Joel Halbert

Lives in United States Tucson, AZ, United States
Works as a Engineer
Joined on Jul 4, 2003

Comments

Total: 77, showing: 1 – 20
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In reply to:

NickyB66: Understandable, if it keeps people, aircraft safe then I don't see a problem.

"TSA has never ever prevented a terrorist attack".

First, do you honestly believe that if TSA and all security checks were disbanded tomorrow, that organized and/or loner terrorists would not jump at the security gap? The answer is obvious; I'm just trying to get you to think about your statement. TSA is a deterrent, a safety layer.

Second, how do you know what active terror plots have been prevented over the years? If you lock your door, you cannot logically say "locking my door never ever prevented a robbery" - whether or not you have ever been robbed,

Link | Posted on Jul 28, 2017 at 04:57 UTC

Hi DPR editors, just a quick proofreading note:
A paperweight is for keeping your stationery stationary.

And in related news, it seems that DPR posters don't appreciate posters....

Link | Posted on Jul 12, 2017 at 15:45 UTC as 18th comment
In reply to:

BobORama: Do large birds obey the flight restrictions?

Aircraft engines are tested to be able to ingest birds and unavoidable bits of trash and debris. Aircraft windshields are tested to withstand frozen chickens shot out of cannon to simulate in-flight impact. Despite those efforts, significant bird encounters (such as dense flocks nesting around airports) are known to endanger commercial and military aircraft.

Drones are made of polymers, metals, wire, glass, lithium-ion batteries etc. that pose additional and avoidable risks.

I doubt that you would appreciate having to dodge an occasional drone while barreling down a well-marked highway at 70MPH; how much more so if you were piloting a large airplane traveling over 200MPH while concentrating on your aerial fire-fighting or personnel transport duties?

Link | Posted on Jul 6, 2017 at 05:22 UTC

"...Franke & Heidecke, which grew from the remains of Rollei..."

Franke & Heidecke was (part of) the original company name. The two employees of Voigtlander left to produce, over the years:
Heidoscop (stereo plate camera to compete with Voigtlander Stereoflektoskop)
Rolleidoscop (roll-film version of same & origin of the "Rollei" moniker,
Rolleiflex & later Rolleicord TLRs, mostly for 6x6 on 120 film (the company's most famous and copied products),
Rollei 35 novel ultra-compact 35mm camera line,
SL66 & derivative SLR (Hasselblad-form) 120 cameras,
SL35 35mm SLR (coming full circle in acquiring the defunct Voigtlander as a co-brand-name)
many more sometimes strange models as the market kept changing.

The company name changed several, incorporating the "Rollei" brand-name and on-and-off the Franke & Heidecke names. In any case, we should not confuse the fact the Franke & Heidecke (the money man and the technically-inspired creator, in that order as usual) were the original founders.

Link | Posted on May 27, 2017 at 08:15 UTC as 2nd comment
In reply to:

Jacob the Photographer: Welcome back Hy6 !
Although not in name it will bear the top quality of Rolleiflex from years by-gone.
For those who are not familiar with Rolleiflex: since the 1930's it was the number one professional camera brand in the world ( see rolleiclub.com ) , in 1966 they came with the most unique medium format SLR ever the Rolleiflex SL66 , followed in the '70's by the Rolleiflex SLX and later the still highly usable Rolleiflex 6006 , 6008 series. Another interesting site to go is sl66.com , I used the Rolleiflex 6000 series for about 20 and still would have had the mother company of Rollei not stuffed up their marketing and technical service so badly. Still : the exceptional craftmanship to build high quality cameras still resides in DW Photo of Braunschweig and I only can hope and wish then good luck !! Once a Rolleiflex fan always a Rolleiflex fan :-)

thyl, the major portion of camera assembly for Leica is done in Portugal. This has been true for many years now. The incomplete but "mostly there" assembly is finished in Germany for critical adjustment, body covering, testing and packaging. Critical operations such as rangefinder adjustment, sensor selection and high-precision mounting, lens-mount trimming etc. are performed as the final assembly proceeds there. It is still European and expensive but the Portugal operation saves significant labor cost.

Link | Posted on May 27, 2017 at 07:40 UTC
In reply to:

RingoMan: Regardless of shutter differences it seems to me that flash photography is still severely punished. I hope that a mirrorless camera in APS-C can help by building an auxiliary leaf shutter in the camera body right behind the lens. The APS-C size would certainly allow for this. This would be like the leaf shutter lenses that were available for focal plane cameras. There is a reason the new Hasselblad still uses leaf shutters!

I'm surprised I could find this online - here is a wonderful and informative 1956 ad for the Konica III (a very nicely made camera).

https://books.google.com/books?id=4F0zAQAAMAAJ&pg=PA17&lpg=PA17&dq=nodal+point+leaf+shutter&source=bl&ots=BJJokONQmU&sig=rUj8jv0lMVnE-WEhrvEMZTs0jc4&hl=en&sa=X&ved=0ahUKEwiVtva-8o3UAhUnxoMKHfocAeUQ6AEIRDAH#v=onepage&q=nodal%20point%20leaf%20shutter&f=false

Note the emphasis on the first page "Between the Lens Shutter", and on the next page, the paragraph "Shutters and Nodal Points", as well as the subsequent paragraph on re-examining one's desire for interchangeable lenses.

Just great, dense ad copy for interested enthusiasts, though one wonders how well it worked for them; here's a later ad for the same camera. By 1958 the pitch was "Just Arrived - and all we can say is WOW!"

https://static1.squarespace.com/static/4ffea670c4aa3b93d374e0cb/t/50e99ca0e4b0955e460052b0/1357487265247/KonicaIII.jpg

Link | Posted on May 26, 2017 at 16:11 UTC
In reply to:

RingoMan: Regardless of shutter differences it seems to me that flash photography is still severely punished. I hope that a mirrorless camera in APS-C can help by building an auxiliary leaf shutter in the camera body right behind the lens. The APS-C size would certainly allow for this. This would be like the leaf shutter lenses that were available for focal plane cameras. There is a reason the new Hasselblad still uses leaf shutters!

RingoMan, the best placement for a leaf shutter is near the nodal point of the lens, the same plane as the optimum aperture-diaphragm location. There are a number of reasons but the easiest summary is that the blades will be completely "out of focus" since in this plane, image rays from every part of the frame pass through every portion of the lens.

The closer the shutter is to the focal plane, the more it takes on the characteristics and problems of a focal-plane shutter. In the case of a roughly round leaf shutter, this means that you will see vignetting because the central portion of the opening is exposed the longest, while the max-opening edges are exposed for the shortest time. This is the opposite outcome of a traveling-slit design architecture, that is adopted specifically to give "equal time" to every portion of the image.

Depending on the lens, there is not necessarily much room between the back element and the cover-glass - just about enough for a "focal-plane" shutter!

Link | Posted on May 26, 2017 at 15:58 UTC
On article 2017 Roundup: Consumer Long Zoom Compacts (172 comments in total)
In reply to:

TheDigitalCruiser: I've literally written the book on the Stylus 1s (Steve Frankel - "The Compleat Stylus 1s and Stylus 1" - Amazon) and I've taken mine all over the world and it's never disappointed As long as you don't use it it in darkness for very dim available-light, you can get fantastic photos with it, even if you use digital cropping and shoot at 600mm. Just see the color plates that illustrate the book -- you can see them for free using the Preview function on Amazon. A constant 2.8 aperture and the same EVF that is used on the Olympus OM-D M10 are features you don't have any right to expect in a $550 camera!

"Compleat" - Not wrong at all. It's a subtle but correct and literary usage:

The first English "guidebooks" or "How-To" books printed in the 16th or 17th centuries were often titled as "The Compleat Guide to _____" or in one example "The Compleat Gentleman". In the spirit of these books, this form of title stuck and found re-use into the 19th century and up to today, despite the archaic spelling of "complete" otherwise falling away. In class-conscious Britain, these books could be social equalizers, giving instruction and information of how to behave and what to know about a subject that otherwise might be passed on only to young aristocrats in exclusive families and schools.

So such usage in a title is meant to convey authoritative, reliable and comprehensive treatment, as well as honoring the tradition of such important instructional books.

That is my compleat guide to the use of "Compleat".

Link | Posted on May 26, 2017 at 09:17 UTC
In reply to:

Joel Halbert: Richard, nice article. A few minor points:

1. Noted by others: "focal plain" and "focal plan" obviously should read "focal plane".

2. Your description implies that focal-plane shutters all use metal multi-blade, vertically-traveling curtains. Popular today, but originally they were roll-up blinds on cylinders, like a window shade. Some of the earliest ones were vertical, then for decades most 35mm cameras used Leica-style, horizontally-traveling rubberized-cloth or foil shutter curtains (Zeiss Contax used a vertical metal "tambour door" style roller-shade). Perhaps you should simply insert
"We'll discuss today's most popular design of electro-mechanical focal-plane shutters:"
right before the sentence
"At the start of the exposure a series of horizontal blades..."

3. Readout speed of FF sensors is not slower due to physical distance; electrons travel very fast. But each pixel is bigger & holds more charge; therefore has higher capacitance and is slower to read with low added noise.

steelhead3: You are getting into semantics quite literally :) Electro-mechanical is a super-set including (and dominated by) electro-magnetic design (motors of all kinds, solenoids, relays etc.) so almost a synonym. There are non-magnetic actuators such as piezo-electric, and on the receiving side, various capacitive and resistive microphones and accelerometers etc.

The electromagnetic force is fundamental and applies to everything we are talking about. So Copal or others may correctly describe a shutter mechanism as "electromagnetic but calling it "electro-mechanical" is still correct also
I think you'd find that 1/4000 shutters and /8000-capable shutters are both implemented as electro-mechanical designs ( or electromagnetic if you prefer). .

I did see in the search, that some Canon cameras with 1/8000 speed also feature a "soft-touch electromagnetic shutter release button" instead of a conventional switch. Could that be part of what you are referring to?

Link | Posted on May 22, 2017 at 19:07 UTC
In reply to:

Joel Halbert: Richard, nice article. A few minor points:

1. Noted by others: "focal plain" and "focal plan" obviously should read "focal plane".

2. Your description implies that focal-plane shutters all use metal multi-blade, vertically-traveling curtains. Popular today, but originally they were roll-up blinds on cylinders, like a window shade. Some of the earliest ones were vertical, then for decades most 35mm cameras used Leica-style, horizontally-traveling rubberized-cloth or foil shutter curtains (Zeiss Contax used a vertical metal "tambour door" style roller-shade). Perhaps you should simply insert
"We'll discuss today's most popular design of electro-mechanical focal-plane shutters:"
right before the sentence
"At the start of the exposure a series of horizontal blades..."

3. Readout speed of FF sensors is not slower due to physical distance; electrons travel very fast. But each pixel is bigger & holds more charge; therefore has higher capacitance and is slower to read with low added noise.

Txoni, in this context, electron or hole drift is not the limit of the signal transmission rate, and the length of conductors within the camera is not a practical limit (though good transmission-line techniques will help maintain the cleanliness and fidelity of the signals). The capacitance of the photo-wells is, as I mentioned in earlier comments.

Link | Posted on May 22, 2017 at 17:46 UTC
In reply to:

Joel Halbert: Richard, nice article. A few minor points:

1. Noted by others: "focal plain" and "focal plan" obviously should read "focal plane".

2. Your description implies that focal-plane shutters all use metal multi-blade, vertically-traveling curtains. Popular today, but originally they were roll-up blinds on cylinders, like a window shade. Some of the earliest ones were vertical, then for decades most 35mm cameras used Leica-style, horizontally-traveling rubberized-cloth or foil shutter curtains (Zeiss Contax used a vertical metal "tambour door" style roller-shade). Perhaps you should simply insert
"We'll discuss today's most popular design of electro-mechanical focal-plane shutters:"
right before the sentence
"At the start of the exposure a series of horizontal blades..."

3. Readout speed of FF sensors is not slower due to physical distance; electrons travel very fast. But each pixel is bigger & holds more charge; therefore has higher capacitance and is slower to read with low added noise.

(...continued)

At some level, the thing must be electro-mechanical because the shutter button itself is not a mechanical trip mechanism, and also the electronic exposure sequence must be synchronized with the curtains. So for many reasons, all-mechanical just cannot be the case.

The issue of fastest speed: this is a combination of the shutter curtain travel rate and the minimum slit-width, i.e. how closely the 2nd curtain can follow the 1st. To achieve 1/8000 etc. without a hard-to-control, very narrow slit width, you may need a faster curtain which is more expensive to achieve with constant rate across the image plane (and requires more extensive shock-absorption to keep down noise and blur-inducing vibration). That is probably why cheaper cameras have slower top speeds (could also have a market-differentiation strategy component). Again, I think electro-mechanical is the only practical and cost-effective concept.

This side discussion, of course, does not belong in the article.

Link | Posted on May 22, 2017 at 17:37 UTC
In reply to:

Joel Halbert: Richard, nice article. A few minor points:

1. Noted by others: "focal plain" and "focal plan" obviously should read "focal plane".

2. Your description implies that focal-plane shutters all use metal multi-blade, vertically-traveling curtains. Popular today, but originally they were roll-up blinds on cylinders, like a window shade. Some of the earliest ones were vertical, then for decades most 35mm cameras used Leica-style, horizontally-traveling rubberized-cloth or foil shutter curtains (Zeiss Contax used a vertical metal "tambour door" style roller-shade). Perhaps you should simply insert
"We'll discuss today's most popular design of electro-mechanical focal-plane shutters:"
right before the sentence
"At the start of the exposure a series of horizontal blades..."

3. Readout speed of FF sensors is not slower due to physical distance; electrons travel very fast. But each pixel is bigger & holds more charge; therefore has higher capacitance and is slower to read with low added noise.

steelhead3: Well, I did a quick search on the 6d for "mechanical shutter", and what I found was a discussion of electronic or "silent" shutters and electronic first-curtain modes. So in that context, "mechanical" shutter is a reference to the physical shutter curtains. It does not necessarily mean, and I doubt it does, that those mechanical curtains are mechanically timed. Today it's hard for me to imagine that a clockwork timer is cheaper than an electronic timer. Making this even more unlikely is that without a wind lever, you'd need motor power just to wind the clockwork. Some shutters now use linear motors or glorified solenoids. Also, these complex partially-electronic exposure modes would be hard to integrate with a clockwork shutter. Therefore at some level I believe that all of these cameras have an electro-mechanical shutter mechanism, even though the word "mechanical" may appear in discussions to contrast with sensor-based "shutter" modes.

(continued...)

Link | Posted on May 22, 2017 at 17:34 UTC
In reply to:

Alex Permit: "Smaller sensors also have an advantage in this respect: less physical distance to travel means rows can be read-out quicker"

How does the PHYSICAL distance effect the electronic read speed of a sensor? Electromagnetic waves travel at one foot per nanosecond, so it can't be how long it takes the electrons to move.

noirdesir, see my comments just after this (i.e. just above in my comment-page layout). There are fundamentals (though not physical distance across the sensor) that challenge the readout rate of high-pixel count with large pixels. True that engineering fast readout generates more heat, but for low duty-cycle still photography application, I don't think that is the primary issue. It becomes more so in video which is constantly reading out and re-setting.

Link | Posted on May 22, 2017 at 16:56 UTC
In reply to:

Joel Halbert: Richard, nice article. A few minor points:

1. Noted by others: "focal plain" and "focal plan" obviously should read "focal plane".

2. Your description implies that focal-plane shutters all use metal multi-blade, vertically-traveling curtains. Popular today, but originally they were roll-up blinds on cylinders, like a window shade. Some of the earliest ones were vertical, then for decades most 35mm cameras used Leica-style, horizontally-traveling rubberized-cloth or foil shutter curtains (Zeiss Contax used a vertical metal "tambour door" style roller-shade). Perhaps you should simply insert
"We'll discuss today's most popular design of electro-mechanical focal-plane shutters:"
right before the sentence
"At the start of the exposure a series of horizontal blades..."

3. Readout speed of FF sensors is not slower due to physical distance; electrons travel very fast. But each pixel is bigger & holds more charge; therefore has higher capacitance and is slower to read with low added noise.

Kharan:
Right, I was responding to the text "less physical distance to travel means rows can be read-out quicker", which refers to an all-electronic process, so it shouldn't relate to the physical curtains. I'm saying the readout rate is challenged by a) the number of pixels (rows x columns) but also by b) the photo-well capacity -> electrical capacitance, and not incidentally by the requirement to maintain low noise. The same characteristics that give FF sensors higher dynamic range makes them harder to read out very fast.

Link | Posted on May 22, 2017 at 16:50 UTC
In reply to:

Joel Halbert: Richard, nice article. A few minor points:

1. Noted by others: "focal plain" and "focal plan" obviously should read "focal plane".

2. Your description implies that focal-plane shutters all use metal multi-blade, vertically-traveling curtains. Popular today, but originally they were roll-up blinds on cylinders, like a window shade. Some of the earliest ones were vertical, then for decades most 35mm cameras used Leica-style, horizontally-traveling rubberized-cloth or foil shutter curtains (Zeiss Contax used a vertical metal "tambour door" style roller-shade). Perhaps you should simply insert
"We'll discuss today's most popular design of electro-mechanical focal-plane shutters:"
right before the sentence
"At the start of the exposure a series of horizontal blades..."

3. Readout speed of FF sensors is not slower due to physical distance; electrons travel very fast. But each pixel is bigger & holds more charge; therefore has higher capacitance and is slower to read with low added noise.

steelhead3: True that an overlapping-rigid-blade shutter can be mechanically timed, but I don't think that's very popular anymore. All-mechanical shutters had a certain "pro" appeal in film cameras that could function with a completely dead battery, but this is of little note in a digital camera where battery power is essential. So yes, in my suggestion you could drop the "electro-mechanical" modifier, but I'd leave it in as the "most popular" or "most common" type. Mostly, I was concerned that a newcomer might read the article and come away thinking that "focal-plane shutters work just like this" which is not the case.

Link | Posted on May 22, 2017 at 16:49 UTC

Richard, nice article. A few minor points:

1. Noted by others: "focal plain" and "focal plan" obviously should read "focal plane".

2. Your description implies that focal-plane shutters all use metal multi-blade, vertically-traveling curtains. Popular today, but originally they were roll-up blinds on cylinders, like a window shade. Some of the earliest ones were vertical, then for decades most 35mm cameras used Leica-style, horizontally-traveling rubberized-cloth or foil shutter curtains (Zeiss Contax used a vertical metal "tambour door" style roller-shade). Perhaps you should simply insert
"We'll discuss today's most popular design of electro-mechanical focal-plane shutters:"
right before the sentence
"At the start of the exposure a series of horizontal blades..."

3. Readout speed of FF sensors is not slower due to physical distance; electrons travel very fast. But each pixel is bigger & holds more charge; therefore has higher capacitance and is slower to read with low added noise.

Link | Posted on May 22, 2017 at 16:13 UTC as 30th comment | 13 replies

When Best-Ever Gadget Company runs a contest or sweepstakes to create excitement around their products, the rules will read as

"Entry not open to individuals or family members employed by Best-Ever or its subsidiaries, advertising partners, consultants or contractors" etc.

This is in addition and in spite of to all efforts to keep the judging and/or prize drawings completely above-board. It simply defeats the purpose of the contest to have suspicion and bad publicity cloud the outcome, and in the case of a skills competition, it ruins the inclusiveness aspect that draws enthusiastic participants.

In other words, this incident illustrates the soundness of some very old and well-established principles, and the dangers of trying to ignore them.

Link | Posted on May 2, 2017 at 16:36 UTC as 38th comment
In reply to:

Peerg: Great lens. I have the panasonic 7-14. And that sense does not work well on olympus bodies under some circumstances, and give purple blobs. Will this 8-18 lens fix that problem? I love the 7-14 light and good performances. The oly 7-14 is good too, but to big!

It seems that the core issue is that Panasonic lenses (coatings) do not block UV spectrum because that is taken care of in the sensor stack. Olympus is the opposite; the lenses do not pass near-UV but the sensor records it. Therefore the "purple blob" issue, in flare-prone shots, needs to be addressed with an add-on filter when using Panasonic lenses on Olympus bodies. One of the lesser but still troublesome interoperability concerns in the MFT system.

The Lumix 7-14 has no filter thread or slot, but some people have rigged solutions to add one.

The fact that you can screw on a UV-blocking filter is a reason to believe that the 8-18 can do better than the Lumix 7-14 on Olympus bodies. You should buy a top-quality filter, with excellent coating, to minimize additional reflections with the wide-angle lens.

Link | Posted on Apr 19, 2017 at 16:27 UTC
On article Archos to make Kodak-branded Android tablets (142 comments in total)
In reply to:

Stacey_K: What is sad, Kodak used to manufacture world class optics in the US back in the first half of the 20th century, as well as their film products. They actually made some good CCD sensors at the start of the digital revolution. Then at some point a few CEO's types wanted to become super rich milking the company dry, thousands of people lost their jobs so these few could afford a bigger yacht. And now they are trying to milk the last dime out of the brand name.

What happened to Kodak is not simply about financial types milking the assets (Sears would be a sad example of that). Kodak wanted to stay in business as a growing and innovating concern; they just completely underestimated the pace of the digital-camera market takeover (despite essentially inventing the technology and trying to participate), the rate of plummeting film sales, and the almost-complete switch-over from paper photos to electronic PC and phone display & sharing. Film was so profitable, and disappeared so fast, that the company couldn't and didn't anticipate the pace of needed re-structuring. Any of us, even armed with the exact history of what happened, would be hard-pressed to go back to 1995 and shepherd the healthy re-shaping of Kodak into a different huge company, based on a vastly different technology and a completely different consumption model.

Link | Posted on Feb 17, 2017 at 06:38 UTC
On article Archos to make Kodak-branded Android tablets (142 comments in total)
In reply to:

OlyPent: They aren't the only ones who have fallen. Look at the crap Vivitar is making/rebranding:
http://www.abcactionnews.com/news/region-east-hillsborough/plant-city/exclusive-ear-phones-exploded-in-plant-city-mothers-ear-while-she-was-wearing-them

BlueBomberTurbo is correct. Vivitar (originally Ponder & Best) was always an importer and seller of re-branded and own-brand (custom contract-designed) photo equipment, usually running somewhere from decent to very good performance and quality.

Vivitar has since been sold a few times (?) but it's not really a "fallen" and now-licensed brand like Kodak and Polaroid. Those were among the legion of American designer/manufacturers whose famous but nearly-defunct brand name became a bankruptcy-court asset. Vivitar had some fine and famous products but they were always designed and manufactured under contract or simply re-branded. The current Vivitar may be more of the latter.

Link | Posted on Feb 17, 2017 at 06:18 UTC
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