IS substitute for faster glass in low light? Not convinced.

[rocketdesigner]

Neuro, Mt Spokane et. al. where do you typically have sharpness set? Or do you sharpen in post?

[briansquibb]

And then there is the 24-105 f/4 IS that will require a slow shutter speed to gather enough light at f/4, where the 50mm f/1.2 set at f/4 will still be able to use a quicker shutter speed to stop the subject motion.  If there is no subject motion, then it doesn't matter much if you can hold the camera steady or have a tripod.

Have you mis typed this - you seem to be saying that 2 lens at f/4 will have different shutter speeds

[marekjoz]

And then there is the 24-105 f/4 IS that will require a slow shutter speed to gather enough light at f/4, where the 50mm f/1.2 set at f/4 will still be able to use a quicker shutter speed to stop the subject motion.  If there is no subject motion, then it doesn't matter much if you can hold the camera steady or have a tripod.

Have you mis typed this - you seem to be saying that 2 lens at f/4 will have different shutter speeds

It might be true  if they would differ enough in their "T" values...

[Radiating]

IS vs faster glass has many variables.

First off with high megapixel cameras it helps them acheive a sharper image by default, to the equivalent of shooting at 1/focal length x 2. Second most manufacturers exagerate when they say it's 4 stops of light, maybe in some situations, but really it's really more like 3-3.5.

So at 70mm without IS your minimum shutter speed will be 1/140th to get a tack sharp image, but your minimum shutter speed is only 1/17 at 70mm with IS for tack sharp images. As you can see this tends to lend itself more to subjects that aren't moving much.


Hope that helps.

[briansquibb]

IS vs faster glass has many variables.

First off with high megapixel cameras it helps them acheive a sharper image by default, to the equivalent of shooting at 1/focal length x 2. Second most manufacturers exagerate when they say it's 4 stops of light, maybe in some situations, but really it's really more like 3-3.5.

So at 70mm without IS your minimum shutter speed will be 1/140th to get a tack sharp image, but your minimum shutter speed is only 1/17 at 70mm with IS for tack sharp images. As you can see this tends to lend itself more to subjects that aren't moving much.


Hope that helps.

Once you get to 1/17? shutter speed you will start to incur handshake induced motion blur - even if the subject is stationary.

[neuroanatomist]

Neuro, Mt Spokane et. al. where do you typically have sharpness set? Or do you sharpen in post?

I shoot RAW, and I usually use the default setting for sharpness in DxO Optics Pro, unless the shot needs more or less sharpening.

[neuroanatomist]

And then there is the 24-105 f/4 IS that will require a slow shutter speed to gather enough light at f/4, where the 50mm f/1.2 set at f/4 will still be able to use a quicker shutter speed to stop the subject motion.  If there is no subject motion, then it doesn't matter much if you can hold the camera steady or have a tripod.

Have you mis typed this - you seem to be saying that 2 lens at f/4 will have different shutter speeds

They'll probably have the same shutter speed as metered (at least, that's the case for my 85/1.2L II vs. 24-105mm), but the image from the f/1.2 lens will actually be a little brighter.  The difference is about 1/3 stop, nothing I'd consider a significant benefit in terms of stopping subject motion. 

[Mt Spokane Photography]

Neuro, Mt Spokane et. al. where do you typically have sharpness set? Or do you sharpen in post?

I use Raw, setting sharpening in Camera is only for jpegs.

I have a different default sharpening and NR set for each ISO in Lightroom, so its set automatically on import.  Most raw images benefit from a little sharpening, LR 4 lets you sharpen selectively only the areas that need it, like hair.  That must be done manually with the brush function.

[Caps18]

Have you mis typed this - you seem to be saying that 2 lens at f/4 will have different shutter speeds

I tested it out, and my assumption was incorrect. 

At least in daylight photos, both my 16-35mm (@17mm) and 17mm TS-E at f/4 and ISO100 needed a 1/125sec shutter speed to get the exposure meter to come out the same.  In very low light, I still thought I saw a difference between different lenses when using the same ISO and f-stops.

I did do one test in December that I should upload the pictures that showed the sharpness difference that you get by stepping down a 50mm f/1.2 lens in low light compared to 50mm lens with a slower f-stop rating.

And with the faster glass, you still have the option to drop the aperture in order to raise the shutter speed at the cost of depth of field.