mgrum

Lives in United Kingdom United Kingdom
Joined on Jan 14, 2009

Comments

Total: 525, showing: 1 – 20
« First‹ Previous12345Next ›Last »

The problem with Arsenal is they always try and walk it in...

Link | Posted on Jun 3, 2017 at 11:09 UTC as 10th comment
In reply to:

makofoto: But long lenses don't need curved sensors

But there are lenses that aren't long

Link | Posted on Jun 1, 2017 at 14:44 UTC
On article Sony a9: more speed, less dynamic range (666 comments in total)
In reply to:

Dr Blackjack: As expected I guess from the company that effectively makes the D5 sensor. The R series sensors have always been about DR, and a lot of high speed cameras sacrifice low ISO DR for high ISO performance and speed. No free lunch as of yet...

Technically Sony make the D5 sensor, but it's Toshiba IP so not comparable to Sony's Exmor sensors.

Link | Posted on May 18, 2017 at 13:42 UTC
On article Sony a9: more speed, less dynamic range (666 comments in total)
In reply to:

MayaTlab0: Could that be one of the reasons why S-log has been dropped ?

No

Link | Posted on May 18, 2017 at 13:37 UTC
On article Sony a9: more speed, less dynamic range (666 comments in total)
In reply to:

bilcobarnes21: Am I the only one getting a little tired of DP Reviews obsession with the A9 and Sony in general?
It makes me wonder what involvemt Sony have with DPR 🤔

Yeah Sony clearly paid dpreview to write an article bashing the DR of their flagship camera...

Link | Posted on May 18, 2017 at 13:31 UTC
On article Sony a9: more speed, less dynamic range (666 comments in total)
In reply to:

Henrik Herranen: "In a perfect world, Sony would have offered a 12-bit Raw mode with a lossless compression curve (without that second stage of localized compression that leads to edge artifacts) for smaller file sizes with minimal loss in quality."

Um, by definition, fitting 14 bits to 11 bits is _not_ lossless. The difference may not be easily visible if a properly optimized curve is used, but the operation is definitely not lossless. Lossless means that you are able to get _exactly_ the original samples back. Example from the audio world: MP3 is not lossless, not even at the highest bit-rates, but FLAC is.

@noirdesir

visually lossless != lossless. What DPreview wrote is incorrect, you can't have a lossless compression curve.

Link | Posted on May 18, 2017 at 13:11 UTC
On article Sony a9: more speed, less dynamic range (666 comments in total)
In reply to:

Ayoh: "The Continuous drive modes, however, switch the sensor into a 12-bit** readout mode which, by definition, means files with no more than 12 stops of dynamic range." Are you sure about this limit?

Yes - a linear encoding with 12 bits cannot have more than 12 stops DR at native resolution. Normalised to 8MP like DXO do it can be >12 stops.

Link | Posted on May 18, 2017 at 13:10 UTC
On article Sony a9: more speed, less dynamic range (666 comments in total)
In reply to:

sts2: Well that helps understand why all of the testing was done in brightly lit sports centres with huge windows, and why they had massive softboxes overhead the running track.
...aka a real world situation for any sports photographer *cough*

You've not read/understood the article - the A9 has less DR (compared to the very good A7RII) at ISO100, above ISO640 it's much better, so well lit sports venues would be worse for the camera (relative to the competition), not better.

Link | Posted on May 18, 2017 at 13:08 UTC
In reply to:

Arastoo Vaziri: I stopped reading when I hit the chart and read "equivalent F-number". The nonsense doesn't seem to ease away.

Unfounded?? Really? Just how much evidence do you need?

It's funny that you mention Galileo above as this reminds me of people that insist the sun orbits the Earth regardless of how much evidence to contrary!

Take an image with M43 at f/1.4 ISO1600 and one with 35mm full frame at f/2.8 ISO400 and compare the DOF and noise. It's a simple as that.

It's not "endless equations", all you have to do is multiply two numbers together. It's not that taxing, but if that's too complicated then you can chose to ignore it, but you can't use that to say it's wrong. Let the people who want to learn, learn.

Link | Posted on May 15, 2017 at 17:07 UTC
In reply to:

Arastoo Vaziri: I stopped reading when I hit the chart and read "equivalent F-number". The nonsense doesn't seem to ease away.

He wrote about the entrance pupil (rather than f-stop) being the determining factor in depth of field, which is ultimately what equivalence comes down to - comparing at the same entrance pupil rather than the same f-stop. Everything that applies to DOF also applies to the total light projected onto the sensor or film.

Link | Posted on May 15, 2017 at 15:31 UTC
In reply to:

mgrum: If you look at the lens diagrams for the Sony RX1, Fuji X100F, Sigma DP2 you'll see they all have a very large rear element that sits only a few mm above the sensor. This is impossible to replicate in an interchangeable lens camera (unless you make the mount enormous) and provides a clear optical advantage (when compared to interchangeable pancake lenses).

So if you want compactness just get a fixed lens camera, ILCs just can't compete.

The Mitakon Lens Turbo is nothing like the lens in a fixed lens compact as it has a rear element that has to fit within a small mount which is at least 18mm from the sensor.

The rear element in the RX1 lens is much larger than that of the Lens Turbo, and much much closer to the sensor.

Link | Posted on May 15, 2017 at 14:30 UTC
In reply to:

Arastoo Vaziri: I stopped reading when I hit the chart and read "equivalent F-number". The nonsense doesn't seem to ease away.

@Arastoo Vaziri "there is no such thing as 'equivalent aperture'."

There is such as thing as equivalent aperture if you measure exposure by total light rather than light per unit area. When you do this "equivalent exposure" also yields equivalent noise [and provided the FOV is the same] equivalent DOF, equivalent diffraction, equivalent background blur, equivalent camera shake etc.

Basically you're getting the same image, just with the light spread over a smaller or larger area, exactly like using a teleconverter or speedbooster.

If you express ISO in terms of noise rather than saturation (which is allowed under ISO 12232:2006) then a M43 camera at f/2.8 would indeed meter the same as a 35mm full frame camera at f/1.4

Fortunately the number of people who think this simple concept (total light is more relevant than light per unit area) is an "absurdity" is getting smaller over time.

Link | Posted on May 15, 2017 at 14:05 UTC
In reply to:

Arastoo Vaziri: I stopped reading when I hit the chart and read "equivalent F-number". The nonsense doesn't seem to ease away.

The "nonsense" follows directly from the thin lens equation, and can be followed by anyone with a basic grasp of mathematics (multiplication and division). Discussion of "equivalence" can be found in Moritz von Rohr's 1906 publication "Die optischen Instrumente", so it's been around for well over 100 years.

And no it wont go away - because it's how lenses work.

Link | Posted on May 15, 2017 at 13:59 UTC

If you look at the lens diagrams for the Sony RX1, Fuji X100F, Sigma DP2 you'll see they all have a very large rear element that sits only a few mm above the sensor. This is impossible to replicate in an interchangeable lens camera (unless you make the mount enormous) and provides a clear optical advantage (when compared to interchangeable pancake lenses).

So if you want compactness just get a fixed lens camera, ILCs just can't compete.

Link | Posted on May 15, 2017 at 10:48 UTC as 208th comment | 5 replies
In reply to:

ramonjsantiago: "85mm F1.2 is equivalent to 67mm F0.95"
How is that? Maybe its equivalent to to a 67mm F1.2.

@digifan: the equivalence debate is very stale

I still fail to see why it's even a debate - it's basic optics, it all derives directly from the thin lens equation.

Link | Posted on May 10, 2017 at 20:39 UTC
On article Canon EOS Rebel T7i / 800D review (386 comments in total)
In reply to:

mgrum: Another Canon article? Are dpreview being paid by Canon?

@TyphoonTW "Seriously? After days of Sony A9 articles popping out even to discuss the menus?"

http://i2.kym-cdn.com/entries/icons/original/000/012/132/thatsthejoke.jpg

Link | Posted on May 4, 2017 at 12:57 UTC
On article Canon EOS Rebel T7i / 800D review (386 comments in total)

Another Canon article? Are dpreview being paid by Canon?

Link | Posted on May 4, 2017 at 08:59 UTC as 35th comment | 6 replies
In reply to:

Alex Permit: I see far more people using DSLR's than I ever saw SLR users in the film age. In fact, I see more DSLR users now than I did five years ago.

I think there are two reasons for the decline in sales over the last few years. One reason is the market has become saturated. Another is that digital cameras have gotten so good people don't upgrade there digital cameras as often as they used to.

The financial crisis of 2008 also played a large part, if you look at DSLR sales they peak in 2008. Since then wages have fallen and people have been reluctant to spend on what my be seen as luxuries, there were a lot of people who would have previously splashed out on a DSLR on a whim who would instead use their phone.

Link | Posted on May 3, 2017 at 20:47 UTC
In reply to:

zakk9: I don't mind that dpr writes about the A9, but conveying as "news" the fact that Sony has finally implemented functionality that has existed on pro level cameras for a decade or more strikes me as odd. Even my $900 G85 and slightly more expensive GX8 offer most of these options by pushing a button, flipping a switch or turning a wheel. Most Panasonic and most Nikon cameras that I own or have owned do this. The fact that Sony has relied on deep diving into menus to change primary settings doesn't make the improvement a revolution.

I know expecting people to actually read the article before criticising is a big ask these days, but had you done so you'd see they explain, in detail, how the A9 feature differs from what was possible previously.

Link | Posted on May 2, 2017 at 14:10 UTC
In reply to:

Triplet Perar: Half-fake news are even worse than fake news, and this is becoming too ridiculous. Sony a9 is just one big over-hyped clickbait, and users discover daily that the reality about this camera is quite different, wildly mixed results. That alone shows how amateurish and irresponsible company is Sony, and how naive people are. Compare that to companies who built their reputation on reliability, decades of great customer service, fine tuning, proven performance in all circumstances, and fair assessment of their products.

How can a camera be clickbait?

It's funny that despite being "amateurish and irresponsible"* their market share is increasing.

*ignoring for now the Oscar they picked up for supplying their amateurish equipment to huge budget Hollywood blockbusters...

Link | Posted on May 2, 2017 at 13:06 UTC
Total: 525, showing: 1 – 20
« First‹ Previous12345Next ›Last »