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09/26/2006 05:49:09 PM · #1 |
I was reading a photozone.de review of this lens and found the statement:
"It is quite interesting to note that the lenses looses between 1.5 to 2 f-stops in speed when set to the min. focus distance. This is in line with other macro lenses featuring an internal focusing (IF) mechanism. The focal length will also be affected here (aka reduced)."
Does this mean that when you are at the closest focusing distance you will have to use a smaller aperture or it will be darker or what? |
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09/27/2006 10:19:47 PM · #2 |
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09/27/2006 10:31:17 PM · #3 |
I think my 105 macro nikon does the same. Although my lens is an f2.8, when I am focused on something "macro", I notice on the "detail" screen my appature says 3.4(ish) and I can't seem to get ti to say 2.8 at that distance.
I think it is just some kind of "closeup" limitation on those lenses.
This is just my opinion from experience...I could be wrong !
Kenskid
Originally posted by bfox2:
I was reading a photozone.de review of this lens and found the statement:
"It is quite interesting to note that the lenses looses between 1.5 to 2 f-stops in speed when set to the min. focus distance. This is in line with other macro lenses featuring an internal focusing (IF) mechanism. The focal length will also be affected here (aka reduced)."
Does this mean that when you are at the closest focusing distance you will have to use a smaller aperture or it will be darker or what? |
Message edited by author 2006-09-27 22:31:50.
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09/28/2006 12:00:07 AM · #4 |
| I guess thats fair. For macro would you generally be using a smaller aperture anyway to be sure of getting good DoF? |
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10/03/2006 10:07:31 AM · #5 |
If you are shooting a single lens or adding extension tubes, yes.
Probably wise to stop down a few stops... Not too far though... f/5.6 should be fine, or if you want lots of DOF, f/16 would be about as far as I would go. |
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10/03/2006 10:22:53 AM · #6 |
I've had this lens for a week now and love it. As has been said in this thread already, you will most likely be stopping down to gain DOF but if you do wish to get less DOF it should stay 2.8, 3.5 on occasion. If you want it, get it. You won't be sorry.
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10/03/2006 11:32:02 AM · #7 |
The optical design of a macro lens is an interesting thing. There are two different categories of lens design commonly in use:
- Standard (non-IF) design. Just moves the entire lens assembly further from the sensor to obtain near focus. It's like adding an adjustable extension tube to a 100mm prime. You *will* see a reduction in light as you focus very close, because the image being projected is growing and thus the same light is spread over a larger area. The lens is still technically f/2.8 because the aperture size and focal length have not changed, but the exposure *will* change.
- IF (Internal Focus) designs. Moves a group or groups of elements independently of the front element. In order to achieve near focus, the focal length of these lenses typically does decrease somewhat as you approach maximum magnification. The physical isze of the aperture does not change, and so with a reduced focal length the lens should be "faster", but this is more than offset by the loss from the additional magnification. the end result is a lens that still acts "slower" at maximum magnification, but not as much so as the standard design. Working distance will be a little shorter due to the reduced focal length. |
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10/04/2006 04:13:05 AM · #8 |
| It's not very often that in Macro you find yourself really needing a SHALLOWER depth of field... Usually with a 1:1 ratio, it's already getting pretty difficult to manage DOF. |
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