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11/20/2007 05:11:51 AM · #1 |
I have been reading up on extension tubes. Everywhere says that the downside is light loss and so either a longer shutter speed or larger apature are required. I have not been able to find out by how much the light is lost and the exact modifications to exposure settings are required per millimeter of extension for instance. Does anyone know of any guides, tutorials, calculations etc... that can shed some light on this.
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11/20/2007 07:47:57 AM · #2 |
i'd be interested to know the answer too. I've read about it. But bottom line I bought some and used them. As I use them with my 85mm 1.8, I can compensate with aperture. And actually, have found little practical issue even with full extension (I have a set of 3 extenders).
here's a test shot done with extenders
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11/20/2007 08:41:49 AM · #3 |
About halfway down the page here is a formula, although I'm not sure that the equation is stated correctly (I think it should be {FL/L}/2 ). I was looking at this just the other day, coincidentally.
Message edited by author 2007-11-20 08:46:50.
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11/20/2007 09:18:36 AM · #4 |
Good article here at macrophotography.org
R.
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11/20/2007 09:30:18 AM · #5 |
I use extension tubes a lot. I don't have the answer you need, but I don't think it matters. Bottom line is you're going to need an external flash. You can't compensate for light loss with aperature because you need all the depth of field you can get.
Message edited by author 2007-11-20 09:30:37. |
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11/20/2007 09:32:58 AM · #6 |
Originally posted by hopper:
I use extension tubes a lot. I don't have the answer you need, but I don't think it matters. Bottom line is you're going to need an external flash. You can't compensate for light loss with aperture because you need all the depth of field you can get. |
It still matters for CALCULATING the compensation, unless you have the expensive tubes that allow the camera to link its electronics up...
R.
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11/20/2007 10:04:39 AM · #7 |
I guess I'm just curious why you'd want to do that. A simple glance at the camera will tell you if the exposure is off. It doesnt seem to be a necessary calculation to me.
edit to add: I've never heard or read anyone say that light loss is a downside to using extension tubes because even the cheapest of flashes will easily compensate for the light loss using a tube. And 9 times out of 10, you're going to need a flash for any kind of macro work ... tubes or not.
Originally posted by Bear_Music:
Originally posted by hopper:
I use extension tubes a lot. I don't have the answer you need, but I don't think it matters. Bottom line is you're going to need an external flash. You can't compensate for light loss with aperture because you need all the depth of field you can get. |
It still matters for CALCULATING the compensation, unless you have the expensive tubes that allow the camera to link its electronics up...
R. |
Message edited by author 2007-11-20 10:07:40. |
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11/20/2007 10:26:27 AM · #8 |
Originally posted by hopper:
I guess I'm just curious why you'd want to do that. A simple glance at the camera will tell you if the exposure is off. It doesnt seem to be a necessary calculation to me.
edit to add: I've never heard or read anyone say that light loss is a downside to using extension tubes because even the cheapest of flashes will easily compensate for the light loss using a tube. And 9 times out of 10, you're going to need a flash for any kind of macro work ... tubes or not.
Originally posted by Bear_Music:
Originally posted by hopper:
I use extension tubes a lot. I don't have the answer you need, but I don't think it matters. Bottom line is you're going to need an external flash. You can't compensate for light loss with aperture because you need all the depth of field you can get. |
It still matters for CALCULATING the compensation, unless you have the expensive tubes that allow the camera to link its electronics up...
R. |
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Does your camera have a built in flashmeter?
The camera will compensate if you're using E-TTL or some other auto mode, but if you're shooting with manual flash and using a meter, you will need to know how many stops to tweak your exposure due to the extension.
Message edited by author 2007-11-20 10:29:53. |
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