Questions about "fast lenses"

[bryantluna]

Hello, geometry dash lite (https://geometry-dash-lite.com)
Why are they called "fast"? I mean, I know what a "fast lens" is, I'm just wondering where that name comes from? Is it literally just that they have a larger aperture opening, so the shutter speed can be "faster"? Is there an actual specific f/stop that a lens needs to be considered "fast" (like, anything that opens up more than, say, f/2.8 is considered a "fast lens"?
Hope that anyone can explain for me. Thanks in advance!

[Mark J]

Yes i think it came from the exposure being faster. Probably in Victorian times when lenses like the Petzval were introduced, and exposures could then be in seconds rather than minutes.

[Kevin Crisp]

I always assumed they just didn't eat on weekends. But that wouldn't explain why fast lenses are typically fatter than slower lenses.

[xkaes]

A fast lens means you can use a FASTER shutter speed -- even though the time of the exposure is SHORTER. Maybe they should have called them "QUICKER" lenses. But a "fast" lens varies by the focal length. For example, at 50mm, a lens has to be wider that f1.7 to be considered FAST. At 300mm (or 18mm) an f2.8 lens is considered FAST.

[ic-racer]

Fast lens uses a fast shutter speed. Slow lens needs a slow shutter speed.

[Mark Sawyer]

Fast lenses are like fast women, they'll both just get you in trouble...

[reddesert]

I don't know when this usage became common, but as others have said, it probably goes all the way back to early plate photography when exposure times were long and shutters were a hat. The "Rapid Rectilinear" lens name dating from the 1860s is clearly such a usage.

[Mark Sawyer]

The "Rapid Rectilinear" lens name dating from the 1860s is clearly such a usage.

As were earlier lens terms, such as "Schnellarbeiter" and "Quick Worker". Wollensak's most popular lines of lenses were the Velostigmat and Raptar, both words having an etymology relating to speed.

[Eric Woodbury]

As for 'is there an f/# at which a lens is fast. It's a relative term used in comparison to other lenses of the same focal length.

As lenses get longer, then they are harder to make what we think of as fast. Too many physical constraints and some of the assumptions in lens design start to fall apart from second order effects.

[Vaughn]

I don't know when this usage became common, but as others have said, it probably goes all the way back to early plate photography when exposure times were long and shutters were a hat. The "Rapid Rectilinear" lens name dating from the 1860s is clearly such a usage.

"Rapid" worked its way into paper, too. I enjoyed using Portriga Rapid way back when, beautiful paper and surface (111), but it was no faster nor slower than most single grade papers were at the time. Fiber base, so 'Rapid' did not refer to speed of processing the paper. Around the same time there was an enlarging paper called Pal Print -- slowest enlarging paper on the block. 16x20 prints were a SOB.

My Red Dot Artars (19" and 24") are f/11 -- on the slow side of the speed spectrum. It can be challenging to see the full image on the GG in the deep forest -- yet out in the Death Valley light it is a breeze to see, but closing down all the way does often does not give me multiple second exposures (which are easier to time without a shutter). It's a tough life out there!

One of the advantages of cut/clipped corners on one's GG is in low light situations and/or with slow lenses. After using the clipped corners to check for vignetting, I use the much brighter aerial image visible in the corners to see exactly how the corners of the image will work with the rest of the composition.

[pgk]

In the 19th century weren't some lenses described as being 'fast acting' (ie wider apeture)? Is this where the derivation comes from?

[jnantz]

The new leisure-class an’t get too much “leisuring” with a slow lens.
I always thought the terminology had to do with modernity..
not to be confused with the 19 teens -30s-fast that was all about NYC,
bags of White Castle hamburgers and the hustle.

[mhayashi]

In the 19th century weren't some lenses described as being 'fast acting' (ie wider apeture)? Is this where the derivation comes from?

I think you mean “quick acting.”
English catalogs used rapid worker and quick worker for Voigtlander petzvals for their serial groups in some periods, for example.

[pgk]

I think you mean “quick acting.”
English catalogs used rapid worker and quick worker for Voigtlander petzvals for their serial groups in some periods, for example.

I though I'd seen 'fast acting' but having waded through a lot of contemporsry publications I have no idea where. If I spot the phrase used I will post a link.

[Vaughn]

In the 19th century weren't some lenses described as being 'fast acting' (ie wider apeture)? Is this where the derivation comes from?

For awhile there, light was considered as acting like a chemical (being matter rather than energy). Perhaps it was thought that a lens that let in a lot of light allowed the light to react faster with the silver.

[alkman]

Google n-gram for the term shows an early usage from the 1840s which seems to imply a fixed lens for a lighthouse, but otherwise it seems by the 1900s the term refers to wide aperture lenses where the shutter mechanism matters. The ngram view shows little usage during the 19th century with usage picking up in the 1890s and early 1900s.