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<blockquote data-quote="Texas" data-source="post: 668796" data-attributes="member: 42267">What irks me is the F stop numbers are on all lenses and I assume them to be mostly believable.&nbsp; Even zooms that have an F stop range that changes with a particular zoomed focal length print the range on the lens.But macro lenses, that's another story.&nbsp; Their printed and spec'ed F stop is measured at infinity focus and is way off for any close focusing.&nbsp; Well probably not off at all based on how the max advertised F stop is calculated.&nbsp; But you do need more iso or more light to get the same exposure when you close focus.Many zooms have a much different than advertised focal length when focused closely.I'm supposing that a fixed focal length macro lens keeps its advertised focal length when close focusing, but could be wrong.Of course this is nit-picking, they all have excellent photo capability.</blockquote>

[QUOTE="Texas, post: 668796, member: 42267"] What irks me is the F stop numbers are on all lenses and I assume them to be mostly believable. Even zooms that have an F stop range that changes with a particular zoomed focal length print the range on the lens. But macro lenses, that's another story. Their printed and spec'ed F stop is measured at infinity focus and is way off for any close focusing. Well probably not off at all based on how the max advertised F stop is calculated. But you do need more iso or more light to get the same exposure when you close focus. Many zooms have a much different than advertised focal length when focused closely. I'm supposing that a fixed focal length macro lens keeps its advertised focal length when close focusing, but could be wrong. Of course this is nit-picking, they all have excellent photo capability. [/QUOTE]

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