Do we still "need" fast lenses ?

Started 6 months ago | Discussions thread
JimKasson
JimKasson Forum Pro • Posts: 24,260
Re: Do we still "need" fast lenses ?

nigelht wrote:

JimKasson wrote:

nigelht wrote:

vyoufinder wrote:

primeshooter wrote:

vyoufinder wrote:

primeshooter wrote:

vyoufinder wrote:

You pretty much nailed it. The only real reason for fast lenses nowadays is bokeh isolation. A secondary reason could be for opening up brighter on dSLR's to help see. For any other purpose, you generally get better image quality with a slower lens which has fewer/thinner glass elements inside.

And when you are shooting a moving subject in lower light and are unable to use flash, sports, wedding...please explain how a slow aperture and vr would help and why "they are just for bokeh".

Not the same picture. I would not adjust my aperture based on the amount of light, I'd adjust my ISO or film speed. Adjusting aperture is more like a desperate measure to get something at all, but isn't the same as having a subject entirely in focus. It's kind of the point of the OP is that there is no need to get desperate with opening up beyond what you want to with a modern camera.

The ability to open up and isolate something is a great tool, but it's not for every picture and is not the only reason for a full frame camera.

Raising iso lowers IQ much faster than my idea.

Your idea doesn't produce the same image. It's irrelevant. IF it were relevant, I would also argure that, no, it doesn't. The difference between f1.2 and f4 is as different as apples and oranges whereas iso 100 vs. iso 1200 is almost unnoticeable. I'll re-iterate though, it's not a matter of image quality, it's a matter of a different image entirely. One has depth of field and sharp focus while the other will not.

Right. You're going to shoot ISO 100, 1/1000, f4 in poorly lit high school gyms when folks are shooting ISO 6400, 1/500, f2.8 in the same conditions.

These numbers don’t make sense to me. What is your point here?

The point is that he would be shooting terribly underexposed in the lighting conditions often encountered by sports shooters.

The fallacy that everyone has the option of starting at ISO 100 is common in these kinds of threads.

Just start at ISO 100 and push three stops. See! There's zero impact on IQ! There's no need for fast lenses! Modern sensors are ISOless!

But with the example you used, there was only a one-stop difference between the lenses, yet a huge difference in the ISO setting. What's that about?

primeshooters question was:

And when you are shooting a moving subject in lower light and are unable to use flash, sports, wedding...please explain how a slow aperture and vr would help and why "they are just for bokeh"

The tediously narrow minded "I only care about how I shoot" answer was:

I'd adjust my ISO

Okay, how much of that do you want to do when starting at ISO 6400?

None if you can help it. Hence fast lenses.

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