Really Warrants Larger Aperture Fast Lenses

[jamesev]

So the utopian status is to have a set of lenses that are f2.8. (1.4 if sub 50mm)

Yes I appreciate that they will allow greater DOF if required
and will allow higher shutter speeds if using them at f2.8
and usually have better glass

but

To addressing these points

If you aren't using them in the 2.8 range but more in the 3.5-4 range upwards, is the only real difference the glass quality.
I am assuming that a lens that has max aperture @ 3.5 will give the same exposure and give the same fastness, ie result in the same shutter speed @ say f4, as a lens that has a max aperture also being set at f4 (if I was using aperture priority)

Would this glass quality be really noticeable if you aren't producing images for commercial reasons where the consumer wants that differentiator, and just wanting to be a keen amateur?

Thoughts?

[zona5101]

Originally Posted by jamesev

Would this glass quality be really noticeable if you aren't producing images for commercial reasons where the consumer wants that differentiator, and just wanting to be a keen amateur?

Thoughts?

Yes there is a difference and it's not just shooting wide open but also the image quality when stopped down a stop or two. Most lenes are sharpest stopped down a bit...for instance 2 stops... on an f2.8 lens youd be at f5,6 on a 3.5 you'd be at f7 that's enough of a difference that you may not even get the shot you're after.
Now, whether or not its worth it to you to spend the $$ is your choice. Clearly you will be in the minority if you buy all super glass.

[mshockley]

There is a difference. For example, my 85mm 1.8 blows away my 55-200mm lens at 85mm with the same aperature setting--say f/5.6--image quality, sharpness, etc., all superior when using the 85mm.

There's a difference, but hey, if that thought keeps you warm at night... go for it.

I refuse to buy cheap anymore.

Not worth the hassle.

~Eric

The other's mentioned the image quality factor. There is also a difference if you are using auto focus. A DSLR is able to use the lens wide open to focus and only stops down when the image is taken.. this extra light allows for faster. more accurate autofocus.

[dannyrich]

I wasnt convinced until I bought the Nikon 135mm f2...

Buy fast glass, its expensive but worth very penny!

[dlambert]

The biggest advantages you'll get w/ slower glass are weight, size and cost.

Of these consideration, weight and size are mainly only problems in larger telephoto applications. Read right at the end of this post where Scott Kelby talks about the weight of the lens over the course of a day-long shoot. I'll be the first to admit this is a relatively rare problem, and if *I* ever complain about an f/2.8 lens being too heavy, I give you permission to throw daggers at me, but if you're really going to haul a lens all over the place, I can see where that f/4.0 lens might start looking pretty svelte.

Just as a for-instance, a 300mm f/2.8 Canon lens is about 5.6 lbs (2550g), while the f/4.0 version is about half that, and the differences get more pronounced as you get into even longer lenses. Again, this is a pretty academic problem for most people, and I have no idea what sort of focal lengths you're talking about here, but I felt obligated to offer a dissenting opinion. ;-)

[RichardTaylor]

(1) Faster lenses allow shallower DOF (not greater)

(2) On good lenses the IQ is noticable (sharpness, colour & contrast and possibly bokeh) as soon as you view the the photograph.

(3) As Papa Rotzzi says it can be a lot easier to capture an image in the first place, especially if the lens has better build quality.

For example I own a Canon 135 F2 L and a Tamron 17-50 F2.8.
In low light the Tamron is awfull . It will not
autofocus when shooting in conditions like the pic below.
Now days I don't even bother packing it in my bag for low light shooting.


Camera Canon EOS 40D
Exposure 0.005 sec (1/200)
Aperture f/2.0
Focal Length 135 mm
ISO Speed 3200
Exposure Bias 0 EV
Flash Off, Did not fire

You may not realise, and I didn't, that you have no idea of what a great lens is until you own or use one (and I do own only one).

[jdepould]

Another thing to consider is the coatings and general build. Often, faster glass does a better job controlling CA/fringing, flare, that sort of thing. Additionally, they're built to be more robust, and generally have weather sealing.

[Jim Bryant]

The quality of the more expensive, fast lenses cannot be beat in terms of sharpness, high quality glass, color coatings and in general sturdiness.