Thank you, brad-man and infared, for the information.
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I used it several times in portrait shooting occasions and the images are visibly softer comparing it with the result from 85/1.4, 135/2, 200/2 (all at F 2.8 [I usually use F 2.0-2.8]), thus I asked the question, whether my copy of 100L is not under the average... (Other than portrait images with focus distance about 15-20 meters are quite OK.) (+ in direct comparison with Nikon 105 VR images taken with my 100L looks pretty softer too - especially till F4 of contrasty jewelry with small details...)Anybody here owning 100L and 135L?
Comparison of my copies make clear winner 135 @ F2.8. Do you have any opposite experience?
(Of course comparison is done on NON-macro shots...)
I have them both and love them both, but I don't think I've ever made a direct comparison (I probably have a slight bias in favor of the 135 but I'm not sure I have anything to back it up). In what way(s) do you think the 135 is the "clear winner"?
I meant the same framing, of course.Another example: shooting straight en face with 50/2.8 both eyes are sharp pretty the same, but shot with 300/2.8 = it is easy to say which eye was focused on.Sure it is, if you are shooting at the same distance - in that case, if the face fills the 300mm frame, it's only a small portion of the 50mm shot, and if it fills the 50mm frame then your 300mm shot is only showing the eyes (or would be, if you weren't closer than the MFD of the lens). But if you're 6 times further away at 300mm compared to 50mm, so the framing is the same, then the DoF is the same.It always has and always will be difficult to convince people that what they think they see is not in fact true (even with explanations and examples).Through the filter of our own misconceptions, everyone else's statements are part of the blurry background.
If you crop just the tower from both images, and view them at the same size on the screen, they will look identical. That means the blur is identical.Thx for the link - there is deep explanation we all agree with (I suppose).
Examples from http://toothwalker.org/optics/dof.html.
The car to the right of the subject has more blur with the 100mm lens than with the 28mm lens, right?
Wrong. Same blur. That's the case even in your extreme example.
I'm not saying it looks the same, the tower and car do look more blurred with the longer focal lengths. Like I said, it's good illusion.
You did the operation which affects DOF - you changed magnification - look at: http://en.wikipedia.org/wiki/Depth_of_fieldExactly. Your eyes are being fooled. The blur is the same. That it doesn't look that way is an illusion. But...it's a good illusion.I think that we need to define "background blur" now, because it does not look like the same COC at 200mm and 400mm.
And what about my extreme examples in the previous post? Do you still call it: "my eyes are fooled"?
Background blur is already well defined, you are not using it in its common context. As I said, the towers are both blurred exactly the same, below is an image where I have made the tower the same size from the 200 and 400 shots, they are exactly the same.
You are not referring to how blurred an object is, you are referring to how big objects at different distances are in relation to each other. That is perspective, not depth of field. For a same sized subject and aperture a longer lens shot from further away will give you a bigger apparent background object, hence the illusion of it being more blurred.
It is not confusion of those characteristics, but sum of all that make final subject isolation, which OP was asking about. There is only one place (distance from camera) which is in the perfect focus, all other things at other distances are blurred, but if you use longer focused distance or bigger F number or smaller FL the blur is smaller ~ even invisible on the final picture...No, look again, the actual blur of the tower is the same, BUT the tower is much bigger with the 400, you are looking at the effects of perspective in those shots NOT depth of field.Yes - the tower is bigger and blurred part is bigger too - thus better blur in my eyes.
In the extreme smallness, the tower will be one pixel width -> perfectly "in focus" = the worst background blur possible, for me...
Opposite extreme: the tower fills whole background = one gray color around the subject = the most blurred background (little boring thus I do not call this "the best" though still good example of the biggest isolation).
You're confusing what is in the background vs. how much that background is out of focus.
Exactly. Your eyes are being fooled. The blur is the same. That it doesn't look that way is an illusion. But...it's a good illusion.I think that we need to define "background blur" now, because it does not look like the same COC at 200mm and 400mm.
No, look again, the actual blur of the tower is the same, BUT the tower is much bigger with the 400, you are looking at the effects of perspective in those shots NOT depth of field.Yes - the tower is bigger and blurred part is bigger too - thus better blur in my eyes.
---CUT---The images of FL 200mm and 400mm in the link prove my point of view - blur of tower is much bigger at 400mm.
This means, as has been said, that 600 f4 has exactly the same dof as a 17mm @ f4 if the subject is the same size in both frames. The images look quite different, but that is because of perspective, this series of images might help. http://www.luminous-landscape.com/tutorials/dof2.shtml
Hmm, than the winner should be Sigma 200-500/2.8.My guess would be the EF-800mm F/5.6My too.
I use/d 85/1.4, 135/2, 200/2, 300/2.8 and the most blurred background I've got with longer FL.
FL does affect the isolation of the subject more than open [wide] aperture.
(Using the same framing of a human body / face.)
If the two of you are guessing based on the maximum physical size of the aperture, then the winner is actually the 600 f/4. The 400 f/2.8 and the 800 f/5.6 are tied for second.
800 / 5.6 = 142.857
600 / 4 = 150
400 / 2.8 = 142.857
If you're going off focal length, then the 600 with a 1.4x teleconverter would beat the 800 without one.
At the same time, there's really not any significant difference in actual aperture size between them, just a small fraction of a stop: stop the 600 down to f/4.5 (a third of a stop, one click of the wheel) and it's now got a 133mm physical aperture.
If you were trying to decide between the three, your decision should be made primarily on focal length needs and you shouldn't give any consideration to the physical aperture. Indeed, they might all actually be the same, what with rounding and all: 600 / 142.857 = 4.2, which is closer to f/4 than f/4.5.
I do not know math behind the scene, but you hardly find the real aperture size of any lens with selected F stop. Thus the real aperture size is not attribute I can use to choose lens to shoot with. I know subject isolation ~ DOF of my lenses and longer FL isolate the subject more than shorter; even if I need to step back to maintain the framing & prolong focus distance.My guess would be the EF-800mm F/5.6FL does affect the isolation of the subject more than open [wide] aperture.
Not quite. Contrary to popular opinion, Depth of Field is not affected by focal length only the physical size of the aperture (when maintaining subject height). To maintain subject height in the image the subject distance must be increased as you increase focal length (in other words, you have to step back when using a longer lens). Now, greater subject distance increases depth of field but a longer lens with the same f-number (eg. f/2.8 ) has a physically larger aperture which decreases depth of field. It turns out the the increase of DoF due to increases subject distance is almost exactly offset by the decrease in DoF due to the physically larger aperture with the result that focal length does not affect DoF.
My guess would be the EF-800mm F/5.6My too.
I guess you're talking about the 24-70F2.8L2 and the 70-200ISF2.8L2. Both are really excellent lenses with full frame and are complementary. Since your 50L1.2 covers the middle of the 24-70 focal range, you should get the 70-200. It is the best compromise. Of course if you have the money, you should get both and still keep the 50L2 for very low light or shallow dof work.+1
+1She's my fiance
You lucky Bastard...