A Few Tips for Using Rectangular Filters in Photography
- By: Luis Argerich
This is the first article of a two part series about the world of rectangular filters. These are the ones you use along with a filter holder instead of screwing them to the lens. The most popular filter used from a holder is the graduated neutral density filter (grad-ND) and I will discuss a basic setup and a few tips.
I’ll be skipping the discussion between using filters vs taking 2 or more photos and combining them digitally. Let’s say taking 2 photos is not an option because of movement in the scene or because you like to use filters.
Why you may need to use rectangular filters
The big difference between rectangular filters and the circular screw-in filters is that you can move rectangular filters and place them in different ways in front of the camera. This is needed for graduated filters as the horizon line, or the line where illumination changes, may not be in the same place for every photo. So you put the filter in the holder and move it until you get the effect you want. You can even hold the filter in front of the camera with your hand if you don’t have a holder.
About Filter Holders
I normally use Cokin-P size filters and holders even with a full-frame camera, the reason is simple: I can find very cheap holders and accesories and the good quality filters are cheaper too. If you have to choose spend money in the filters and not the holders. The holder won’t affect image quality. One holder is enough and you adapt it to your different lenses putting different rings on the back. There are rings from 52mm to 77mm depending on the filter size of your lens. Singh-Ray, HiTech and Lee produce excellent rectangular filters that won’t change the colors in your photos.
If vignetting is a problem I use a 1-slot holder. These are special for wide angle lenses where vignetting can be a problem. If you only use 1 filter this is probably the holder you want to use as it minimizes the risk of vignetting.
Using Graduated Filters
There are many types of graduated filters, you can choose how dark they are and if you want a soft or hard transition. I normally use 3 stops or darker filters because if less is enough then the camera’s dynamic range will probably be ok for the scene. A filter that I find really useful is the “reverse” graduated ND filter. In a reverse grad the darkest part of the filter is not at the border but in the center (horizon). Reverse grads are needed whenever the horizon is the brightest area of the scene and that’s common in sunrises and sunsets. If you like to shoot sunrises and sunsets then you need a reverse grad and not a regular graduated filter.
Normal grad filter on the left and reverse grad on the right. You can see how the darkest part is on the border for the regular grad and in the center for the reverse grad.
Adding a Polarizer
If you want to combine a polarizer with a rectangular filter you have different solutions. You can use a screw-in polarizer, rotate it until you have the effect you want and then attach the filter holder to the polarizer to use the graduated filter. This setup is not available if your polarizer is of the slim type without frontal filter threads.
A second solution is to use a polarizer for the filter holder, these are available and work exactly as any polarizer filter but they are placed in the filter holder and you can rotate them to get the effect you want.
Adding a lens hood
If you want to avoid flares in your photos and you are not using a wide angle lens you can combine the filters with a lens hood using modular hoods for the filter holder. You can add as many modules as you want depending on the focal length you are using to avoid flares without adding vignetting problems.
The photo shows a filter holder, a rectangular filter and 3 modules of lens hood used together.
Rectangular filters are used to give the photographer flexibility about the way the filter will affect the scene, using the holder the filter can be placed in different positions for different effects. Rectangular filters can be combined with a polarizer and lens hood without a problem.
In my next article I will discuss a few tricks you can do with filters. Stay tuned.