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Author Topic: IS substitute for faster glass in low light? Not convinced.  (Read 6700 times)

rocketdesigner

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Re: IS substitute for faster glass in low light? Not convinced.
« Reply #30 on: February 18, 2012, 10:50:09 AM »
Neuro, Mt Spokane et. al. where do you typically have sharpness set? Or do you sharpen in post?

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Re: IS substitute for faster glass in low light? Not convinced.
« Reply #30 on: February 18, 2012, 10:50:09 AM »

briansquibb

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Re: IS substitute for faster glass in low light? Not convinced.
« Reply #31 on: February 18, 2012, 11:06:14 AM »
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 :o :o :o

marekjoz

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Re: IS substitute for faster glass in low light? Not convinced.
« Reply #32 on: February 18, 2012, 11:18:39 AM »
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 :o :o :o

It might be true  if they would differ enough in their "T" values...
« Last Edit: February 18, 2012, 11:24:18 AM by marekjoz »
flickr | youtube | 5D2, 50 F/1.4, 24-105 F/4 L IS, 300 F/4 L IS, x1.4 II

Radiating

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Re: IS substitute for faster glass in low light? Not convinced.
« Reply #33 on: February 18, 2012, 11:45:02 AM »
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

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Re: IS substitute for faster glass in low light? Not convinced.
« Reply #34 on: February 18, 2012, 12:05:25 PM »
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

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Re: IS substitute for faster glass in low light? Not convinced.
« Reply #35 on: February 18, 2012, 01:15:04 PM »
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.
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neuroanatomist

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Re: IS substitute for faster glass in low light? Not convinced.
« Reply #36 on: February 18, 2012, 01:27:05 PM »
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 :o :o :o

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. 
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Re: IS substitute for faster glass in low light? Not convinced.
« Reply #36 on: February 18, 2012, 01:27:05 PM »

Mt Spokane Photography

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Re: IS substitute for faster glass in low light? Not convinced.
« Reply #37 on: February 18, 2012, 01:28:51 PM »
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

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Re: IS substitute for faster glass in low light? Not convinced.
« Reply #38 on: February 18, 2012, 02:10:04 PM »
Have you mis typed this - you seem to be saying that 2 lens at f/4 will have different shutter speeds :o :o :o

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.
5D mark 2, 16-35mm f/2.8, 17mm TS-E f/4, 85mm f/1.8, 300mm f/4 + 1.4x, 580 EX Flash

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Re: IS substitute for faster glass in low light? Not convinced.
« Reply #38 on: February 18, 2012, 02:10:04 PM »