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Old 02-08-2019, 12:36 PM   #1
hal
 
Join Date: Aug 2004
Location: Buffalo, New York
Default Camera Lenses in GURPS HIGH TECH

Hi Folks,
In trying to correlate real world cameras with GURPS data, I came across the following explanation...

Anyone have a method for converting real world camera lenses to GURPS values?

For instance, it seems that a 50mm lens is about equal to what the human eye sees without distortion, making that a x1 lens if you will. Multiple of 50mm would imply that at 400mm, we're looking at a +2 lens (x8) and a lens rated at 200mm would be rated in GURPS as a +2 zoom lens?

Just checking...
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Old 02-08-2019, 04:41 PM   #2
Þorkell
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Default Re: Camera Lenses in GURPS HIGH TECH

A 50mm lens on a 35mm sensor or film. A smaller sensor/film crops the image. Most consumer DSLRs today have a crop sensor so they'd give you an image like a 75-80mm lens.

Furthermore the 50mm is what the human eye sees without distortion isn't entirely agreed upon. Some people insist that something closer to 40mm should be the normal lens.
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Old 02-08-2019, 06:22 PM   #3
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Default Re: Camera Lenses in GURPS HIGH TECH

A lens that isn't backed by a human eye doesn't really have a magnification. It has a field of view and a resolution, though most commercial systems have less than their limit resolution. A 50mm lens is in principle capable of about 17x the resolution of human central vision, but is also limited to (sensor spacing or film grain size) / (field of view). For a typical lens with a 50mm focal length and 35mm film rated for 70 lines/mm, field of view (long axis) is 0.7 radians and you have 2450 lines, so max resolution is 0.00028 radians, which is roughly equal to human vision.
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Old 02-09-2019, 12:39 AM   #4
hal
 
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Default Re: Camera Lenses in GURPS HIGH TECH

Would it be out of line to treat the lens as I suggested then when it comes to the detail that can be made out?

50mm = +0
100 = +1
200 = +2
400 = +3
750 = +4
1500 = +5

The question being, Is how much detail will a telephoto lens grant the photographer in game terms?

If that is a good structure to use, then with luck, I could perhaps rule that a failed roll in the skill use means a grainy blurred picture out of focus etc, and use the range penalties as given...

It gets to be hard to take a long range photo of someone - I was hoping to treat the lenses like binoculars - use that bonus based on range etc, and take it from there.
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Old 02-09-2019, 02:47 AM   #5
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Default Re: Camera Lenses in GURPS HIGH TECH

The problem is that with more zoom, it's harder to get a good photo. You have to adjust more for lower light, subject movement and camera shake, realistically. In cinematic-style action though, all of that is ignored, and your bonuses would be fine.
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Old 02-09-2019, 03:11 AM   #6
hal
 
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Default Re: Camera Lenses in GURPS HIGH TECH

Quote:
Originally Posted by Daigoro View Post
The problem is that with more zoom, it's harder to get a good photo. You have to adjust more for lower light, subject movement and camera shake, realistically. In cinematic-style action though, all of that is ignored, and your bonuses would be fine.
Good points about camera movement and the like. Using the descriptions for motion adjusted cameras - with the ability to avoid penalties up to -3, that combined with lenses of today's digital cameras might be doable.

In my current Cyberpunk campaign - I introduced a villain who used cell phone technology to his advantage - having hacked into the computer systems of multiple telecom companies. The character got off scott free, leaving a bad taste in the player's mouths. Problem is - the villain's home territory is in Asia - more specifically, Hong Kong of 2049. Cameras are going to play a major part in the game, as is the fact that DNI (Digital Neural Interfaces) combined with computer implants make the gathering of data all the more important. Knowing what the cameras can or can't do will have a major impact on the game as it were. Couple this with Social Media, facial recognition, Closed Circuit Television cameras - and well, things are going to get a bit hairy.

What makes this whole thing harder is the fact the player characters are going to be operating in an area that they're not culturally familiar with, and the fact they're non-orientals. Granted Hong Kong is cosmopolitan and speaks both Cantonese and English as official languages, the player characters are going to be sticking out about as equally as if they were black skinned in a largely Caucasian population. I don't expect they will be gawked at, but I also expect that if someone talks about a Gweilo - people will remember them.

Gotta love YouTube and the videos that have been posted by tourists. Of even more interest for me is the GoogleMaps with satellite mapping enabled. One gets to get a street view of the city itself.

Pictures - gotta love em. :)
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Old 02-09-2019, 03:03 PM   #7
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Default Re: Camera Lenses in GURPS HIGH TECH

Most TL 7 films have in effect negative night vision. ISO 100 film means full sun is a 1/100s exposure at f/16, or a 1/6400s exposure at f/2, which is probably as far as a 50mm lens goes. It's generally considered difficult to take non-blurry pictures at less than 1/60 of a second, so that's adequate for up to 1% of full sun, which is about 1,000 lux. By comparison, GURPS doesn't start applying night vision penalties until 100 lux, and because vision functions differently from film, we handle inadequate light a bit better.
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