[Lowell Goudge]

It used to be that the best (35mm format) lenses were at least f2.8 and sometimes faster. Those lenses had the best build quality, the best glass, the best features. And, in the time when low-light capability was weak, the faster the lens, the better. Of course, aperture is also about depth-of-field and not merely light control, but many photographers do not need extremely narrow DOF for most purposes.

Times have changed. My K-5 takes good photos in very low light, especially paired with modern image-editing programs.

Can manufacturers now produce f4 lenses that are top quality in build, glass, and features? If so, can most photographers who needed f2.8 lenses in the past now function well with f4 lenses? Would the shift to f4 lenses make them much less expensive than f2.8 lenses, even if f4 lenses were top quality?

What are the issues involved in making fast, good lenses these days?

I would have to assume the discussion is aimed at zooms because many primes are several stops faster than this.

I think the issue is one of being designed to be sharp wide open or not. Many lenses need to be stopped down 1-2 stops to be at the sharpest, the same number of stops down from 2.8 is still a stop faster than F4. Also. You still get a brighter viewfinder

[tclausen]

Star lenses don't have variable apertures How about compromising at F3.5?

F/2.8 is already a compromize, Adam The FA Ltd set the bar very high, and back in my OM days, I got addicted to f/2 (f/1.2, even).....granted, for primes....

[Kerrowdown]

back in my OM days, I got addicted to f/2 (f/1.2, even)

A bit less of the old days please.

The main stay on my four everyday usage lenses are F2.8 or below.

SMC Pentax-A 50mm F1.2, SMC Pentax-A* 85mm F1.4, SMC Pentax-A* 135mm F1.8, SMC Pentax-A* 200mm F2.8 ED

[reeftool]

Faster lenses make a big difference when you manually focus, even if you never shoot wide open. The viewfinder is much brighter. On longer lenses, f/4 is a good compromise, especially if it is sharp wide open. My K300/4 is a heavy beast and a 300/2.8 is worse yet. The K300/4 is still bright enough for manual focus and I have no issues with my Katz Eye prism blacking out. I'm really not comfortable hand holding it although when I was younger, it didn't seem as heavy as it does today.

[GlennG]

There are top notch F4 lenses out there. The Canon 70-200 f4, the Pentax DA 60-250 F4, DA 15

I'd add Canon 24-105 and 17-40, at least from some very nice photo's I've seen. I have DA 17-70 and like it a lot, so, yes, I do believe that manufacturers can make some very good f/4's. I consider constant f/4 to be the ideal mix of speed, price, and weight. I've considered that there will be very few times where f/4 will NOT be fast enough that f/2.8 will be. I'm not a pro, and the wedding 'togs sure seem to like/want their 2.8's, so there must be something to that. FWIW, a few years ago, I concluded that people use the focal length range of 50-70 (for lenses that have that range) three times more often than people use an aperture less than 4.0 (for lenses that have that option). That is why I have a 17-70/4 and not a 16-50/2.8.

[Kerrowdown]

it didn't seem as heavy as it does today.

It's just like the rest of us, you gain a few pounds with age.

[Digitalis]

It is easier to design slower lenses - and it is also less costly to produce them from a manufacturing point of view as well. The glass blanks are smaller - which makes it more economical to order large quantities of them. The larger a glass blank is generally the more it costs to produce a optically perfect one from which a lens can be made, there is also the fact that slower lenses typically do not need the kind of optical aberration correction that faster lenses do*. Also faster lenses typically require exotic glass types to correct for optical aberrations as well, there is also the use of aspherical lenses - which require specialised machines and tools to create.


*Though this really depends on the focal length of the lens.

Many lenses need to be stopped down 1-2 stops to be at the sharpest, the same number of stops down from 2.8 is still a stop faster than F4. Also. You still get a brighter viewfinder

Correct, though this does depend on the focal lengths of the lens and the optical construction of the lens as well. My sigma 100-300mm f/4 performs extremely well from f/5.6 -just one stop down, but a wide angle lens like the Pentax DA 16-45mm f/4 only performed consistently at f/8.

DA*300 f/4 and the Sigma 100~300 f/4 are 2 top quality feature rich f/4 lenses.

Indeed they are but the Sigma doesn't have the kind of flare tolerance the DA*300mm f/4 does - one of the biggest faults of sigma lenses, I have panned Sigma for years over how bad their optical coatings are.

Though that hasn't stopped me from obtaining good Images from my Sigma 100-300mm f/4 APO EX DG

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Last edited by Digitalis; 04-19-2013 at 01:21 AM.

[c-meier]

Times have changed. My K-5 takes good photos in very low light, especially paired with modern image-editing programs.

That's my experience with modern cameras as well. A high-quality, relatively light, weather-sealed 24-70 f/4 (in FF terms) would be the ultimate all-around lens for me. Covers all but the most specific situations.

[...]one F/2.8 and one F/4.0 is 10% or less I'll get the F/2.8 every time. If it's more than 25% I'd probably get the F/4.0, From 10% to 25% it would depend on an number of different factors.

I think the difference would probably be more than 25%. The Canon 24-70 f/2.8 L costs, for instance, about $1300, while the 24-105 f/4 L is "only" $1000. And the latter has a longer range and is stabilized. But who knows...

[tclausen]

I consider constant f/4 to be the ideal mix of speed, price, and weight. I've considered that there will be very few times where f/4 will NOT be fast enough that f/2.8 will be. I'm not a pro, and the wedding 'togs sure seem to like/want their 2.8's, so there must be something to that. FWIW, a few years ago, I concluded that people use the focal length range of 50-70 (for lenses that have that range) three times more often than people use an aperture less than 4.0 (for lenses that have that option). That is why I have a 17-70/4 and not a 16-50/2.8.

See, that's where I - with all due respect - think you're wrong. If you have it, you /will/ use an aperture at or below f/2.8 almost 100% of the time: for composing/framing, and for focusing....and, occasionally, also for exposing the frame/sensor. For all of these, a faster lens is a huge plus.

The only argument, imo, that may exist in favor of an f/4 over an f/2.8 (or f/1.x) for focal lengths

[GlennG]

See, that's where I - with all due respect - think you're wrong. If you have it, you /will/ use an aperture at or below f/2.8 almost 100% of the time: for composing/framing, and for focusing....and, occasionally, also for exposing the frame/sensor. For all of these, a faster lens is a huge plus. The only argument, imo, that may exist in favor of an f/4 over an f/2.8 (or f/1.x) for focal lengths

Well, thank you, then So I guess I don't know what I don't know, and it certainly is good to know more, which is what you've provided here. I was just thinking that if the 2.8 was that useful we'd see many more shots at 2.8 than we do. At that time I made my observation, I looked at the first 100 PPG photos of the 16-50 and so few (about 8%) were less than 4.0. So my conclusion at the time was, gosh, for the price, size, and weight premium the 2.8's carry, you'd think the users would be shooting that really wide aperture literally all the time.

[GeneV]

See, that's where I - with all due respect - think you're wrong. If you have it, you /will/ use an aperture at or below f/2.8 almost 100% of the time: for composing/framing, and for focusing....and, occasionally, also for exposing the frame/sensor. For all of these, a faster lens is a huge plus.

The only argument, imo, that may exist in favor of an f/4 over an f/2.8 (or f/1.x) for focal lengths

Especially useful for manual focus or judging the autofocus.