Coloured filters? what do they do

[dude163]

Hi

I am awaiting a helios 40 package and it comes with 3 different coloured filters, I assume they were used back in the day for different effects while using Black and White

however, what effects exactly?


thanks

[rawhead]

Well colored filters have preference for letting through those colors (and cutting off the others, especially on the other side of the spectrum), so but a blue filter and shoot at the blue sky and you'll get white, put on a red filter and shoot at the blue sky and you'll get black.

So, e.g., when you have a a sky with nice blues contrasting with white clouds, you can put on a red filter to really bring out the contrast (cuz blue will go black, the white clouds will stay white) or put on a blue filter and take away the contrast (since both the sky and clouds will be white).

Just Google for B&W film and color filters and you'll see plenty of examples.


http://www.cambridgeincolour.com/techniques/color-black-white.htm

does a good job of eplaining, though geared towards digital.

[RioRico]

Yo dude! For film, filters have various effects. Back before we could set WB in-camera, color-correction filters were used to match the color film with the light-source temperature. Some modern color films have wide temperature latitude, but CC filters are still used by many film shooters.

B&W filters influence contrast and tone in monochrome images. As rawhead said, they block and pass various wavelengths of light, with different cut-off characteristics. They can *mostly* be simulated with digital filtering such as your Kx and all PP software provides. Mostly, but not completely.

The most common B&W filters are Yellow, Orange, Red, and Green. Green is mostly used to lighten foliage; Yellow, Orange, Red give increasing amounts of contrast. For portraits, you might use Yellow to touch up the contrast in a smooth face, and Red (with dramatic lighting) to bring out ever crease and crinkle in a craggy face. Blue would be used to lighten skies and darken everything else.

To SEE how these filters operate, shoot some RAW pictures and develop them in whatever warez Pentax included with the Kx -- for my K20D, that's PentaxPhotoLab3 but yours is different. Anyway, you should be able to set the Image Tone from Natural to B&W, and that activates the filter choices. Now step through all the colors and see what happens. NOTE: The IR tone is NOT real InfraRed, just a deeper Red.

Some optical filters cannot be replicated (very well) digitally. Here are some special uses:

* An InfraRed-pass filter blocks some or most visible light. Digital sensors are sensitive to IR, and virtually all digicams have an IR-block Hot.Filter in front of the sensor. The best IR work requires that the Hot.Filter be removed, but that's beyond the scope here.

* A Red optical filter effectively increases resolution a bit when shooting digital B&W, due to the nature of the RGGB Bayer filter on top of a digicam's sensor.

* A Yellow optical filter gives interesting tonal effects when shooting garish neon lights at night in color. Don't stroll the Ginza or Times Square without one!

* Light Blue and Violet filters (some CC filters) replicate early B&W photographic emulsions that only 'saw' ACTINIC light, the UV-Violet-Blue portion of the spectrum. I use such for REAL old-timey effects, none of this sepia crap. (And I don't use UV-block filters at all.)

Many old filters are available REAL CHEAP on eBay. I'll admit to accumulating far more than I need, but who knows? Maybe I'll shoot more B&W film someday. Anyway, it can't hurt to get a 49mm set for your Taks and see how they work. Have fun!

[dude163]

thanks for the information guys

just another thing to explore in my voyage with MF lenses

[AhamB]

I definitely wouldn't bother with those filters for digital b&w applications; only if you shoot film.

Digital cameras have red, green and blue filters built in, so you can emulate red/green/blue filters and combinations of them (yellow, orange, etc.) by different levels of attenuation of the R/G/B colour channels.

[dude163]

Well Ihad 2 reasons for wanting to use them


1: finding a 66mm filter to protect the main optics from dirt/scratches/kids

2: they would look really cool hahahaa

[gsxronax]

Well colored filters have preference for letting through those colors (and cutting off the others, especially on the other side of the spectrum), so but a blue filter and shoot at the blue sky and you'll get white, put on a red filter and shoot at the blue sky and you'll get black. So, e.g., when you have a a sky with nice blues contrasting with white clouds, you can put on a red filter to really bring out the contrast (cuz blue will go black, the white clouds will stay white) or put on a blue filter and take away the contrast (since both the sky and clouds will be white).

I totally agree with you sir.

[Scheimpflug]

[RioRico]

The other application I didn't mention is for what I call "spectrum-slicing", using filters to isolate portions of the EMF spectrum. The most prominent of these techniques applies IR-pass filters to block visible light at some cut-off wavelength, marked as 720nm or 930nm or 1000nm or whatever. These work best if a camera's IR-blocking hot.filter has been removed. I use a variety of these filters on my Sony DSC-V1 'NightShot' P&S, which allows the hot.filter to be flicked out of the optical path.

With or without the hot.filter bypassed, I also use various B&W filters for their spectral effects, sometimes stacked. With the hot.filter bypassed in NightShot mode, ISO effectively jumps from a maximum of 800 to about 2500. Thus, stacked B&W filters, or even IR filters up to 900nm or 930nm, don't demand long exposures in daylight. NightShot does introduce some effects that require a bit of PP, but its effects are difficult or impossible to duplicate with PP.

My other spectrum-slicing trick uses CC (color correction) filters to replicate 'actinic' light. The earliest photo emulsions only saw such actinic (UV+violet+blue) light. Emulsions only became sensitive to green, yellow, orange, red, and IR by adding colored dyes to their chemistry. Some modern emulsions and sensors still maintain this actinic sensitivity: copy, litho, and similar orthochromatic films and papers. We also see this in earlier generations of copiers, where yellow and red marker lines are rendered as black -- because its sensor doesn't 'see' those frequencies.

So, with maybe an 80A or 82A (light blue), or 80B (dark blue), or 47B (blue-violet) filter, on the Sony NightShot camera or my Pentax K20D, I can get a taste of early photography, but without the chemicals.

I got into actinic digital photography because I uncovered some shots I took in the mid-1970's. I'd used Kodalith or other orthochromatic films in my ancient German 1934 Kodak Retina I, the first 135 camera, with a 50/3.5 lens. For some reason, the ultra-slow non-panchromatic film, pushed a few stops to show gray-scale while retaining its nearly grainless character, rendered DOF much shallower than did the somewhat faster Panatomic-X film I normally used. I've been trying to get that same thin DOF effect on a digicam -- no success yet. But the pre-1880 B&W tones are just so different that what we're used to.

The moral of this tale is: Don't throw away those filters! Play with them! Experiment with them! See what hidden corners of the EMF spectrum you can disturb!