I know that my Nikon lens takes a 52mm filter size, however I also have two other lenses but they are Sigma lenses and don't have the mark to find the size for filters. How do I find the filter size for my Sigma lenses?
There is always a specification. You will find it in three places:
- On the lens, either at the edge around the front optical element or on the side of the barrel.
- In the manual that came with your lens.
- On the web. Here is one on Sigma's site. Click Tech Specs to see the table where it says Filter-Size.
There will be many numbers on the lens itself but you can almost always guess which one is the filter-size because it corresponds to the diameter of the filter-thread.
Filtering just means changing something. Polarizing is one type of filter which only lets light through with a certain polarization. There are many other types of filters too.
I believe that the easiest way to find out the filter size of a lens is to look at the lens cap. Pretty much the only information that you would find on the cap is who made it and the filter size that it fits. (Provided of course that it's the type of lens cap that attaches to the filter thread.)
The lens cap from my Sigma 50-500 lens for example has this information:
- LCF-86 II
- 86 mm
- Made in Japan
From that you can easily see that the filter size is 86 mm.
Polarizing is one form of filtering. So the difference is that polarization is a specific way of altering the incoming light, while filtering includes many different ways of altering the incoming light. Besides polarization filters there are for example color filters, neutral density filters and effect filters.