You can find a selection of second-hand Cokin filters and adaptors including some hard to find sizes here: Second-hand Cokin Filters
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.
In the early days of the polarising filter there was just one type – the linear. The circular type arrived when the cameras with advanced metering (and later focusing) systems arrived. The Canon T90 and Olympus OM4 both had new advanced TTL metering that would be affected by the way a linear polarising filter worked. So A circular had to be used instead.
Later, when autofocus came along, some systems got confused by the affect of the polariser. So, as a rule of thumb, use a linear on old manual and semi automatic cameras and circular on newer modern multi menu models.
If you do have a linear filter and a modern sophisticated digital SLR it will still work, but you may get inconsistent exposures. This is easily rectified by looking on the LCD preview and reshooting with necessary compensation applied.
The top ten filters you should own will obviously vary from person to person but our choice is most definitely the following:
- 1 Circular Polariser (glare reduction and colour saturation)
- 2 Grey Grad 4x (balance sky brightness)
- 3 Skylight (protects lens)
- 4 Neutral Density x4 (reduces overall exposure)
- 5 81A (warms up skin tones)
- 6 Close up +4 (for the macro shots)
- 7 Grey Grad 2x (a weaker variation on 2)
- 8 Neutral Density x8 (a stronger variation on 4)
- 9 Softar style diffuser (best softener for when you cant be bothered doing it in Photoshop)
- 10 Star 8 (Adds star burst to shot – great for jewellery)
Good selection? Let us know your top ten.
The ND filter is one of the more useful additions to the filter bag. Digital image processing can do many things but it can’t reduce the light reaching the film or CCD. That’s the job of the camera’s exposure system and an ND filter throws in a helping hand.
The name explains its purpose. It’s neutral (in colour) and it has a density (level of opaqueness)
Neutral Density filters come in a range of densities. The basic ND2 is 2x exposure factor (or one f/stop) and an ND4 is 4x (two f/stops). There’s also an ND8 (8x or three f/stops) and a less common ND64 (64x or six stops).
The filter goes over the lens and reduces the light reaching the film by the exposure factor of the filter.
If for example you had an exposure of 1/125sec at f/11 and you added an ND8 the shutter speed would reduce to 1/15sec or the aperture would need to be opened to f/4.
The reason to use an ND filter suddenly become obvious. If you want to force a slow shutter speed, for motion blur, or you want the lens at the widest aperture, for shallow depth-of-field, the ND filter can help.
It can also be used in combination with a flash to effectively reduce the guide number for close range photography.
The ND2 is hardly worth bothering with so we’d suggest you’re first ND filter be a ND4.
