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tballphoto · Apr 6, 2021

MattKing said:
CPL has always referred to a Circular polarizer in the past. In many cases, you don't want to use a polarizer, particularly if you have standing water in your shot.
A polarizing filter is a special purpose filter that should be used intentionally, not generally.
And a skylight filter is essentially a "mild" UV filter, so I don't know how you are going to combine them.

ref;ecte

reflected light on water neutralized by CPL. why would anyone want light reflected on water or any other shiny surface when they can get a CPL and not use photoshop on everything

GLS · Apr 6, 2021

tballphoto said:
ref;ecte

reflected light on water neutralized by CPL. why would anyone want light reflected on water or any other shiny surface when they can get a CPL and not use photoshop on everything

It depends on the situation. A middle ground with partial polarisation is often best. Unfiltered reflections off water etc can be a nuisance, but to cut them entirely can end up looking very unnatural.

Also polarisers can darken & saturate the sky significantly which sometimes looks over the top, especially on slide film. Wide angle lenses can also see enough of the sky that the polarisation affect becomes uneven across the frame.

grain elevator · Apr 6, 2021

If you have the affordable 50 1.8 lens, what's the point of spending good monies to "protect it" from something that probably never happens? The protective filter idea may have merit for more expensive lenses... and for image quality purposes mainly of you shoot color, over long distances (so more important with long lenses), more important at altitude. I don't use them. I do use lens hoods. They give a degree of protection and are beneficial for image quality.

AgX · Apr 6, 2021

tballphoto said:
CPL is the abreviation.... it combines skylight and uv with better and improved performance.

-) To me CPL means circular polarizer.
It came up in this thread as it it can, as a UV filter, darken a sky. In case that would the photographer's main concern, on other aspects it fails against the UV-filter.

-) In contrast to what you said, a Skylight filter already is a UV filter added with some density in the visual blue too, thus being perceived as slightly roze tint

To go on with terminology issues:

-) the plain, colourless, UV-filter is also designated UV (0)

-) the Skylight filter is also designated UV (1A) and UV (1B), depending on strength of roze tint.

Nicholas Lindan · Apr 6, 2021

I'll voice a dissenting opinion.

Filters are fetish objects. I don't think you can buy an optically inadequate filter. What you can run into is a filter with a very poorly made mount ring and these sometimes jam. A $5 'filter wrench' will take off a jammed filter but it is nicer to have filters that don't jam.

You can save money and buy used filters. They don't wear out, they can only get scratched.

The two 'protective filters are UV and skylight. A skylight filter will give an ever so slight warming effect and very slightly darken blue skies. UV filters claim to cut through mountain haze, but I've never seen much difference with and without.

A protective filter can be a good idea if you are going to be photographing in a dusty or sandy environment. Cleaning dust from a lens will often scratch it. Better to scratch a cheap filter. Ditto grease.

If you want to protect the lens because the camera is going to get knocked around then a screw-in lens-hood is the way to go - a lens hood is always a good idea in any case. The point about filters protecting the lens' filter mounting ring is good advice; I suppose you could bash the glass out of a filter and just use the rim - a filter with the ultimate in optical quality.

grain elevator · Apr 6, 2021

Nicholas Lindan said:
I suppose you could bash the glass out of a filter and just use the rim - a filter with the ultimate in optical quality.

This is how I make lens hoods, from gimmicky effect filters.

AgX · Apr 6, 2021

Nicholas Lindan said:
The two 'protective filters are UV and skylight.

Meanwhile there are protective panes in filter mounts from plain, untinted optical glass.

Donald Qualls · Apr 6, 2021

tballphoto said:
And you also get light loss with a linear polarizer as well last i looked. But hey, dont feel left out if you dont want the usefulness of 3 filters in one.

Point being that unless you need polarization, neither a circular (unnecessary for film) or linear polarizer is desirable. Not only loss of 1 1/2 stops (which makes a big difference if, say, you're hand holding with ISO 100 film and it's not bright and sunny), but cost -- circular costs more than linear, last I checked.

AgX · Apr 6, 2021

Donald Qualls said:
Point being that unless you need polarization, neither a circular (unnecessary for film) or linear polarizer is desirable.

We are now leaving the topic of this thread but there are indeed film cameras that need the circular version of a polarizer.

Donald Qualls · Apr 6, 2021

AgX said:
We are now leaving the topic of this thread but there are indeed film cameras that need the circular version of a polarizer.

Must be for the meter. Film doesn't detect polarization in any way, as far as I'm aware.

Craig75 · Apr 6, 2021

jesus boys, isiah is just starting - give him a break.

AgX · Apr 6, 2021

What can we do? He opened a can of worms...

MattKing · Apr 6, 2021

Donald Qualls said:
Must be for the meter. Film doesn't detect polarization in any way, as far as I'm aware.

Any camera that uses a beam splitter for the metering system won't meter properly with a linear filter.
But yes, to the OP, many of us do use UV or skylight filters to both provide a subtle but useful amount of filtration, while also providing some protection to lens surfaces.
And it is true that a poorly made or damaged filter can reduce resolution.

GLS · Apr 6, 2021

My 2p:

I don't use protective filters at all. If I were to work near blowing sand or salt water spray then I would reconsider, but otherwise I don't think they are necessary. Lens hoods are perfectly adequate protection in most situations.

wiltw · Apr 6, 2021

Nicholas Lindan said:
I'll voice a dissenting opinion.

Filters are fetish objects. I don't think you can buy an optically inadequate filter. .

False. You can buy single-coated filters which have about 7% reflectance and transmit only 93% of the light that should pass thru them.
You can buy multicoated filters, which pass 97% of the light that should pass thru them.
You can buy 'supermulticoated' filters which pass 99%+ of the light that should pass thru a filter.
Back in 2012 I posted this, on the topic...

"The old HMC filters transmit 97% in a 8-layer formula....The Pro1 D's are cheap crap. Don't waste your money on em.
Hoya's web site is rather non-specific about specs on the Pro1 Digital coating DMC. Per this site http://photofilter.com/hoya.htm

the SMC filter 7-layer coatings are effective to 99.7%. "Hoya HMC Camera Filters feature 3 layers of Multi Coating applied to each side of the filter, average light transmission is over 97%
Hoya SMC Camera filters have 7 layers or multi coating applied to each side of the filter
average light transmission is over 99.7% Works great with your Digital Camera"

This web site has similar information about SMC filters http://camerafilters.net/hoya.htm

Both web sites lack transmission information about the Pro 1 Digital filters, just as Hoya's own web site lacks that information.

The first post here http://www.fredmiranda.com/forum/topic/680035 shows SHMC > DMC > HMC in terms of resisting flare."

This filter comparison, in a test performed many years ago, proves my points above...

https://www.kenandchristine.com/Other/Equipment-Tests/Filter-Tests

Look at the test for the Tiffen filter in high flare conditions, and compare the results to the multicoated filter low flare.

I once had a Tiffen polarizer. If you looked thru the filter as you rotated it in your hand, it was readily apparent that the filter acted like a prism, bendling light off to one side and distorting the image seen thru the Tiffen...I crushed it under my heel rather than ever sell it off to some innocent buyer!

BTW, I agree with the rest of your comments in that post...just not the blue text.

wiltw · Apr 6, 2021

Donald Qualls said:
Must be for the meter. Film doesn't detect polarization in any way, as far as I'm aware.

Yes. For example, my Olympus OM-1 can take any polarizer, but the OM-4 has to use a CPL.
Additionally, the AF film cameras, like the Canon EOS, also need CPL for AF functionality.

Donald Qualls · Apr 6, 2021

wiltw said:
Yes. For example, my Olympus OM-1 can take any polarizer, but the OM-4 has to use a CPL.
Additionally, the AF film cameras, like the Canon EOS, also need CPL for AF functionality.

That explains why I didn't know this also applied to film cameras, then -- I've never owned one as new as an OM-4, never mind an auto-focus SLR.

Andrew O'Neill · Apr 6, 2021

I have them on all student cameras. They make a great lens cap. They are very rough on equipment.

AgX · Apr 6, 2021

wiltw said:
This filter comparison, in a test performed many years ago, proves my points above...

https://www.kenandchristine.com/Other/Equipment-Tests/Filter-Tests
Look at the test for the Tiffen filter in high flare conditions, and compare the results to the multicoated filter low flare.

The Ken & Christine test compared apple to oranges and can thus not be used as comparison in AR coating efectiveness.

wiltw · Apr 6, 2021

AgX said:
The Ken & Christine test compared apple to oranges and can thus not be used as comparison in AR coating efectiveness.

Can you elaborate 'why not'? It seems to me if you take three filters with different coating qualities and directly compare them under identical circumstances, there is no 'apples vs. oranges' comparison. Are you wanting to compare Hoya single coat vs. Hoya HMC vs Hoya SMC?

AgX · Apr 6, 2021

For any test you must chose samples which only differ at one characteristic.

The Tiffen filter was a laminated filter. The filter proper or the cementing could be cause for the results and not the air-glass surfaces.

wiltw · Apr 6, 2021

AgX said:
For any test you must chose samples which only differ at one characteristic.

The Tiffen filter was a laminated filter. The filter proper or the cementing could be cause for the results and not the air-glass surfaces

OK, I see your point. The improper construction could indeed affect that filter far worse than simply economy of coating...but that is an indictment against that manufacturer's filters and QC, regardless...particularly when I had direct experience with a 'filter prism' from Tiffen!

Autonerd · Apr 6, 2021

Yes to UV filters! Sometimes I use 'em just for dust proection -- if the filter has gotten dirtyand I don't have a cloth handy, I'll pop off the UV filter, get my photo and put it back on.

If you're shooting B&W, consider yellow and red filters, which can make the skies look darker and more dramatic.

Aaron

grat · Apr 7, 2021

AgX said:
What can we do? He opened a can of worms...

Portion them out, and not turn into dpreview.

Jim Jones · Apr 7, 2021

I rarely use filters for protecting lenses. Because of this, I've had to retire two favorite lenses, a 50mm Summicron and a 203mm f/7.7 Ektar. That's a tiny price to pay in comparison to the cost of film over 7 decades. Today's best multicoated lenses and filters permit excellent photos in certain adverse lighting. Using a filter for protection makes more sense now than it did before multicoating. I wouldn't use any polarizer just for protection. In addition to reasons in earlier posts, polarizers are subject to deterioration due to their complex construction. I've had polarizers from Leica and Nikon fail not from obvious physical damage, but perhaps from high humidity or desert heat.

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