I'm still rather new to DSLRs and my K-x, but I have discovered a few things that have helped me take better pictures. One issue that regularly comes up is Circular Polarizers (CPLs). I've tested and compared a few of the middle range ones to see if they are good enough.
First, here are some of my initial premises:
- In general, I don't use any filters (or protector filters) at all.
- In general, a hood is more important than a filter. I almost always use a hood.
- I don't use a CPL on my lens unless the situation demands it.
So, the next issue is what CPL to buy. Yes, you can buy some for under $10 and some will cost you hundreds. Yes, I know that the general sentiment around here is that it is absurd to put a cheap filter in front of your expensive equipment. BUT...
I'm on the low end of photographic excellence with my K-x and a used Pentax DA 16-45 as my most expensive lens. (I'm not complaining. I'm happy w/ the pics I'm able to get with the budget I'm working on.) So, it also seems somewhat absurd to me to put a CPL that costs $100+, that I only use occasionally, on front of my modest gear.
So, I've read the posts here and looked at that very helpful
Lenstip review, and I've tried to find somewhat inexpensive CPLs that are admittedly
not great but certainly good enough. I'll share some of my experiences, and perhaps it will help others of you in a similar boat.
Here's what I have:
- Kenko CPL Digital Filter High Quality 72mm ($19 on$bay)
- Vivitar Series 1 CPL Multi-coated 67mm ($15 @ Adorama)
- Marumi CPL DHG 58mm ($21 on $bay)
- Massa CPL 52mm (given to me; usually less than $10)
OBSERVATIONS - Each brand has various quality levels of CPLs.
- The Kenko is probably an older one and does not have multi-coating like most of the new (and much more expensive offerings) do. From what I could determine, Kenko is the Japanese edition of Hoya.
- I was mistakenly shipped a Vivitar CPL that was not Series 1. It was not good at all, and I sent it back. The Series 1 is quite nice and advertises its VMC=Vivitar Multi-Coated.
- The Marumi received a very good review on Lenstip. (I think I got lucky on $bay, since what I paid for mine is usually what the cheaper Marumi line sells for. There is also a Super DHG line above the one I have, but I see those are available for $55 in the 58mm size.) The Marumi does not say anywhere on the front of its packaging that it is multi-coated, but the back side does point out its special "ultra-low reflection coating for digital cameras."
- The Massa actually has some kind of coating.
- CPLs can sometimes be a bit tricky getting on/off the lens and adjusting the filtering. These are all fine but getting them off the lens occasionally takes a little extra effort.
- These are all smooth glass filters. (Some filters apparently have something of a texture to them.) They all can be cleaned up if you get a fingerprint on them, but it seems harder to clean them as compared to a camera lens.
- Someone should correct me where I err, but as I understand it, it is the nature of a CPL is to have different characteristics at 90 degree increments and depending which side you view it through. A simple test is to hold a CPL up against a bright monitor. Below you can see the most yellowish tint and the most blue-ish tint at 90 degrees turned.
- I have to believe that the extreme yellows/blues of the Massa are a sign of its lower quality.
- This test also indicated a significant imperfection in the Massa. (Somewhat hard to tell on these pics, but there is a discoloration spot at 11 o'clock on the yellow = 8 o'clock on the blue.)
I next turned the CPLs around to view the polarizing effect.
- It was hard to get these all nicely lined up! The Vivitar does get a little darker and less blue.
- It doesn't appear so on this pic, but the Massa actually allowed the most light through. (Not what you want.)
- There was an obvious imperfection with the Kenko. You can see it from 12-3 o'clock, but it actually goes all the way around. It's as if the polarizing effect does not go all the way to the edge or perhaps the glass was stressed. I was not able to notice any effect of it on any pictures I took.
RESULTS: Now for some actual tests.
- In each case, I have kept ISO and aperture constant and simply adjusted shutter speed.
- In each of the shots below, the pic without any CPL is on the left and the one with the CPL on the right.
- If you click on the pic, you can eventually get to a larger size version of it. All the pics are 100% crops (except the Vivitar which is 65%), and there is no PP applied.
- All the shots were done handheld. (As I'll note below, a fairer test would be to use a tripod, but I'm also interested in seeing how I will use this CPLs in actual practice where I usually don't have a tripod.)
- Each of the CPLs required about 1.5-2 extra stops to get equivalent lighting to that of non-CPL shots.
Here is the
Massa. It should be obvious that there is a significant loss of quality.
Here is the
Marumi. You can see the polarizing effect by the reflection (or lack) in the window. There is definitely some degradation in sharpness, but it is not bad. Looking at the skyline, I do not see any fringing issues. I'm not quite sure why, but the sky is less blue (than the non-CPL) when the lens had maximum polarizing, but using other angles on the CPL made it extremely saturated blue.
Here is the
Vivitar. (below) You can see the polarizing effect in the glass. Again, there is definitely some degradation in sharpness, but it really isn't visible except at larger size viewings.
Here's the
Kenko. (below) You can something of the polarizing effect in the right glass pane. Once again, some degradation in sharpness, but it isn't really a problem except at larger viewing sizes. Since this lens appears to be uncoated, I tried some shots that would have flare. This CPL did make the flare worse a bit.
CONCLUSIONS - The Massa is not worth using.
- The Marumi is probably the best of the batch, but it starts getting much more expensive as you move into the 67mm or larger sizes.
- The Kenko is good enough, but I think it would be worth checking the newer coated versions. (If I were to buy one today, I'd get the Vivitar instead.)
- The Vivitar is probably the best value. It really does a satisfactory job, and it is a great price.
- I do use these CPLs (except the Massa) despite the degradation in sharpness. It simply is a matter of a trade-off: sharpness OR less glare, better contrast. I don't know of an easy way to deal w/ glare issues in PP, but it is possible to add a little sharpening. Further, the degradation in sharpness is only noticeable at larger sizes.
- I think part of the lack of sharpness is also due to the extra light requirements imposed by the CPL. The comparison shots above use better shots. I had more shots with motion blur using the CPLs. Part of that problem is my technique, and it could have been avoided if I had used a tripod. Your results may vary...
- Note: I bought the largest (72mm) CPL last. If you can plan ahead better than I did, a good option would be to start with the largest size CPL you will need, get a better quality one, and use step-up rings so that you can use it on a number of your lenses.
BOTTOM LINE
For the $20 or so I paid for each of these CPLs, they represent a satisfactory compromise between cost and quality for my photography needs.
I'd love to hear experiences others have had with similar types of CPLs.
Last edited by mgvh; 10-24-2011 at 08:08 PM.