F stops: Why do some lens contain a single f-stop in their description while others have 2, separated by a hyphen?

trapper1 Loc: Southside Virginia

Why do some lens contain a single f-stop in their description while others have 2, separated by a hyphen?

Kozan Loc: Trenton Tennessee

trapper1 wrote:

Why do some lens contain a single f-stop in their description while others have 2, separated by a hyphen?

The ones with one F-stop means it has a constant F-stop throughout the range. For instance, the Nikon 200-500mm F/5.6 has a constant F-stop all the way from 200mm through 500mm.

Other lenses that list two F-stops lists the F-stop at the shortest focal length, then the F-stop at the longest focal length. The F-stop of the lens changes depending on the focal length the lens is set to.

Hope that is clear.

jdubu Loc: San Jose, CA

Kozan wrote:

The ones with one F-stop means it has a constant F-stop throughout the range. For instance, the Nikon 200-500mm F/5.6 has a constant F-stop all the way from 200mm through 500mm.

Other lenses that list two F-stops lists the F-stop at the shortest focal length, then the F-stop at the longest focal length. The F-stop of the lens changes depending on the focal length the lens is set to.

Hope that is clear.

Yes, but even more detail might be helpful for the OP.

The f-stop listed as Kozan wrote would be the widest open f-stop available for that lens. Either as a constant widest possible (f4 for example) or a varying f-stop (f4-f5.6 for example) at any given focal length. That does NOT mean you cannot go smaller in f-stop for the lens, just not able to go wider.

lamiaceae Loc: San Luis Obispo County, CA

trapper1 wrote:

Why do some lens contain a single f-stop in their description while others have 2, separated by a hyphen?

What the others said plus, generally the lens with one F number say f/2.8 is the more expensive higher quality lens.

tommy2 Loc: Fort Worth, Texas

lamiaceae wrote:

... f/2.8 is the more expensive higher quality lens.

Much heavier too.

Julian Loc: Sarasota, FL

lamiaceae wrote:

What the others said plus, generally the lens with one F number say f/2.8 is the more expensive higher quality lens.

This is not necessarily so unless you are comparing equal focal length lenses.

Fotomacher Loc: Toronto

Julian wrote:

This is not necessarily so unless you are comparing equal focal length lenses.

I think that ratings and experience indicate that a Nikkor AFS 70-200mm f/2.8 shot at 100mm f/8 will produce better IQ than a Nikkor 28-200mm f/3.5-5.6 shot at 100mm f/8. The less expensive lens has great range and a price advantage. The more expensive lens has better IQ. You decide.....

saxman71 Loc: Wenatchee

You have probably heard the term "prime lens". Those are the lenses that have one f number. If you own a 70x200 MM, f/2.8 lens you can use f/2.8 at 70MM and at 200MM and at every focal length in between. On the other hand if you own a lens that has a range of f/3.5 to f/5.6 (the Nikon 18x140 for example) when you are shooting at 18MM you can use an f stop as wide as 3.5. However on the long end at 140MM, your most open aperture value will be f/5.6. In between 18MM and 140MM the widest f value you can dial in will vary between f/3.5 and f/5.6. Prime lenses are almost always heavier and more expensive and are considered "faster" lenses because you are able to use a higher shutter speed in waning light by opening up the aperture which lets in more light.

dsmeltz Loc: Philadelphia

Fotomacher wrote:

I think that ratings and experience indicate that a Nikkor AFS 70-200mm f/2.8 shot at 100mm f/8 will produce better IQ than a Nikkor 28-200mm f/3.5-5.6 shot at 100mm f/8. The less expensive lens has great range and a price advantage. The more expensive lens has better IQ. You decide.....

The fact that the f/2.8 lens will open to 2.8 anywhere along its range during AF also means you are more likely to nail focus no matter what f stop you use for the exposure.

rehess Loc: South Bend, Indiana, USA

saxman71 wrote:

You have probably heard the term "prime lens&... (show quote)

A prime lens has one focal length. A 70-200mm f/2.8 is not a prime lens; 70mm f/2.8 and 200mm f/2.8 are prime lenses.

saxman71 Loc: Wenatchee

rehess wrote:

A prime lens has one focal length. A 70-200mm f/2.8 is not a prime lens; 70mm f/2.8 and 200mm f/2.8 are prime lenses.

You're right of course. Another good reason why I should refrain from answering questions here.

rehess Loc: South Bend, Indiana, USA

saxman71 wrote:

You're right of course. Another good reason why I should refrain from answering questions here.

No, anyone {including me} can make a mistake; if only perfect ones responded, the silence would be deafening.

FreddB Loc: PA - Delaware County

rehess wrote:

No, anyone {including me} can make a mistake; if only perfect ones responded, the silence would be deafening.

I thought I made a mistake once, but I was wrong.
😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈😈

gvarner Loc: Central Oregon Coast

Non-zoom lenses and some zoom lenses have only one number that shows it’s widest aperture. Most zoom lenses have two numbers. The smallest one states the widest aperture opening available at the closest zoom setting, say 2.8 at 70mm, and the largest number states the widest aperture opening available at the longest zoom setting, say 5.6 at 200mm.

jerryc41 Loc: Catskill Mts of NY

If the single f/stop lens is a zoom, it's better, and it costs more. : )