[Christine Tham]

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We know the sensor dimensions/area and the pixel count.

That tells us very little. At best it gives an upper bound of the size of each pixel, the effective size of the light collection area for each pixel may be a lot smaller. The assumptions behind the Zeiss formula may be less and less relevant as the sensor size gets smaller.

To quote wikipedia:

The Zeiss formula is apocryphal, in the sense that it has grown to be a well-known named concept by propagation through the internet, even though it has no official origin, little connection to Carl Zeiss Company, and no recognition or usage in the photographic industry outside the web community.

Basically the Zeiss formula comes from an ASSUMPTION that the CoC for a 35mm full frame camera is EXACTLY 0.025, which itself was based on analysing the DOF markings on a Zeiss lens.

This would assume essentially no interpixel gap, which is progressively less true as sensor size diminishes and the gap between pixels becomes significant in relation to pixel size.

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Last edited by Christine Tham; 07-12-2011 at 12:55 PM.

[lol101]

YouTube - ‪PENTAX Q (Digital Mirrorless) : Touch & Try Event‬‏


rather slow AF

Hey, who needs AF with such a small sensor?

Give me a good hyperfocal mode and I'm done!

[Art Vandelay II]

Hands on report with the Q from Quesabesde:
quesabesde.com/noticias/pentax-q-analisis-fotos-video,1_7779

Still no sample images though.

[jsherman999]

That tells us very little. At best it gives an upper bound of the size of each pixel, the effective size of the light collection area for each pixel may be a lot smaller. The assumptions behind the Zeiss formula may be less and less relevant as the sensor size gets smaller.

To quote wikipedia:


Basically the Zeiss formula comes from an ASSUMPTION that the CoC for a 35mm full frame camera is EXACTLY 0.025, which itself was based on analysing the DOF markings on a Zeiss lens.

This would assume essentially no interpixel gap, which is progressively less true as sensor size diminishes and the gap between pixels becomes significant in relation to pixel size.

But any small difference in the CoC there would amount to maybe a fraction of a stop in DOF, not a full stop or (good grief) multiple stops, as you were saying... If it did, it would be the most revolutionary sensor ever designed to date. I doubt that the 'Q' is getting this future tech before CaNikon

Here, this sort of addresses these CoC rounding errors:


"...Using the “Zeiss formula”, the circle of confusion is sometimes calculated as d/1730 where d is the diagonal measure of the original image (the camera format). For full-frame 35 mm format (24 mm × 36 mm, 43 mm diagonal) this comes out to be 0.024 mm. A more widely used CoC is d/1500, or 0.029 mm for full-frame 35 mm format, which corresponds to resolving 5 lines per millimeter on a print of 30 cm diagonal. Values of 0.030 mm and 0.033 mm are also common for full-frame 35 mm format. For practical purposes, d/1730, a final-image CoC of 0.2 mm, and d/1500 give very similar results."

At this point I should probably say this - if you (or anyone) are fully aware of the probable limitations of the Q, but still find it compelling enough to try, more power to you, I'm sure it can make some good images for you. My main problem isn't that it's useless, it's that it's not an investment in K-mount, and it's (IMO) not robust enough to survive in it's own silo, where there's a lot of competition, priced better for the same performance. In this regard it represents a drain on Pentax's resources without a likely payoff.

I hope to be wrong.


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Last edited by jsherman999; 07-12-2011 at 02:48 PM.

[Aristophanes]

Background OOF blur on the Q will supposedly be a software, not an optical feature. That alone speaks volumes. The min. CoC appears to be 6 feet using a calculator.

[fearview]

available in ebay

Pentax Q Digital Camera with 8.5mm Lens (White),NIB JPN | eBay

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[stevbike]

I looked at the E-bay site. Two items of note. The first is the camera is listed as a SLR camera. It is not one. The second that the battery is not shipped with the camera due to rules that the Japanese mailing system. The price is very high as well at 990.00 US dollars. I can see this coming down sooner then later.

[eddie1960]

Given all the north american pre orders are 799 i cant see why you would order from japan and be warranty and return rights lost
Supposed to be end of august for it

[ogl]

[Ash]

Yep, that's pretty small.

[pinholecam]

Anyone has info if C-mount lenses for security cameras are actual usable on the Q?

C h i i f C a m e r a s - Pentax 25mm/f1.4 for Micro Four Third Sensor Cameras

[Christine Tham]

But any small difference in the CoC there would amount to maybe a fraction of a stop in DOF, not a full stop or (good grief) multiple stops, as you were saying...

Actually, I was not saying that at all - if you reread the post, I made no allowances for errors caused by using the formula - it was just another source of uncertainty.

To quote, I said "So, even if we assume the Zeiss formula is applicable to the Q ..."

But rather than assume this or that, why don't we just wait for the camera to be released and then we can all make up our own minds about the image quality.

[Christine Tham]

Background OOF blur on the Q will supposedly be a software, not an optical feature.

The Q&A info provided by Pentax at PMA on this feature makes interesting reading. Apparently it's not just pure software post-processing, it uses subject distance information from the AF.

At this stage, we don't have enough info to judge how effective the implementation is. If it does take distances of objects into account, the result could be quite realistic.

[jsherman999]

The Q&A info provided by Pentax at PMA on this feature makes interesting reading. Apparently it's not just pure software post-processing, it uses subject distance information from the AF.

Subject distance taken from the AF would be required for the software. That value would be passed as a parameter to the software to determine at what point to start the 'blur' routine, and to vary degree in front and back from that point, with the degree of blur increasing with distance from that point.

[Aristophanes]

Yep, that's pretty small.

The sensor?