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| p.3 #1 · ROKKOR Wide/UlW Image Thread |
Yes, due to refraction of the glass, also the thickness is a factor (thicker = puts focus point more rearward) essentially a "slowing" of the light, puts the focus at a different place than it would be otherwise. it only applies to filters at the back (or middle) of the lens, not the front. There's an optical formula that allows calculation of it but I don't have it offhand. It's why sometimes you see "thick" elements that could otherwise not have so much glass "doing nothing" in the middle of the element. It's done to move the image back, mostly seen in retrofocus lenses.