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01/20/2007 01:54:44 PM · #1 |
I have the Sigma 70-300 APO DG Macro lens and have been plating around with it in macro mode lately. One thng I notice is that when it is in Macro mode it seems to ignore my apature setting. The below image was taken with an apature setting of f/29 but clearly this is not the case.
When I look at it in Raw Shooter it has the following information:
190mm (70-300mm f/4.5), f29.0, 1/5 sec., ISO 400
Normally there are not two f/ values listed, only in macro mode. Does anyone understand this behaviour?
EDIT: correct typo
Message edited by author 2007-01-20 14:00:40.
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01/20/2007 01:57:26 PM · #2 |
Why do you say "this is clearly not the case"? I don't see anything in the image that even HINTS it was shot at f/4.5, but in the EXIF data I see 1.5 seconds at ISO 400, which is a LONG exposure in any reasonably bright light and suggests that indeed you had f/29...
R.
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01/20/2007 02:00:13 PM · #3 |
At f/29 I would have expected the whole of the image to be in focus but if you look to the right it gets quite OOF. The subject was at an angle so that the left side ia about 1 inch forward of the right side. Given f/29 I shouldnt have this OOF effect I'd have thought?
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01/20/2007 02:01:01 PM · #4 |
Originally posted by Bear_Music:
Why do you say "this is clearly not the case"? I don't see anything in the image that even HINTS it was shot at f/4.5, but in the EXIF data I see 1.5 seconds at ISO 400, which is a LONG exposure in any reasonably bright light and suggests that indeed you had f/29...
R. |
And I had a typo, it was 1/5 sec, not 1.5 seconds ;)
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01/20/2007 02:06:09 PM · #5 |
Originally posted by Nuzzer:
At f/29 I would have expected the whole of the image to be in focus but if you look to the right it gets quite OOF. The subject was at an angle so that the left side ia about 1 inch forward of the right side. Given f/29 I shouldnt have this OOF effect I'd have thought? |
You'd be thinking wrong. At 1:1 magnification at f:32 your DOF is still negligible. Seriously. I can't even find an online DOF calculator that measures such small increments :-) You're talking fractions of an inch at 1:1 magnification. ANY noticeable deviation of the subject from a plane perpendicular to the lens axis is going to produce some OOF blur no matter how far you stop down, basically.
R.
Message edited by author 2007-01-20 14:07:14.
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01/20/2007 07:48:59 PM · #6 |
Originally posted by Bear_Music:
Originally posted by Nuzzer:
At f/29 I would have expected the whole of the image to be in focus but if you look to the right it gets quite OOF. The subject was at an angle so that the left side ia about 1 inch forward of the right side. Given f/29 I shouldnt have this OOF effect I'd have thought? |
You'd be thinking wrong. At 1:1 magnification at f:32 your DOF is still negligible. Seriously. I can't even find an online DOF calculator that measures such small increments :-) You're talking fractions of an inch at 1:1 magnification. ANY noticeable deviation of the subject from a plane perpendicular to the lens axis is going to produce some OOF blur no matter how far you stop down, basically.
R. |
OK, thanks. I'm just starting to play with the macro mode so no doubt I'll make a few more incorrect assumptions along the way. Thanks for clearing that up.
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