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01/06/2008 06:40:27 AM · #1 |
HI,
I have a sigma 12-24mm for my 5D. At the rear of the lens is a slot for gel filters. Has anyone ever managed to but a Gradient Filter for this lens or now of where to get filters and cut them down?
Thanks
Tim |
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01/06/2008 07:52:52 AM · #2 |
| Outta my league, but I found this on the Canon Forums . |
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01/06/2008 09:08:35 AM · #3 |
I haven't used that specific lens, but have used many that take rear filters including the Sigma 14mm. I often use infrared gels, and before digital, color correction gels.
There is practically no way to use a rear gradient filter for three reasons. One is the area the gradient takes to take from light to dark would be too great an area for it to do much good on the much smaller rear elements, as they are designed for in front of the lens. Two you would have to make a gel for every f-stop and change them out every time you changed the aperture since the horizon line would move with aperture changes. Third, besides the variation in f-stop you would also need to make many different gels for different compositions, cause you would hate to put the horizon in the center every time.
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01/06/2008 11:06:55 AM · #4 |
thanks fot the advice. Thought that the use of a gradient filter at the rear would cause too many problems...
Tim
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01/06/2008 11:26:42 AM · #5 |
The cokin system may work on the longer side of that lens. And they make larger gel filter holders, so if you are really determined to use a gel, you can.
If you don't need to meet DPC rules, I recommend bracketing and either using HDR techniques or using layer masks to simulate a gradient filter. |
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01/06/2008 01:28:18 PM · #6 |
Originally posted by hankk:
The cokin system may work on the longer side of that lens. And they make larger gel filter holders, so if you are really determined to use a gel, you can.
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Most of Sigma's lens hoods for its extreme wide-angles are two-piece units that have filter threads which allow the use of filters
and If you were using a APS size sensor you would be correct, but not on the 5D'd full frame.
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01/06/2008 01:35:22 PM · #7 |
| I've been looking at gradient filters for a wide angle... And my research showed up probably getting a Lee filter holder and then either buying the (expensive but top notch Lee filters) or getting the relevant cokin filters. That would be using the widest setting on the Lee filter possible and the biggest filter you can get to avoid vignetting - i think the Lee's can put "wings" on the holders to give you the use of a big filter which will make sure you dont get vignetting caused by the filter holder at extreme angles. Whole set-up is around the £100 mark for me, so i am waiting for a bit until i try it out. |
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