Fast(ness)

[aam1234]

I'm a first class noob, so pardon the silly question. I wanted to ask that Q for a long time, so might as well do now.

For lenses, the wider a lens can go the more prized it is (and a hefty price premium to go with it). Sure, it's useful for low light situations. However, me think a wide open aperture has issues of its own, namely very shallow DOF (i.e F2), and loss of quality.

So my question is why do people like fast lenses, if the mentioned disadvantages are true (are they true?).

Thanks

[Jon]

Shallow depth of field isn't an automatic disadvantage. It helps when you want to isolate something from its surroundings, even in bright light conditions.

Yes, the faster lenses are harder to correct, but you'll often find that, say, an f/2 lens stopped down to f/4 is sharper than an f/4 of the same focal length, but wide open. There's a thread on here from the last day or so, IIRC (on dial-up at the moment) where someone was comparing a wide non-L to an
L zoom which was a couple of stops slower, so he was using them at the same aperture for the comparison. Several people suggested that he try the one he was criticizing stopped down an equivalent amount for a more balanced comparison.

[CyberDyneSystems]

'cause there faster.... 8)

Really it has to do with the increased functionality of the lens. In darker conditions.. the "slower" lenses become as usefull as a brick. Doesn't matter how much $$ you saved if the lens will not do the job.

Faster lenses are sharper overall as a general rule. Even if the lens is not razor sharp at f/2.8... it may be at f/4... if you have a lens that starts at f/5.6 it may be f/11 before it is as "tack sharp".

Also.. the "coveted" fast lenses ARE sharp wide open... this is why lenses like the Sigma 24-70mm f/2.8 are NOT coveted... it isn't very sharp untill f/8! Where as a 50mm f/1.4 is.

[aam1234]

Thank you guys for your replies,

I'm aware that a shallow DOF is desirable in certain situations.

Let's take a real life (indoor) situation as an example. Say your aunt and grandma are having dinner (low light) at a round table but not opposite each other (i.e not the same focal plain). When the "fast" lens is wide open it won't make both of them in focus, right.

Also, and sorry, but the idea of a fast lens stepped down sounds counter logical. You paid dearly to have a fast lens (wide open) but you step it down to get an optimum results...I don't know. It's like buying a Ferrari but drive it slowly. If you can't use what you paid for, me think you've wasted your money.

[timmyquest]

What is the fastest lens you own aam?

[aam1234]

F3.5

[timmyquest]

F3.5

I figured. You can worry aobut DOF all you want, but once you get a fast lens you will never go back.

The ability to shoot without the need of the flash, the ability to isolate your subject, and the typically better optics of faster lenses...it's just fantastic.


ISO 800
1/50
f/1.8
50mm
Completly natural pose, candid, natural light.
http://www.questphotos.com/Football/game5/images/332D9459.jpg

My suggestion to you is to invest in the 50mm f/1.8 and make your decision from there. If you still feel the same way about faster lenses then you can live life a richer man :-)

[aam1234]

timmyquest that photo illustrates my point exactly.

Look at what's "in focus". It's the no. 30 on his shirt. Everything beyond that is (semi) out of focus, like his hand and face.

[CyberDyneSystems]

Also, and sorry, but the idea of a fast lens stepped down sounds counter logical. You paid dearly to have a fast lens (wide open) but you step it down to get an optimum results....

No... I don't.. that was my point.

The Fast lens... if it is a good one.. a desireable one... is sharp wide open.

I mentioned the 50mm,.. and there are many more that are sharp wide open. This is what we are looking for.

No one "craves" a soft fast lens... they may compromise and get just that because it is more affordable.

I think part of the misunderstandig is the assumption that larger aperture means softer 100% of the time.

But in fact what we are striving for is fast and sharp.

[aam1234]

I think part of the misunderstandig is the assumption that larger aperture means softer 100% of the time. It does not.

From what I've read, lenses don't do well either wide open or really stepped down. Laws of physics.

[CyberDyneSystems]

Physics yes.. but some lenses are "magic" :lol: :lol: :lol:

Like the 135mm f/2L ... wide open it will blow the doors off of a 70-300mm zoom at 135mm even if it's stopped down to f/16

[CyberDyneSystems]

P.S.

If you want some nice samples.. forget toddlers like me..

Check out Blair's work... he is a master with a fast lens;

http://www.blairbunting.com/

[aam1234]

it will blow the doors off of a 70-300mm

Not a fair comparison. It's like putting me against Mohammed Ali in his prime in the same ring. He will knock me out in 1/30 sec. :D

[maderito]

There are shots that are simply not possible with a slower lens. In shooting indoor sports, I cannot get a well-exposed shot unless I'm at f/2.8 or wider most of the time, even with ISO pumped up to 800 or more.

Part of the art of low light photography is dealing with the shallow DOF. Maybe Grandma and daughter aren't in the same plane of focus. So you work within that limitation to create effects, e.g.
http://www.pbase.com/maderito/image/26202805/original

Faster lenses open up different possibilities for photographic expression.

[aam1234]

Another example of my original question.

A fast lens loses a lot of DOF to a point that I'm not sure it's worth paying big $$ for it.

In the example above, only her right side is in sharp focus. The rest is acceptable, sure, but you've paid a lot for that?

[CyberDyneSystems]

Did you look at Blair bunting's Site?

The images in the montage .. at least about 90% of them, are taken using very large apertures.. and a good part of his artistry lies in his use of that DOF.

This has no impression on you?

I would say then at this point.. if you don't see the value in it.. then they are not for you.

Depth of feild is about NOT having everything in sharp focus.
If that is what you require.. then you need to shoot at f/8 - f/16 or higher with wide angle lenses.

We're certainly not going to convince you that fast lenses are "better" if your not interested in what they acheive.

It's a matter of taste I guess. 8)

[aam1234]

Where is Blair bunting's Site. Would be nice if you can paste a link to it here. It might clear things up a bit.

To sum up my point...
You pay too much to gain too little.

As an economist, that doesn't make much sense. (btw and trust me, I don't have a problem spending money...but need to be convinced before I do so)

[CyberDyneSystems]

Uhhh .. it's at the link I posted when I first mentioned him.... ???

I get the feeling your not reading any of our replies :(

Again it's;

http://www.blairbunting.com/

[maderito]

I'm a first class noob, so pardon the silly question. I wanted to ask that Q for a long time, so might as well do now.

...

Sure, it's useful for low light situations...

...

So my question is why do people like fast lenses, if the mentioned disadvantages are true (are they true?).


You've already partially answered your own question. What remains to be said has already been stated in the above posts.

Manipulation of DOF through aperture selection is a fundamental part of artistry and technique in photography - just like choice of ISO and shutter speed. Small (or large) DOF can be a positive or negative attribute of any given image. Excellent photographs typically are remarkable for good or creative use of DOF (small or large).

If you want to limit your your shots to situations were there is adequate light for exposure settings that fully cover the DOF of your intended subjects, then don't worry about fast lenses. Or if all your photos are landscapes shot at noon on sunny days, then forget about fast lenses. But if you want to expand your range of possibilites, try out a fast lens.

[timmyquest]

The fact is that there are two major adjustments that a photographer must change while taking any picture.

Shutter speed
Aperature

The 1D (although not the MKII ???) has a max shutter speed of 1/16,000. Have i ever taken a picture at that speed? No...Am i glad i have the option, yes.

New canon cameras have an ISO 3200 option. Would you really use it in a serious shoot? Not likely...are you glad it's there? Yes.

As was stated there are lenses out there that are simply amazing wide open, sharper then most stopped down. 135 f/2 200 f/1.8 (CDS where are your photos from this lens?!) 34 f/1.4 50 f/1.4 These lenses not only give you the option of shooting in low light situations, but also the option of shooting in very artistic fashions.

Hmm, maybe tomorrow i'll go take some shots with the 50 at f/1.8 1/16,000 in the bright sun :)

[Quinn Porter]

aam1234, I must say I'm envious of you. If only I too had no appreciation for shallow depth of field, I would have saved so much money! :wink:

Seriously, if you are happy with your 3.5-5.6 zooms, enjoy them in peace and stop trying to harass more experienced photographers.

[aam1234]

and stop trying to harass more experienced photographers.

The intention is to be educated not to harass anybody :cry:

[CyberDyneSystems]

It's cool aam...

...we may get a little frustrated.. :roll: ...but we know you aren't harassing us! :mrgreen:


I'm sure Quinn was just defending us poor easily confused gear-heads knowing we can't maintain proper "composure" when it's our Glass being maligned! :lol: :lol: :lol: :lol: :lol:

It's like the episiode of Star Trek (the original) where the Klingons are first insulting Mr. Scott.. he keeps it together,.. then his Captain,.. he keeps it together..., finally they make the mistake of calling the Enterprise a "Garbage Scow"... Obviously "Scotty" looses it and starts swinging! 8) :wink:

[maderito]

and stop trying to harass more experienced photographers.

The intention is to be educated not to harass anybody :cry:
Well . . . I think we were beginning to wonder whether your were listening. As an economist, there is perhaps a formulaic bent to your mind that by-and-large serves you well - except when applied to photography.

Example: http://www.pbase.com/maderito/image/30721571
This shot was taken with a 50 mm lens at f/1.4, 1/60s, ISO 400, handheld, on a late afternoon illuminated only by window lighting. It is not posed. It is not tack sharp. But capturing this moment required a very fast lens.

How would you have taken this shot with your existing equipment? Would you pass up the opportunity? Would you turn on your flash? Would you drop the shutter speed to 1/10 second? Would you increase the ISO to 3200?

And most important -- is this simply a bad image with a very, very small DOF and thus is not worthy of printing or sharing.

[Quinn Porter]

and stop trying to harass more experienced photographers.

The intention is to be educated not to harass anybody :cry:

Sorry aam1234, I was a bit tired last night and lacking patience. There is another reason fast glass costs more. It is often better built. Take a look at the material and construction quality of Canon's L primes (which are usually faster) vs. the consumer line-up and you will see a big difference.

I agree with Timmy, you should think about buying a 50mm f/1.8 and giving it a shot. If you don't like it you can always sell it with just a minimal loss.

[aam1234]

Thank you guys, that was very informative.

Blair's work and maderito photo of his kid illustrate the point very well.

Thank you again.

[aam1234]

Sorry to revive this thread. Wasn't convinced at the 1st run, not even the second. Then I examined TQ's photo of the football player again...and knew what you guys are talking about.