Rishi Sanyal

Rishi Sanyal

DPReview Administrator
Lives in United States Seattle, WA, United States
Works as a Deputy / Technical Editor
Has a website at www.rishi.photography
Joined on Feb 25, 2014
About me:

Although I'm a scientist by training, having recently completed my Ph.D in biophysics, photography has always been a huge passion of mine. It's been an incredible opportunity to meld these two interests together here at DPReview!

Comments

Total: 3943, showing: 1 – 20
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On article Medium-format mirrorless: Hasselblad unveils X1D (1186 comments in total)
In reply to:

Dr_Jon: BTW I'm assuming it's the same sensor as the Pentax 645Z, so you can compare DR right now...
http://www.photonstophotos.net/Charts/PDR.htm#Canon%20EOS%205DS%20R,Nikon%20D810,Pentax%20645Z

Rick - please don't twist anything I've said or drag me into a conversation I'm not a part of.

Dr_Jon: "So you're saying the D810 doesn't switch at 12,800 and it's just noise reduction? Also you're saying the 645Z is cooking the raws? Oh and the D810 as well... actually that's a big thing! Could be a hard sell perhaps?"

Not a hard sell at all, and actually largely accepted by most. Also pretty evident in Sony shots - you can see it in our studio scene. The chroma noise gets softer at ISO 12,800 and above on the a6300, for example. It's also not that big of a deal - it's fairly minor, and only at those really high ISOs.

But don't take my word for it; see for yourself here: [Sony a6300 chroma noise smudges as you go from ISO 6400 to 12,800, while the D500 shows no such smudging](http://bit.ly/28YS24J).

Which matches up with Bill's [PDR data on these 2 cameras](http://bit.ly/28Znh09).

As you can see in the PDR data, the dual gain switch for both cameras happens at ISO 400.

Link | Posted on Jun 27, 2016 at 20:25 UTC
On article Sony Alpha 7R II Review (2158 comments in total)
In reply to:

Duncan D: No one is "chocked" that they are testing both Nikon and Canon with a Sigma lens which is known for not being good in low light.. hahah seriously why not use a nikon and a Canon lens ? don't tell me that a Sigma was all they had at DPreview ? !

Am I the only one thinking that here ?

Sigma lenses are known for not being good in low light? Evidence?

We got the same results shooting on-brand lenses. In some cases, the Sigma lens actually outperformed some on-brand lenses. We used the Sigma to level the playing field between the DSLRs. The unfair bit was to use ultra soft and low contrast Sony FE 35 on the a7R II. When we followed up this test with the same Sigma lens, the a7R II performed even better.

But we didn't go back and remake the video just to address these points when the outcome and overarching points would be the same: that the a7R II can catch up to DSLRs in low light if you attach fast lenses (e.g. F2.0) to it.

If you disagree, please do the experiment that proves otherwise, and we'll be all ears.

Link | Posted on Jun 27, 2016 at 07:07 UTC
In reply to:

Robert Schroeder: Should owners of a non-PD-capable Sony "stay clear", too? Are they at all affected by the issues mentioned? Have there been improvements for them? And how about Micro Four Thirds, which clearly is included in the Metabones press release, too? What do Micro Four Thirds users have to expect (those with and without the phase-detection capable E-M1), and why should they care about that warning?

I find the article rather confusing.

OK, thanks for the heads up. Will give an a7S II a try tomorrow.

I appreciate that this is very complicated. Different lenses have different ideal step sizes and ranges, so it can't be easy to make a 'one-size-fits-all' adapter for all different types of Sony bodies, and all different types of lenses... Very cool you can do any of this, really.

Link | Posted on Jun 26, 2016 at 23:21 UTC
In reply to:

Robert Schroeder: Should owners of a non-PD-capable Sony "stay clear", too? Are they at all affected by the issues mentioned? Have there been improvements for them? And how about Micro Four Thirds, which clearly is included in the Metabones press release, too? What do Micro Four Thirds users have to expect (those with and without the phase-detection capable E-M1), and why should they care about that warning?

I find the article rather confusing.

As we understand it, native AF only applies to Sony cameras, not mFT. And as we said, we found performance to go *backward* on Sony cameras. Didn't try it on the a7S II- but that never had PDAF to begin with, so the a7S II may not have these drawbacks, but it probably won't benefit much either.

Outside of the small central area, even Eye AF on the a7R II reverts to Face Detection (the full face has a box around it, the eye isn't isolated), but with extra hunting compared to Face Detection in 'wide' mode in the 'Green' mode prior to the update. So I'm really failing to see any benefit(s), and a number of *disadvantages*. Though, of course, you can always shift the adapter back into Green mode even after the firmware update (not sure how to make it default again, or if this kills the 'Advanced' mode).

mFT videographers may see a benefit from smooth iris, but that's it far as we can tell. We haven't had a chance to try the smooth iris yet.

We've updated our text to clarify these points

Link | Posted on Jun 26, 2016 at 00:50 UTC
In reply to:

SaltLakeGuy: Sorry guys if I offended you regarding your endless desire to mix and match. To me it's a bit like a "low rider", they butcher up a car to modify it beyond it's original design for their own amusement. Hey, it's a free country, knock yourselves out as it's your $$$ that supports their mechanical experimentation's.

Entropy512: All good points. However, I'm confused then how:

1. Canon dual pixel AF works just fine with Canon DSLR lenses in terms of video AF.

2. Once the a7R II with adapted Canon DSLR lens 'locks on' in AF-C (in Metabones adapter's default 'Green' mode), why do things work quite well? Pretty smooth (though somewhat stuttered of course) continuous adjustments for approaching / receding objects, and not too much back-and-forth movement of focus like I'm seeing with video AF with the new firmware (and a Sigma adapter, for that matter)?

And wow, nice work. I remember reading some of your threads previously but I really need to take some time and digest your findings! Thanks for sharing them - very cool stuff.

Link | Posted on Jun 25, 2016 at 17:18 UTC
On article Medium-format mirrorless: Hasselblad unveils X1D (1186 comments in total)
In reply to:

Dr_Jon: BTW I'm assuming it's the same sensor as the Pentax 645Z, so you can compare DR right now...
http://www.photonstophotos.net/Charts/PDR.htm#Canon%20EOS%205DS%20R,Nikon%20D810,Pentax%20645Z

Noise reduction. If you have a dual gain architecture, you most certainly wouldn't design the switch to higher gain at ISO 12,800... :)

Link | Posted on Jun 25, 2016 at 17:03 UTC
In reply to:

MaxDiesel: Seems DPR only tested AF-C and not AF-S as for pictures and not video it works pretty well.

AF-S focus and eye focus is pretty good (contrast and phase areas)
AF-C is terrible outside of the phase area which is much smaller then native.

Tested on:
Canon 50mm 1.2,
Canon 85mm 1.2 II
Canon 70-200 2.8 II
Canon 35mm 2
Sigma 18-35mm 1.8

We actually tested both AF-C and AF-S.

AF-C is far worse on an a7R II because PDAF becomes limited to a tiny central region. In the 'Green' mode, you have PDAF over a far larger region.

AF-S is also worse because you, again, lose PDAF over most of the frame, only getting it in a small central region.

Even within that small central region where you have PDAF, PDAF is pretty inconsistent with all the lenses we tested, reverting to hunting quite often, and refusing to focus altogether on subjects far away.

If AF-C is terribly outside of the PDAF area, why are you suggesting AF-S is any better? If it's CDAF outside of the central area for AF-S, how is that any better than *prior* to the firmware update?

It's not. Apart from eye subject recognition. Big deal.

We stick to our initial assessment: most users should *not* even bother trying this update. It's wonderful *in principle*, but *in practice* it *just doesn't work*.

Link | Posted on Jun 25, 2016 at 03:46 UTC
In reply to:

SaltLakeGuy: Sorry guys if I offended you regarding your endless desire to mix and match. To me it's a bit like a "low rider", they butcher up a car to modify it beyond it's original design for their own amusement. Hey, it's a free country, knock yourselves out as it's your $$$ that supports their mechanical experimentation's.

@armandino - we're finding video constantly hunting back and forth, with constant minute microadjustments that kill the sound feed and make out-of-focus bokeh/highlights constantly pulse. Not finding it very useful... you are though?

I think the PDAF system needs to be 'damped' with DSLR lenses. Sony native lenses don't 'pulsate' back and forth like this, yet I've noticed this constant pulsing with both the Metabones adapter and Sigma adapter in these native emulation modes. Makes for very 'jumpy' - and therefore inaccurate - AF.

Link | Posted on Jun 24, 2016 at 18:26 UTC
On article Medium-format mirrorless: Hasselblad unveils X1D (1186 comments in total)
In reply to:

Dr_Jon: BTW I'm assuming it's the same sensor as the Pentax 645Z, so you can compare DR right now...
http://www.photonstophotos.net/Charts/PDR.htm#Canon%20EOS%205DS%20R,Nikon%20D810,Pentax%20645Z

Exactly right @whakapu.

Dr_Jon: We know it's not dual gain because it's the same sensor in the 645Z, which we and others have already tested. As I said above, you can already look at controlled low light results in our studio scene: you'd be very, very hard pressed to see a difference in noise performance between the a7R II and 645Z at high ISO. The 645Z does beat the a7R II at base ISO DR though, but only barely edges out the D810 in this regard (yet edge sit out at high ISO).

Link | Posted on Jun 24, 2016 at 17:48 UTC
In reply to:

FuhTeng: Ooo - very exciting. Looking forward to videos showing how well it works.

I'm sorry but some of the comments here make no sense.

On an a7R II:

AF-C already worked well with the old firmware across most of the frame for most lenses. It's crippled in the new firmware, only working in the center, and even there poorly.

AF-S also worked well, and now works worse because PDAF points are only available centrally. So even AF-S got worse.

About the only benefit I can think of is Eye AF without PDAF in AF-S (too much hunting in AF-C to be usable). That's hardly a benefit- you could just stick to the old firmware and use face detection or a single point and have it focus much faster because at least it'd be using PDAF.

So, again, what do you think the advantage of the update is for a7R II or a7 II or a6300 users?

It was nice in principle, and hopefully it'll improve, but in its current form, it's not an upgrade at all for most users.

Link | Posted on Jun 24, 2016 at 17:40 UTC
In reply to:

Adam Palmer: I'll add to the list of people who jumped on this and kind of wished I didn't. Limits you to just the middle PDAF points. I was able to switch the adapter to automatically load to old system.

This is the method from the metabones website.

Changing the default mode permanently

With no lens attached, turn on camera body.

While holding down the WO/CF button on the adapter, attach lens.

Without ever releasing the WO/CF button, switch off the camera's power.

Repeat to restore the default mode to Advanced mode again. With Mark I, Mark II, Mark III and the original Speed Booster, you may make the switch for only about 10 times. After that you can only make temporary mode changes. A firmware update will fully restore the capability to permanently change the default mode. There is no restriction on default mode changes with Mark IV and Speed Booster ULTRA.

? Off-center points don't even offer PDAF *at all* with the new firmware. Whereas previously they did, though some lenses with severe focus breathing didn't function well with small off-center points (image probably moved too much during the hint).

So this update is a significant step *backward* for the a7R II. I'm unclear why you're suggesting otherwise.

Link | Posted on Jun 24, 2016 at 17:20 UTC
In reply to:

FuhTeng: Ooo - very exciting. Looking forward to videos showing how well it works.

I don't particularly find it much faster in AF-S compared to the old Green Mode AF-S, which at least maintains PDAF across the entire PDAF area.

I'm confused - what do you think this update brings that wasn't already there in the a7R II?

Sure with the original a7 and a6000 it brings some PDAF to the central focusing points, but it's so unreliable (hunting, doesn't focus on far away subjects) that I'd again rather just use the original 'Green' mode.

Trust me, of all folks, I *really* wanted this to work, as I love Eye AF. But the reality is, it just doesn't.

Link | Posted on Jun 24, 2016 at 05:28 UTC
In reply to:

Adam Palmer: I'll add to the list of people who jumped on this and kind of wished I didn't. Limits you to just the middle PDAF points. I was able to switch the adapter to automatically load to old system.

This is the method from the metabones website.

Changing the default mode permanently

With no lens attached, turn on camera body.

While holding down the WO/CF button on the adapter, attach lens.

Without ever releasing the WO/CF button, switch off the camera's power.

Repeat to restore the default mode to Advanced mode again. With Mark I, Mark II, Mark III and the original Speed Booster, you may make the switch for only about 10 times. After that you can only make temporary mode changes. A firmware update will fully restore the capability to permanently change the default mode. There is no restriction on default mode changes with Mark IV and Speed Booster ULTRA.

Yeah, frankly, we can't recommend anyone even try this update as it stands.

You literally cripple the number of PDAF points available. Better to not update at all.

Link | Posted on Jun 24, 2016 at 05:24 UTC
In reply to:

Chris Yates: Great! They now need to unlock the $400 gouging price tag and possibly undercut Sigma. Otherwise, the Sigma (with it's superior build) still gets my cold hard cash.

Updated review from DPR means Sigma is still superior.

... and none of them work anywhere near as well as native FE glass, so it's still really not ideal. If you're just a casual shooter, though, sure, this might satisfy your needs. Then again, if you're a *casual* shooter, I'm not sure why you'd be buying a $400 *adapter*...

Link | Posted on Jun 24, 2016 at 05:23 UTC
In reply to:

FuhTeng: Ooo - very exciting. Looking forward to videos showing how well it works.

I disagree. Sure I had some findings not already noted in the limitations list - like that PDAF only works in tiny central region, which actually makes it *worse* than 'Green' mode, where PDAF tends to work across the entire, massive phase-detect area.

This holds true even for the officially supported lenses.

Furthermore, I tried the adapter on the a6000 in this mode. While, yes, technically it enables PDAF with *some* lenses on the a6000 (which the Green mode doesn't), it's so unreliable as to be largely, well, useless. Focus only locks on 1 out of 4 or 5 attempts, can't focus on far away objects, and, again, only a small central region works. It's barely better than just CDAF in 'Green' mode.

I understand this must be a very technically difficult thing to do. I guess emulating a Sony adapter is a better way to go at the moment for DSLR lenses than emulating a native lens (judging from the performance of this firmware update, & of the Sigma adapter, which fares better actually).

Link | Posted on Jun 24, 2016 at 00:25 UTC
On article Medium-format mirrorless: Hasselblad unveils X1D (1186 comments in total)
In reply to:

Dr_Jon: BTW I'm assuming it's the same sensor as the Pentax 645Z, so you can compare DR right now...
http://www.photonstophotos.net/Charts/PDR.htm#Canon%20EOS%205DS%20R,Nikon%20D810,Pentax%20645Z

Dr_Jon: Of course shot noise makes a difference - it's the *dominant* form of noise in most images!

However, the a7R II can often catch up in low light b/c of its higher efficiency (BSI), which lowers *its* relative shot noise (b/c it can catch up in light gathering ability to a certain extent - tho not fully). The rest of its 'catch up' comes from its lower read noise at ISOs 640 & above, b/c of its dual gain architecture.

And my point was also that at ISO 64, the D810 can *also* catch up with respect to shot noise, by eating up 2/3 EV more exposure before clipping the same scene tones. That *also* lowers its relative shot noise, to the levels of the 645Z, almost (there's still a tiny advantage to the 645Z).

But, as I pointed out further down below, for any given ISO, shutter speed, and aperture, of course the MF has the advantage compared to the D810 because it's collecting more overall light (larger sensor = better). Vs. the a7R II is tricky tho, b/c of its increased efficiency.

Link | Posted on Jun 23, 2016 at 22:36 UTC
On article Medium-format mirrorless: Hasselblad unveils X1D (1186 comments in total)
In reply to:

Dr_Jon: BTW I'm assuming it's the same sensor as the Pentax 645Z, so you can compare DR right now...
http://www.photonstophotos.net/Charts/PDR.htm#Canon%20EOS%205DS%20R,Nikon%20D810,Pentax%20645Z

"At some point you need to actually take the car out of the garage to see what it can really do."

Are you implying we don't go out in the real-world & shoot? Odd, because many of our shootouts and demonstrations are *done* in the real-world. We've *shown* you are results that back up our claims, you've just made claims and shown nothing. Moreover, our results agree with the hardcore, [quantitative analyses](http://photonstophotos.net/Charts/PDR.htm#Nikon%20D810,Pentax%20645Z,Sony%20ILCE-7RII) Bill Claff and others have performed, and even match with the theory (higher full-well capacity on the D810, higher efficiency/lower read noise on the a7R II). So I think I'll take our well-vetted results over your hearsay, with all due respect.

Also - I never said the MF 50MP sensor won't ever be better than the D810/a7R II, so I'm not sure why you're implying I did. I said *in certain situations* - e.g. when you can use the D810 at ISO 64, or the a7R II at high ISO - those FF cameras catch up.

Link | Posted on Jun 23, 2016 at 22:26 UTC
On article Medium-format mirrorless: Hasselblad unveils X1D (1186 comments in total)
In reply to:

blurredvision: Why exactly is the price increase so dramatic for such small increase in sensor size?

No, I'm saying it's just marketing obfuscation. :) Yes, the ADCs are 14-bit, so no way you're getting any more than 14-bit in your files. That's not necessarily a problem, though, since shot noise usually dithers tones so you don't need that much bit-depth to accurately represent tones and gradations. What you *do* need the extra bit depth for is for dynamic range, if your pixel level full-well capacity divided by read noise is greater than 14 EV.

Bit-depth and tonal gradations are often conflated and misunderstood, when what bit depth at the level of the ADC *actually* helps with is dynamic range...

Link | Posted on Jun 23, 2016 at 22:18 UTC
In reply to:

FuhTeng: Ooo - very exciting. Looking forward to videos showing how well it works.

It really doesn't work well at all. Kind of useless, sorry to report. Just updated the story.

Link | Posted on Jun 23, 2016 at 21:59 UTC
On article Medium-format mirrorless: Hasselblad unveils X1D (1186 comments in total)
In reply to:

rfsIII: Hasselblad rockin it as usual with 16-bit color. Why can't we DSLR people have that kind of visual awesomeness? That, plus the amazing lenses is what prevents us from getting even close in quality.

rfsIII: How do you get '16-bit' from a 14-bit ADC?

Thematic: fjfjjj is right - 16-bit has its benefits in post-processing workflow. However, in this particular case, because the ADC is 14-bit, all the talk of '16-bit color' is marketing nonsense. I take 14-bit D810 and a7R II and 5DS files and work with them in 16-bits per color too - should we start calling them 16-bit color now as well?

Also, a lot of this talk of 14-bit vs 16-bit also miss the fact that, in most cases, that extra bit-depth wouldn't do a thing about 'tonal gradation', because shot noise dithers those transitions anyway. All you need is an ADC that matches full-well capacity/read noise for a sensor, and in most cases, 14-bits is enough. It's actually *more* than enough for a 5DS R, which could've gotten away with a 12-bit ADC with absolutely *no impact* on Raw image quality.

Link | Posted on Jun 23, 2016 at 00:18 UTC
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