ilza

Lives in United States United States
Joined on Nov 2, 2008

Comments

Total: 120, showing: 1 – 20
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In reply to:

mrschmo: Can you do depth screening with a Lytro Illium camera for stills?

What good is “the face in focus” if diffraction restricts the total image resolution to 1.5MPix equivalent?

Did you actually USE the system to achieve the effect you describe?

Link | Posted on Apr 21, 2016 at 02:55 UTC
On article Crossing the Bridge: Canon XC10 Review (260 comments in total)
In reply to:

nathanleebush: You guys were much too delicate with this monstrosity. "Not so good for: photographers who require RAW file support" .. What is this, 2003? How did the A6300, which seemed to fall from the heavens, only score 5 percentage points higher? It's half the price with 10x the features, and a nicer image to boot, for both stills and video! This emerged like a hot turd from the depths of hell, and will soon return whence it came.. Canon really needs to get it together, but they obviously are not aware of the internet, or they would have fixed their broken product development culture by now. It's amazing to watch them blow their massive video lead with disappointment after disappointment.

smh

This is supported by his claim that ISO800 is not good, but ISO100 and ISO200 are acceptable — with (practically) ISO-invariant hardware!

The only sensible approach is, IMO, to ignore ISO setting, and shoot at a particular f-number/angle with a particular headroom…

   [However, keep in mind that I have practically
    zero experience with videography, only with
    photo.]

Ilya

Link | Posted on Apr 9, 2016 at 05:05 UTC
On article Crossing the Bridge: Canon XC10 Review (260 comments in total)
In reply to:

nathanleebush: You guys were much too delicate with this monstrosity. "Not so good for: photographers who require RAW file support" .. What is this, 2003? How did the A6300, which seemed to fall from the heavens, only score 5 percentage points higher? It's half the price with 10x the features, and a nicer image to boot, for both stills and video! This emerged like a hot turd from the depths of hell, and will soon return whence it came.. Canon really needs to get it together, but they obviously are not aware of the internet, or they would have fixed their broken product development culture by now. It's amazing to watch them blow their massive video lead with disappointment after disappointment.

smh

@Richard:

I do not think the tests of News Shooter make a lot of sense. Take the “scientific approach” to rolling shutter: using a variable-speed fan without mentioning WHICH speed was selected!

Anyway, while THIS test is not “very scientific”, it addresses a REAL concern: rolling shutter is not good. The other two complaints (aliasing, and noise-at-midgray-level) just do not make ANY sense at all.

Aliasing: the main mode of usage “for broadcast” (shoot at 4K, postrocess to HD) was not addressed at all — and judging by the provided samples, it would COMPLETELY eliminate anti-aliasing.

Noise-at-midgray: with Bayer sensors of today THIS should depend on the area of the sensor ONLY. AND: the measurements make NO SENSE at all unless one specifies the headroom available for “brighter-than-white”.

So my first idea is that the guy just does not know that different systems need different level of EV-correction to achieve the same headroom…

ToBeContinued…

Link | Posted on Apr 9, 2016 at 05:02 UTC
In reply to:

yslee1: Sad. It's usefulness in stills might have been questionable, but in video it would've been awesome. Do your focus pulling during post, instead of the hectic nature of the live shoot.

Maybe… But remember that what we discuss is “blurring”, and not “making more sharp”. Plenoptical is always going to be NOT LESS BLURRY than the corresponding “ordinary-focal” shot.

So the possible benefits are not
  • to shoot something with AF, then “improve
     sharpness”, but
  • to shoot something with AF, then “blur
     selectively”.

Ilya

Link | Posted on Apr 8, 2016 at 23:11 UTC
In reply to:

yslee1: Sad. It's usefulness in stills might have been questionable, but in video it would've been awesome. Do your focus pulling during post, instead of the hectic nature of the live shoot.

@Rishi:

1st, I remembered wrong: 1.5MPix limit is for 50° field of view, and (corrected!) 1m–∞ refocusing ability.

2nd: I assume a camera which allows 1Dioptry refocusing ability (e.g., captures image with 1.5MPix resolution at 2m, but allows resolution better than 0.75MPix in the range 1m–∞).

3rd: these are THEORETICAL limits (very similar to Heisenberg principle — and actually proven the same way) for synchronous plenoptical capture. With any particular implementation, one gets even worse results.

Ilya

Link | Posted on Apr 8, 2016 at 07:55 UTC
In reply to:

Everlast66: "we were competing in an established industry where the product requirements had been firmly cemented in the minds of consumers"

So its customers' fault for not realising the great potential of your product?
If I understand correctly, they introduced their innovative product, superior to everything else at same price-point, or maybe solving customers' "big focusing problem", and we customers, with our backward cement-brains simply could not grasp their grand idea?

Sorry, Lytro, but this is totally the wrong attitude!
Every decent entrepreneur knows that you can not argue with the market. You have to read it, understand it, and then add something that solves REAL problems better then competitors.

I'd applaud every innovator, even if they fail, but take the lesson out of that failure. But Lytro don't seem to be willing to admit their mistakes and are not showing they learned their lesson, despite its worth of $50 million of investors' money.

@Rishi:

> Why hold up today's product as representative
> of the potential the technology holds?

This technology holds NO potential. A simple calculation shows that the whole idea is a snake oil. One cannot get more resolution that with a hyper-focal shot by the usual camera. (Read: very blurry, about 1.5MPix max for typical examples of usage.)

YES, there is A benefit comparing to a hyperfocal shot: one can make this blurry image yet-more-blurry away from a particular “focused surface”. But THIS benefit is not what the advertisement were promising.

Link | Posted on Apr 6, 2016 at 06:11 UTC
In reply to:

yslee1: Sad. It's usefulness in stills might have been questionable, but in video it would've been awesome. Do your focus pulling during post, instead of the hectic nature of the live shoot.

Depends on the range of the distance you want to be able to focus-pull to. With a reasonable range (IIRC, 2m–∞) the theoretical max of resolution is about 1.5Mpix (with std focal length). Not enough for video applications.

If one restricts this range of distances (say, to 2m–2.5m), then one can reach the resolution needed even for 4K video. I’m not in a position to judge if such tiny freedom in focus post-pulling is worth the troubles.

Link | Posted on Apr 6, 2016 at 06:02 UTC
In reply to:

greenlens: Yes, LoCA is there but no onion rings so far.

@Rishi:

I have doubts about LEDs as “bokeh subjects”: too large. For my testing, I reflected LED from a ball bearing. With LED about 10 ball’s diameters away, the reflection is really dot-like.

Link | Posted on Apr 4, 2016 at 02:31 UTC

Could you please fix your reference to read noise of 1e⁻?

You forgot to read http://sensorgen.info/Calculations.html. Summarizing:

The quoted numbers are obtained by fitting a certain formula to the measured data. The formula assumes a simple model of the sensor readout. This simple model works remarkably well for most of the sensors — but it does not work AT ALL for sensors “changing the layout” depending on the ISO setting.

The A7S (ii?) sensor uses a trick (capacity change or somesuch) somewhere about ISO6400 (do not remember the details; see the Jim Kasson’s detailed investigation). As a result, the numbers you refer to are entirely a red herring.

AFAIK, the best sensors have the best read noise close to 2e⁻. (SOME of the numbers on sensorgen which are below 2e⁻ contradict my [much more advanced than curve-fitting] research. So I assume their approach is flawed in this regard too. For example, AFAICS, they do not take into account the quantization of the noise by ADC.)

Link | Posted on Mar 29, 2016 at 00:11 UTC as 31st comment

I’m completely confused by this interview… Correct me if my reading is wrong: He says:
  • Cinematographers react quickly to changes in tech;
  • Until the last year, he thought that film has better DR;
  • AFAIK, in Super 35mm film vs FF digital, w.r.t. DR, digital
    wins for 8–10 years already (at least for photo cameras).
How to combine these? Are cinema camera so far behind?

I see that Alexa is about 6 years old — and it looks it can easily match the performance of photo cameras… How to understand all this?

Link | Posted on Mar 18, 2016 at 10:18 UTC as 17th comment
On article CP+ 2016: Things we found that had been cut in half (136 comments in total)
In reply to:

Onur Otlu: "..and features a new XA (extreme aspherical) element which has been rendered even more aspherical in this lens by being cut in half."

This was my favourite of them all - along with "ugly bokeh".

Thanks for the humor, and Rishi was right - you've *got* to keep this going!

1-element lens is very easy to design — at least if you have a material with VERY high refraction index not depending on wavelength.

The best lens is going to be very thin, going along the sphere. Radius = focal length, center is in the center of image.

This design has f-number up to f/0.5, no spherical aberration, and no coma — but it has very strong astigmatism: the tangential/saggital curvature of field are: flat vs focal length.

From this description, it is very easy to calculate the ellipses of confusion. So this design may be good for supertelephoto only…

Link | Posted on Mar 1, 2016 at 01:04 UTC
On article CP+ 2016: Things we found that had been cut in half (136 comments in total)
In reply to:

Everlast66: I don't know why, but I find this old Nikon F and Canon F-1 much more nicely engineered.
Somehow they look much more clean, solid and passionately designed. Of course to some extent this is due to the actual technology being much simpler.

Ha! What do you know about Americans?

Big percentage of them has 6,000 years of history!

Link | Posted on Mar 1, 2016 at 00:51 UTC
On article CP+ 2016: Things we found that had been cut in half (136 comments in total)
In reply to:

YTY: Pretty sure that the Sony 70-200 F2.8 has 64 elements (32 x 2) when cut in half (instead of 46 written in the article)... unless my brain is cut in half and I can't do math.

Looks like it was…

It is 46. (Same misprint repeated again and again…)

Link | Posted on Mar 1, 2016 at 00:45 UTC
In reply to:

ilza: For people who cannot read the original paper:

They have the “lenslet” size Δ=30µ, which, with distance d=500µ to the sensor, gives the blur of 4° (see p.5; I’m using THEIR notations). So, with “normal lens’” 50° field of view, this gives a resolution bounded by about 12×12 pixels.

(They do not state the field of view, but on illustrations, it is close to that.)

Enough said. (I expect the resolution may be improved a bit. I would think that 50×50 pixels may be — theoretically — achievable.)

Ilya

@EskeRahn:

I’m starting to think that you are missing a lot. First of all, diffraction does not care what is behind the entry pupil: when the incoming rays are scrambled, there is no way to unscramble them. Second, the smaller the pinholes, the WORSE is the resolution (diffraction-wise).

For example, with 1µ pinholes, and 60° field of view, there is non way to get the resolution more than 4×4 pixels (maybe even 2×2 — I’m always forgetting what the coefficient is!).

Link | Posted on Feb 23, 2016 at 05:28 UTC

DP Reviewers, could you please clarify the water-depth rating?!

There are two conflicting standards used in the industries:
    https://en.wikipedia.org/wiki/IP_Code#Liquid_ingress_protection
    https://en.wikipedia.org/wiki/Water_Resistant_mark

So, is this 20m rating the IPx8 rating?

Link | Posted on Feb 23, 2016 at 03:38 UTC as 18th comment
In reply to:

ilza: For people who cannot read the original paper:

They have the “lenslet” size Δ=30µ, which, with distance d=500µ to the sensor, gives the blur of 4° (see p.5; I’m using THEIR notations). So, with “normal lens’” 50° field of view, this gives a resolution bounded by about 12×12 pixels.

(They do not state the field of view, but on illustrations, it is close to that.)

Enough said. (I expect the resolution may be improved a bit. I would think that 50×50 pixels may be — theoretically — achievable.)

Ilya

@EskeRahn:

Diffraction ALWAYS matters (with small apertures). It does not matter what you put BEHIND the pinholes; it is enough that diffraction scrambles the rays of the incoming lightfield.

With a 30µ pinhole, you CANNOT get resolution above about 1° (with visible light).

About your illustration: can you please mark the page/column/paragraph of the Arxiv paper it would match? I see no relation of your picture to what the paper discusses.

(BTW, I did not look VERY careful into the paper. It looks very similar to the “bright 3D display” idea mentioned here some time ago — and THAT paper I did read through [it was fun!]. If so, your picture has NO RELATION to the idea of the device.)

Link | Posted on Feb 21, 2016 at 01:27 UTC
In reply to:

ms18: Amazing.... And sigma please make some primes also. f/0.95 may be? Even f/1.2 is ok but make sure they sharp wide open as Fuji lenses.

22mm

53mm

10mm

400mm f/5.6 which is far light weight than existing full frame EF 400mm f/5.6. Or increase the aperture to f/4 and keep same weight.

?! The tech was available for several years already.

The only difference now is that it is not built out of two subunits…

Link | Posted on Feb 20, 2016 at 05:17 UTC
In reply to:

ilza: For people who cannot read the original paper:

They have the “lenslet” size Δ=30µ, which, with distance d=500µ to the sensor, gives the blur of 4° (see p.5; I’m using THEIR notations). So, with “normal lens’” 50° field of view, this gives a resolution bounded by about 12×12 pixels.

(They do not state the field of view, but on illustrations, it is close to that.)

Enough said. (I expect the resolution may be improved a bit. I would think that 50×50 pixels may be — theoretically — achievable.)

Ilya

Well, I did not try to redesign their system myself — so I’m not 100% sure about the effects of diffraction in their design.

In this sensor, the image at every sensel is formed by a COMBINATION of the individual “squares” of the mask. From this, it is clear that the resolution cannot be better then the blur created by every particular square. However, the contribution of diffraction may be somewhere “in between” the contribution of an individual square, and the contribution of the full mask. (This may also depend on the used algorithm of de-masking.)

So I would not be surprised that the contribution of diffraction may be 2 (or 3? probably not stronger than this) times smaller than what an “individual masklet” would create.

But I already took this into account in my estimate of 50×50 resolution! (And, in their particular design, the diffraction is way below the defocus-blur, so these fine points do not matter.)

Link | Posted on Feb 20, 2016 at 04:03 UTC
In reply to:

ilza: For people who cannot read the original paper:

They have the “lenslet” size Δ=30µ, which, with distance d=500µ to the sensor, gives the blur of 4° (see p.5; I’m using THEIR notations). So, with “normal lens’” 50° field of view, this gives a resolution bounded by about 12×12 pixels.

(They do not state the field of view, but on illustrations, it is close to that.)

Enough said. (I expect the resolution may be improved a bit. I would think that 50×50 pixels may be — theoretically — achievable.)

Ilya

No, it is 12×12 image (which is subsequently mutilated by their complicated mask) read by 512×512 sensor — with attempt to demutilate it in post-processing.

The resolution limit is hardwired into the geometry of the mask element. With higher-resolution sensor one might be able to implement a (slightly) better demutilation — but there is no way to reduce the blurring due to the “defocus+diffraction”.

Link | Posted on Feb 19, 2016 at 08:46 UTC

For people who cannot read the original paper:

They have the “lenslet” size Δ=30µ, which, with distance d=500µ to the sensor, gives the blur of 4° (see p.5; I’m using THEIR notations). So, with “normal lens’” 50° field of view, this gives a resolution bounded by about 12×12 pixels.

(They do not state the field of view, but on illustrations, it is close to that.)

Enough said. (I expect the resolution may be improved a bit. I would think that 50×50 pixels may be — theoretically — achievable.)

Ilya

Link | Posted on Feb 17, 2016 at 12:21 UTC as 9th comment | 15 replies
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