Why do you buy fast lenses/cameras?

Started 5 months ago | Polls
Lee Jay Forum Pro • Posts: 55,036
Why do you buy fast lenses/cameras?

No text.

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POLL
Mostly to get faster shutter speed and good image quality in low light.
44.4% 83  votes
Mostly to get better control over depth of field (shallower DOF).
15.5% 29  votes
About half-and-half, speed and DOF control.
32.6% 61  votes
Some other reason.
7.5% 14  votes
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Dennis Forum Pro • Posts: 19,247
Re: Why do you buy fast lenses/cameras?
6

I voted half and half, but it varies somewhat by lens ... with a wide/normal, I'm more interested in speed for low light than for shallow DOF. With a portrait lens, it's primarily for shallow DOF (I shoot casual candids where I'm not controlling the background). And with my 70-200, it's primarily for shutter speed, but I usually appreciate the shallow DOF.

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hotdog321
hotdog321 Forum Pro • Posts: 20,439
Re: Why do you buy fast lenses/cameras?
2

Thankfully, modern digital cameras have enabled the easy use of f/2.8 lenses in low light sports. During the film era I remember restricting myself to the brightest area of high school football fields or checking for burnt out lights in the ceiling of high school basketball gyms. For many years my "go-to" lens was a 50mm f/1.4 or 85mm f/1.8 lens for basketball to achieve marginal results. Phew! Digital allows us to use the "slower" and far more flexible f/2.8 zooms with much better results.

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Michael Fryd
Michael Fryd Forum Pro • Posts: 12,055
Re: Why do you buy fast lenses/cameras?
24

Don't forget:

  • Brighter Viewfinder 
  • More accurate auto focus
  • They tend to be sharper (a high quality f/2.8 lens is likely sharper at f/3.5 or f/5.6 then a lens with a maximum aperture of f/3.5).
  • The wider apertures tend to be bundled with other features (i.e better build quality, weatherproofing, better optical quality).
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Barry Twycross Senior Member • Posts: 1,764
Re: Why do you buy fast lenses/cameras?

As I said in a recent comment "I just like fast glass, and owning a 1.2 makes me feel good."

But low light performance is a good rational justification. The fast aperture allows for a shallow depth of field, should I want it, but I've found I often prefer a stopped down version if I have enough light.

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stevo23 Forum Pro • Posts: 22,907
Re: Why do you buy fast lenses/cameras?
3

Lee Jay wrote:

To go with my fast car.

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justinwonnacott Contributing Member • Posts: 938
Re: Why do you buy fast lenses/cameras?
1

Brighter viewfinder in a dslr easier to focus in low light. Otherwise I avoid paying a premium for them because of the usual performance loss wide open, large and heavy piece of expensive kit that costs too much. I like sharp images, not images with a tiny zone of sharpness. Extremely thin DOF is a fashion/fad of extremely limited use and I will not pay for that unless I have no choice.

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Reilly Diefenbach
Reilly Diefenbach Forum Pro • Posts: 13,518
Re: Why do you buy fast lenses/cameras?
11

Abstaining.  The absolute last thing I want on my camera is one of these two pound f1.4 monstrosities.   The world really doesn't need another one eyelash in focus blurry nose and ears masterpiece :^)

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tony field Forum Pro • Posts: 10,380
Re: Why do you buy fast lenses/cameras?
1

Michael Fryd wrote:

Don't forget:

  • Brighter Viewfinder
  • More accurate auto focus

If you are using a camera with a padf system, why would an F 1.4 lens provide more accuracy then an F 4 lens or F 2.8 ??

  • They tend to be sharper (a high quality f/2.8 lens is likely sharper at f/3.5 or f/5.6 then a lens with a maximum aperture of f/3.5).
  • The wider apertures tend to be bundled with other features (i.e better build quality, weatherproofing, better optical quality).
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Jonsi
Jonsi Veteran Member • Posts: 4,644
Re: Why do you buy fast lenses/cameras?

40% - better low light ability

15% - DOF control

45% - better quality glass

OP Lee Jay Forum Pro • Posts: 55,036
Re: Why do you buy fast lenses/cameras?

Jonsi wrote:

45% - better quality glass

This one isn't a given.  There are some outstanding slower lenses now.  For example, the Canon 70-200/4L IS II and the Canon 100-400L IS II are both excellent optically.  I bought the 70-200/2.8L IS II, but interestingly one of the two reasons is not even in my poll - compatibility with a 2x teleconverter.  The other reason is speed in low light.

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trungtran Contributing Member • Posts: 960
Re: Why do you buy fast lenses/cameras?

Interesting people buy faster lenses for the better IQ in low light.

If i want better IQ in the low light, i use a bigger sensor and a speed light.

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Barry Twycross Senior Member • Posts: 1,764
Re: Why do you buy fast lenses/cameras?
2

trungtran wrote:

Interesting people buy faster lenses for the better IQ in low light.

If i want better IQ in the low light, i use a bigger sensor and a speed light.

I don't want to carry a bigger sensor, and flash is taking a totally different picture.

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trungtran Contributing Member • Posts: 960
Re: Why do you buy fast lenses/cameras?
1

Barry Twycross wrote:

trungtran wrote:

Interesting people buy faster lenses for the better IQ in low light.

If i want better IQ in the low light, i use a bigger sensor and a speed light.

I don't want to carry a bigger sensor, and flash is taking a totally different picture.

Valid points.

I started with a 40D, acquired the Canon 28 1.8 lens because i was told it would improve my indoor shots.

Never really happy with that lens, especially shooting wide open. Picked up a flash and it made my photos so much better than just the lens.

There are ways to use a flash that can make images look natural. I agree it does change the look, but i take the IQ improvement if possible to use a flash.

Photography is changing, i think fast lenses will be less relevant in the future as sensor development and computational algorithms improve.

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Jonsi
Jonsi Veteran Member • Posts: 4,644
Re: Why do you buy fast lenses/cameras?

trungtran wrote:

Interesting people buy faster lenses for the better IQ in low light.

Generally better IQ in all light.

If i want better IQ in the low light, i use a bigger sensor and a speed light.

So you go from a full frame sensor up to what?

And why would you use a speedlight if a larger aperture would do the job in natural light ?!

tko Forum Pro • Posts: 12,966
nope
4

trungtran wrote:

If i want better IQ in the low light, i use a bigger sensor

Bigger sensor don't gather more light, but bigger lenses do.

and a speed light.

If you like the deer in the headlight look, with everything in the foreground overexposed and the background dark. Good luck lighting up a building, a dark alley, or even a simple vacation shot.

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Michael Fryd
Michael Fryd Forum Pro • Posts: 12,055
Re: Why do you buy fast lenses/cameras?
4

tony field wrote:

Michael Fryd wrote:

Don't forget:

  • Brighter Viewfinder
  • More accurate auto focus

If you are using a camera with a padf system, why would an F 1.4 lens provide more accuracy then an F 4 lens or F 2.8 ??

Take the Canon 5D 4 for instance. There are 61 Autofocus points, but not all are created equal. Each point has from one to four PDAF sensors in various orientations; horizontal, vertical, right diagonal, and left diagonal.

Some of the sensors work with lenses that's f/8 or faster, some work with lenses that are f/5.6 or faster.

A few of them are slightly higher precision, but only work with lenses that are f/4 or faster.

Five AF points near the center offer the highest precision, but only work with lenses f/2.8 or faster.

Take the center AF point. With an f/8 lens the horizontal and vertical PDAF sensor will do a good job with most lenses. However, the right and left diagonal sensors can provide higher precision results with lenses faster than f/2.8.

As the camera focuses with the lens wide open, you get the benefits of the high precision focus points with an f/2.8 lens, even if you are shooting at f/8.

Thus the f/2.8 version of the 70-200 lens may yield more accurate focus than the f/4 version, even if you are shooting at f/4 or slower.

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Michael Fryd
Michael Fryd Forum Pro • Posts: 12,055
Re: nope

tko wrote:

trungtran wrote:

If i want better IQ in the low light, i use a bigger sensor

Bigger sensor don't gather more light, but bigger lenses do.

In terms of the lens, the angle of view and aperture diameter are the two main factors in how much light you gather.   Generally, for a given angle of view, it's easier to find a lens with a large aperture for larger sensor cameras.

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trungtran Contributing Member • Posts: 960
Re: Why do you buy fast lenses/cameras?

Jonsi wrote:

trungtran wrote:

Interesting people buy faster lenses for the better IQ in low light.

Generally better IQ in all light.

I agree faster lens have generally better optics but i have a have 35F2 Yongnuo which although decent has a lot to be desired at F2.

If i want better IQ in the low light, i use a bigger sensor and a speed light.

So you go from a full frame sensor up to what?

I don't know?  ! started with a compact but im at FF. Every generation of FF is improving.

Maybe i get a ginormous speed light.

And why would you use a speedlight if a larger aperture would do the job in natural light ?!

Honestly i rarely shoot below F2.8.

I photography people singles and groups. I don't like the one person in focus and the other person not. If i don't have a speedlight or can't use it then sure i use the faster aperture, but i rather just use my zoom and have most people in focus.

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OP Lee Jay Forum Pro • Posts: 55,036
Re: nope

Michael Fryd wrote:

tko wrote:

trungtran wrote:

If i want better IQ in the low light, i use a bigger sensor

Bigger sensor don't gather more light, but bigger lenses do.

In terms of the lens, the angle of view and aperture diameter are the two main factors in how much light you gather. Generally, for a given angle of view, it's easier to find a lens with a large aperture for larger sensor cameras.

Correct, and the reason for that is larger sensors require longer focal length for the same angle of view, and longer focal length means slower f-stop for the same aperture diameter.  Slower f-stops are easy to design and correct, with the limiting factor the fact that you can't scale the refractive index of glass.

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Lee Jay

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