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10/19/2010 08:27:13 AM · #1 |
Hello guys,
I'm an amateur photographer and always loved Macro shooting. I bought recently a Canon EF 100mm f/2.8 Macro and was taking some pictures using my tripod. The point is that I can't focus properly if I angle the camera close to 60º degrees.
Is that a normal behavior on the lens?
Thanks in advanced,
c0rreia |
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10/19/2010 08:30:44 AM · #2 |
The focal plane at 100 mm and f/2.8 is VERY THIN. You do have focus, you're just not used to the change in the focal plane.
Here are some I took with the 60 mm and f/2.8. You can easily see how small the focal plane is. At 100 mm, its going to be even smaller.
  
When you shoot at an angle, you have a lot more coming at you and away from you than if you were normal to the plane. General rule of thumb for macro photography is to focus 1/4 of the way in to your subject for the proper DOF positioning as opposed to 1/3 for normal lenses.
Message edited by author 2010-10-19 08:34:16. |
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10/19/2010 08:32:31 AM · #3 |
I haven't noticed any problems like you mention, but the in-focus area is indeed very thin.
I usually use the autofocus once, and then either use manual focus or move the camera closer/further away to focus. |
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10/19/2010 08:38:42 AM · #4 |
Thanks for the replies!
By shooting with the camera in a 180º degrees angle I have perfect focus indeed. What troubles me still shooting with the camera in certain angle, it won't focus manually or automatically.
PGerst, awesome macros, congratulations! :) |
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10/19/2010 08:53:03 AM · #5 |
Originally posted by c0rreia:
By shooting with the camera in a 180º degrees angle I have perfect focus indeed. What troubles me still shooting with the camera in certain angle, it won't focus manually or automatically. |
Maybe you are too close?
Turn autofocus off, set the distance to 30 cm on the dial on the lens (that counts from the back of the camera (the sensor, to be exact) to the object). If you have the lens hood on, that's only a few centimeters from the lens hood. Then look through the view finder and move the camera back and forth - you should be able to see the in focus area wander back and forth as you move the camera, no matter the angle to your object.
Maybe you can post a shot to clarify what your problem is exactly. |
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10/19/2010 08:57:56 AM · #6 |
Thanks. Though, I posted the "bad" ones to show you the angle. I have others in my profile such as this one:
You will have problems at 180° because at that angle your subject is in the plane and can easily be passed.
I'd send you a DOF calculator but the ones I've seen online are useless because the plane is so thin that it is below the rounding resolution of most online calculators. Plus, those are more designed for normal lenses.
Oh, I have found that auto focusing is useless in macro photography because the focal plane moves so quickly, especially if you are hand holding the camera or its a windy day (as in my grasshopper photo).
Originally posted by c0rreia:
By shooting with the camera in a 180º degrees angle I have perfect focus indeed. What troubles me still shooting with the camera in certain angle, it won't focus manually or automatically.
PGerst, awesome macros, congratulations! :) |
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10/19/2010 09:45:37 AM · #7 |
Some of the macro shots that you will see are composites of several images that have been "focus stacked" using processing software like Photoshop.
It's a technique where a group of images of the exact same scene are shot with each one having a slightly different focus point, and then they are layered, and the area best in focus of each image is combined with that of the others for a finished product.
If you are trying to use autofocus on something linear, and shooting it at an angle, the camera does not know what part of it you are wanting to focus on. The best way to focus when shooting macro is to manually focus the lens to the magnification that you want, or "frame" the shot, then move the camera in and out to get focus on the desired point. The closer you focus, the narrower the focus plane will be.
Another difference between most true "macro" lenses and normal lenses is that the macro lenses focus in a flat plane, like a sheet of paper, but a normal lens focuses in a curved plane, like the inside of a ball, which is the reason that you can get focus edge to edge when shooting at 90 deg to a flat subject using a macro lens.
You can clearly see the "plane of focus" as a line across the banana leaf in this shot, done with a 105mm macro lens.
If the fly had been at an angle or head on, then only a thin slice of the fly would be in focus.
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10/19/2010 09:52:31 AM · #8 |
send a pm to  Roz she can prob tell you everything you need to know about shooting with that lens |
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10/19/2010 05:00:01 PM · #9 |
Just some tips. Manual focus for any macro work. Use a solid tripod and shutter release, with mirror in the locked position. If your hand holding the camera, set focus and just move your body back and forth. Just keep those shutter speeds high enough, to freeze the scene. It seems the Canon 100mm macro, performs best at an f stop around f11. This will give you the best sharpness, out of that lens.
Your going to love this lens. Once you get the hang of it, it's a great tool! Good Luck!
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10/19/2010 05:19:07 PM · #10 |
Originally posted by PGerst:
Here are some I took with the 60 mm and f/2.8. You can easily see how small the focal plane is. At 100 mm, its going to be even smaller. |
No it's not. DOF at macro distances is dependent on reproduction ratio, not focal length. At 1:1, at identical physical apertures, the DOF will be identical.
R. |
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10/19/2010 05:40:57 PM · #11 |
I shoot all macro by hand, no tripod. I also set the camera, on a Nikon in continuous focus, I guess Canon is AI servo?? f11/16 will give a good DOF and if on P or A will give pretty good results.
ETA: As a old codger, continuous focus allows for the shakes:)
Message edited by author 2010-10-19 17:42:17. |
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10/19/2010 06:26:00 PM · #12 |
Thanks for correcting me. I did make the assumption, forgetting about the magnification. D'Oh. :)
Originally posted by Bear_Music:
No it's not. DOF at macro distances is dependent on reproduction ratio, not focal length. At 1:1, at identical physical apertures, the DOF will be identical.
R. |
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10/20/2010 12:40:57 AM · #13 |
Originally posted by PGerst:
Thanks for correcting me. I did make the assumption, forgetting about the magnification. D'Oh. :)
Originally posted by Bear_Music:
No it's not. DOF at macro distances is dependent on reproduction ratio, not focal length. At 1:1, at identical physical apertures, the DOF will be identical.
R. |
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Robert, can you elaborate on the "identical physical" apertures? Do you mean an actual aperture opening of 10mm in a 50 mm lens gives the same DOF as an aperture opening of 20mm in a 100mm lens if the magnification of the subject is the same, say for instance 1.5/1 in both cases?
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