ProfHankD

ProfHankD

Lives in United States Lexington, United States
Works as a Professor
Has a website at http://aggregate.org/hankd/
Joined on Mar 27, 2008
About me:

Plan: to change the way people think about and use cameras by taking advantage of cameras as computing systems; engineering camera systems to provide new abilities and improved quality.

Comments

Total: 521, showing: 1 – 20
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On Rode unveils RodeLink wireless audio system article (17 comments in total)
In reply to:

faithblinded: Odd that they chose the most crowded consumer frequency range, rather than the traditional VHF/UHF. It seems the chance for interference would be much greater. On a good day in my city, I'm in range of 20-30 wifi networks in the 2.4ghz range no matter where I go.
I'd recommend spending the extra $200 for the proven Sennheiser or Sony UHF units.

2.4GHz is a crowded band alright, but the digital encoding and low data rate means you will not observe problems in these transmissions (actually, why not just do 802.11?). Anyway, all these digital 2.4GHz devices do pretty much destroy the handful of 2.4GHz analog signals out there -- mostly old cordless phones, baby monitors, and cheap wireless surveillance cameras.

Direct link | Posted on Jan 22, 2015 at 12:27 UTC
On Panasonic Lumix DMC-GF7 flips for selfies article (357 comments in total)
In reply to:

PerL: Selfies with "Slimming mode"...talk about a camera for the narcissistic age.

Just think of all the scandals when people notice you can tell a shot was taken in slimming mode by looking at the EXIF data.... ;-)

Direct link | Posted on Jan 20, 2015 at 11:34 UTC
In reply to:

Steve Bingham: Ah, come on guys. This is not a camera rating, but a smart phone rating. Shame on you. Keep those hits coming! Jerks.

Nevermind.

Direct link | Posted on Jan 17, 2015 at 06:30 UTC

The "slight vignetting" on FF shown in the FAQ on their WWW site is actually not the corners, but a diffuse border around the whole frame... in other words, it looks like it's coming from a mask in the lens. I wonder if that mask can come out? If so, I also wonder if the IQ holds up to the FF edges?

Anyway, pretty good looking macro alternative.... The bokeh look especially nice, and 2X sure beats the 1/2X of most old manual macros.

Direct link | Posted on Jan 14, 2015 at 19:32 UTC as 20th comment
On Opinion: The myth of the upgrade path article (1279 comments in total)
In reply to:

ProfHankD: The one wildcard here is FOCAL REDUCERS, which really do give your lenses highly similar functionality on FF and APS-C. The catch is that none of the focal reducers offer fast AF -- pitty nobody has made an LA-EA2+focal-reducer, but then the PDAF SLT in the adapter wouldn't fit with the glass needed for the focal reducer. Anyway, the point is that focal reducers do solve the problem for us folks who predominantly use manual lenses, and they increase the lens effective aperture by a stop at the same time, largely compensating for the smaller pixels of APS-C (you can get similar DoF and use a 1-stop lower ISO with the same shutter speed to get similar noise properties).

For those who don't know: Focal reducers require a shorter flange-to-sensor distance than the lens was designed for, so I'm really talking SLR lenses on mirrorless bodies to have that choice. You will not find any focal reducers for Canon or Nikon APS-C bodies.

Direct link | Posted on Jan 10, 2015 at 19:52 UTC
On Opinion: The myth of the upgrade path article (1279 comments in total)

The one wildcard here is FOCAL REDUCERS, which really do give your lenses highly similar functionality on FF and APS-C. The catch is that none of the focal reducers offer fast AF -- pitty nobody has made an LA-EA2+focal-reducer, but then the PDAF SLT in the adapter wouldn't fit with the glass needed for the focal reducer. Anyway, the point is that focal reducers do solve the problem for us folks who predominantly use manual lenses, and they increase the lens effective aperture by a stop at the same time, largely compensating for the smaller pixels of APS-C (you can get similar DoF and use a 1-stop lower ISO with the same shutter speed to get similar noise properties).

Direct link | Posted on Jan 10, 2015 at 19:22 UTC as 85th comment | 4 replies

Looks like a very flexible set, adding a lot of capability in a very compact set of lenses. I already have stunningly complete lens coverage in manual and A-mount lenses I use on my E/FE-mount bodies (from 8mm-1,250mm), but these three lenses cover a heck of a lot very nicely. The first two provide nicer alternatives to the Tamron SP 90mm f/2.5 macro and Sigma 28-200mm A-mount that are among the lenses I use most often. A Minolta MC 28mm f/2.5 is another favorite of mine, and the 28mm f/2 looks like a potential upgrade from that. The wide and fisheye converters sound interesting too, if IQ is good enough. The fisheye could be particularly attractive. The only "miss" I see is that I think 21mm isn't quite wide enough for the wide converter, somebody probably figured that it's a better middle ground between fisheye and 28mm....

Direct link | Posted on Jan 10, 2015 at 15:56 UTC as 49th comment
On Canon announces five PowerShot compacts article (150 comments in total)

Nice to know what cameras I'll be using with CHDK once the porting is done. Looks like they've finally bumped past the old 16MP sensor in the A4000 and ELPH115, although I wonder a bit about the "Image processing may cause a decrease in the number of pixels" note. If you look at the CHDK raws, Canon has been grossly understating how wide their lenses go because they have tons of distortion, vignetting, and centering issues -- which burn a lot of pixels to fix, but still delivered an interpolated 16MP JPEG from the camera. Does the decrease in pixels note mean something different is going to be happening with the new models, such as delivering fewer pixels in the JPEG?

Direct link | Posted on Jan 5, 2015 at 15:00 UTC as 63rd comment
In reply to:

Blue Swan Media: Just what the world needs - another black box running proprietary software to suck up an HDMI port on your TV.

Yeah, a seriously under-featured box for the price... BUT it does have a whole bunch of things that nudge you to buy new (2015) Canon cameras, etc. In sum, it's a Canon brand-entrapment device; they should include it, or a discount coupon for it, with every camera they sell over $1000.

Direct link | Posted on Jan 5, 2015 at 14:50 UTC
In reply to:

ProfHankD: Interesting. The Samsung NX1 raws look class leading (as they should be for a backside-illum APS-C sensor), but the Sony A6000 JPEGs are much nicer, especially at high ISOs (way less smeary). Well, I guess we know the next thing for Samsung to work on.... ;-)

Well, not to be inflamatory, but Canon's the only sensor maker that really sticks out in a bad way these days.... :-(

Direct link | Posted on Dec 23, 2014 at 14:18 UTC

Interesting. The Samsung NX1 raws look class leading (as they should be for a backside-illum APS-C sensor), but the Sony A6000 JPEGs are much nicer, especially at high ISOs (way less smeary). Well, I guess we know the next thing for Samsung to work on.... ;-)

Direct link | Posted on Dec 22, 2014 at 18:29 UTC as 29th comment | 3 replies
On BPG image format aims to replace JPEGs article (206 comments in total)
In reply to:

ProfHankD: Fabrice Bellard is the guy behind TCC (Tiny C Compiler), QEMU (a generic machine emulator and virtualizer), and FFMPEG. It's not easy to impress me with one's programming skills and knowledge, but Fabrice consistently awes me. I wasn't aware of the BPG work he's been doing, but I can say without doubt that it's worth taking seriously....

Incidentally, we all know good old JPEGs are riddled with artifacts. There are aspects of JPEG2000 that largely fix those problems, but standards that come before easily-adapted public implementations don't prosper. PNGs are not a very efficient way to encode natural scenes. In sum, an H.265 variant for stills with a public implementation, and potential to leverage video compression hardware, sounds worth a look. Storing big files might not be the big issue it once was, but transmitting ultra-high-res images is becoming a bigger issue.

Yes, we strongly disagree. A lot of JPEG "detail" is really artifacting due to the DCT compression of 8x8 blocks:

http://aggregate.org/DIT/ITDP/img20.png

I'm not saying BPG should replace all image formats, but it seems about as big an upgrade from JPEG as PNG is from GIF.

Direct link | Posted on Dec 16, 2014 at 11:54 UTC
On BPG image format aims to replace JPEGs article (206 comments in total)
In reply to:

ProfHankD: Fabrice Bellard is the guy behind TCC (Tiny C Compiler), QEMU (a generic machine emulator and virtualizer), and FFMPEG. It's not easy to impress me with one's programming skills and knowledge, but Fabrice consistently awes me. I wasn't aware of the BPG work he's been doing, but I can say without doubt that it's worth taking seriously....

Incidentally, we all know good old JPEGs are riddled with artifacts. There are aspects of JPEG2000 that largely fix those problems, but standards that come before easily-adapted public implementations don't prosper. PNGs are not a very efficient way to encode natural scenes. In sum, an H.265 variant for stills with a public implementation, and potential to leverage video compression hardware, sounds worth a look. Storing big files might not be the big issue it once was, but transmitting ultra-high-res images is becoming a bigger issue.

The JPEG2000 codings look pretty good to me, although this is obviously not lossless JPEG and we don't have access to all the tunable parameters for JPEG.

To me, BPG seems to have very natural-looking artifacting at very high compression rates, basically a loss of textural detail while still keeping edges cleaner than most compression methods. I agree that it isn't awesome for the highest quality, but to fill a WWW browser window on a 4K display with a viable image.... It seems to be an incremental improvement, mostly in how natural the artifacts look,

Direct link | Posted on Dec 16, 2014 at 03:31 UTC
On BPG image format aims to replace JPEGs article (206 comments in total)

Fabrice Bellard is the guy behind TCC (Tiny C Compiler), QEMU (a generic machine emulator and virtualizer), and FFMPEG. It's not easy to impress me with one's programming skills and knowledge, but Fabrice consistently awes me. I wasn't aware of the BPG work he's been doing, but I can say without doubt that it's worth taking seriously....

Incidentally, we all know good old JPEGs are riddled with artifacts. There are aspects of JPEG2000 that largely fix those problems, but standards that come before easily-adapted public implementations don't prosper. PNGs are not a very efficient way to encode natural scenes. In sum, an H.265 variant for stills with a public implementation, and potential to leverage video compression hardware, sounds worth a look. Storing big files might not be the big issue it once was, but transmitting ultra-high-res images is becoming a bigger issue.

Direct link | Posted on Dec 16, 2014 at 02:17 UTC as 51st comment | 5 replies
On Canon EOS 7D Mark II Review preview (1230 comments in total)
In reply to:

ProfHankD: What you call "ISO-Invariance" here has long been discussed in the forums as "ISO-less" behavior. It's a good thing to test and know about.

BTW, I had students do projects on it last year and this year in my Cameras as Computing Systems course, and have a research paper titled "ISO-less?" accepted to appear at the IS&T/SPIE Electronic Imaging conference February 10, 2015.

You're right, it's not just the sensor... although a heck of a lot of it is on that chip. Image capture system architecture isn't bad, but it's the whole system, all the way to making a JPEG.

BTW, I meant to ask: the line pattern noise is repeatable or varies from frame to frame for the same scene? There used to be a lot of that kind of dynamic noise when ADCs were not on the sensor chip (transmission line effects; wires as antennas), and repeatable patterns were also common due to fab process variations in pixels, but I've not seen so much of either on high-end cameras lately.

Direct link | Posted on Dec 12, 2014 at 13:12 UTC
On Canon EOS 7D Mark II Review preview (1230 comments in total)
In reply to:

ProfHankD: What you call "ISO-Invariance" here has long been discussed in the forums as "ISO-less" behavior. It's a good thing to test and know about.

BTW, I had students do projects on it last year and this year in my Cameras as Computing Systems course, and have a research paper titled "ISO-less?" accepted to appear at the IS&T/SPIE Electronic Imaging conference February 10, 2015.

Yeah, ISO-less isn't right for describing sensor behavior... but neither is ISO-invariant. Basically, you get different characteristics for different mixes of analog/digital "amplification." My paper ends up looking at how to take ISO out of the exposure formula, instead picking parameters based on scene analysis in the camera.

Direct link | Posted on Dec 12, 2014 at 10:40 UTC
On Canon EOS 7D Mark II Review preview (1230 comments in total)

What you call "ISO-Invariance" here has long been discussed in the forums as "ISO-less" behavior. It's a good thing to test and know about.

BTW, I had students do projects on it last year and this year in my Cameras as Computing Systems course, and have a research paper titled "ISO-less?" accepted to appear at the IS&T/SPIE Electronic Imaging conference February 10, 2015.

Direct link | Posted on Dec 12, 2014 at 01:49 UTC as 226th comment | 4 replies
On WaterWeight rethinks the sandbag approach to stability article (78 comments in total)
In reply to:

coronawithlime: Maybe I could use this to replace my hip flask :)

Or vice versa. Any weight on an appropriate cord can work, including a cord you simply step on.

Direct link | Posted on Dec 10, 2014 at 03:36 UTC
On Tamron 16-300mm Di II VC PZD real-world samples article (103 comments in total)
In reply to:

ProfHankD: Please test multi-mount-option APS-C lenses on sensors that are at least the standard APS-C size -- not Canon's slightly smaller ones. IQ issues are most likely near the edges, and using Canon's smaller sensor hides edges that would be visible for Nikon, Sony, and Pentax, whereas using any of the others would trivially allow the Canon-cropped edges to be ignored.

Given the proliferation of full frame bodies, it might even be appropriate to test using one of them, because many of us sometimes use APS-C lenses on FF bodies. Certainly, it will be appropriate to test ONLY on FF when we have FF sensors in the 50MP+ range (i.e., FF sensors with roughly the same APS-C crop resolution as the best APS-C sensors).

APS-C is "Advanced Photo System -- Classic" which is a standard film format of 25.1 × 16.7mm with a 3:2 aspect ratio. Even the aspect ratio of digital APS-C sensors varies a bit, but the standard APS-C film area is about 26% bigger than sensors in Canon EF-S bodies! Canon's interpretation is an extreme outlier; most APS-C sensors are only about 13% smaller than film APS-C. Put another way, Canon's sensors are about 11% smaller than most, and still 6% smaller than the few smaller-than-normal-for-Nikon outliers. That is more than enough difference to hide potentially problematic vignetting when testing only on Canon sensors.

Incidentally, there is some ambiguity about how sensor size should be measured. The pixels encoded in JPEGs are normally surrounded by pixels used only to avoid edge interpolation artifacts, and those are surrounded by masked pixels used as a dark reference. Perhaps common APS-C sensors actually are very close to the standard size counting all pixels?

Direct link | Posted on Dec 9, 2014 at 04:05 UTC
On Tamron 16-300mm Di II VC PZD real-world samples article (103 comments in total)

Please test multi-mount-option APS-C lenses on sensors that are at least the standard APS-C size -- not Canon's slightly smaller ones. IQ issues are most likely near the edges, and using Canon's smaller sensor hides edges that would be visible for Nikon, Sony, and Pentax, whereas using any of the others would trivially allow the Canon-cropped edges to be ignored.

Given the proliferation of full frame bodies, it might even be appropriate to test using one of them, because many of us sometimes use APS-C lenses on FF bodies. Certainly, it will be appropriate to test ONLY on FF when we have FF sensors in the 50MP+ range (i.e., FF sensors with roughly the same APS-C crop resolution as the best APS-C sensors).

Direct link | Posted on Dec 8, 2014 at 16:07 UTC as 17th comment | 4 replies
Total: 521, showing: 1 – 20
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