If shooting at f/22, is a fast 1.8 lens still considered fast?

Started Apr 17, 2011 | Discussions thread
edwardaneal
Senior MemberPosts: 9,101Gear list
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so you finally admit you dont really know - - thank you
In reply to noirdesir, Apr 27, 2011

Okay - you want circumstantial evidence that Nikon does in fact use this type of sensor - how about the fact that in the scientific test I posted Nikon had higher low light accuracy with fast lenses than Canon did

If Canon were the only manufacture to have these special sensors wouldn't you expect it to give them the advantage with fast glass?

Canon doesn't really tout the fact they have these sensors, they only point out that they are only active when fast glass is mounted. Perhaps Nikons sensors are always active and they dont think it is a big deal

Fact is you have no clue if nikon camera can or cant take advantage of lenses faster than f/5.6 - you are only guessing - and you just admitted it

Finally - thank you

noirdesir wrote:

Two simple reasons:> - (1) Only Canon talks about these f/2.8 AF sensors, nobody else does. Why would Canon trumpet its advantage but no other camera maker does it? Canon very openly tells you which of their AF points get additional precision from f/2.8 lenses and which AF points do not. Following your logic that Nikon and Canon have the same technologies at their disposal, if Canon only adds these f/2.8 sensors to some of its AF points so would Nikon. And why would Nikon then withhold the information which AF points profit from f/2.8 lenses?

This is only circumstantial evidence but pretty strong one

  • (2) You can very simply test whether there are AF sensors for other apertures beyond the f/5.6 ones by adding a blocking ring at the exit of your lens that blocks the f/5.6 ring, as indicated in red in the image below. People have done this with Nikon bodies and the result was no AF action at all. If there were f/2.8 sensors, they would not be blocked and the AF system would be able to focus.

What you provide as evidence that faster lenses have faster and more precise AF is also only circumstantial evidence as it is comparing different lenses, not the same lens manually stopped down to either f/2.8 or f/5.6. And that AF motor speed and accuracy can vary a lot between different lenses is not exactly an unlikely idea, nor is the idea that different optical qualities (think of it in terms of SLRgear-type blur indices) can have an influence on AF accuracy and speed that far-fetched.

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My kit - D200, 10.5mm f/2.8D, 35mm f/1.8G, 50mm f/1.4G & 70-300VR
SB800, SB600 and other misc lighting equipment

Lenses worth mentioning owned and sold– 12-24 f/4, 17-55 f/2.8, 35-70 f/2.8, 80-200 f/2.8, 20mm f/2.8, 35mm f/2, 50mm f/1.8, 50mm f/1.4D, 60mm f/2.8D, 85mm f/1.8, 105mm f/2D-DC, 180mm f/2.8, 300mm f/4D-ED

 edwardaneal's gear list:edwardaneal's gear list
Sony Alpha NEX-7 Sigma 60mm F2.8 DN Carl Zeiss Touit 1.8/32
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