2.8 lens owners: how often do you shoot wide open?

[Ken Fong]

Hello all,

I'm still trying to understand the benefits of a fast lens even if I will rarely shoot at the widest aperture (DOF will be very narrow unless subject is far). I've been told that optics are still better than a slower lens even at the smaller apertures (e.g. shooting 5.6 on a 2.8L lens is a lot better than shooting 5.6 on a 3.5-5.6 lens)...but how?

And if these improvements are noticed only on the edges, is this all a wash for digital SLR owners since the sensor crops out the edges anyway?

So, for 2.8L users, how often and for what do you shoot wide open? and if it is not often, has it still been worth the extra investment?

(This is all in context of justifying a replacement for a Canon 28-135 f3.5-5.6 with IS for a 24-70 f/2.8L no IS to do general and portrait work with a DSLR (10D) and EOS3 as backup. The existing IS would seem to negate the need for a faster lens. They say the blur of a faster lens is nicer...but I think I have no preference on that; however, I certainly don't mind the more solid construction of the L lens.)

thanks in advance
-Ken

[Haifidelity]

I shoot as often as I need to (i.e. low light). As for applicable apertures of L series lens vs consumer lens, there will be obvious differences.

The only thing that the two would match is probably sharpness, BUT the L lenses typically produce better color rendition and improved contrast. If you're critical of bokeh, most the L lenses i've used excel at it, usually matching the bokeh on my prime lenses.

-hza

[CoolToolGuy]

I have been doing a lot of shooting of high school events in an auditorium environment - a play, concerts, and other ceremonies. Even at f1.8 or f2.0 I am raising the ISO to 200 or higher to get decent shutter speeds. I have been using my primes, and putting on the 24-70 L only for the wide shots. At f2.8, combined with the size and weight of the 24-70, a monopod is highly desireable. This has reawakened my appreciation of prime lenses. I will be doing some outdoor action stuff soon, and that is where I think the zooms will outshine the primes.

I'm no optical expert, but I believe the softness that occurs wide open can affect more than just the edges of the frame, so the crop factor is not necessarily a cure in all cases.

[G3]

I end up shooting wide open quite a lot, if I'm shooting a portrait and want the backround blurred out, if I'm shooting existing light, say in a church where it's dim and I can't use flash...

[lensecap]

You pay the big bucks, and carry the extra weight of a fast lens because you need a fast lens. If you don't need a shallow DOF and if you don't shoot in low light, then don't use fast glass. For portraits a shallow DOF is a good thing. One of my favorites is the 85mm 1.8. The soft product at wide aps' happens through out the image, not just at the edges. I tried tokina wide zooms, because I liked the feel, but at 2.8 I could not accept the soft detail. Tried three different lenses and all the same. I tried a sigma and no problems. At 2.8 with my 70-200 I get a very nice image. At f8 I can shave with it. The trick is to find the right glass for your camera that gives a nice clean shot at larger apetures, and of course it will just get better as you go down.
If you don't need fast glass, sports, indoor events, then don't carry the weight. All my glass is fast, why not have gear that will meet every need.

[scottbergerphoto]

A wide aperture is a useful tool in two situations:
1. Low light and capturing the action is more important then having everything in sharp focus.
2. Creative use of DOF, getting a narrow zone of focus. This picture was taken with a 70-200 f/2.8 at f/2.8. You can see that only one bud is in sharp focus:
http://www.pbase.com/image/20018504.jpg
Regards,
Scott

[Tom W]

Nice shot, Scott. And a nice illustration of f/2.8 through a fine lens.

Myself, I'm inclined to use the 2.8 on occasion. I thought that a fast 50 would be all I needed, but last Christmas, I tried to shoot a night-time outdoor lit-stage event and came up woefully short on shutter speed, even with 800 ISO film (before the 10D) using an f/3.5-4.5 lens. The extra stop at the long end would have helped immensely (as would the digital processing available to get rid of the lighting cast).

But my example is just a low-light situation - Scott has shown a good example where light is ample, but short DOF is desired for effect. Only a wide aperture lens in good hands can give that effect properly, and only good glass can do it while providing an excellent image.

[Ken Fong]

Thanks all for the explanations and helpful examples. I understand the benefits of using a wide aperture to isolate the subject through narrow DOF, esp for portraits, but I was wondering if there was a downside to shooting at *the* widest setting...in this case 2.8.

The scenario is an indoor group shot with moderate light. If I shoot at 2.8, I will get enough light, but my fear is that the DOF will be so narrow that only one layer of subjects will be in focus, or maybe worse only the nose on a person's face, so I will be more inclined to shoot at a smaller aperture. But then again, I've been told the DOF isn't that narrow as increase distance (zoom) at wide open. Or, most likely, I will be using a smaller aperture with a flash...but the 2.8 will be handy to have for other situations as folks have shown.

thanks again

[Tom W]

Thanks all for the explanations and helpful examples. I understand the benefits of using a wide aperture to isolate the subject through narrow DOF, esp for portraits, but I was wondering if there was a downside to shooting at *the* widest setting...in this case 2.8.

The scenario is an indoor group shot with moderate light. If I shoot at 2.8, I will get enough light, but my fear is that the DOF will be so narrow that only one layer of subjects will be in focus, or maybe worse only the nose on a person's face, so I will be more inclined to shoot at a smaller aperture. But then again, I've been told the DOF isn't that narrow as increase distance (zoom) at wide open. Or, most likely, I will be using a smaller aperture with a flash...but the 2.8 will be handy to have for other situations as folks have shown.

thanks again

You're reaching the point of trade-offs in that scenario. You can generally shoot wide-angle at a larger aperture than normal or tele, and still get a deeper DOF, but you may still reach the point where you are getting soft focus on the back row at f/2.8. The fact that the DigiRebel and 10D both produce very clean images at ISO 400 and fairly clean images at ISO 800 might be helpful in this case, by allowing you to stop down to f/4.0 or 5.6 to get the whole group in focus and still get adequate shutter speed. If the subjects are still and you use a tripod, 1/30 or 1/45 second might work (kids probably require a higher shutter speed as they don't hold still all that well).

Flash or multi-flash probably is a good idea in this situation.

This is the nature of the beast when we use sensors that approach the size of 35 mm film or larger. I can shoot group portriats with my S-400 all day at its wides angle setting at f/2.8 and not worry too much about DOF. Of course, I do have to worry about noise and such, but DOF isn't an issue with such a short focal length in that situation.