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Author Topic: Very slow lenses  (Read 883 times)

Dan Wells

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Very slow lenses
« on: June 11, 2020, 01:11:49 am »

After I wrote the article a couple of weeks ago criticizing manufacturers for extremely slow lenses (essentially beyond f5.6 without a good reason - e.g. supertele zooms may have to be f6.3), Canon decides to up the ante... The rumor sites are reporting a couple of Canon f11 telephotos are coming! I was wondering who'd be cheeky enough to introduce the first non-mirror f8 lens from a major brand (other than the old and ultra-exotic Nikkor 1200-1700 f5.6-8 zoom), and Canon decides to blow right past f8 and go for f11.

The only f11 lenses I can think of for formats smaller than 8x10" fall into three categories.

1.) Super-cheapie T-mount extreme telephotos (mostly sold by the less reputable of New York camera dealers).
2.)Built-in lenses on some film compacts with long zooms.
3.) Literal telescopes jury-rigged into camera lenses

Categories 1 and 3 are related - those T-mount lenses were basically simple Galilean telescopes...

What do others think - do these very slow lenses have a place?

Dan
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shadowblade

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Re: Very slow lenses
« Reply #1 on: June 11, 2020, 03:50:02 am »

I don't see the point of f/11 lenses in anything other than extreme configurations - say, 1200mm primes and the like for birders, or relay lenses like the Laowa 24mm macro.

But the f/7.1 and f/8 zooms may have a place, even among high-end lenses. It all depends on their other characteristics - specifically, optical performance and maximum aperture at 400mm.

Currently, we have 100-400mm general-purpose telephotos. Sharp within that range and managing f/5.6 at 400mm, they're not wildlife or sports lenses (unlike the common perception) but general-purpose telephotos that work well for everything from landscapes, to portraits, to semi-macro shots, to the occasional wildlife or sports work on trips not dedicated to wildlife/sports photography.

If the f/7.1 or f/8 zooms can maintain this performance and achieve f/5.6 at 400mm, while extending the maximum focal length, they could do very well. Essentially, they'd be like the current 100-400 lenses, but with an inbuilt teleconverter to extend the range when needed. You'd still use a longer/faster lens for dedicated wildlife or field sports shooting, but this would add further versatility to am already-versatile type of lens.

Of course, all this is contingent on the lenses being sharp, well-corrected and with good bokeh - as good or better than the 100-400 lenses currently made by Canon and Sony (and the Sony one is among the sharpest out there) within that focal length range. But long lenses are relatively easy to design with large zoom ranges, unlike wider lenses.

So, if they're like 100-400s with extra capabilities, they could be great. But if they're slower at 400mm or optically compromised, they'd be little more than consumer lenses and a cheap way for low-end users to reach 500/600/700mm for a once-off holiday to East Africa or similar.
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rdonson

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Re: Very slow lenses
« Reply #2 on: June 11, 2020, 10:59:39 am »

I don't understand why rumors interest you so much.
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Ron

TonyVentourisPhotography

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Re: Very slow lenses
« Reply #3 on: June 12, 2020, 11:29:45 am »

It looks like they are just trying to keep up with the look of m43.   ;)
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Tony
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RichDesmond

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Re: Very slow lenses
« Reply #4 on: June 12, 2020, 03:56:18 pm »

It looks like they are just trying to keep up with the look of m43.   ;)

LOL, there was actually a thread kind of on this topic on the m4/3 forum.
Basically, that a slower FF lens could be functionally identical (or very close) to a faster m4/3 lens, and be the same size. Given the inherent DR/noise benefits of FF, FF ISO 800 ought to be about the same as m3/4 ISO 200. Meaning that, for example, an F4 50mm FF prime shot at ISO 800 would give the same "look" as a 25mm F2 m4/3 prime. Same DOF, same DR/noise characteristics, same size.

https://www.mu-43.com/threads/equivalence-hypothesis-could-future-ff-mirrorless-f-8-and-f-5-6-lenses-ever-so-slightly-press-upon-the-m43-pro-system.107179/#post-1351580

At first I thought the whole idea ridiculous, but after a while it made a little sense. You could have a standard FF system, with those benefits, but if you needed a lightweight travel kit buy a couple of those small, slow lenses and bump the ISO. There's not much difference in the body sizes, so the LW FF kit would be about the size/weight of the m4/3 setup.
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kers

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Re: Very slow lenses
« Reply #5 on: June 12, 2020, 04:17:56 pm »

I can imagine that you can make small lightweight lenses for full frame.
The IS in most mirrorless bodies will help you some stops.
However AF will be a problem.
In that respect f5.6 lenses would be a better plan. Also considering the circle of confusion.
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Pieter Kers
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Petrus

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Re: Very slow lenses
« Reply #6 on: June 16, 2020, 11:58:57 am »

If the f/7.1 or f/8 zooms can maintain this performance and achieve f/5.6 at 400mm, while extending the maximum focal length, they could do very well.

When the first 200-400 f/4 zoom with built in 1.4x extender was announced by Canon, I seriously asked why it was not simply designed as a 200-560mm f/4-5.6 zoom. Same thing but simpler to operate. Then Nikkor came out with 180-400 f/4 with built-in extender. What? I suspect the reason was that a variable aperture zoom (law of physics!) screams AMATEUR! while a constant aperture one is more professional and serious. Even if a clumsy extender makes it a f/5.6 lens all the way when switched on. A 200-400mm f/4 zoom could also (in theory) be a better 200-400mm f/2.8-4 zoom, but is that also amateurish?
« Last Edit: June 16, 2020, 12:12:23 pm by Petrus »
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