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05-31-2022, 05:49 AM   #1
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Purpose of 81A Filters ?

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I have just received a used Hoya filter from Ebay, not an 81A, but the keeper case has a chart of filter factors on the back. Under 81A it says it is for use with "Cloudy" and also with "Electronic Flash".


That's news to me, I always thought the 81A was for using tungsten-balanced film in normal daylight, as described in an old Hoya catalogue I have (part-page shown below). Bear in mind that the catalogue was probably from around 1985 and the filter box is the hinged type which I believe Hoya started using much later than that (and up to the present).


I do have an 81A filter that came in a job lot some time back. I have tried to sell it on Ebay once or twice but it seems that users of tungsten film in daylight are a bit thin on the ground. But now I am seeing the 81A in a new light, so to speak.

05-31-2022, 05:56 AM   #2
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If you're using a DSLR and you shoot RAW, you don't need it at all. If you shoot JPEG yes it can be used in cloudy days.

Back when I used a Tokina 19-35mm f/3.5-4.5 as my general purpose zoom, I used an 81A because that lens has quite a cold rendering and the RAW images from the K20D looked more pleasing with the filter on. It was a Nikkor filter so it was very good quality and I was quite pleased with it. Pentax, Sigma and Tamron lenses don't have this cold color cast that this lens had, so I haven't had to use it.
05-31-2022, 06:25 AM   #3
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81 A is (as I recall) basically a strong skylight filter. Tungston to daylight requires a stronger filter. Depending if the film was balanced to 3200 or 3400K, it is one of the B or C as I recall.
05-31-2022, 06:35 AM   #4
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In the old days we all invariably used a skylight filter on our lenses as film was susceptible to a blue cast. The 81A is a stronger version of that.

As noted above you donít need it when shooting raw as the WB can be changed in PP

If you shoot JPEG and want to warm-up your images you can select a WB in the camera to give a warmer result. If you do use a filter to achieve the same affect make sure you select Daylight WB not AUTO !

05-31-2022, 07:21 AM - 3 Likes   #5
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For those interested...............

There were two series of Wratten filters in the 8X series which were used for color temperature ("color correction") adjustments. The 81 series were warming filters (yellowish) and decreased the apparent color temperature while the 80 series were cooling filters (blueish) and increased the apparent color temperature. The letter designated the strength of the filter. There were different "tungsten" sources, so the appropriate color correction filter needed to be matched to the light source. Many early (and some current) flashes tended to be a bit "cool" thus needing a warming filter on the lens. There were some other 8X filters (the 82 and 85 filters) which were similar but not as well specified for color correction uses (and then there were some 8X filters not at all associated with color correction).

As mentioned, this was a film issue since the color temperature a film was made for was unchangeable once the film was produced. The need for these filters with digital photography has all but disappeared. One good use still remains, and that is to make the color temperature of a flash match the ambient color temperature (usually gel filters) since many scenes can still be illuminated by "tungsten" lighting. (Sometimes ambient tungsten lighting is made to match other non-tungsten lighting with lamp wraps of cooling gels.)

The 81A filter is a slight warming filter which was used with 3400K sources and "tungsten" film (the latter balanced for 3200K), since the 3400K could look a little cold (blue) without this filter. Oh, how complicated in those days................

For a complete list of Wratten filters including the aforementioned, check here:

https://en.wikipedia.org/wiki/Wratten_number

Last edited by Bob 256; 05-31-2022 at 07:39 AM.
05-31-2022, 08:10 AM   #6
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I still use warming filters (81A & 81B) for my film if it's cloudy out. Pentax called the 81A a "cloudy" filter.

Skylight filters (1A) are more pinkish and are for everyday use with colour film, especially E6 slide film.

To shoot Ektachrome 64T outdoors you would use an 85B filter. (That's the only tungsten film I ever used " fresh".)

Phil.
05-31-2022, 10:35 AM   #7
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I use Nikon 81A filters as protective filters. Gives a very slightly warming tone.

05-31-2022, 01:33 PM - 2 Likes   #8
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QuoteOriginally posted by Theov39 Quote
I use Nikon 81A filters as protective filters. Gives a very slightly warming tone.
Note that you might have some difficulty doing this if your camera is a digital camera in the AUTO white balance mode since it will try to cancel out any overall cast. Be sure to switch to manual WB and use a fixed setting (whichever produces the tone you're after). Film cameras using slide film - used this quite a bit myself to get warmer tones as some daylight balanced films can have a colder "clammy" feel to them.
05-31-2022, 03:18 PM   #9
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QuoteOriginally posted by Bob 256 Quote
Many early (and some current) flashes tended to be a bit "cool" thus needing a warming filter on the lens.
A very interesting post. I thought I broadly understood colour correction filters, but what really puzzled me about that chart was Hoya's recommendation to use an 81A with electronic flash. I have never seen that recommendation anywhere else, and I had understood that electronic flash was made to match natural daylight in colour temperature and therefore should need no correction.
05-31-2022, 09:01 PM   #10
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QuoteOriginally posted by Lord Lucan Quote
and I had understood that electronic flash was made to match natural daylight in colour temperature and therefore should need no correction.
Nuh, the flash is very white, very neutral, consistently about 5500K.

Sunlight is anywhere between 4500 and 7000K.
05-31-2022, 10:33 PM - 1 Like   #11
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The chart below will help.
I miss physically changing filters to get the image I wanted. It was always a nervous wait to see the sent away film developed images.....

https://tiffen.com/pages/film-enhancement-guide

Last edited by pjv; 05-31-2022 at 10:45 PM.
06-01-2022, 09:37 AM - 2 Likes   #12
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QuoteOriginally posted by clackers Quote
Nuh, the flash is very white, very neutral, consistently about 5500K.

Sunlight is anywhere between 4500 and 7000K.
More correctly, sunlight (above the atmosphere) is very near 5900K. It's slightly lower after passing through the atmosphere (especially at low angles), but illumination with the atmosphere as a background (which is primarily blue light) can have a significantly higher CT. Light in shadows (mainly lighted by the blue sky) can be especially high in CT when photography is concerned.

So you'd be more correct to say "sunlight conditions can be anywhere between 4500 and 7000K

Side note: A Xenon arc will have a CT of near 6200K but that's influenced by gas pressure and presence of any contaminants. This is a little bluer than noon sunlight. Not a problem with auto white point cameras but it was an issue with slide film balanced for daylight. The most common solution was to use a "goldish" reflector to compensate (once they did that). That's where the 81A came in during film days.

Last edited by Bob 256; 06-01-2022 at 10:05 AM.
06-02-2022, 10:58 AM   #13
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QuoteOriginally posted by Lord Lucan Quote
what really puzzled me about that chart was Hoya's recommendation to use an 81A with electronic flash. I have never seen that recommendation anywhere else, and I had understood that electronic flash was made to match natural daylight in colour temperature and therefore should need no correction.
Less so today, but back then, most indoor lighting was tungsten. People expected to see a level of warmth in such photos, not daytime tones with indoor shots. Women especially, since their makeup was geared to the lighting. For most consumers, flash was only used indoors.

Besides, the more reasons a company could come up with for owning a filter, the more they would sell.
07-15-2022, 03:15 PM   #14
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Back in the day, the 81A or in my case the Pentax Cloudy filter was pretty much required when shooting Fuji transparency film. Especially at the altitude I live--4000 ft. The difference is stunning! Haven't been able to keep my digital images neutral enough to benefit from the dozens of cloudy filters I still own. But if you are shooting Fuji Velvia and Provia outdoors, you need to contact me and buy the Cloudy (81A) filters for your lenses!
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