Variable Max Aperture Lenses

I sometimes see people comment on variable maximum aperture lenses as though they are superman and such lenses contain Kryptonite. What is the big deal, I wonder?

I have the variable max aperture 100-400L, and I mostly just treat the lens like it is a constant f/5.6. Sure, I'm leaving a little on the table as far as maximum aperture at the shorter focal lengths, but otherwise in M mode the use of this lens is no different than anything else I have.

I can kind of understand that for lenses like the 28-135 or the 15-85, locking in a constant f/5.6 makes these lenses kind of slow on the wide end, but isn't that fundamentally the bigger problem (that these lenses are often slow) rather than the fact that they have variable maximum apertures?

So is 'variable max' shorthand for a lot of people meaning 'slow' or am I missing something?

Are there any variable aperture lenses that are fast? At least 2.8 other than the Sigma 17-70.

wfarrell4 wrote in post #13455354
Are there any variable aperture lenses that are fast? At least 2.8 other than the Sigma 17-70.

Nope, I think they are almost always f/5.6 on the long end, which usually covers about 2/3 of the range.

That's why I kind of wonder. People are like "I hate variable aperture lenses." I wonder if this means "I hate slow lenses" or if I'm missing something.

They're annoying walking around because you always have to adjust exposure appropriately if you shoot M mode like I do. On the wid end (18-55, 28-135), they're so slow that most pictures aren't very different than those from quality P&S cameras.

wfarrell4 wrote in post #13455365
They're annoying walking around because you always have to adjust exposure appropriately if your shoot M mode like I do.

Well, that;s what I mean. I just set the aperture for f/5.6 when I am using the 100-400L. It isn't a variable aperture the way I use it, it's a constant f/5.6 zoom.

So, it works for you.

wfarrell4 wrote in post #13455374
So, it works for you.

It's fine by me, I guess.

More the point I was making was that the problem of the 100-400L isn't that the maximum aperture is variable, it is that the maximum aperture is f/5.6 across most of the range. Of course, that isn't all that slow for a 400mm lens, but there it is.

Look at a lens like the EF 28-135 1:3.5-5.6 IS USM. If you want to use this lens in M mode, you need to recognize that it is functionally an EF 28-135 1:5.6 IS USM.

The problem isn't that the lens has a variable aperture, the problem is that the lens is really an f/5.6 wide angle zoom. That's slow.

Additional to your point, it's then said that we should stop down a little for best (sharpest) results from most lenses. So then why the need for high apertures!?

(that is rhetorical, I'm just musing really)

danjama wrote in post #13455405
Additional to your point, it's then said that we should stop down a little for best (sharpest) results from most lenses. So then why the need for high apertures!?

(that is rhetorical, I'm just musing really)

Hope that's a joke.

JeffreyG wrote in post #13455373
Well, that;s what I mean. I just set the aperture for f/5.6 when I am using the 100-400L. It isn't a variable aperture the way I use it, it's a constant f/5.6 zoom.

i have two variable apeture lenses, i am much like you i tend to set the above their max aperture most of the time. most of the time they are at about f/8. i do use the 18-270 below is max of f/6.3 when i am using a flash but even then it is at f/5.6 so it does not change as the focal lenght changes. i am normally shoot in the lower end of it when doing this normally betwen 18 and 50mm. hope this makes sense

Sometimes we just gripe because we're annoyed. For example, I love my SIgma 17-70 f2.8-4.5. The variable nature annoys me. I would rather have a fixed 2.8. But no one makes one with a range like 17-70. I can get a 24-70 with a fixed 2.8, or a 17-55. But nothing with as wide of a range as 17-70 or 15-85. The solution?? Gripe about it.

I don't have a problem with my variable aperture lens, but I'll gladly get rid of it as soon as Canon makes a 14-70 2.8

So how do these lenses work in the Canon world? If you set it to f/4 at 100mm, and zoom to 400mm, what does the aperture readout in the viewfinder say? And, if you set it to f/5.6 at 400mm, is that really f/5.6 or is it f/8?

I'm guessing from your third post that changing the aperture from a nominal f/4 in the viewfinder to a nominal f/5.6 doesn't actually change the aperture at 400mm. On my old OM system, you could verify this by looking at the iris with the lens off the camera. The expensive lenses did this, and the cheaper lenses didn't. I guess a lot of us old-timers don't want to think about it, and therefore don't want to know about these lenses. I got rid of all such lenses back in the 1990s in favour of the OEM Olympus f/4 zooms.

melcat wrote in post #13456356
So how do these lenses work in the Canon world? If you set it to f/4 at 100mm, and zoom to 400mm, what does the aperture readout in the viewfinder say? And, if you set it to f/5.6 at 400mm, is that really f/5.6 or is it f/8?

I'm guessing from your third post that changing the aperture from a nominal f/4 in the viewfinder to a nominal f/5.6 doesn't actually change the aperture at 400mm. On my old OM system, you could verify this by looking at the iris with the lens off the camera. The expensive lenses did this, and the cheaper lenses didn't. I guess a lot of us old-timers don't want to think about it, and therefore don't want to know about these lenses. I got rid of all such lenses back in the 1990s in favour of the OEM Olympus f/4 zooms.

Well old-timer, these new-fangled cameras have an electronic connection between the camera and the lens so the camera always knows the correct aperture for the lens being used. It has been that way for Canon ever since the EOS system was first introduced, which means that back in the 90s the problem with your old lenses was not the variable max aperture, the problem is that they were Olympus instead of Canon.

melcat wrote in post #13456356
So how do these lenses work in the Canon world? If you set it to f/4 at 100mm, and zoom to 400mm, what does the aperture readout in the viewfinder say? And, if you set it to f/5.6 at 400mm, is that really f/5.6 or is it f/8?

I'm guessing from your third post that changing the aperture from a nominal f/4 in the viewfinder to a nominal f/5.6 doesn't actually change the aperture at 400mm. On my old OM system, you could verify this by looking at the iris with the lens off the camera. The expensive lenses did this, and the cheaper lenses didn't. I guess a lot of us old-timers don't want to think about it, and therefore don't want to know about these lenses. I got rid of all such lenses back in the 1990s in favour of the OEM Olympus f/4 zooms.

The 100-400 is a variable f/4.5 - 5.6 lens. If you set it to f/4.5 at 100mm and zoom to 400mm, the aperture changes to f/5.6 (and is indicated as such in the viewfinder). If you set the aperture to f/5.6 at 100mm and zoom to 400mm, the aperture stays at f/5.6.