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10-08-2013, 12:15 PM   #16
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QuoteOriginally posted by Digitalis Quote
The simulated AA filter is nice, but it will have limited use with flash photogaphy - due to the fact that most hot shoe mounted/studio flash units have very short durations.
They must have tested this, and been at least somewhat satisfied, especially since studio shots, fashion, etc would potentially be the most prone to moire. I only have old Vivitar flashes, but on low power they go as short as 1/30000 second or something...

10-08-2013, 04:55 PM - 1 Like   #17
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QuoteOriginally posted by vonBaloney Quote
They must have tested this, and been at least somewhat satisfied, especially since studio shots, fashion, etc would potentially be the most prone to moire.
Pentax states that the upper shutter speed limit for the simulated AA filter is around 1/1000th - many flash units can have durations shorter than 1/10,000th
10-08-2013, 05:25 PM   #18
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QuoteOriginally posted by Digitalis Quote
Pentax states that the upper shutter speed limit for the simulated AA filter is around 1/1000th - many flash units can have durations shorter than 1/10,000th
This is an excellent point. I guess it remains to be seen how susceptible this 24MP sensor is to moire and under what conditions the AA simulation is actually required. I better keep my K-7 though, just in case. The Einstein E640 t.1 flash duration at lowest power in action mode is 1/13500th sec. I usually shoot in constant color mode, which means anything less than half power may leave the simulated AA filter ineffective.
10-08-2013, 07:16 PM   #19
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QuoteOriginally posted by Digitalis Quote
Pentax states that the upper shutter speed limit for the simulated AA filter is around 1/1000th - many flash units can have durations shorter than 1/10,000th
Well, they say "it won't work as well" or some such rather than "max 1/1000th, period". Still, 1/10000th and faster ought to freeze most anything -- I wonder how fast the sensor actually goes.

It would never be an issue for me (maybe for bug macros with flash?), but for a studio photographer shooting certain things it could be a real problem. Of course you could just take whatever steps are necessary so you can use a higher power/longer duration flash burst so you're in the 1/500th range...

10-08-2013, 09:01 PM   #20
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QuoteOriginally posted by vonBaloney Quote
I wonder how fast the sensor actually goes.
According to the guys at Imaging resource in their " geeks guide to AA the Pentax K-3 AA filter simulation" the sensor oscillates at 500Hz. But from what I am seeing in their data there is also a slight peak at 1000Hz.
10-08-2013, 09:33 PM   #21
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QuoteOriginally posted by vonBaloney Quote
It would never be an issue for me (maybe for bug macros with flash?), but for a studio photographer shooting certain things it could be a real problem. Of course you could just take whatever steps are necessary so you can use a higher power/longer duration flash burst so you're in the 1/500th range...
Much studio work is done with MF cameras, which have no AA filters, and generally larger photosites, which have an increased risk of moiré. They seem to cope. One solution to the Pentax problem, might be for the flashgun to put out four quarter power flashes in quick succession as each pixel is aligned, but I doubt if any gun can do that.
10-08-2013, 09:38 PM   #22
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QuoteOriginally posted by Digitalis Quote
According to the guys at Imaging resource in their " geeks guide to AA the Pentax K-3 AA filter simulation" the sensor oscillates at 500Hz. But from what I am seeing in their data there is also a slight peak at 1000Hz.
Well that would explain the 1/1000 shutter speed spec. If it oscillates completely at 500Hz, that is once every 0.002 seconds, but you only need 1/2 an oscillation supposedly to get the full effect. So every 0.001 second (1/1000) you will get the full effect of the AA simulation.

I don't understand what you mean by a peak at 1000Hz.
10-08-2013, 09:41 PM   #23
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QuoteOriginally posted by Cynog Ap Brychan Quote
Much studio work is done with MF cameras, which have no AA filters, and generally larger photosites, which have an increased risk of moiré. They seem to cope.
Yes, I would hope the incidence of moire would be infrequent. From what I've read I don't feel completely confident that it can be corrected that well in PP.

10-08-2013, 11:34 PM - 1 Like   #24
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QuoteOriginally posted by rskura Quote
I don't understand what you mean by a peak at 1000Hz.
Imaging Resource's admittedly comprehensive audio analysis they haven't excluded the possibility of the 500hz peak they are seeing could possibly be a resonant frequency - and that the actual frequency of the sensor vibrations could actually be 1000Hz.

If the sensor is vibrating at 500Hz at 1/1000th shutter speeds and higher the anti-aliasing effect would be inconsistent across the frame, when taking into account the small amount of the sensor is exposed to light at those shutter speeds. For complete Anti-Aliasing across the frame the most effective shutter speed to use it would be at 1/180th because the sensor in its entirety is exposed to light. Imaging resource admitted their figure of 500Hz is based on analytical scrutiny - pentax hasn't explicitly stated the speed of the sensor platforms movement.

It has also occurred to me that using de-convolution sharpening methods to correct for blur with this AA technique could be rendered ineffective because of the inconsistencies caused by the sensors motion. The AA filter has a predictable amount of blur across the frame - With the K-3 AA filter simulation the sensor is moving in a circular motion (AA mode 2) - depending on the shutter speeds used this will cause inconsistencies in the blur pattern - similar to that caused by atmospheric distortion.

For critical applications I prefer the use of diffraction to blur the image - because diffraction follows a consistent pattern.

Last edited by Digitalis; 10-08-2013 at 11:47 PM.
10-08-2013, 11:37 PM   #25
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How about shooting at f/11 (or whatever it is for 24MP) and let diffraction take care of the moire? That might sometimes work in the studio with clean backgrounds and lots of flash power available.

Regards,
--Anders.
10-09-2013, 06:22 AM   #26
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Well, it will be interesting to see both the susceptibility of this sensor to moire and the effectiveness of the simulated AA filter as shutter speed or flash duration changes. I am hopeful that Pentax studied this potential limitation and decided that the likelihood of moire occurring under these circumstances was small. I'm sure there will be many that will study/comment on this in the coming months. This will definitely be on my mind when my K-3 arrives.
10-09-2013, 07:42 AM - 1 Like   #27
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QuoteOriginally posted by rskura Quote
Yes, I would hope the incidence of moire would be infrequent. From what I've read I don't feel completely confident that it can be corrected that well in PP.
My K-5IIs has had over 58,000 shutter actuations. (Admittedly only a few 1000 in the studio). I've only spotted moire in one of them, and that disappeared when printing or reducing for the web.

I'm sure moire will be a problem for some people, but even before knowing about the K-3's AA feature I had already decided never to buy a camera with an AA filter again.
10-09-2013, 12:50 PM   #28
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QuoteOriginally posted by Barry Pearson Quote
I'm sure moire will be a problem for some people, but even before knowing about the K-3's AA feature I had already decided never to buy a camera with an AA filter again.
Thanks for that. It makes me feel a lot better, although I suspected it wouldn't be a major issue for me. My main motivation for upgrading from my K-7 is for better high ISO performance. The improved IQ with an AA filter-less sensor is an exciting additional benefit. I don't think I am going to regret it in any way.
10-09-2013, 03:02 PM   #29
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I don't get it. The K3 adds a few more fps and a bigger buffer for $1300. All the rest is just fluff and barely used, or even recognized, by your average shooter. Give me an articulated LCD and decent live view and I'm in. Otherwise, there is nothing really new here since I bought my last Pentax, the Kx. Still waiting while they play catch up. Does Ricoh really think pro shooters invested in thousands of dollars worth of lenses are really going to switch to the K3? It's delusional.
10-09-2013, 03:20 PM   #30
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QuoteOriginally posted by tarsus Quote
I don't get it. The K3 adds a few more fps and a bigger buffer for $1300. All the rest is just fluff and barely used, or even recognized, by your average shooter. Give me an articulated LCD and decent live view and I'm in. Otherwise, there is nothing really new here since I bought my last Pentax, the Kx. Still waiting while they play catch up. Does Ricoh really think pro shooters invested in thousands of dollars worth of lenses are really going to switch to the K3? It's delusional.
If the K-x does all you want, then that's great. However, I don't share your view about all the improvements made in various iterations since the K-x are just "fluff". Neither do I think that Ricoh is delusional: they seem to know what they are doing.
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