjustment...).

For FF it's enough if the image circle has +-0.5mm extra, which I think most existing FF lenses can support without much vignetting.

05-27-2013, 06:34 AM   #84
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QuoteOriginally posted by Fogel70 Quote
But the whole movement of 3mm is not used for SR. For 4 stops of SR on a APS-C camera it's probably closer to +-0.3mm movements needed. The larger movement is needed for acceleration of the sensor (which can be done outside the image circle), and is used for other features (video, composition adjustment...).

For FF it's enough if the image circle has +-0.5mm extra, which I think most existing FF lenses can support without much vignetting.
So... The extra large image circle of the DA lenses is just for kicks?

0.3mm? Are you serious? Take the lens off your Pentax DSLR, switch it to LV and stare down the mount. You'll see the sensor float around A LOT more then just 0.3mm. (Seriously cool to see though!)

BTW, the 3mm sensor movement is not something I made up. It is confirmed as the SR sensor movement.
05-27-2013, 07:04 AM - 1 Like   #85
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The skills of photographers in the film era were amazing. They could manually focus, adjust their aperture and speed and still keep their camera's steady.
05-27-2013, 07:05 AM   #86
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QuoteOriginally posted by Clavius Quote
So... The extra large image circle of the DA lenses is just for kicks?

0.3mm? Are you serious? Take the lens off your Pentax DSLR, switch it to LV and stare down the mount. You'll see the sensor float around A LOT more then just 0.3mm. (Seriously cool to see though!)

BTW, the 3mm sensor movement is not something I made up. It is confirmed as the SR sensor movement.
SR for LV and video require much more movements as the sensor is moving constantly. For "normal" use the sensor only move a fraction of that.

It's easy to check how much movement is needed in normal use by turning off SR and check how many pixels the blur is if using 4 stops longer shutter speed than you can get sharp images.
05-27-2013, 07:19 AM   #87
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QuoteOriginally posted by Fogel70 Quote
SR for LV and video require much more movements as the sensor is moving constantly. For "normal" use the sensor only move a fraction of that.
Yes, during LV it moves constantly, and in "normal" use it is only activated during focussing and pressing the shutter.

Can you explain why the short timespan translates to a smaller requirement in sensor movement? And can you explain why pre-LV Pentax DSLRs also had the 3mm sensor movement then? And, for the last time, why do DA lenses have an image circle that much larger then APS-C requires then?
05-27-2013, 07:56 AM   #88
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QuoteOriginally posted by Clavius Quote
Yes, during LV it moves constantly, and in "normal" use it is only activated during focussing and pressing the shutter.
For normal use the sensor is only moving after shutter button is pressed.
QuoteQuote:
Can you explain why the short timespan translates to a smaller requirement in sensor movement? And can you explain why pre-LV Pentax DSLRs also had the 3mm sensor movement then? And, for the last time, why do DA lenses have an image circle that much larger then APS-C requires then?
As camera shake is low frequency (usually 1-10hz) it does not take very fast shutter speed before the sensor movement when the shutter is open is much less, than full movement when using LV/video.

As I said before, the extra movement is needed for accelerating the sensor before the shutter opens, but it does not matter if this movement is done outside the image circle of the lens.

I'm not sure why image circle vary so much on Pentax APS-C lenses, but I doubt it has anything to do with SR. But you will probably also find that most FF lenses have a image circle that is much larger than FF.
05-27-2013, 08:31 AM   #89
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QuoteOriginally posted by Clavius Quote
And, for the last time, why do DA lenses have an image circle that much larger then APS-C requires then?
Kind of a false challenge -- when designing lenses there is no reason for them to shrink the image circle as much as they can. Sure, they can make smaller lenses in general if the target format is smaller, but that doesn't mean that if an optical design happens to have a little extra than they need that they are going to make it a priority to make sure the image circle gets smaller -- only if by doing so they will gain significant additional advantages in terms of the factors that are really important -- the optical quality, size, weight, number of elements, and manufacturing costs. In general, I think you'll find that longer lenses tend to have image circles that are larger than wide-angles. But just because an image circle is bigger doesn't mean that whole additional space is "useable" -- up to acceptable optical quality.
05-28-2013, 12:14 AM   #90
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QuoteOriginally posted by Fogel70 Quote
But you will probably also find that most FF lenses have a image circle that is much larger than FF.
Nope! That's the problem. I use lots of my old Pentax glass on my 5DII and they already show vignetting and serious border and corner problems on a static FF sensor. What if it starts moving, even just a tiny little bit!?

(Admitting: I am a big fan of 100% corner to corner sharpness. What's the use of going FF, with an "FF compatible lens" if it requires your to crop off the bad borders aftwards? Then I can just as wel keep mounting them on my crop sensor camera and shoot the best bit straight away.)
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