Need advice on two filters

by Volker Weber

I found two filters in my bag of old photo equipment. Both have 52mm threading and should fit the new lens I am getting:

  1. Hama HTMC - UV 390 (O-Haze) M52 (IV)
  2. KAISER 52mm POL-CIRC.
Can I use these filters on my new lens with a D70, or am I just messing up the camera? I think I can use the first filter as a protection for the lens and leave it on all the time. But what about the other filter? I am confused about linear and circular pol filters. This one has a metal ring that lets you turn the filter.


I only know, that you should use a circular pol filter for a digital camera. Don't know exactly why, but I read this advice several times in de.rec.fotografie.

Dirk Olbertz, 2005-11-05

Volker lass den UV drauf, aber nur als billigen Schutz für das edle Objektiv. Die vielen Glaskörper sollten UV Schutz genug sein und da Du eine Digitalkamera hast korrigiert der Sensor das sowieso, normale Filme haben ebenfalls eine UV Filter Schicht. Die Filterwirkung Deines Filters ist also überflüssig

Polfilter verbessern den Kontrast und vermindern Spiegelungen, satte kräftige Farben sind das Ergebnis. Allerdings wirkt das im Alltag oft recht unnatürlich. Wenn Du weniger Wert auf wirklichkeitsgetreue aber umso mehr auf plakative Wiedergabe legst benutze den Polfilter.

Linear ist kaum mehr im Gebrauch, manche Kamermesstechnik reagiert da empfindlich, die Probleme beseitigen die circularen.


Michael Hein, 2005-11-05

You can use both on your camera, they won’t do any harm. Whether you should use them is a different question. People typically fall into one of two categories: The first category likes filters to mechanically protect their lens investments. The second thinks that any additional layer of glass within the optical channel has a detrimental effect on image quality unless the finest quality filters are used. I tend to fall into the latter category and use lens hoods for mechanical protection instead. No religion though. :-)

Ulli Mueller, 2005-11-06

Schmeiß das HAMA Teil weg. Dadurch versaust du dir nur die (optische) Qualität des Objektivs. Die Frontlinse sitzt so weit hinten (das Objektiv hat ja praktisch eine eigene Gegenlichblende), und ist dadurch praktisch nicht schutzbedürftig. Den Polfilter solltest du von Zeit zu Zeit -- besonders bei Landschafts- und Architekturfotos verwenden, aber nicht immer: er schluckt auch eine Menge Licht.

Moritz Petersen, 2005-11-06

Das hatte ich mir wegen der Gegenlichtblende auch schon überlegt. Wenn ich vorne einen Filter aufsetze, dann habe ich sofort mehr Streulicht. Witzig: Mit dem Polfilter kann ich das Bild auf einem LCD fast komplett wegblenden.

Volker Weber, 2005-11-06

UV filter is useful for physical protection of your front lens and on very bright days (I use one all my expensive lenses, although not necesserily on the cheap ones). Hama is probably not the highest quality vendor, but since it is HTMC, it should be good enough.

Pol Filter is nice for occasional use for me (more saturated blue skies). Circular type works on all cameras. Linear type does effect metering in SLR type cameras (= Spiegelreflexkameras), afaik has soemthing to do with the built-in prism or mirror) but works perfectly fine with the other didgital cameras where there is the sensor directly behind the lens.

ps: I enjoy your column very much!

Eberhard Blind, 2005-11-06

Volker, for lens protection you should acquire a Heliopan 007 Clear with SH-PMC coating. This is a filter for protection with a suitable coating that a) lets water pearl off completely (good feature for outside shots) and b) is perfectly color-neutral in artificial light conditions (and I know that you know what I'm talking about when it comes to available light photography). B+W also manufactures a super-coated 007 clear, but I have been told that the Heliopan quality is a bit better. Due to the same price tag on both filters I bought the Heliopan and I am very happy with it.

The circular polarizer is ok to use for autofocus cameras, no matter if analog or digital. Don't know about the Kaiser glass and filter foil quality, but you will use it outside and in bright weather conditions only, I think. If you need superior quality, a standard recommendation would be a circular pol filter according to Käsemann build.


Karsten W. Rohrbach, 2005-11-06

Käsemann polarisers are generally overkill unless you're getting seriously serious about hitting the limits of quality. (A B+W 52mm Käsemann polariser, for instance, is about half of the price of the 50mm/1.8 you just bought.) Circular polarisers, though, are absolutely necessary for most TTL autofocus cameras to function properly. A regular (linear) polariser simply interposes a polarising foil between the real world and the lens, allowing light polarised in a single direction to pass through unattenuated. Typical uses of the filter are to reduce glare from wet or organic "reflections" (it's actually refraction that polarises the light) and darkening blue skies.

Unfortunately, that means that the light that hits the inside of the camera is also polarised in a single direction, and that gives phase-detection-type autofocus sensors a severe case of astigmatism. Depending on the sensor you chose for focus and the orientation of the filter, the camera may or may not focus or meter correctly. A circular polariser effectively uses interference to depolarise the light exiting the filter. Light is still filtered according to its polarity when entering the filter, but the light that leaves the filter is nearly unpolarised (the effect of interference is wavelength dependant, and the Käsemann variety of circular polariser is more effective at depolarising light across the visible spectrum at a severe price penalty). That lets both the autofocus sensors and the metering sensors work properly.

I would be careful about leaving the Hama on your lens all of the time. Coatings are never as good as you think they are, and dissimilar metal corrosion will permanently attach the filter to your lens if it's left there too long. Take the filter off at the end of the day and you'll be okay.

Stan Rogers, 2005-11-06

Oh -- the other advantage of Käsemann polarisers is that the polarisation itself is more sensitive (there is less error in the alignment of the polarisation grid due to the way the foil is tension-balanced when applied to the substrate). That really only makes a significant difference on very long lenses, where the narrow field of view means that reflections will be more uniformly polarised across the field. Of the two main makers of Käsemann polarisers, Heliopan and B+W (Schneider-Kreuznach), only B+W offers Käsemanns in sizes under 80mm, and that's really for the cine market. (Of course, if people want to overspend on their 35mm or digital hobbies, they won't get in anybody's way.)

Stan Rogers, 2005-11-06

This discussion is somewhat moot. I am not going to be buying any filters. I only question whether the ones that I happen to have make any difference.

I just tried the pol filter and it gives me great results. As Moritz suggested, I will leave off the UV filter since the lens is well protected anyway.

Volker Weber, 2005-11-06

My comments can be boiled down to this:

1. Yes, you can use the filters you have;

2. Yes, the polariser is the right kind for your camera; and

3. Never leave a filter on a lens in storage.

I do tend to blather on, don't I?

Stan Rogers, 2005-11-06

:-) Stan, I did not mean to tell you that your advice is not well received. There were a number of people suggesting other stuff to get. That was however not my plan. I was simply asking whether it makes sense to use the stuff I already have.

Volker Weber, 2005-11-06

Volker, I just wanted to illustrate (without further knowledge on the exact details of your Hama thingamabob which is very likely a milk glass) that a) the Hama is probably crap, so it might degrade your lens, so you don't get what you paid for, and b) clear with a good coating provides better color performance than UV (which can — depending on your camera's sensor — lead to unexpected results with red casts in uniform blue areas and so on). Trust me, you will at least want to buy a new filter for protection. No religious wars and definately not a sales pitch for anyone… ;-)

Karsten W. Rohrbach, 2005-11-07

actually, the UV filter can be reused as softener, doing David Hamilton style shots. Just rub some Vaseline on it and you'll get pictures which are not easy to create in Photoshop

Helmut Weiss, 2005-11-08

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