Peter Cockerell

Joined on Mar 7, 2012

Comments

Total: 23, showing: 1 – 20
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In reply to:

Paul_B Midlands UK: Clearly Nikons in the light not sound business. This video is a lot more enjoyable with sound on mute. Some great and poerrful imagery, Nikon is a global brand everyone knows the name. I've never owned one yet.

Absolutely. The voice-over, music and lyrics were all execrable. OK visuals, though.

Link | Posted on Jan 11, 2017 at 09:59 UTC
In reply to:

Peter Cockerell: What assurance is there that these Chinese-manufactured phones aren't sending your Google contacts and captured passwords to a site in China?

I was thinking of this story specifically, for those who haven't seen it:

http://mobile.nytimes.com/2016/11/16/us/politics/china-phones-software-security.html

Plus Huawei (manufacturer if the Nexus 6P) routers, of course:

http://www.techeye.net/business/huawei-products-do-have-backdoors

Personally I'd rather take my chances with the NSA than the Chinese equivalent under Xi Jinping.

Link | Posted on Dec 2, 2016 at 03:39 UTC

What assurance is there that these Chinese-manufactured phones aren't sending your Google contacts and captured passwords to a site in China?

Link | Posted on Dec 1, 2016 at 00:38 UTC as 9th comment | 6 replies
In reply to:

Peter Cockerell: For the 65mm "macro", where are they measuring the minimum focus distance from? If it's the focal plane, as is usual, then the magnification will be 0.43 (1:2.3), far short of a true 1:1 macro. That's actually the best case. If they're measuring it from, say an effective lens plane about halfway through the lens, the magnification will be around close to 0.31 (1:3.2). To be a true macro lens, the minimum focal distance would need to be 0.26m or less (4x the focal length). I always thought that if a lens mentioned "macro" in its name, then it's a true macro lens.

+Henning W, thanks for the clarification. The only macro lens I've owned is a Tamron which is specifically 1:1.

Link | Posted on Oct 10, 2016 at 16:14 UTC

For the 65mm "macro", where are they measuring the minimum focus distance from? If it's the focal plane, as is usual, then the magnification will be 0.43 (1:2.3), far short of a true 1:1 macro. That's actually the best case. If they're measuring it from, say an effective lens plane about halfway through the lens, the magnification will be around close to 0.31 (1:3.2). To be a true macro lens, the minimum focal distance would need to be 0.26m or less (4x the focal length). I always thought that if a lens mentioned "macro" in its name, then it's a true macro lens.

Link | Posted on Oct 6, 2016 at 18:36 UTC as 4th comment | 3 replies
On article Throwback Thursday: Canon PowerShot Pro70 (111 comments in total)
In reply to:

trenzterra: As a Singaporean, I found the photos pretty familiar, then I realised: cool! The sample photos were taken in Singapore.

Was Phil based in Singapore back then?

Interesting, I guess just because a camera produces subjectively appealing shots, that doesn't mean the colors are necessarily accurate!

Link | Posted on Sep 17, 2016 at 02:02 UTC
On article Throwback Thursday: Canon PowerShot Pro70 (111 comments in total)
In reply to:

trenzterra: As a Singaporean, I found the photos pretty familiar, then I realised: cool! The sample photos were taken in Singapore.

Was Phil based in Singapore back then?

Yes, Phil lived in Singapore for several years at the start of dpreview. The sample photos often featured his lovely Singaporean wife, but Phil was never shown. I think I only ever saw one photo of him, where his face was obscured by the camera he was holding!

I still remember his review of the Pro70, which I definitely coveted at the time. Even then, though, the resolution was lower than the cheaper competition (I ended up getting a Casio!) But there's no denying how nice the colors are, and I often wonder why Canon didn't persevere with that alternative to the Bayer mask.

Link | Posted on Sep 16, 2016 at 03:34 UTC
In reply to:

piratejabez: The full PDF has some great examples: http://arxiv.org/pdf/1608.05148v1.pdf
I'm going to extract the images from it for better comparison :)

I wonder what compression was used for the images in the PDF. Lossless, hopefully...

Link | Posted on Aug 25, 2016 at 01:28 UTC
On article Bentley creates a 53 billion pixel car commercial (189 comments in total)

My god, what an utter load of billocks. How does dpreview fall for this kind of crap?

Link | Posted on Jul 21, 2016 at 22:31 UTC as 27th comment
In reply to:

The Squire: Did someone in Sony marketing do that math?

"So 12 cameras, each shooting 4k... that must mean it's a 48K video! WOW! Press release... done!"

Doesn't account for the need to significantly overlap the output from each individual camera.

If there was *no* over lap, then shooting those cameras in portrait and stitching together gives a theoretical output width of 12x2160px = 25.920px... aka 26K?

When pedants and marketing collide...

But this one goes to 11...

Link | Posted on Jan 13, 2016 at 14:57 UTC
In reply to:

tesch: I don't come to this website very often but when I do I find all of the talk is about why Sony isn't a real camera. Very strange!

This is a good article about a lot of things that really have no effect on the images taken by people on this site. If the photographers on this site spent as much time researching composition and color theory they wouldn't have to worry about this nonsense. But that would mean they would have to think which seems to be an issue..........

Get over it!

@HowaboutRAW A better comparison would have been with a composer thinking about music theory when he's composing. Which I imagine he does.

But the issue isn't as moot as tesch seems to think. That "moon and Space Needle" shot doesn't seem like an especially tricky exposure, but it's way too artifacty (which is a word, I've decided) to rank as stock-ready.

Link | Posted on Sep 4, 2015 at 19:01 UTC
In reply to:

Frank_BR: Why doesn't Sony have so far the option of a lossless RAW format? Most critics say that this is just a Sony error, but the question is not so simple. To try to understand better, I did an experiment. I took the RAW files from DPR Studio Scene for Sony 7RII and Nikon D810, and compressed them with WinRAR. The results were as follows:

Camera.....RAW original....WinRAR compr
7RII .........41.4MB...........38.3MB
D810 ........74.3MB..........43.9MB

WinRAR is a lossless compression, so the RARs files contain the same information as the RAWs from camera.

Surprisingly, WinRAR managed to reduce to almost half the size of NEF file, but failed to appreciably reduce the size of Sony RAW. This shows that NEF is inefficient since it produces much larger files than necessary. There is room for a better lossless RAW coding. I draw the conclusion that a reason for Sony has been reluctant to use a lossless RAW coding is that the current processor technology does not allow high efficiency of coding.

I think all Frank is saying is that NEF is quite inefficient if a general-purpose lossless compression algorithm can reduce the size by a third. Since Nikon has a much better knowledge of the data stream than RAR does, it should be able to do even better than RAR. I assume the redundancy comes from keeping data aligned on byte or word boundaries for faster processing (e.g. they might store a 12-bit sample in two bytes, wasting 4 bits per sample, rather than storing two samples in three bytes without waste.

I agree, though, that the main question is why does Sony think it's acceptable to apply lossy compression to their RAW format, especially when it can lead to such ugly artifacts.

Link | Posted on Sep 4, 2015 at 18:47 UTC
On article Phase One 645DF+ with IQ250 field test (138 comments in total)
In reply to:

Peter Cockerell: I'm a bit confused by use of 5/6 as the lens equivalence ratio between the IQ250 sensor and a 35mm one. Of course, it's tricky to come up with a single number when the aspect ratios of the sensors are different, but in this case the relevant numbers are: horizontal: 36/44 = 0.82 (or 9/11 if you prefer fractions), vertical: 24/33 = 0.73 (or 8/11), diagonal: 43.3/55 = 0.79 (or about 393/500, or 8.7/11). Concentrating on the diagonal, since that's what you mention in the article, the fraction is much closer to 4/5 than 5/6, and the focal length equivalents would be: 120mm becomes 94mm, 80mm becomes 63mm, and 45mm becomes 35mm.

True enough. I guess it all comes down how important those incremental differences are to the person taking the photos. I had to make a similar decision last year when I moved from a 5D3 to a GH4, because I was just getting fed up with lugging a around a full-frame and all its associated lenses. For my (purely personal) photography. I'd say for 80% of the photos I take (which are mostly for web display), the loss of resolution and noise performance hasn't made any difference to the end results, but for the other 20% I sorely miss the benefits of the full-frame. Which is why I'm seriously considering buting an A7R II to use with the lenses I couldn't bear to part with (Canon EF 70-200 L II and a couple of Sigma primes).

Link | Posted on Jul 10, 2015 at 20:10 UTC
On article Phase One 645DF+ with IQ250 field test (138 comments in total)
In reply to:

Peter Cockerell: I'm a bit confused by use of 5/6 as the lens equivalence ratio between the IQ250 sensor and a 35mm one. Of course, it's tricky to come up with a single number when the aspect ratios of the sensors are different, but in this case the relevant numbers are: horizontal: 36/44 = 0.82 (or 9/11 if you prefer fractions), vertical: 24/33 = 0.73 (or 8/11), diagonal: 43.3/55 = 0.79 (or about 393/500, or 8.7/11). Concentrating on the diagonal, since that's what you mention in the article, the fraction is much closer to 4/5 than 5/6, and the focal length equivalents would be: 120mm becomes 94mm, 80mm becomes 63mm, and 45mm becomes 35mm.

Thanks for the confirmation, JNR and Androole. Another thing that occurs to me is how close the ratio is to 1. How much of a real-world advantage would a small "medium format" back like this have over, say, an EOS 5DS or a Sony A7R II? Especially when you consider all the other compromises inherent in this model. (Though it's true that the sensor size ratio is more significant if you constrain your 35mm camera to a 4:3 aspect ratio, I guess.)

Link | Posted on Jul 10, 2015 at 16:39 UTC
On article Phase One 645DF+ with IQ250 field test (138 comments in total)

I'm a bit confused by use of 5/6 as the lens equivalence ratio between the IQ250 sensor and a 35mm one. Of course, it's tricky to come up with a single number when the aspect ratios of the sensors are different, but in this case the relevant numbers are: horizontal: 36/44 = 0.82 (or 9/11 if you prefer fractions), vertical: 24/33 = 0.73 (or 8/11), diagonal: 43.3/55 = 0.79 (or about 393/500, or 8.7/11). Concentrating on the diagonal, since that's what you mention in the article, the fraction is much closer to 4/5 than 5/6, and the focal length equivalents would be: 120mm becomes 94mm, 80mm becomes 63mm, and 45mm becomes 35mm.

Link | Posted on Jul 10, 2015 at 14:30 UTC as 40th comment | 6 replies
In reply to:

Robert Garcia NYC: I would've asked him about the noise reduction can you please turn it completely off. This is what makes the Fuji files looks smudgy.

OK, it's not obvious from either my 5D3 or GH4, and indeed the user guides imply the opposite (except for the dark frame subtraction during long exposure NR, but that's a very different kind of NR). I'm actually having trouble imagining how you'd write an NR algorithm that works on a Bayered (or equivalent) image, but it's been a while since I wrote any image processing code, so I can't claim current knowing knowledge of the field.

Link | Posted on Mar 1, 2015 at 03:58 UTC
In reply to:

Robert Garcia NYC: I would've asked him about the noise reduction can you please turn it completely off. This is what makes the Fuji files looks smudgy.

Not sure I understand that. If Robert Garcia is asking for zero noise reduction, presumably he's referring to in-camera JPG conversion, since AFAIK manufacturers don't apply NR to RAW files (they wouldn't be very raw, otherwise). In this case, the quality of LR's RAW conversion is irrelevant.

Link | Posted on Feb 28, 2015 at 16:55 UTC
On article What is equivalence and why should I care? (2341 comments in total)
In reply to:

LaFonte: But why do I even have to care about equivalent or not exposure?
If I say to two guys don't use your camera metering, pull out my old light meter and tell to two guys with very different camera: set your ISO 100, set 1/60, and aperture 2.2 and you will be fine, they would both get properly exposed picture. Right? Even that one geezer have 7d and the other have e-pm.
As I understand, that is the whole point of having equivalent exposure that translates to everybody. So we understand each other without looking what size of sensor you have. Starting recalculating what aperture means in different sensor sizes is good only and only for assuming DOF not for exposure.
So maybe call it equivalent DOF.
Or is it that I totally don't get it?

@quezra
" larger sensors have less signal-to-noise ratio than smaller sensors"

You might want to think about what the expression "signal-to-noise ratio" means and then edit your comment accordingly.

Link | Posted on Jul 10, 2014 at 06:13 UTC
On article What is equivalence and why should I care? (2341 comments in total)

I think what's missing from the ISO discussion is how the image is going to be used. If you're shooting primarily for the web, the size reduction process is going average out so much of the noise that except for at really high ISOs, any FF advantage over a smaller sensor is going to be imperceptible. The same applies to a lesser extent with, say, 4" x 6" 240 DPI prints.

Although it touched on it, the article could have emphasized more that, unlike, say, f-stop equivalency, which is purely mathematical, ISO equivalency is very much affected by physical properties, sensor fabrication technologies etc. and is distinctly nonlinear across the ISO range. After all, if we had "ideal" sensors that generated 0 noise across the whole ISO range, the concept of ISO equivalency wouldn't even exist. There's no similar "ideal" scenario for f-number equivalency.

Link | Posted on Jul 10, 2014 at 02:39 UTC as 239th comment
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