Lens Filter

The diffraction filter is quite a cool effect and was available in the Hoya range back in the 7os under the group Spectral Star. This took the conventional cross screen and straburst filter and added a rainbow like pattern to the points. Hoya produced three filters in this range

The Andromeda that gave a single line through the photo and created ghost like blurs to the subject as well as the multicoloured streak from point light sources.

The Pulsator gave a star 8 like effect with more points in the background.

And the Nebula gave a whiling motion by adding dozens of lines out

But it was Cokin who made the effect become popular when their Special effects filters appeared.

Cokin still produce a series of Diffraction filters

The Cokin Diffractor Cosmos 040 is like the Hoya Andromeda with its single line

The Diffractor Univers 041 is like the Hoya Pulstaor with its eight star burst

And the Diffractor Galaxy 042 is like the Hoya Nebula with its multiple star burst.

Not very original but because of the universal holder became for more popular as you could buy one filter for several lenses.

Hoya not to be outdone created the Hoyarex system which also had a series of diffraction filters.

They made things simpler by calling the filters diffraction and listing the number of points and also increased the choice giving us the widest range of diffractions made.

There was the Hoyarex Diffraction 2x Model No 702, Diffraction 4x Model No 704, Diffraction 8x Model No 708, Diffraction 18x Model No 718, Diffraction 36x Model No 736, Diffraction 48x Model No 748 and the Diffraction Halo Model no 799.

The photo used to illustrate this article is taken with the Hoyarex Diffraction 48x

It’s not easy to recreate this filter digitally and is well worth adding to your collection. Works with glass, water, jewellery and any other item where you can get a sparkle of light to diffract.

A polarizing filter reduces reflections from non-metallic surfaces such as windows and water. In doing so it also increases contrast and makes colours saturated to give more impact and depth to photographs.

It will make blue skies look really deep to add drama to your land and seascapes.  Best results are with the sun at 90 degrees to you.

Slip the polarising filter over the lens and rotate it while you look through the viewfinder. If you use one on a camera without a direct viewer hold the filter in front of your eye, adjust and then with it in the same position fit over the lens.

It works best at about 40 degrees angle from the reflective surface.

Polarising filters have a filter factor of about 3-4 which is 1.5 to 2 stops exposure increase.

Use two polarising filters together and you can create a variable neutral density filter.

Use a polariser with a red filter and you have a powerful filter for infrared.

A linear polariser is best used with older manual cameras and a circular polariser with modern AF cameras.

It’s one of the few filters that cannot be replicated digitally.

Links to buy

Hoyarex 611 Linear Polariser
Hoyarex 621Circular Polariser
Cokin A160 Linear Polariser
Cokin P Linear Polariser
Hoya 49mm Circular Polariser
Jessops 62mm Circular Polariser

Check this page Filters For Sale regularly for updates and other filters

Hoyarex filters were arguably the best filter system made. Optically superb, several made from glass, solid filter holder, brilliant adjustable rubber hood for wide or super telephoto, and a useful range of filters.

While the range wasn’t as huge as Cokin it was certainly substantial.

The illustration to the right shows the filter holder with an adaptor ring (available in sizes from 43mm up to 77mm) and the wonderful rubber Pro hood that clipped on the holder and had a variable extension.

Two filter holder can be clipped together and rotated when special effect filters were inserted.

Here in numeric order is the entire range with links to buy the individual filters at photographyattic.com and links to more info on lensfilter.co.uk.

The Multi-purpose UV is similar to the skylight, absorbing the ultraviolet rays which often make scenic shots hazy and indistinct. Moreover, the UV, especially when used with black & white film, increases contrast, reduces haze and generally improves the “sharpness” of your photographs

UV filters look like clear glass filters.

Many photographers buy a UV filter for each lens and leave them screwed on to protect the lenses’ front elements.

UV filters are available in round type that screw into the lens in ever size imaginable. They were also made by Hoyarex for their square filter system.

Links to buy
Hoyarex 021 Filter

When taking colour photographs in bright sunlight, especially by the sea or in the mountains, ultra-violet rays and the brightness of the sky throw out the picture’s overall colour balance.

The Skylight “filters out” the excess bluish tone, improving the overall clarity of the photograph while helping to restore the film’s natural colour balance. It also keeps skin tones free of colour reflections from nearby objects such as tree shade.

Skylight filters are available in two strengths 1A and 1B, the latter being a slightly stronger pink colour.

Many photographers buy a skylight filter for each lens and leave them screwed on to protect the lenses’ front elements.

Skylight filters are available in round type that screw into the lens in ever size imaginable. They are also made by Cokin for the square filter system, and Hoyarex and the likes used to make them for their systems.

Links to buy
Hoyarex 011 Filter
Cokin A230

One of the more useful, but under used  filters in the Cokin kit is the Incolor 061. Unlike many of the other spot filters this one is practical and can be used in different ways for different effects. The spot filters with colour can look quite naff whereas this one can be adjusted to give a soft focus style effect or a lovely white vignette. This makes it perfect for wedding photography or portraits. The filter is available in A and P series and has a small hole in the centre.  When placed in front of the camera lens the hole will either appear small or large, hard edged or soft edged, depending on the lens focal length and aperture used. To get a large soft edge you should take photos using a longer focal length (around 50-80mm is fine with this filter) and use a wider aperture. If you want a more pronounced circle, use a wider lens and a smaller aperture.

The texture on the filter can be made to look white/grey or neutral depending on how parallel it is to the ccd/film…and if light is reflecting on the rear surface	You could focus lock on the filter so the subject through the hole is blurred and the filter texture sharp. This makes interesting creative shots.
A longer lens and wider aperture was used here. Notice how soft the edge is and how neutral the filtered area is.	Here the filter was adjusted so the spot was on the face. You can do this if the filter is hand held in front of the camera. The filter was held further away and angled so light reflected on it.
Here’s the filter being used to it’s best. Good choice of aperture and focal length gives a lovely diffused vignette.	Another version with a slightly more defined effect. Using the filter like this is great for wedding photography and romantic portraits.

You can buy the filter here: Cokin A series 061 Spot In color Filter

Hoyarex was a filter system developed by Hoya. Hoya was the big name in optical filters and then French manufacturer Cokin appeared with a system that would revolutionise the filter world.

Hoya reacted fast but not fast enough. Cokin had soon taken hold of the filter market with serious and special effect filters. Photographers were no longer buying one or two filters they were investing in cases full.

The Hoyarex system emulated what Cokin had done, but in our opinion did it better, some filters were glass, others had frames around them so handling was better. The holder was more flexible and had a more versatile lens hood. The filters slotted in more comfortably and the adaptors clipped in easier.

But they were too late and Cokin won the battle. Hoyarex disappeared as quick as they came.

You can still find remnants of the system sold in the second-hand sections of various photographic retailers, and there are a few on Photography Attic web site here: Hoyarex Filters

Wratten is a brand name from Kodak used for their series of coloured gelatin correction and conversion filters. There’s a wide range – each one identified by its Wratten number. The filters can be held or taped in front of the lens (or flash). Alternatively you can buy a gelatine filter holder for most filter systems for a neater way to attach the filter to the lens.

A Stepping ring is a ring with a female filter thread on one side and a male thread on the other. The threads are different sizes so a filter can be attached to a lens with a different sized thread.

There are step up and step down rings and these are always from the lens to the filter. If you have a lens with a 52mm filter thread and a 49mm filter you would buy a 52mm to 49mm step down ring. If you have a lens 49mm filter thread and a 58mm filter you would buy a 49mm to 58mm step up ring.

Take care that you don’t obscure the edges of the frame when using a stepping ring. This is more common on step down rings where the edges protrude into the frame and cause vignetting. You may also find the increased depth of the ring causes vignetting on wide-angle lenses. Use the camera’s depth-of-field preview to see if any vignetting is occurring.

The filter factor is highlighted on many filters as a mutliple (or x). Its simply the amount you need to increase the exposure by to compensate for light absorbed by the particular filter being used.

x2 is a one stop increase
x4 is two stops
x8 is three stops
x16 is four stops

So if you have a x4 orange on the lens, the exposure has to be increased by four times, or two full f/stops / shutter speed increments.

Lets say you have an exposure of f/5.6 (aperture) and 1/125sec (shutter speed) and added the x4 filter. You would either have to adjust the aperture two stops to f/2.8 or the shutter speed two stops to 1/30sec or both one stop so the exposure would be f/4 at 1/60sec.

Fortunately with modern through-the-lens (TTL) metering and automatic cameras the filter factor is taken care of, but you need to make the necessary adjustments when using manual cameras or manual exposure with flash.

To make things a little more complicated, some filters such as the polariser have variable exposure factors as you rotate the filter, and others have incremental factors such as 1.3x which makes it hard to adjust if you have an older camera with only full stop increments.