ilza

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

Comments

Total: 133, showing: 1 – 20
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In reply to:

RPJG: Another question from a flash newbie:

Why can't flashes stay on for the (relatively short) time needed to high speed sync with focal-plane shutters? Is that not how the bulbs work? Or, overheating maybe?

@chetan crasta: the current-voltage dependence of the arc is quite simple. (It is similar to kinda-reverse-Ohm-law V·I = const.) There is nothing mysterious there.

So to make the discharge longer, one would just increase the stored energy (capacitance). But this leads to other problems mentioned above.

Link | Posted on Sep 19, 2016 at 00:22 UTC
In reply to:

RPJG: Another question from a flash newbie:

Why can't flashes stay on for the (relatively short) time needed to high speed sync with focal-plane shutters? Is that not how the bulbs work? Or, overheating maybe?

The reason is, AFAIU, the color temperature. The source of light is an electrical arc, which MUST be very hot (otherwise the gas won’t be conductive). Since the brightness is 4th power of temperature, an arc is very bright (so draws a lot of power). Sustaining an arc for a long time requires too much of energy.

The only solution I can see is to make the arc smaller — but then you won’t be able to use your flash in high-power short-burst-of-light mode. Moreover, making arc not touch the glass (so that overheating is avoided) could make the bulb too large to be useful.

Link | Posted on Sep 18, 2016 at 02:39 UTC
On article This film camera is 100% 3D-printed, including the lens (142 comments in total)
In reply to:

PerL: I think 3-D printing is overhyped. Massproduction and economy of scale is the key to low prices. Just compare the cost per page of printing with an ink jet vs a real printed page. And the limitations of the material/plastic vs complex constructions with many different metalls, glass, electronics etc.
Fantasy seems to be running wild.

@Perl.

There is economy of scale, but scale has its prices too. I was told that in many cases the cost of storing + maintaining reliable inventory + fetching from megameters of shelves makes 3d-printing-on-demand a costwise viable option.

Probably not for 5DmIV, though.

Link | Posted on Sep 13, 2016 at 03:29 UTC
On article This film camera is 100% 3D-printed, including the lens (142 comments in total)
In reply to:

lotzi: Of course, if he would have printed all the camera body, mechanism, etc. but would have complemented it with a glass lens, the sample photos would have looked indistinguishable from any other camera, and thus, unremarkable.

So really, we are here celebrating the bad lens, which is there such that the 100% printed claim can be made. Of course, the film was not 3D printed, so the 100% is still questionable.

No, it is not a bad lens.

It is a bad lens COMBINED with a bad design of shutter. Look at the scheme (on his page) and note how different parts of a frame are exposed for different time. (It is as if an iris was slowly opening, then slowly closing ON THE FOCAL PLANE.)

Link | Posted on Sep 13, 2016 at 03:22 UTC
In reply to:

Leonp: "As final results can sometimes look unpleasant to the human eye" meaning it only works very very bad at the moment?

Sooo, in the future we will not be able to see some people on photo's anymore, if google decides they are an unimportant detail.

@Leonp: (disclaimer: what I read is only this synopsis on DPR): it looks like what program does is it tries to predict the “perceived quality” of the compression. This is the focal point of every lossy compression algo: you cut away info until you reach the required level of “perceived quality''. (Like: “this is not going to be visible anyway; no need to spend bits on it”.)

The typical algos have very naive estimators of perceived quality, which means that for some regions they would save too much data (decreasing available space for other regions!). A good estimator would allow much better worst-case-quality/size ratio.

So I read “can sometimes look unpleasant ” as: this estimator is much better than what is available, but is NOT YET ALWAYS right.

Link | Posted on Aug 25, 2016 at 00:20 UTC
On article Bolt-on 21: Fujifilm WCL-X70 sample images (54 comments in total)
In reply to:

GabrielZ: Everybody's saying the quality is great. But look at the photo above, the one before you click on the 'View our gallery...' Look at the extreme distortion of the house and telephone pole. They're both literally leaning over!

@Xentinus:
You are confused in:
> If you want to fill the frame with the tall buildings,
> you will need to change the direction of the camera.
> So you will need number 2 too.(unless you have a tilt-shift lens).

No, this condition breaks your No.1, not No.2. With F·tan(α) angle-to-position mapping function (in plain words: “no distortion” ;—]) your No.2 is irrelevant. (See
   https://en.wikipedia.org/wiki/Fisheye_lens#Mapping_function
.)

Link | Posted on Jun 20, 2016 at 04:42 UTC
On article Bolt-on 21: Fujifilm WCL-X70 sample images (54 comments in total)
In reply to:

GabrielZ: Everybody's saying the quality is great. But look at the photo above, the one before you click on the 'View our gallery...' Look at the extreme distortion of the house and telephone pole. They're both literally leaning over!

@Xentinus:
> camera needs to be
>   1-parallel to the horizon
>   2-at the at the middle of the building from ground level...

With a rectilinear lens, your “2” is not necessary. (This is the whole idea of the [tilt-]shift lens.)

> so do buildings on the horizon.

In my analysis, I only looked at the closest building — and only at the vertical lines. Assuming that most of them are REALLY vertical, this allows to find the direction of the horizon line. (Horizontal lines of this building have significant perspective distortions — so the front of the building is not parallel to the plane of the sensor. — This, I think, contributes to the general confusion created by this image.)

Link | Posted on Jun 16, 2016 at 17:43 UTC
In reply to:

Rexgig0: My wife has been using a Sun-Sniper sling since shortly after its introduction. She later added another type of attachment point, that allows for tripod mounting, made by a company other than either Sun-Sniper or BR. Perhaps because she lived in Europe for several years, she prefers the version with the metal cable inside the strap; perhaps thieves cutting camera and bag straps is more common in Europe than North America?

Following my wife's lead, I acquired a Sun-Sniper sling system, but I disliked the camera being upside down. It works better (for me) when attached to the tripod foot of a telephoto lens, with the tripod ring rotated so the camera hangs more upright.

I misplaced my Sun-Sniper sling, and substituted a Magpul sling; rather than something inspired by a carbine sling, I now use an authentic carbine sling. (When not using a large tele lens, I prefer using a Peak Design Slide, Think Tank Strap, or Leica strap, depending upon the size/weight of the camera/lens.)

Quoting: ilza: Europe: "22,000 vs USA: 12,000" WRONG! You are comparing a "Continent to an individual country". Your comparison is not apples to apples...

To the contrary, what I said is 100% correct. And comparing continent to a country is in no way meaningless. MOREOVER, this is the comparison (EU vs US) made by the poster I replied to (who, apparently, cannot read, and never was in US).

Link | Posted on Jun 16, 2016 at 07:06 UTC
On article Bolt-on 21: Fujifilm WCL-X70 sample images (54 comments in total)
In reply to:

GabrielZ: Everybody's saying the quality is great. But look at the photo above, the one before you click on the 'View our gallery...' Look at the extreme distortion of the house and telephone pole. They're both literally leaning over!

Interesting: I rotated the (low-resolution) image 4.75° clockwise, and most of what looks like the “perspective distortion” in the house is gone. All the vertical lines of the house but one become “practically vertical” on the screen.

So it looks like the top window of the house has a certain defect; this, the slanted horizon, and the low point of view contribute to a “feeling of strong perspective distortion” — while the actual distortion IS present, but is very weak. Do I deceive myself?

Link | Posted on Jun 16, 2016 at 07:00 UTC
On article Bolt-on 21: Fujifilm WCL-X70 sample images (54 comments in total)
In reply to:

GabrielZ: Everybody's saying the quality is great. But look at the photo above, the one before you click on the 'View our gallery...' Look at the extreme distortion of the house and telephone pole. They're both literally leaning over!

There must be practically no perspective distortion in this shot. Look at the horizon — it goes ALMOST through the center of the shot. When horizon goes EXACTLY through the center (axis of the lens is horizontal), there would be NO perspective distortion.

Link | Posted on Jun 14, 2016 at 02:46 UTC
In reply to:

Rexgig0: My wife has been using a Sun-Sniper sling since shortly after its introduction. She later added another type of attachment point, that allows for tripod mounting, made by a company other than either Sun-Sniper or BR. Perhaps because she lived in Europe for several years, she prefers the version with the metal cable inside the strap; perhaps thieves cutting camera and bag straps is more common in Europe than North America?

Following my wife's lead, I acquired a Sun-Sniper sling system, but I disliked the camera being upside down. It works better (for me) when attached to the tripod foot of a telephoto lens, with the tripod ring rotated so the camera hangs more upright.

I misplaced my Sun-Sniper sling, and substituted a Magpul sling; rather than something inspired by a carbine sling, I now use an authentic carbine sling. (When not using a large tele lens, I prefer using a Peak Design Slide, Think Tank Strap, or Leica strap, depending upon the size/weight of the camera/lens.)

Fujica: your reading comprehension is exactly backwards: Europe: 22,000 vs USA: 12,000.

Link | Posted on Jun 13, 2016 at 04:51 UTC
On article Processor designer ARM acquires Apical (29 comments in total)
In reply to:

maljo@inreach.com: Sounds like a good move.
(I've never heard of either of these companies)

@Richard:

Are you sure? What I’ve heard was that Sony‘s α100 was using Apical’s algorithm, but later versions switched to a different algorithm of DRO. But I never checked this…

Link | Posted on May 21, 2016 at 07:58 UTC
On article Benchmark Performance: Nikon D810 review (1989 comments in total)

@Rishi:

I have no clue how you reached the conclusion that D810 gives a dynamic range similar to MF. Looking at YOUR shots:
  http://www.dpreview.com/reviews/image-comparison/fullscreen?attr226_0=nikon_d810&attr226_1=nikon_d800&attr226_2=pentax_645z&attr226_3=canon_eos5dmkiii&normalization=compare&widget=329&x=0.46943794036589725&y=1.0658090200157284
what I see is a MUCH WORSE dynamic range.

Could you explain this, please?

P.S. Of course, I’m discussing the VISIBLE dynamic range; it may be that changing postprocessing options could change this. But this is the fault of EVERY comparison you do on DPR. Using ACR for comparison is bramaged, since it has different (hidden) biases for different cameras/systems. (I would use DCRaw, which has a straightforward/transparent treatment of RAW files.)

Link | Posted on May 15, 2016 at 00:14 UTC as 67th comment | 1 reply
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
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