[jacobush]

OMG - negative is the format for making prints. And the prints are hardly 35mm, are they? Maybe I was too brief, and I was pedantic, but not pointlessly so.

Some points -

- as it was formulated, you could have assumed they meant positive and negative film

- you make prints from negative film

- plot twist - those images don't reflect the resolution of 35mm at all, or even small prints made from 35mm film. So the text says there are 800 000 35mm film images - but what we see are 800 000 NTSC video stills. Quite the difference.

[Bluestrike2]

That's because the digitized images (at minimum, the majority) aren't from the original film. Around 1989, the Municipal Archives Collection started archiving the most recent images on LaserDisc. That process was clearly destructive (to the 'archived' copy; not the original); given that the landscape photos fill the frame, they were clearly cropped. When the MAC went to digitize the images, they "extracted low-resolution tiffs of each frame from the LVDs for viewing in the gallery."[0] Others at that link appear to have been pulled from the original film. Hopefully, that means all of the originals were preserved for future scanning.

Anyhow, according to a separate source quoting a NYC Tax Photos page that's no longer available,[1] the used 35mm film when they originally shot every building in the five boroughs between 1939 and 1941 (~ 720,000 black-and-white 35mm negatives) and when they later updated the photos between 1983 and 1988 (~800,000 negatives and prints). Starting ~1989, they then archived those latest photos on LaserDisc. Presumably because they'd be easier for tax assessors to work with.

The 1939-1941 collection was shot on black-and-white negative film. For the 1983-1988 photos, all of the sources I've found state that they were "in both print and negative formats." Which may or may not be helpful, as it's not uncommon for people to sometimes positive/slide film as "negatives" even though it's...wrong. You'd probably have to contact the archive to verify that.

Given the use case--a massive archive of images that can be quickly referenced by tax assessors--I find that odd if not unlikely. For that kind of massive volume, slides are easier to work with (toss a bunch on a giant light box) and take up much less storage space. Most importantly, slide film was--I believe--generally cheaper to buy and process in the 80s, not to mention it let you skip having to get prints made altogether.

Aside from the DOF tax photos, the MAC has a massive number of other photos and documents online. Assuming you don't die of boredom waiting for the pages to load, it's fascinating.[2]

0. https://robincamille.com/2016-08-09-the-municipal-archives-t...

1. https://macaulay.cuny.edu/eportfolios/napoli13/2013/03/12/ta...

2. http://nycma.lunaimaging.com/luna/servlet/NYCMA~4~4

[jacobush]

Wow, thank you so much!

I have an interest in this from several points of view. I like photography, in particular on film, I have a modest Laserdisc collection and I am interested in the history of that format. Presumably the images are in "CAV" format, which means they would be perfect still images on a TV set and also searchable by index. IIRC 9999 images could be searched on a single Laserdisc. (But maybe more, certainly the format is capable of holding many more images per side, IIRC 50 000 images per side, but maybe not in individual indexes.)

Also the Laserdisc existed in a write once, read many format - rather similar to CDR technology, but of course analog and very expensive by today's standards. I imagine that is what they used, although they could have ordered a limited pressing run, but that would have been incredibly expensive if they didn't need many copies of the discs.

Fascinating links.

[latchkey]

Watching the quality of your replies improve in this thread is exactly why I love reading the comments on HN. This is a prime example of an effective community.

[jacobush]

Watching someone write a well researched and thought out answer to a, let's face it, sketchy (as well as downvoted) comment is another reason to love HN. :)