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Kodak still makes some film stocks specifically for aerial imaging uses: https://www.kodak.com/en/advanced-materials/page/aerial-imaging-aerial-films.

I'm surprised that film is still being used in an application where it seems to (uninformed) me that digital would have significant advantages. In the other applications where film is still being used (motion pictures, "regular" still photography), it seems to mostly be used because of its artistic appeal, rather than for any true technical superiority (minus some edge cases like large format's extreme effective resolution).

Why is film still viable/preferred for some aerial imaging applications?

Andrew Madsen
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    Welcome to Photography Stack Exchange! Good first question! – Zeiss Ikon Nov 30 '21 at 19:24
  • BTW, the link you included above doesn't work for me, but I can't be sure it's not a network block (answering from work). – Zeiss Ikon Nov 30 '21 at 19:32
  • Hmm, I just tried it again directly from the body of my question and it works fine. Anyway, it's the first Google result for 'Kodak aerial film' as of today. – Andrew Madsen Nov 30 '21 at 21:00
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    just as an aside... the first Google result for you does not mean it is the first Google result for everyone. – osullic Nov 30 '21 at 23:10
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    Just a guess, thus not an answer: the equipment is expensive and is made to withstand the stresses of takeoff, flight, and landing. Therefore it is likely it has a long lifetime and a high replacement cost. IOW, I wouldn't be surprised if a significant portion of the equipment flying is older than digital photography. – Jörg W Mittag Dec 01 '21 at 07:52
  • @ZeissIkon working here from the UK on a network with very little blocking – Chris H Dec 01 '21 at 09:31
  • Aerial cameras are extremely expensive, it is a capital investment that you want to stretch out for some time. Film grain can be vastly superior to digital, but as with any aerial photography you must then perform rectification, which is quite easy with modern computing, just got to determine the trade-off. And from my knowledge Kodak has a history of supporting film types for some time. – RomaH Dec 02 '21 at 21:30
  • Good question, I had it too. Some manufacturers like Agfa and Tasma still make black and white areal films. – e_asphyx Dec 04 '21 at 00:17

3 Answers3

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Film has some advantage over digital for certain kinds of imaging and image storage.

First, a genuinely huge amount of information can be stored in a modestly sized film negative (with my flatbed scanner, I can pull almost a hundred megapixels out of 6x9 cm 120 negatives, and aerographic film is usually used in much larger formats, with better optimized lenses than I can afford, and digital files are needed, scanned at far higher resolution than I can manage). Second, that storage doesn't require constant format/media updates like digital images (what's your oldest hard disk? Can you still read a 3 1/2" floppy?), and a film negative will look like a picture even to the naked eye. Additionally, properly processed and stored silver-image film has a recoverable lifetime many times that of magnetic, optical, or flash RAM media -- measured in lifetimes, rather than years. Even if I still had a working 5 1/4" floppy drive, I wouldn't expect to still be able to read backup disks I made in the late 1980s, but film negatives three times that old are still printable and contain (most of) their original information.

Also worth noting that film negatives are error-tolerant. Ever seen a .jpg file that had all sorts of color stripes, image sections stepped over, and so forth? That can happen when a single byte is changed near the beginning of the file. A small scratch, speck of dust, or even a significant piece missing from a film negative loses only the information in the damaged area, the rest of the negative is just fine and fully usable.

Finally, there's a fairly large installed base of aerial photography equipment -- cameras, comparators, 3D viewers, and so forth -- that runs on film, and it's far cheaper to continue making certain kinds of records the same way they've been made since, in some cases, the end of the Second World War, than it is to replace expensive equipment with newer expensive equipment and convert all the records in a database -- or potentially lose access to them because they weren't converted.

Zeiss Ikon
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    Thanks for the great answer! I hadn't thought about it likely using large format film, rather than 35mm or even MF, and of course liking using very high end optics. That said, I have a hunch that the last paragraph is the biggest factor here. The other benefits of film apply even in the industries where it has mostly been supplanted. (Personal context: media in general is a hobby of mine, and I can read 3.5" and 5.25", and even 8" floppies and paper tape. My oldest working hard drive is a 10MB Widget in an Apple Lisa. But I'm an outlier. I also regularly shoot film and own many film cameras.) – Andrew Madsen Nov 30 '21 at 21:07
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    I think the last consideration (legacy) is actually the most important. It is unlikely new film equipment gets installed routinely, despite all other advantages. By the way, the film size on the top aerial cameras was huge: like, 230 mm, and I think I've seen even wider. – Zeus Nov 30 '21 at 23:57
  • Yep, and a better scanner can pull lots more data out of square centimeter of negative than my flatbed. The other answer gives what's probably the biggest advantage of digital: motion compensation via stacking/adding multiple shorter exposures. Same advantage digital has for astronomy. – Zeiss Ikon Dec 01 '21 at 12:12
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    It's possible to develop digital image file formats that are error tolerant. Maybe they already exist. – gerrit Dec 01 '21 at 12:43
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    what's your oldest hard disk? Late eighties, 52 MB, still working well. Can you still read a 3 1/2" floppy? Come on, give us something challenging. The Samantha Fox GIFs look better than ever. – pipe Dec 01 '21 at 12:54
  • @gerrit "It's possible to develop digital image file formats that are error tolerant." -- Xtol? Or some special military/intelligence developer? What time/temp? – Zeiss Ikon Dec 01 '21 at 13:21
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    @pipe can you still read your ZIP™ disks? How about the Sony TR-4 4GB tape that I just discovered collecting dust at the back of the shelf in my office? ;) (I actually just chucked my ZIP drive about a year ago. 100MB was huge! back in the day, but nearly useless these days.) – FreeMan Dec 01 '21 at 15:05
  • Exactly. I used to back up on QIC-80, then bought the QIC-160 tapes (twice the tape to fit the same drive), with compression I could get over 300 MB on a single tape (overnight, roughly). I've got individual photo files that big now, if they weren't compressed. – Zeiss Ikon Dec 01 '21 at 15:12
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    @gerrit I'd say that uncompressed with some error correction codes is minimally error tolerant. Don't know a standard format for that (maybe tiff?). Unfortunately does not protect from most physical problems (apart from bit errors). – Pablo H Dec 01 '21 at 15:18
  • @gerrit Error-tolerant is often called multiple backups ;) Something which is not possible, without degradation, for originals on film. – Andrew Morton Dec 01 '21 at 16:43
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    @AndrewMorton Backups are great! Good luck making off-site backups of physical negatives... (maybe it can be done — I don't know — but the cost is probably much, much higher than for digital images, and indeed any copy will be lossy) – gerrit Dec 01 '21 at 16:44
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I do not think it is preferred; it's just a last vestige of film... it has no real technical advantage. IMO the only reason it remains viable and in use is because the cost of conversion is quite high. No one even makes the IR color film anymore (whereas IR digital conversion is fairly simple).

I am not aware of any aerial camera manufacturer who still supports their film cameras... Leica quit supporting their aerial film cameras years ago and has since advanced multiple digital cameras instead. Which, combined with software for motion neutralization, can achieve recorded resolutions in excess of 2.5cm GSD (ground sample distance), where 15+cm is common with film. Even when the GSD is the same/similar the digital advantage often remains.

Left is aerial film scanned with 15cm GSD vs digital at 17cm GSD (ca 2003)

enter image description here

https://www.midwestaerialphoto.com/services-and-technology/film-photography-and-sensors/

https://www.midwestaerialphoto.com/services-and-technology/digital-imaging-and-sensors/

Steven Kersting
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    What is "IR color"? We can't see IR, therefore it can't have color. Do/did they have film which would result in a colour image similar to what one would get by (digitally) combining different IR bands? – gerrit Dec 01 '21 at 12:40
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    @gerrit Color Infrared Film – J... Dec 01 '21 at 13:48
  • It was used to differentiate areas of building/farming/etc by their heat signature (IR reflectance). https://blog.hxgncontent.com/impact-of-color-infrared-photography-and-color-infrared-images/ – Steven Kersting Dec 01 '21 at 14:20
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    Not "heat signature". Near-IR captured on film is not the same as thermal IR. Thermal IR relies mostly on emitted, not reflected, radiation. The IR captured by color infrared film is much closer to visible light than thermal radiation. – jeffB Dec 01 '21 at 17:06
  • @jeffB, Ok... not sure I see the difference between emitted vs reflected radiation. I can see a potential difference in frequency between heat generated IR and near IR... not sure they can't/wouldn't overlap either; but I don't have much actual experience with IR so I'll defer. – Steven Kersting Dec 01 '21 at 18:08
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    @StevenKersting the term "IR" covers all the way from 1mm wavelength (far IR) right down to ~750nm (near IR, where "red" begins). Thermal imaging happens around 10um, for picking up room temp variations - more than an order of magnitude longer from visible light (which is a lot: the whole visible spectrum only reaches from 700nm to 400nm, and 100nm is extreme UV!). Thermal imaging does overlap with nearer IR, if you're looking at higher temperatures, eg heatseeking missiles use ~5nm. Normal phonecams easily pick up IR to about 1.1um, but room-temp thermal needs specialized materials. – SusanW Dec 01 '21 at 22:56
  • erratum: heatseeking missiles use ~5um, not 5nm. Sorry. – SusanW Dec 21 '21 at 22:03
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Films can be made very large very easily, while digital sensors not so much. A digital sensor beyond 645 format is more or less reserved for military or space applications, while a 8x10 offers much higher resolution and is much cheaper. Larger films are also available and are no more expensive per unit area.

Another contributing factor is that this industry is quite conservative in terms of technology, due to its market size, return-on-investment, etc. This is the same reason that aeroplanes here are still using leaded fuel: the equipment was all designed and made decades ago and no one is willing to invest the money to update them. And there's indeed no such need: the market simply doesn't need a lighter, smaller, faster and cheaper-per-use aerial imager.

Toby Speight
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user3528438
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