Richard Butler

Richard Butler

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

Comments

Total: 4683, showing: 1 – 20
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On article What is equivalence and why should I care? (2405 comments in total)
In reply to:

stefanorossettophotos: You guys at DPreview are amazing! I'vr really appreciated this article!

I did not understand this passage on page 2, talking about ISOs:

"This means that, a Four Thirds camera with a 50mm f/2 lens at ISO100 should produce a JPEG of the same brightness as a Full frame camera with a 100mm f/2 lens at ISO100 and, set to the same F-number and shutter speed, even though its smaller sensor means it is receiving 1/4 as much total light"

I'd expect the F value on M4/3 to be 4 not 2... what am I missing?

Thank you for you help!

Oddly enough, I'm not going to re-write the entire article in an response clarifying a single point.

Yes, aspect ratios play a role: you can't actually take the same photo with a 4:3 camera and a 3:2 one (not without cropping one or the other). But that sounds a lot like trying to find threads to pull on, rather than acknowledging the bigger picture.

Link | Posted on Mar 24, 2017 at 21:58 UTC
In reply to:

Yake: The equivalence argument is baaaack. "The fastest lens on Fujifilm’s GFX roadmap is F2, which in full-frame equivalent terms is F1.56". No. And f/2 lens is always an f/2 lens, regardless of film or sensor size. From the beginnings of photography to the present, aperture has always meant aperture, not depth of field. That's why a light meter needs the aperture, not the sensor size. Lenses are not exclusively used at their widest aperture, and lenses are not defined by their shallowest depth of field. Photographers know that different formats yield differences in depth of field. There is no need to muddy the clear meaning of aperture with this equivalency nonsense. The photography world doesn't need this.

I'm fully aware that 'actual aperture is real,' I'm also aware that it allows you to standardize (with a degree of fuzziness) the light per unit area projected by different lenses. That's how exposure is defined, with ISO ensuring that it works fairly consistently. Nothing I have said questions any of that.

Equivalent aperture is no less 'real' (in that it's a calculated value that normalizes certain characteristics of different lenses. The difference being that is normalizes different parameters).

I'm not said formats themselves are equivalent. Equivalence is a means of working out the region over which different formats will and won't behave in an equivalent manner, precisely so that you can understand where to expect difference is behavior. Equivalence considers the effect of lens and format - you literally cannot use it without considering both aspects.

Link | Posted on Mar 23, 2017 at 18:36 UTC
In reply to:

egrme: Yes, but is it stuck in that requirement that cameras which are not designated as video cameras can only shoot up to 20 min continuously?

No, it isn't.

Link | Posted on Mar 23, 2017 at 16:59 UTC
In reply to:

Tom_A: I am still puzzled about the hoopla about aperture equivalence.
F2 is f2, a handheld meter will not ask you about the camera format.
Yes there is a kind of equivalence for depth of field but not exposition. I still don't understand any real use for "light gathering capability".
The way I see it, if you shoot both a "small MF" camera like this one and a full frame camera at f2 or higher, then the larger sensor size and resolution will play a role. In my own perception and just like with "real" mf film camera it is the subtlety of for example skin rendering that gets better, more importantly than resolution.

The factors that vary (sensor performance, lens performance, etc) generally tend to make less of a difference than the difference in sensor size.

But I'll be the first to make clear that it's a guide, rather than a definitive calculation: that's why Rishi's article goes into specifics about different camera's sensor performances, rather than just stating the purely theoretical case.

Even with some variability about how each specific sensor/camera/lens lives up to its full potential, it's more useful than just waving your hands and saying 'well, bigger sensors tend to be better,' by some unspecified amount.

Link | Posted on Mar 22, 2017 at 19:42 UTC
In reply to:

Tom_A: I am still puzzled about the hoopla about aperture equivalence.
F2 is f2, a handheld meter will not ask you about the camera format.
Yes there is a kind of equivalence for depth of field but not exposition. I still don't understand any real use for "light gathering capability".
The way I see it, if you shoot both a "small MF" camera like this one and a full frame camera at f2 or higher, then the larger sensor size and resolution will play a role. In my own perception and just like with "real" mf film camera it is the subtlety of for example skin rendering that gets better, more importantly than resolution.

rbach44 - it doesn't contradict conventional wisdom, but it does require you to understand the conditions that are applied when thinking in terms of exposure and be willing to put them to one side for a moment.

It provides a mechanism for understanding the potential of different systems, relative to one another. If you read the article, you'll see it contains photographic examples that demonstrate that it is factual.

Nobody says that it should be used as you take photos, but it provides an effective tool for understanding where one system has strengths. If understanding the capabilities of different systems is distracting then this probably isn't the article for you.

Link | Posted on Mar 22, 2017 at 18:50 UTC
In reply to:

kgp2: "Thinking about upgrading to FF? Read that first. You can get an equivelant of 27-150mm f/2.7 in your APS-C camera with the Sigma 18-35mm f/1.8 & 50-150mm f/1.8 lenses"... it would be nice to see that on dpreview. But i guess its all about the FF Holy Grail right?

Or [this front page article](https://www.dpreview.com/articles/8451918712/), calling for more equivalent lenses, so that APS-C can be used to its full potential?

Or [this one](https://www.dpreview.com/articles/5678273556/), pointing out that manufacturers like you to feel you're on an 'upgrade path' to full frame, rather than properly supporting APS-C systems?

Link | Posted on Mar 22, 2017 at 18:05 UTC
In reply to:

Henrik Herranen: Very interesting, Rishi!

Apart from a few minor typos ("a f/.." instead of "an f/.." in a couple of places), I think there is one place where there is a factual (math) error. Here:

"One thing does make us hopeful - recent conversations with some forum members alerted us to the fact that certain full-frame lenses, like the Zeiss Otus primes, actually project an image circle large enough for at least a square crop on Fujifilm's new MF format. That would essentially get you high quality F1.1 equivalent glass on the GFX 50S."

Not quite so. If you use a square crop, then the effective sensor size is 33mm x 33mm, which is only slightly larger than FF. The (reverse) crop factor is now 0.93, not 0.79, and e.g. an 85/1.4 lens installed this way would be equivalent to 80/1.3 on FF - which is hardly a relevant difference.

Apart from this one thing, I thought this was a really well thought of article of an interesting technical subject. Thanks!

test2 - you're saying the same thing as Henrik (and you're both right - I've corrected the article).

Link | Posted on Mar 22, 2017 at 17:39 UTC
On article What is equivalence and why should I care? (2405 comments in total)
In reply to:

stefanorossettophotos: You guys at DPreview are amazing! I'vr really appreciated this article!

I did not understand this passage on page 2, talking about ISOs:

"This means that, a Four Thirds camera with a 50mm f/2 lens at ISO100 should produce a JPEG of the same brightness as a Full frame camera with a 100mm f/2 lens at ISO100 and, set to the same F-number and shutter speed, even though its smaller sensor means it is receiving 1/4 as much total light"

I'd expect the F value on M4/3 to be 4 not 2... what am I missing?

Thank you for you help!

So this is talking about the effect of ISO, so is talking about conventional exposure. ISO is what ensures that the same F number gives the same JPEG brightness regardless of format.

So:

Four Thirds: 50mm, F2, ISO 100, 1/60th

Full frame: 100mm, F2, ISO 100, 1/60th

Will give the same JPEG brightness, but the full frame camera will have shallower depth of field and less noise (because it's getting 4x as much total light).

Four Thirds: 50mm, F2, ISO 100, 1/60th

Full frame: 100mm, F4, ISO 400, 1/60th

Will give the same image brightness, the same depth of field and (assuming no radical difference in sensor performance), very similar noise levels.

Link | Posted on Mar 22, 2017 at 17:32 UTC
In reply to:

Tom_A: I am still puzzled about the hoopla about aperture equivalence.
F2 is f2, a handheld meter will not ask you about the camera format.
Yes there is a kind of equivalence for depth of field but not exposition. I still don't understand any real use for "light gathering capability".
The way I see it, if you shoot both a "small MF" camera like this one and a full frame camera at f2 or higher, then the larger sensor size and resolution will play a role. In my own perception and just like with "real" mf film camera it is the subtlety of for example skin rendering that gets better, more importantly than resolution.

Tom A - It's a bit of a long read, but [try this article](https://www.dpreview.com/articles/2666934640/).

Equivalence is a way of looking at the overall effect of sensor size and lens and is based on considering the whole final image viewed at the same scale (ie: image quality of your final print). It is a tool for thinking about the effects of format in a comparable manner.

Exposure, by comparison, is a per-unit-area way of considering light, with ISO defined such that the same light per unit area gives the same final image brightness (which is why your light meter doesn't care what size sensor you use).

Ultimately, you can choose to solely look at the world in terms of F numbers and conclude that bigger sensors are just somehow better.

Or you can step back, look at the problem from a whole-image perspective and see why different formats perform differently and by roughly what degree (and understand where they will offer the same or very similar performance).

Link | Posted on Mar 22, 2017 at 17:27 UTC
In reply to:

kgp2: "Thinking about upgrading to FF? Read that first. You can get an equivelant of 27-150mm f/2.7 in your APS-C camera with the Sigma 18-35mm f/1.8 & 50-150mm f/1.8 lenses"... it would be nice to see that on dpreview. But i guess its all about the FF Holy Grail right?

You mean [something like this](https://www.dpreview.com/articles/7351383545/dpreview-gear-of-the-year-2013-part-4-sigma-18-35mm-f18-dc-hsm):

"*The key to understanding the Sigma 18-35mm F1.8 is to realize that it gives the same control over depth-of-field as a 28-50mm F2.8 would on a full-frame camera - it also allows you to shoot at wider apertures in any given situation, effectively cancelling out the greater low-light ability that a larger sensor would otherwise give. And, especially if you own a high-end APS-C camera, that can help to reduce some of the motivation for moving to full-frame.*"

Link | Posted on Mar 22, 2017 at 17:18 UTC
On article Sony SLT-A77 In-depth Review (4 comments in total)
In reply to:

Scottelly: Richard Butler . . . the author, doesn't seem to exist. Click his name.

Pardon?

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

ArtAlt: Brilliant logic BUT I saw an ACTUAL DEMONSTRATION of the Fuji medium format camera at Fotocare in NYC, tethered to a screen. SCARY GOOD. Jaw dropping.

Really I've never seen anything like it other than the demonstrations of medium format Hasselblads and Phase One at Fotocare. I don't think that my D810 or an AR7II are quite the equal.

It is possible that there is just something uniquely beautiful about medium format? The photographs have a stunning grace. Maybe it's because the pixels are so much larger?

I suggest we defer assessment until we see some comparisons.

Ultimately, we will also defer assessment until we've shot some comparisons.

However, this article gives a good idea of what the differences might be and where they might exist

Link | Posted on Mar 21, 2017 at 23:55 UTC
In reply to:

TheWhiteDog: It is a strange(though informative) piece. None of this was ever brought up when the Pentax 645 was discussed- or the Leica medium format, or even the new Hasselblad. Why are they singling out this Fuji camera for this type of treatment(essentially saying: "It's not worth it, don't buy it.")? I've never seen this type of article about any other camera, regardless of brand or sensor size. Apparently presells of this camera are really great(taking into account its price). Are other camera companies putting pressure on dpreview to downplay this camera? I hope not, nor, if that were true, I hope that dpreview wouldn't give in to such pressure. But the doubt is there.

I'd love to know what the presumed mechanism would be for a camera company to 'put pressure on us.' But no, that's not happening.

Rishi has seen a lot of hyperbole floating around the web from people who assume medium format is magically better because the sensor is bigger, and wanted to make clear that it's not *that much* bigger and that fast lenses don't currently exist.

The reason for the greater attention on the GFX 50S is that it's the first significantly sub-$10,000 medium format camera and the first one we've been in a position to review. This is not the review, it's an opinion piece that sets out the scope of what reasonable expectations are.

Link | Posted on Mar 21, 2017 at 23:41 UTC
In reply to:

Shockwave: I'm confused. So what you are saying is don't buy the GFX, rather buy 3 DSLR's because you're comparing the strengths of 3 different cameras to the GFX. Why not throw in the 1D as well just to be "fair" and say that they also have the best AF and a 100 shot buffer.

We're not saying anything about what to buy. Rishi is just saying 'don't assume that a larger sensor guarantees better-than-full frame performance.'

Link | Posted on Mar 21, 2017 at 22:41 UTC
In reply to:

dennis tennis: Was this a "camera" review or a "system review". Basically, don't buy this CAMERA because it doesn't have the LENSES. If DPR had been consistent it how it reviews CAMERAs, it would have said. MFT sucks no F1.0 or faster primes, APS-C sucks no F2.0 constant zoom lenses. I've yet to see such comments from DPR in their reviews of mFT or APS-c CAMERAs.

It's not a review at all. It's an opinion/analysis of a system's potential.

Link | Posted on Mar 21, 2017 at 22:39 UTC
On article Fujifilm X-T20 Review (291 comments in total)
In reply to:

Alejandro Cifuentes H: Why the A6300 have a MSRP of $899 on the comparative chart? On most sites it's $999 (Amazon, B&H, Sony)...

Hmm, I'm going to have to assume that's just an error. I've corrected it.

Link | Posted on Mar 21, 2017 at 22:33 UTC
On article Fujifilm X-T20 Review (291 comments in total)
In reply to:

zodiacfml: I'm glad you have considered USB charging as an advantage. I found that I always leave a lot of charge in my Nikon DSLR after a day of shooting as a tourist and I would appreciate it if it can charge through USB so I can leave the dedicated charger, there is virtually unlimiited charge through affordable smartphone Power Banks and no need to remove batteries from the camera.

For the last couple of years, now, we've considered USB charging a pro and the lack of an external charger to be a con. On this camera, you get the best of both worlds.

Link | Posted on Mar 21, 2017 at 22:30 UTC
On article Fujifilm X-T20 Review (291 comments in total)
In reply to:

arhmatic: USB CHARGING! Really, my only suggestion for future Fujifilm cameras..

It's got it.

Link | Posted on Mar 21, 2017 at 22:29 UTC
On article Fujifilm X-T20 Review (291 comments in total)
In reply to:

Antonis30: Interesting how this camera got the same score as the Canon EOS M5, 82%.Frankly due to the superior lens lineup and seemingly better sensor, I expected a higher score for the X-T20.

It's something that's always been a problem.

For instance, Nikon has lots of lenses you can mount on its APS-C cameras, but some of them won't AF on some models, others simply aren't the focal lengths many people would want for APS-C, so how do you rank those?

Similarly, when you're reviewing a camera for which 90-something percent of users will never buy a second lens, how much weight should you give to the existence of a 70-200mm F2.8 that costs three or four times as much as the camera body?

Finally, how do you take into account gaps in the range? If one system has the specific lens you need, then that system is best, regardless of how many 18-XXXmm zooms another system offers.

At a certain point, we need to leave that decision to the buyer.

Link | Posted on Mar 21, 2017 at 21:48 UTC
In reply to:

Sirus A: Great article. At first glance it seems the arguments are compelling, however, I think we need to slow down a bit. What I find bothering is that Fuji's MF is compared tp the best FF cameras of each category. Yes I agree that MF looses to an imaginary camera that has the ISO performance of Sony a7R2 and the dynamic range of Nikon D810 and the resolution of Canon 5dR. The problem is: it doesn't exist! I think it is only fair to compare this MF to another FF as a whole. I think the best argument against it is lack of great lenses.

This isn't an argument against the GFX, *per se*, it's just saying that, with the current lenses, the GFX won't necessarily have an advantage over the best of full frame, in any respect.

Yes, it may well end up having the DR to match the best FF, Noise to match the best FF, Resolution to match the best FF. Just not necessarily the hands-down advantage that you might expect if you've not considered equivalence.

Link | Posted on Mar 21, 2017 at 21:40 UTC
Total: 4683, showing: 1 – 20
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