Fotomacher Loc: Toronto

A lens with only one available aperture makes no sense. A user would have to control exposure using only shutter speed which would be very limiting and probably frustrating most of the time. Not only that, but a f/1.4 lens will be sharper at f/2.8 than a f/2.8 lens shot wide open.

cthahn

Instead of thinking up stupid questions, take some cources in photography, learn the basics of photography, and take pictures. Join a camera club.

burkphoto Loc: High Point, NC

Many professional grade Micro 4/3 lenses and even some pro-grade full frame lenses are designed to perform their best at nearly wide-open apertures. MOST lenses perform best at one to three stops down, if you believe the MTF charts at dxomark.com.

However, it is unrealistic to assume that an f/1.4 lens will ALWAYS be used wide open, or near wide open. Some of us hate the cliche look of wafer-thin depth of field. It is over-used, and can distract viewers from the intention of the photo. It has its place, but if I'm thinking about the shallow depth of field, and how unnatural that is, and wishing I could see more of the subject clearly, I'm probably not getting the point of your image!

When I make portraits, I generally like my subject to be in focus. I don't mind blurring the background, but I don't want the subject's eyes sharp and ears blurred. So I'll stop down just enough to keep the body sharp.

Many of us have fast glass, but we must use it in bright daylight. We intentionally carry ND filters to reduce the light level, allowing us to use wider apertures to lessen depth of field, avoid diffraction limits on sharpness, and/or use apertures where the lens performs its best.

therwol Loc: USA

Set your lens at f1.4 and walk around taking a bunch of pictures and you'll see why nobody would buy such a lens. People use wide apertures to give shallow depth of field, but you need the whole range to adjust to each situation. You may even want to shoot the same picture at different apertures to make sure you get the exact effect you're looking for. One advantage of a fast lens in the film days was that it would let in more light for a brighter focusing screen, and the shallow depth of field made manual focusing easier.

jeep_daddy Loc: Prescott AZ

Why would you want a lens with such a limitation as only being an f/4 aperture. You wouldn't be able to stop down for the star burst effect, stop down for MORE DOF, stop down for long exposures, etc. Not for me.

RobertW Loc: Breezy Point, New York

My 4/3-------25mm (50mm=35) Leica Summilux lens is f1.4

blackest Loc: Ireland

Pentax 110 lenses are f2.8 no aperture. They are are adaptable to m43.

https://en.wikipedia.org/wiki/Pentax_Auto_110

The Shutter and Aperture were one and the same.

The Pentax Auto 110 featured fully automatic exposure, with no user-settable exposure compensation or adjustments. Metering was TTL (through-the-lens) and center-weighted. Unlike 35 mm SLRs, the system's lenses did not have a built-in iris to control the aperture. Instead, an iris was mounted inside the camera body, and functioned as both an aperture control and a shutter. This mechanism was capable of programmed exposures between 1/750 s at f/13.5; and 1 s at f/2.8. To ensure that light travelling past the diaphragm blades could not get through to the film over time, the camera's mirror system also functioned as a light-tight seal when in the viewing and focusing position. Since the iris was part of the camera, all of the system's lenses had to be constructed with an f/2.8 aperture. The lens' designs, based upon the film dimensions, resulted in the 24 mm lens being the 'normal' focal length (i.e. equivalent angle of view to a 50 mm lens on a 135 format camera), while lenses of wider angles or longer focal lengths were larger.

therwol Loc: USA

Many lenses have a maximum aperture of f1.4. The question was why a lens isn't made that can only be used at 1.4. Your lens (and my 1.4 lenses) can all be adjusted and to use smaller apertures.

BebuLamar

Actually there are lenses that have ony one fstop but they are not fast. The mirror lenses.

romanticf16 Loc: Commerce Twp, MI

Or Waterhouse stops?

gekeller Loc: New Jersey

Having a fixed aperture lens on a smartphone is the worst part of using a camera phone. Not having more flexibility in setting exposure and DOF is more limiting than the tiny sensor or lack of a viewfinder. This would be the same problem with a fixed aperture lens on an ILC.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

No. I have a fixed aperture reflex lens, which for 500mm at f/8 isn't too bad, but the problem is there is no control over DOF. I also have an old manual focus 55mm f/1.2 prime which is superb, primarily because it delivers that razor thin DOF, but it is controllable. You might be a market of one, which isn't a commercially viable proposition.

Bill_de Loc: US

Where did you find the "many people"? Did you just throw that out there as a thread starter?

I admit the 200-500 F5.6 and the 800 F5.6 are used mostly wide open. The main reason is to maintain a high shutter speed. The 50 F1.4 and 35 F1.8 get used at F8 as often as wide open.

That's just me of course.

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burkphoto Loc: High Point, NC

It behaves like an f/2.8 full frame 50 for depth of field and field of view. Still, it's a great lens!

BebuLamar

There is no demand for it. Even you said you are going to be online to buy one you expected it to be cheaper than a regular lens. Making any product for only a few would be expensive even if it's a simpler one. So no there is no way any manufacturer would make such a lens.