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Kodak Alaris warns the TSA's new airport CT scanners can damage undeveloped film

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Re: Kodak Alaris warns the TSA's new airport CT scanners can damage undeveloped film

#121

Post by paulmd »

tel wrote: post #30
colejohnson66 wrote: post #2

Genuine question: Why do people still use film anymore? I know some big movie studios do sometimes use it (The Hobbit comes to mind), but I don’t understand why anyone would use film when we have DSLRs that can have resolutions over 30 megapixels. EDIT: added “why” at beginning

You’re getting all kinds of answers but a key one, for me, is that film is unavoidably slow and expensive. Digital cameras teach you that each frame is cheap and throwaway. That encourages some kinds of photographic/artful thinking while obscuring others. Old masters of large format film photography have a workflow and thought process that’s vastly different from modern digicam shooting. When you have just one or two…

You can really skip The Camera if you like, it's 1930s era large-format-camera buying advice and isn't very relevant anymore.

The Negative is absolutely indispensable and should be read by every shooter, film or digital. The Zone System conceptually works the same for everything, whether B+W or color, film or digital. It's a generalized system for placing an exposure level onto the sensor's available range.

I suspect The Print is probably not entirely relevant anymore to most people who are doing hybrid-digital workflows (scanning their negatives), but may be of interest if you want to do wet printing. Which you should, it's super fun and rewarding and I can more easily deliver a better print than I can digitally.

One thing it doesn't cover is split-grade printing, which is very easy to produce high-quality results, but requires "modern" variable-contrast emulsions which didn't exist in his day.

Re: Kodak Alaris warns the TSA's new airport CT scanners can damage undeveloped film

#122

Post by dahart »

freeone3000 wrote: post #110
welly wrote: post #39

Earlier quoted context omitted.

Why do people use hand saws and chisels when powered table saws, compound saws and biscuit joiners are available to us? As someone who shoots film, there are a number of reasons, one being the asthetic you get from film that you can't (even with x hours in Photoshop) get from digital. I shoot large format and there are no (within my budget, at the very least) 8" x 10" digital sensors. Film also more or less forces yo…

What makes a digital picture any physical size? Is there a standard assumed pixel density?

Yes for me when making large prints. You don't get good prints at less than 150 dpi enlarged, generally, and 300+ dpi is preferable and more comparable to a large format negative, so you'd like a ~75 megapixel camera just for poster sized prints, and more for prints larger than that.

Note some people use large format negatives for ultra-sharp small prints, in that case you might be looking for 1000 dpi or higher to match the fidelity of a large negative.

Re: Kodak Alaris warns the TSA's new airport CT scanners can damage undeveloped film

#123

Post by dahart »

mark-r wrote: post #83
welly wrote: post #39

Earlier quoted context omitted.

Why do people use hand saws and chisels when powered table saws, compound saws and biscuit joiners are available to us? As someone who shoots film, there are a number of reasons, one being the asthetic you get from film that you can't (even with x hours in Photoshop) get from digital. I shoot large format and there are no (within my budget, at the very least) 8" x 10" digital sensors. Film also more or less forces yo…

An 8" x 10" digital sensor would take a whole silicon wafer. Doubt you'll see one, ever.

The LargeSense LS911 features a single shot 9×11-inch monochrome CMOS sensor with a 75-micron pixel size, a high base sensitivity of ISO 2100, and a maximum sensitivity of ISO 6400.

https://petapixel.com/2018/04/17/largesense-unveils-worlds-f...

Re: Kodak Alaris warns the TSA's new airport CT scanners can damage undeveloped film

#124

Post by i_am_proteus »

klodolph wrote: post #72
modo_ wrote: post #45

I've never run into any trouble getting film hand checked while traveling within the US. Sadly it's a completely different story internationally. Indian security has been the strictest in my experience -- flat out refusal to do anything other than run the film through the X-Ray machine. I don't travel with fast film (800+ ISO) anymore. It's just not worth the stress.

I decided to switch to digital for anything where I want to go over 400 ISO. My personal feelings are that the image quality of 800 ISO film is just terrible. YMMV based on personal preference, I know people who really like the look of fast film.

Tri-X 320 pushes to 800 pretty well.

Re: Kodak Alaris warns the TSA's new airport CT scanners can damage undeveloped film

#125

Post by wtallis »

CamperBob2 wrote: post #116
thedance wrote: post #105

Earlier quoted context omitted.

I posted the same comment yesterday and for some reason got downvoted to oblivion. SSDs do not rely on bits being correct. Raw bit error rates in multi-level flash are generally over 1%. In other words if you read a 4K page you are guaranteed to get several wrong bits. The only reason a of it works at all is because of sophisticated error-correcting codes.

I posted the same comment yesterday and for some reason got downvoted to oblivion. Probably because of the "90% bit error rate" part of the comment. Obviously SSDs can't tolerate anything close to 90% bit errors. If that kind of error rate could be corrected in the general case, it would have profound implications for information theory in general, not just hard drive manufacturing. It would be equivalent to a data c…

Based on publications from SSD controller vendors, it looks like current 3D TLC NAND has raw bit error rates on the order of 10^-3 or better when it's healthy. Raw bit error rates in the 1-2% range correspond to a drive that's either worn out its write endurance, or has been sitting on a shelf in high temperatures for years and has some data retention issues. It looks like most SSD controllers are designed to maintain some degree of usability with ~1% raw bit error rates (albeit with performance penalties), but 2% RBER is pushing the limits of even the last-resort layer of ECC.

Re: Kodak Alaris warns the TSA's new airport CT scanners can damage undeveloped film

#126

Post by dahart »

scblock wrote: post #100
scblock wrote: post #8

Earlier quoted context omitted.

I don't know that I believe this is a "genuine question", because it's quite easy to look up that yes, people still use film, and the article itself is a clear indication that Kodak still produces and sells film. As far as not understanding, there are things about film that are different than digital. It's may not necessarily be a technical discussion any more (though others may disagree with me), but artistic choice…

I see the comment I replied to was edited. It originally started off with "Genuine question: do people use film anymore" or a very similar statement. I don't believe that was a genuine question, because it is very well documented that people do.

For what it's worth...

"Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize. Assume good faith.

"Be kind. Don't be snarky. Comments should get more thoughtful and substantive, not less, as a topic gets more divisive. Have curious conversation; don't cross-examine.

"Please don't post shallow dismissals..."

etc.

https://news.ycombinator.com/newsguidelines.html

Re: Kodak Alaris warns the TSA's new airport CT scanners can damage undeveloped film

#127

Post by paulmd »

freeone3000 wrote: post #110
welly wrote: post #39

Earlier quoted context omitted.

Why do people use hand saws and chisels when powered table saws, compound saws and biscuit joiners are available to us? As someone who shoots film, there are a number of reasons, one being the asthetic you get from film that you can't (even with x hours in Photoshop) get from digital. I shoot large format and there are no (within my budget, at the very least) 8" x 10" digital sensors. Film also more or less forces yo…

What makes a digital picture any physical size? Is there a standard assumed pixel density?

There is a mathematical relationship between the sensor size and the optical properties (particularly focal length) of the lens that affects the result.

Bigger sensors tend to have shallower depth of field for a given aperture, which requires stopping down the lens further or using lens movements to compensate to keep the subject in focus. But that can be desirable where you want to isolate a subject or otherwise create an effect.

However, stopping down further also tends to cause an increase in diffraction as the Airy discs become larger and start to engage each other in constructive/destructive wave interference which reduces the theoretical resolution of the system. This particularly affects smaller sensors but since you stop a larger lens down farther it also affects them as well.

And in contrast - smaller sensors need wider apertures for a given amount of subject isolation, but they are also subject to diffraction at much wider apertures. This means you need a lens that can deliver maximum resolution at very wide apertures. This is why your cellphone camera has a f/2 or f/1.8 lens, the sensor is tiny and it needs a very wide aperture or diffraction will rob the image of all sharpness. It's also why, for the most part, cellphone cameras haven't gone much above the 10-12mp range.

https://www.cambridgeincolour.com/tutorials/diffraction-phot...

(I've always suspected there is probably some asymptotic limit to the amount of resolution that can be extracted for a given amount of depth of field, even with an infinitely large film/sensor size. as you increase the sensor size you have to stop down further and the diffraction becomes stronger and limits the lp/mm)

Re: Kodak Alaris warns the TSA's new airport CT scanners can damage undeveloped film

#128

Post by zippergz »

joecool1029 wrote: post #97

My first job over a decade ago was managing a photo lab. The x-ray machines would often damage film that people traveled with. Amateur photographers just weren't aware. The damage typically looks like white fuzzy diagonal lines across the image. It's not enough to completely destroy a picture, but it'll ruin it. The most common widespread damage we saw were people that bought like 50 disposable cameras for their Cari…

Ever get any of that Seattle FilmWorks film? Not C41 process, but people didn't understand that, and I learned it the hard way myself when I first started working at a lab. I had some really frustrating conversations with customers who thought I was lying to them when I told them we couldn't process it for them.

Re: Kodak Alaris warns the TSA's new airport CT scanners can damage undeveloped film

#129

Post by klodolph »

i_am_proteus wrote: post #124
klodolph wrote: post #72

Earlier quoted context omitted.

I decided to switch to digital for anything where I want to go over 400 ISO. My personal feelings are that the image quality of 800 ISO film is just terrible. YMMV based on personal preference, I know people who really like the look of fast film.

Tri-X 320 pushes to 800 pretty well.

I’m not happy with it. YMMV. I don’t like Tri-X in general though.

Re: Kodak Alaris warns the TSA's new airport CT scanners can damage undeveloped film

#130

Post by paulmd »

garmaine wrote: post #89
paulmd wrote: post #44

Earlier quoted context omitted.

It doesn't. Once film is fixed it's insensitive to further radiation, by design. Light is just radiation at a different wavelength from x-ray, if the fixing didn't work then the negative would fade out very quickly from ordinary light. Yes, at some scale, if you put it in the jet of a black hole the radiation is going to destroy the image from physically blasting it off. That's not a reasonable concern to raise about…

The negative would fade out rather quickly if exposed to natural light, e.g. if left outside. It is incorrect to say that radiation has no effect. The effect is just greatly reduced.

Analogous to the "don't project slides for months on end" - I would not stick it on the radiation source and leave it there for months, but it's not an amount you need to worry about for a reasonable number of trips (let's say less than 100) through the scanner.
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