More Advice sought - polarizing filter.

[DickyOZ]

Well, my Circular Polarizing filter finally arrived. I gave it a quick test by holding it in front of my PC monitor and rotating it. The view went from transparent to opaque just as it should. It has been overcast all day so I couldn't do any field trials.

When I mounted it on my lens I found two difficulties.

1. With the lens hood on it is quite difficult to rotate it and keep my fingers clear of the glass.

2. I have no idea how far I have rotated it because there are no reference points visible and no datum.

My solution to 1. is to temporally remove the lens hood. But I have no solution as yet for 2.

If anyone has some helpful hints they would be most welcome.

Dicky.

[Manfred M]

Yes, you need to remove your lens hood to use it.

Markings are irrelevant. You need to watch to see the effect the filter is having on the scene through the viewfinder, whether you are trying to crank up the contrast between the sky and the clouds or if you are trying to reduce reflections or glare from non-metallic surfaces

Work with it and you will quickly figure out how you will use it.

[DanK]

Exactly as Manfred wrote. Canon now sells at least one (very expensive) lens that comes with a lens hood with a little porthole you can open for this purpose, but I don't know if anything like this is generally available. I find that some lens hoods are short enough that I can rotate the ring with one finger, but I have long hands. the only other option is to take off and replace the hood, or take the hood off and use one hand to shade the lens from whatever direction needs shading.

[Mike Buckley]

If you practice turning the filter while the hood is in place, you might get better at doing it more easily. My wife's lens hood (she uses only one lens) presents the problem you explained and she got used to it over time.

A separate tip: When using the polarizer to minimize glare on opaque objects such as vegetation, sometimes the change is subtle, especially if the angle of the lens to the sun is small enough or if the light is diffuse enough that the filter has little effect. In that situation, I always point the lens toward the sky and adjust the polarizer to achieve maximum darkening of the blue area even when the sky will not be included in my scene. That's because the slight change in the sky will be easier to detect than the same change in the vegetation. When the sky is changed the most, the glare on the vegetation will also be reduced the most.

[rpcrowe]

As mentioned above, rotating a CPL when "most" lens hoods are attached is difficult and a big PITA. UNLESS, you have fingers like the Grinch


Seriously, I can usually rotate my CPL using a single finger which just touches the front portion of the filter ring. I do this very carefully so that I don't touch the front of the glass. I think that this is a learned ability and is easiest when using a "petal" shaped lens hood...

There are some lens hoods which make it easier to rotate a CPL:

1. First is the retractable hoods on the 300mm f/4L IS and the 400mm f/5.6 L (and probably other) lenses.

It is quite easy to slide back the hood, rotate the CPL and then extend the hood again. This was the main reason that I kept the two above lenses until...

2. Canon offers a locking lens hood with a sliding door to enable rotation of the CPL on the hood for their 100-400mm f/4.5-5.6 IS II lens. IMO, this feature was copied from a Pentax hood...

However, the Canon version is as least as good, if not better than the Pentax


3. In some full frame lenses when shooting with a crop camera, you can substitute a generic round hood which screws into the front threads of a CPL ( top lens). I will occasionally use this type of hood on my 70-200mm f/4L IS and my older 28-135mm f/3.5-5.6 IS lenses...

You can rotate the CPL by simply turning the hood. This cannot be used on full frame cameras because it causes vignetting and cannot be used on many other lenses, even on 1.6x cameras, because of the same reason.

[Mike Buckley]

One other point: If your zoom lens turns as it changes focal length, be sure to set the focal length before setting the position of the polarizer.

[Dave Humphries]

One other point: If your zoom lens turns as it changes focal length, be sure to set the focal length before setting the position of the polarizer.

Or indeed focus - IIRC many film era 'standard' lenses rotated the front element to focus, as do a few digital ones, I believe.

[NorthernFocus]

When lighting conditions are such that the CPL is useful is when the hood is least useful. But if you don't wear a hat, maybe it's time to start now that you use a CPL.

1) remove lens hood
2) rotate CPL to best effect
3) if there is any sign of lens flare and/or sun is falling directly on the filter, take off the hat and hold it such that it casts a shadow on the lens

[Mike Buckley]

take off the hat and hold it such that it casts a shadow on the lens

You've got it all wrong, Dan. It's the spouse that should hold the hat for you...even if you're using a tripod and could hold the hat yourself.

[NorthernFocus]

You've got it all wrong, Dan. It's the spouse that should hold the hat for you...even if you're using a tripod and could hold the hat yourself.

That would be expensive, very expensive

[Mike Buckley]

That would be expensive, very expensive

True. I found out far too late about that.

[DickyOZ]

One other point: If your zoom lens turns as it changes focal length, be sure to set the focal length before setting the position of the polarizer.

Thankfully the lens doesn't rotate when it zooms.

[DickyOZ]

Many thanks to all who replied. With a little practice I seem to be able to rotate the filter with one finger and not touch the glass; having a long finger nail helps. Since the filter always screws onto the lens in the same position I will paint a small red blob on the rotating bit at TDC to give a quick reference point.

Plus I always wear a wide-brimmed hat. The Queensland sun is fierce all year round; the Boss says I look stupid, but I don't get sunburnt or baked.

Dicky.

[Mike Buckley]

One last idea: Always rotate the filter in the direction that tightens it. Otherwise, it's possible to accidentally loosen it, especially if you're rotating it when the lens hood has been removed.

[Mike Buckley]

I will paint a small red blob on the rotating bit

I just now remembered why so many polarizers have a dot on them. It has to do with using the filter on a lens that rotates when it zooms in and out. In that situation, if you capture a photo at one focal length and then zoom in or out to capture a different composition, one way to ensure the same amount of filter effect is to note the position of the dot before zooming. Doing so makes it easy to return the filter to the same position after zooming.

I can't imagine that dot being helpful in any other situation. I have five polarizers, one for each lens. Four of them have the dot and I've never had a need to use a reference point. If I did, I would just as easily use one of the words or letters already printed on the rotating part of the filter for that purpose.

[dem]

The dot on the rotating ring of the polarizer has a special meaning: to maximize the effect of the polarizer the dot has to point towards the light source, the sun.

This is a design feature that allows a polarizer to be used on a rangefinder-type camera that has a dedicated optical viewfinder (as opposite to an SLR that is seeing the world through the lens).

If this dot is missing, normally the beginning of the logo is used as a mark.

[Mike Buckley]

to maximize the effect of the polarizer the dot has to point towards the light source, the sun.

That makes sense. I hadn't thought of that possibility.

[Shadowman]

The dot on the rotating ring of the polarizer has a special meaning: to maximize the effect of the polarizer the dot has to point towards the light source, the sun.

This is a design feature that allows a polarizer to be used on a rangefinder-type camera that has a dedicated optical viewfinder (as opposite to an SLR that is seeing the world through the lens).

If this dot is missing, normally the beginning of the logo is used as a mark.

Never paid attention to the dot before, I just used my fingers positioned as a pistol pointed sideways.

[Mike Buckley]

I just used my fingers positioned as a pistol pointed sideways.

If we ever find out that you've been arrested, we'll know why.

"But officer, I was only..."

[Shadowman]

If we ever find out that you've been arrested, we'll know why.

"But officer, I was only..."

And probably considered rude in most countries.