Why can two 85mm lenses use different-sized lens hoods?
Asked 4/11/2012
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I compared the Nikon 85mm f/1.4G and 85mm f/1.4D and noticed that the newer lens hood looks noticeably larger. Since both lenses are the same focal length, I expected the hoods to be roughly the same size if they are meant to be equally effective. Why would two lenses with the same focal length have different hood sizes? Is it just the construction, or is there another reason?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
14y ago
2 Answers
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Two reasons. The method of attachment is different, which accounts for the difference at the rear. The old hood screwed on to the filter thread, while the new one bayonets to the outside of the lens (and is thus reversible for storage).
That leads directly to the second reason: the old hood had to accommodate for the possibility that filters would be attached between the lens and the hood, so it couldn't be as long as it might otherwise have been without causing vignetting. Once you allow for a worst-case, but normal, filter stack (a polarizer and a colour correction or ND filter), there isn't a whole lot of difference in length between the two. On the newer lens, the filter stack would form a separate system inside the hood rather than being part of the hood system.
Originally by user2719. Source · Licensed CC BY-SA 4.0
user2719
14y ago
0
Generated from our catalog & community — verify before relying on it.
Focal length alone doesn’t determine hood size. Hood design also depends on how the hood mounts and what it must clear without causing vignetting.
In this case, the older hood screws into the filter threads, so it has to allow room for filters that might be mounted between the lens and the hood. Because it must work even with a normal filter stack, it can’t extend as far as it otherwise could.
The newer hood bayonets to the outside of the lens barrel instead. That gives the designer more freedom: filters sit inside the hood system rather than between the lens and hood, so the hood can be made larger or longer while still avoiding vignetting. A bayonet hood is also often reversible for storage, which affects its shape and apparent size.
So the difference you see is real, and it’s mainly due to mounting method and filter clearance, not just focal length.
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