M Vers wrote: Yohan Pamudji wrote: n0b0 wrote:
If I can MF the MP-E 65mm at 5:1 with the Rebel VF, I sure as hell can MF any lens with this 7D. You guys whinge too much.
Max aperture on the MP-E 65mm is f/2.8. Stock focusing screens can show accurate DOF for f/2.8. It\'s when you get to larger apertures that you start having problems. When an f/1.2 lens has DOF like an f/2.8 in the viewfinder, you\'re not sure if you\'ve nailed focus or not until you\'ve taken the shot.
Have you no experience with macro, let alone at 5x mag? If you did, you would understand that the DOF is literally razor thin even when stopped down. Remember, distance plays an enormous role pertaining to DOF, the closer you are to the subject the less perceived DOF.
Have you no experience manually focusing fast glass? If you did, you\'d understand what Yohan is talking about here. It has nothing to do with distance or DOF and everything to do with the fact that a stock focusing screen cannot accurately represent what is in focus when using lenses faster than f2.8. What looks to be in focus will not necessarily be in focus.
In other words, manually focusing the MP-E 65 with a stock screen at any magnification is doable because it is an f2.8 lens. The stock screen will be accurate enough because that is what it is designed for. For faster lenses it won\'t, regardless of focus distance or anything else. This is precisely why the type S screens are offered for other bodies. Hence, n0b0\'s statement is irrelevant. Being able to focus the MP-E 65 with a stock screen (regardless of magnification) does not mean he can easily focus faster glass on a stock screen (regardless of what camera he is using, the distance, the aperture, or anything else).
But ignorance is bliss, so if you want to go on believing that S type screens are unimportant, then by all means...
Sep 02, 2009 at 02:54 PM
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