To step up or not to step up, that is the question?

[Jayson]

Ok, I am not sure if I am going to get a larger mm threaded lens that I will use a polarizer with, but wanted to know your opinions on getting a polarizer.


I am buying a B+W CPL and didn't know if I should just get it in the size of 67mm as with my Tamron and 70-200, or should I get the 77mm one and then just buy a step up ring? If I buy the 77mm one, does it make a difference if I buy a Kenko or B+W step up ring. My UV filters are already B+W.


Thanks,


Jayson

[neuroanatomist]

Hi Jayson,


Good quality CPLs are pretty expensive, and obviously the cost goes up proportionately with the diameter. The usual recommendation is to get one appropriate for the largest diameter lens you have, then use step up rings. There's no direct optical penalty for using a filter that's larger than your lens. There is a potential indirect optical downside in that alarger diameter filter with step-up ring may prevent you from mounting the lens hood with the filter in place, so there's a greater risk of flare. It might not be a big deal with the CPL, since in some cases (e.g., with deep round hoods as on f/4 tele-zooms), you can't reach into the hood to turn the CPL, so you'd remove/reverse the hood anyway.


So, if you know you'll be getting a lens with a 77mm filter in the foreseeable future, I'd say get the 77mm CPL, unless you're willing to invest in multiple CPLs. But, if you have no plans to get a lens that will use 77mm filters (or that lens will be an ultra-wide angle lens, where a CPL doesn't always give good results), then just get the 67mm version to fit your current lenses.


The step-up rings from different brands do the same job, but reportedly the B+W rings have better quality threads that makes them less susceptible to binding up.


Personally, I have a 77mm B+W Käsemann Slim mount CPL, 77mmB+W ND filters (#103/0.9 and #110/3.0), and B+W 67mm→77mm and 72mm→77mm adapter rings. I have an Adorama-branded 58mm→77mm ring, since B+W doesn't make one. To be honest, I haven't used the step-up rings much, since four of my seven lenses use 77mm filters.


One minor point, especially if you're going to use adapter rings or you intend to stack your CPL on top of your UV filters (best to switch them, but I know from experience that there's not always time for that!), you might want to pick up a set of filter wrenches.


Hope that helps.


--John

[Jayson]

John,


Thank you very much. That was exactly what I am looking for. I was worried that there would be a problem with having a filter that was bigger than what threads were on mylenses, but this works. I have been trying to decide on my next lens purchase and cannot decide if I want the 24-105 and get rid of my tamron since I never use it (it isn't long enough for my liking and find myself using primes), buy a 300f4 for other stuff, or a 135 for taking pictures of the kids. All have bigger thread sizes and so I was going for the largest of the group. I have never used a polarizer before, but read Bryan's reviews today after seeing a beautiful sunset last night and wishing I had one. Might have to invest in some ND filters too in the near future, but first things first.


Thanks again,


Jayson

[Brian Kreitman]

I agree completely with neuroanatomist: buy the largest CPL filter that you *may* need. I originally bought a 67mm CPL and then had to buy a 77mm CPL when I upgraded to a higher quality lens. Most of normal Canon's L lenses use 77mm front filters, except for the 16-35mm which has an 82mm filter, and the 70-200 f/4 lenses that use 67mm. I don't know what the super zooms use.


I also bought a *slim* CPL filter when when you go really wide, just so you do not have to buy yet another filter.





There is also a very nice post, courtesy of neuroanatomist, that demonstrates the vignetting by filters of various thicknesses.



http://community.the-digital-picture.com/forums/t/3516.aspx

[barba]

I agree with the other posters. I never use a hood with a circular polarizer, so buy the biggest and best you can afford.


I recommend the B&W step-up ring. The threads are better. I learned the hard way that when a step up ring and a rotating filter get stuck together it can be a nightmare getting them backapart.

[wickerprints]

Here's the thing: If your intent is to use a CPL, then if you are using a wide-angle lens, a hood is generally not very deep, and the polarizer effect may actually be undesirable in those situations where flare avoidance (and thus a hood) is desired.


If you are using it on a telephoto, then a hood is rarely necessary--and if it is, shading with your hand is effective.

[Jayson]

Thanks everyone for all of your replies. I went with the B+W 77 cpl and got their step up ring. The widest lens I have is the Tamron 17-50 and I think it will work fine on that and the 70-200 F4 IS that I have. I was going to do an engagement shoot Friday and going to give it a try for some of the sunset pictures. They are family so don't really care about me experimenting.


Thanks again,


Jayson