Is There Such Thing As a "Best" Normal Lens for Crop?
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pwp said:
Exactly! For a lot of things I use the 15-85 on my 7D because it has a very nice zoom range. There is a price to pay for every lens choice though. You'll have to weigh limiting factors such as aperture (e.g. the 15-85's widest aperture is f3.5 on the wide end) and optical aberrations (making corrections in pp can be cumbersome and time-consuming) against benefits like the versatility. In the end, what the "best" lens is for you depends on your specific needs and may vary with different situations.
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Going back to my photography school days almost 30 years ago. A "normal" lens is defined by the film size or sensor size. That is the diagonal of the sensor size in mm is equal to the "normal" lens size in mm.
Using the Pythagorean Theorem which is a square + b square = c square. Therefore the APS-C sensor on the 7D for example which is 22.3 mm x 14.9 would result in a normal lens of 26.82 mm.
A full frame sensor would have a "normal" lens of 43.27 mm.
Anything greater than the "normal" lens which is defined by the sensor size would be considered a telephoto lens and anything lesser than the "normal" lens would be considered a wide angle.
When I was using an 8x10 view camera in photography school, the normal lens for that camera was a 12.8 INCH lens or a 322 mm lens. I think the actual lens we used was a 300mm.
In theory a 26mm lens on an APS-C would give the same field of view as a 43mm on a full frame and the same field of view as a 322mm on an 8x10 view camera.
My Hasselblad used an 80mm as a normal lens.
Using the Pythagorean Theorem which is a square + b square = c square. Therefore the APS-C sensor on the 7D for example which is 22.3 mm x 14.9 would result in a normal lens of 26.82 mm.
A full frame sensor would have a "normal" lens of 43.27 mm.
Anything greater than the "normal" lens which is defined by the sensor size would be considered a telephoto lens and anything lesser than the "normal" lens would be considered a wide angle.
When I was using an 8x10 view camera in photography school, the normal lens for that camera was a 12.8 INCH lens or a 322 mm lens. I think the actual lens we used was a 300mm.
In theory a 26mm lens on an APS-C would give the same field of view as a 43mm on a full frame and the same field of view as a 322mm on an 8x10 view camera.
My Hasselblad used an 80mm as a normal lens.
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curtisnull said:
This is a rather dogmatic view of what "normal" means. "Normal" is supposed to mirror human's field of view, which is close to fisheye with terrible resolution off center, and long telephoto with good resolution. When comparing different aspect ratios, comparing the FL to horizontal or vertical size becomes inconvenient; then the diagonal is more convenient as some kind of average of the two. One can also take the square root of the area instead.
Once we decide that the we prefer the diagonal as a linear measure of the size of the film/sensor, then FL=diagonal is as "normal" as FL=1.12345*diagonal. Choosing it to be exactly equal to the diagonal sounds a bit mystical, so it must be right.
If you really want to know what "normal" means, this can only be determined with experiments with people. It is tricky because the AOV depends on the distance to the print, and the latter would depend on how large the print is, in a non-linear way.
Yes, I know what wikipedia says.
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Setting aside the question of a "normal" human field of view (I personally can't imagine a rectangular sensor producing anything like it), I've noticed that about 50mm on crop or 70mm on FF seems to match the magnification of my eye. In other words, if I look at an object with my naked eye and then through the viewfinder, it appears the same size in my field of vision. Does anyone know the correct term for this "normal" magnification concept?
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Loswr
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aroo said:
That's going to depend on the viewfinder magnification. For example, the 7D has a 1x magnificaiton, whereas the T5i/700D's VF mag is only 0.85x.
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Not going to get into the debate of what is "normal," but I'm very happy with the original 35mm 2 on crop. It's a nice compact lens with good IQ for the money.
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Loswr
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aroo said:
VF magnification determines how big something looks, but the sensor size is proportional to the field of view for a given focal length (although that's affected by viewfinder coverage...for example, the 7D has a 100% VF, you see everything the sensor sees, whereas the T5i has 95% coverage, meaning there are things at the very edge that you don't see in the VF, but that the sensor captures).
Take the example of a 100mm Macro lens shooting a coin at the minimum focus distance for the lens (i.e. 1:1 image magnification)
- Looking through a 7D, an Indian head gold dollar (a coin smaller than a dime) will appear life sized and just fill the VF
- Looking through a T5i, that same coin would appear smaller than life size (0.85x), and the stippled edges at the top and bottom would not be visible through the VF, although they would show up in a picture
- Looking through a 5DIII, that gold coin will appear much smaller than life size (0.71x), but you could put a Canadian quarter next to that little gold coin and still fit both in the frame
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Then what's the best "normal" prime/zoom combo?
For telephoto it's clearly the 100 2.0, 200 2.8 II and 100-400. :-*
:-*
For telephoto it's clearly the 100 2.0, 200 2.8 II and 100-400. :-*
:-*
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My favorite normal lens would be the Canon 28mm F1.8 USM. It's not as sharp as my 50mm but very near it in terms of sharpness. It's not too wide nor too tight for a crop. I've tried the almost similar Sigma 30mm F1.4 and don't like it that much. The Canon is simply smoother and focuses faster even in low light. I've used the 17-55 and 15-85 and found that I like both. They're just too expensive for me to invest something that I'll not use in the future (6D is coming)...
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The most versatile "normal" range crop lens is the 17-55. It's sharp and fast and minimizes the need for a flash.
My favorite "normal" range lens, crop or full frame, is the 40 f2.8 pancake. Technically, a tad long on crop (like a 64mm on FF), but it's fun to use. Sometimes, the limited, slightly tighter focal length can be liberating in a way. No time wasted at zooming for the best framing, you spend more time on you subject and framing with what you have. (Of course, if it's critical event to cover for someone else, then I use the 17-55 on crop.)
My favorite "normal" range lens, crop or full frame, is the 40 f2.8 pancake. Technically, a tad long on crop (like a 64mm on FF), but it's fun to use. Sometimes, the limited, slightly tighter focal length can be liberating in a way. No time wasted at zooming for the best framing, you spend more time on you subject and framing with what you have. (Of course, if it's critical event to cover for someone else, then I use the 17-55 on crop.)
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