Originally posted by que es tu Well, I finally got around to testing this, and here is what I found out: the 55-300 f4-5.8 @ 300mm with the Canon 500D closeup filter at MFD shows 25mm
I also now have a DFA 100mm macro, and that lens shows just over 23mm. Pentax says the sensor is 23.5 mm wide, so that should be perfect.
Just for fun, I put the closeup filter on the macro lens and got 18.5mm. So, 5% above life sized??
I suppose the 55-300 gives just under life size with the close up filter which is good enough for me!! Thank you for your help!!
Let me give you some caveats:
1) Achromatic lenses generally work better at modest focal length. The best IQ with a 55~300mm + 500D* will probably be in the 75~200mm range
2) At about 1/4 life-size the depth of field starts to get really, really shallow. Focus is critical (move the entire camera + lens, the focusing ring and AF will not be useful)
3) Also at about 1/4 life-size, camera shake becomes a major issue. At that magnification it's like trying to hand-hold a 500mm lens @ 1/60 0f a second
At about 1/4 life-size and greater magnification it's best to use a tripod and/or a strobe, otherwise too many images will fall short because the focus wasn't right or because of blur caused by camera shake. A tiny breeze in the field, trying to photograph an insect at say 1/3 life size, will throw your subject far out of focus, blur it badly, and even push the subject completely out of framing. If you do macro in the range of 1/4 life-size and greater magnification, you need different technique and a high tolerance for images that don't turn out as hoped or expected.
* Canon's "500D" designation is supposed to indicate that when attached to any lens that is focused @ infinity, the 500D will bring the focus distance down to 500mm (= 0.5m). The Canon 250D brings to focus distance down to 250mm (= 0.25m). This applies to any lens, any focal length, prime or zoom, when the lens is set to infinity.
Last edited by WPRESTO; 05-09-2022 at 12:56 PM.