Richard Butler

Richard Butler

DPReview Administrator
Lives in United Kingdom Seattle, United Kingdom
Joined on Nov 7, 2007


Total: 4947, showing: 21 – 40
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In reply to:

MaKeR: "Pentax pressed on with progressively trying to modernize their 1950s film mount."
The Pentax K mount was introduced in 1975 as a replacement for the M42 screw mount. It would be a stretch to consider the K mount a progressive modernisation of M42. Rather it was a pretty clean break, albeit with the option of using an adapter to mount legacy M42 lenses.
So Pentax pressed on with progressively trying to modernize their 1970s film mount, not their 1950s film mount.
Just for the record.

Thank you for that, I'll correct it. As someone whose first SLR was KA mount, I assumed K had existed forever.

Link | Posted on May 23, 2017 at 17:41 UTC
In reply to:

cdembrey: Use of legacy (obsolete intended) lens is not a good idea. "Yesterdays Technology Today" is a catchy hook to build your advertising around—not! How about "Suddenly It's 1̶9̶6̶0̶ 1987"—no that's too honest to be used in advertising.

The are a lot of legacy (obsolete intended) Nikon F lenses that will mount on modern Nikon cameras, but will not function. Better to do to the EF mount, what was done with legacy (actual meaning is obsolete) FD lenses.

Cdembrey - you could be right. Most puns are terrible so I didn't think flagging one up (and doing so overtly) would make anyone think I was clever. I was expecting more of a 'oh, did you have to?' response.

Link | Posted on May 23, 2017 at 15:23 UTC
In reply to:

Matsu: So far backwards compatibility has only helped Nikon and Canon. Moving the extant mounts to mirrorless costs nothing but a bit of body depth. The author's assumptions are not quite accurate regarding lens design. Once phase detection is moved onto the sensor there's no reason to design photographic lenses any differently. There is some difference in the demands of a video versus stills focused lenses, and that's where you see different technologies tried. But, they can all work perfectly well within the same mount.

There are good cost reasons for "each sensor size" to have an appropriately sized mount, which Canon is already addressing with EF-M. I would advise Nikon do the same for DX.

@Matsu - you could well be right, it's just interesting to see that Sony rarely used ring-type motors in its E-mount lenses and I'm not sure video needs alone explain that.

@peter zuehlke - I completely agree. I didn't mean to imply there's much scope for lenses to be smaller with a shorter flange back distance. If that's the way it reads, I'll try to tweak the phrasing.

Link | Posted on May 23, 2017 at 15:16 UTC
In reply to:

IdM photography: What is rumoured in this article just won't happen... What Nikon and Canon don't have is a FF sensor with integrated phase detect AF, and therefore they haven't released a mirrorless FF camera yet... Canon already have a mirrorless mount (1mm larger compared to Sony's E-mount, therefore FF compatible). I hope Nikon will be smarted and create a new mount also compatible with larger (medium format sensors)... But creating MF cameras based on their current DLSR mounts is a too ugly solution for companies like Canon and Nikon...

@IdM photography - have a read of our [explanation of Dual Pixel AF]( from when it was first introduced and you'll see it absolutely *is* on-sensor phase detection. The only difference is that every pixel looks left and right, rather than having strips or clusters of left or right-wing pixels.

Link | Posted on May 23, 2017 at 15:10 UTC
In reply to:

Mariusz Wozniak: Great article Richard!
I think this sentence isn't quite right:
"Fluorescent lights are more of a problem: they are significantly less bright during the negative phase of the A/C cycle and are usually designed to flicker at much higher frequencies to make this less of a problem."
The fluorescent lights are less bright when sinusoidal A/C wave crosses zero. The negative part is as bright as the possitive!

I knew that would be the area where I'd fall over.

How about:

'Fluorescent lights are more of a problem: they are significantly less bright during the phase change of the A/C cycle'

Link | Posted on May 22, 2017 at 23:14 UTC
In reply to:

Average User: In your comments on the A-99II, you say it loses about half a stop of light. I've seen some pretty vigorous discussion that suggests the light loss is more like 10%. Given the many incredible features of this camera, it would be worth your time to try to do some testing to get a real answer to this critical question. Not sure the best way to do this, but maybe use a very high quality A mount lens, and use it also with the A7rII using an LAEA3 adapter. An example related issue: is it better for iq, low light, fast focus, accurate focus, to use the A7rII with LAEA3 and Sony 80-400 mm, or the A99II with the same lens?

@contadorfan - more gain (amplification) is added, so that your images end up the expected brightness, but that's the only way in which the deficit can be 'made up for.' Everything we've seen suggests SLT cameras exhibit a roughly 1/2EV image quality cost, compared to the same generation Sony cameras with similar sensors.

1/2EV isn't a huge amount, though, so it's a question of whether the benefits of the SLT system are greater to you than that light cost.

Link | Posted on May 22, 2017 at 18:48 UTC
In reply to:

frankje: Realizing how a leaf shutter works let me expect that they give a smoother bokeh than a focal plane shutter. More or less in the same way as Sony's latest lens with that special filter works. Is that right, Richard?

That's an interesting thought. My guess would be that it it might, at very short shutter speeds (where the opening and closing of the shutter make up a significant proportion of the exposure duration).

Link | Posted on May 22, 2017 at 18:43 UTC
In reply to:

assaft: suggestion: to this sentence - "However, what should also be obvious is that, the faster your shutter" - add "rate is" at the end (to avoid confusion with shutter *speed*).

That's a good point. Thanks for the feedback.

Link | Posted on May 22, 2017 at 17:53 UTC
In reply to:

whyamihere: I love these technical articles! Richard, et al, thank you so much for making them happen.

One item I wish could be added would be an explanation as to why using xenon flash -- or, for that matter, flash sync or HSS -- isn't possible with the current implementation of electronic, non-global shutters. Is it the flash duration, how the sensor readout works, both, or some other wonky technical reason? I have theories, but I have yet to have found a well-researched answer to this.


I think it's basically that electronic shutters take so long to read out that they only fully expose their sensors at very long shutter speeds (as shown in the third diagram on page 2).

Link | Posted on May 22, 2017 at 17:50 UTC
In reply to:

Hugo808: Very interesting. I always wonder why my sensor is exposed when I change lenses, why not cover it with the shutter when it's not in use?

The explanation we were always given was that the glass filter in front of the sensor is a lot more durable than super-thing shutter blades, so it was much less likely that users would cause any damage if the shutter was kept open.

Link | Posted on May 22, 2017 at 17:03 UTC
In reply to:

Alex Permit: "Smaller sensors also have an advantage in this respect: less physical distance to travel means rows can be read-out quicker"

How does the PHYSICAL distance effect the electronic read speed of a sensor? Electromagnetic waves travel at one foot per nanosecond, so it can't be how long it takes the electrons to move.

Joel Halbert - I'll check on that and correct it.

Link | Posted on May 22, 2017 at 17:01 UTC
In reply to:

steinah6: You have a typo in your sub-header "Focal plain shutters" under the Mechanical Shutters section. Should be "Focal PLANE Shutters"

Thanks for spotting that. It's oddly difficult to spot errors in cross-heads.

Link | Posted on May 22, 2017 at 16:04 UTC
On article What is equivalence and why should I care? (2451 comments in total)
In reply to:

GrahamHO: An aperture number for a lens is obtained by dividing the diameter of the lens opening into the focal length. So for example a 100 mm focal length lens with a 50 mm diameter lens opening will be 100 divided by 50 = f2. This is basic optics and is NOT dependant on sensor size. So that lens will still be f2 regardless of the sensor size. It is exactly the same as post cropping a FF image to APSC size. The resulting photo does NOT get darker.
The sensor size does NOT affect the size of the aperture. Only the APPARENT depth of field changes. ( That is the zone of the subject that APPEARS to be in sharp focus )

Take a look at the diagram at the top of page 2. As you can see, using a smaller format means you fail to capture some of the light projected by the lens, leading to less total light capture and the reduced angle of view.


A focal length reducer sits behind the lens and captures that extra light, condensing it down onto the smaller sensor. Consequently, you get the angle of view and the extra light back, which you'll recognise as a shorter (wider) focal length and a faster maximum aperture.

Link | Posted on May 19, 2017 at 17:29 UTC
On article Sony a9 shooting experience (1287 comments in total)
In reply to:

tiptop: I still don't get it in my head that a camera that is introduced in 2017 does NOT have a USB 3.0 port.
We just switched for a few shootings from a Canon 5DM2 (USB 2) to a 5DM4 (USB3) and it makes all the difference when tethering.

I cannot understand that Sony still sells those cameras with an outdated port. Until a few days ago I thought even the Sony A7RII had USB 3 already - which it didn't.

GEONYC - I think you've got your B and your b confused. USB 2.0's theoretical maximum is 480Mbps (60MB/s) and [according to wikipedia](, at least, tends to top-out at 35MB/s, whereas 3.0 will transfer up to around 400MB/s.

Link | Posted on May 19, 2017 at 00:33 UTC
On article Canon EOS M6 Review (349 comments in total)
In reply to:

keeponkeepingon: Again I'm surprised to see the 50mm F1.4 used in the studio tests.

Riddle me this:

Why is the M the only mirrorless system with studio tests conducted with a non-native lens?

Why is the M the only mirrorless system tested with a cheap ($329) lens designed for film cameras 30 years ago?

How am I supposed to use your studio tests to compare when the competitors such as Fuji and sony are equipped with modern $1000 lenses? Am I comparing cameras or am I comparing different generations/classes of lens technology?

Historically, we've had to shoot cameras with adapted lenses where no 85-ish equivalent is available, whether that was initially using the Four Thirds 50mm F2 Macro on Micro Four Thirds or the Pentax 50mm Macro on Samsung NX, it's what we do when there are limited options. We move away from it as soon as a suitable lens exists.

The Canon 50mm F1.4 may be inexpensive but it's optically excellent by F5.6 and there's little to no reason to think it's holding the M6 back.

Link | Posted on May 18, 2017 at 18:35 UTC
On article Canon EOS M6 Review (349 comments in total)
In reply to:

I have a dream: In the table on page 1, why do you compare it with Sony a6000 which is 300$ cheaper and not with the a6300 which is only 100$ more expensive than the M6?
I guess the comparison would have been painful for the M6

Ken Tr - Which is why I specified list price.

List prices indicate who a camera is aimed at and what its peers are. Over time (at different rates in different markets), prices fall. If you try to compare current pricing of new models to ones that had been around for a while, you end up comparing apples with oranges.

Link | Posted on May 18, 2017 at 18:26 UTC
On article Canon EOS M6 Review (349 comments in total)
In reply to:

Richard Murdey: This review is a mess. It comes over as way too anecdotal and targeted.


"As usual, Canon has a different view of the market from everybody else, leaving the M6 as either an expensive, better-built alternative to entry-level mirrorless rivals or as a mid-level/enthusiast model shorn of a viewfinder. "

is a terrible sentence to open the body of the review with after the "Key Features" bullet list. I don't think a review is any place to be second guessing Canon's marketing strategy at all really - that's forum fodder for the armchair generals - but diving into the metaphysical identity of the camera on the front page before you've barely cleared the physical descriptions? Not good.

As I say, your comments are noted. There are certainly aspects of this review that we won't be repeating.

Link | Posted on May 18, 2017 at 15:54 UTC
On article Canon EOS M6 Review (349 comments in total)
In reply to:

Mike FL: 3 DPRs;

SONY a6000 is "Hybrid Autofocus (phase and contrast detection)", not "On-sensor phase-detect" only as you 3 put here.

Virtually all on-sensor phase detection systems use a CDAF step to ensure perfect focus. From the Nikon 1s onwards, that's been the case, so we prefer to point out that it had a PDAF component, rather than use terminology that we don't see widely used.

Interestingly, in Sony's cameras, if you set them to Continuous AF they appear to skip the CDAF step, so get closest to being solely on-sensor PDAF cameras.

Link | Posted on May 18, 2017 at 15:51 UTC
On article Sony a9 shooting experience (1287 comments in total)
In reply to:

Caleb W: Yeah you guys got the resolution on the OLED viewfinder way off. I'm thinking it's 2560X1440 NOT 1280X960. That's like the a6000's viewfinder.

I'm pretty sure we didn't. In most designs it takes three dots (red, green and blue) to make up one pixel, so 3.7m dots is 1280 x 960 x 3. The a6000's viewfinder is 800 x 600 pixels (1.44m dots).

Link | Posted on May 17, 2017 at 21:49 UTC
On article Canon EOS M6 Review (349 comments in total)
In reply to:

Lars101x: 80% seems high for this.

The algorithm is very heavily weighted towards image quality. Since this takes really good pictures in both Raw and JPEG, that gets it a long way towards 80%.

Link | Posted on May 17, 2017 at 21:25 UTC
Total: 4947, showing: 21 – 40
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