Important Things To Remember About IR Contrast!
Infrared converted camera systems are inherently low contrast. This is not a fault of the process but rather with the equipment. You will notice when using different IR converted camera systems that some will generate higher contrast images better than others. The Canon 5D was one of these. Others (most others in fact) generate lower contrast images. The Olympus PEN family falls into this later group. This is not big deal as most IR camera systems are like this! There are several things that you can do to overcome this issue both in camera and in the computer during post processing. Here we will overview these options and techniques for your consideration.
Due to the nature of Infrared light, lens design and sensor sensitivity the camera will always produce low contrast images. There are several rules to follow in order to increase contrast and image quality.
- Always use a Lens Hood. The reason for this is obscure but valid. When light approaches the lens from an extreme angle it has a tendency to hit the objective lens (outside lens) and bounce around the inside of just the objective. This interacts the direct light passing through the objective at a straight angle! What this does is cause a direct loss of contrast and in the worst case a series of sun/lens flairs!
- The choice of Infrared Filter directly influences the camera contrast. The lower in frequency that you go (higher nm number) the greater the in camera contrast will be. So if you find that you shoot most of the time with a 590nm filter and complain about overall contrast, switch to a higher number, say around 720 or 800nm. You will be VERY surprised at the increase in contrast!
An now a secret! Add a polarizing filter, it will not have the same affect as in color work but it will really increase in camera contrast! This is not widely known but it works very well. If you have room on your camera lens (how many filters are there?), the addition of a polarizing filter will really make the darker areas of the image pop without adding noise! Remember, as with all filters, buy the best that you can afford because you only want the highest quality glass in your image path!
Digital image sensors are always soft, this is the nature in which they were designed. You MUST Post Process your image files in Photoshop to overcome physical limitations built into the hardware.
Increase contrast using one of the many tools in Photoshop: Levels, Contrast/Brightness, Curves, Clarity and within NIK filters: Structure. This will increase contrast plus sharpen the image which in itself will increase contrast!
You must be a little careful here, too much contrast will detract from your image. Dark black areas will turn totally black and loose all tonality within their area. This is called “blocking up” and you must learn to avoid this. The old adage “too much of a good thing….” really comes into play here!
Simple, but you would be surprised how many photographers neglect these simple steps! A few seconds of fore thought and 1 or 2 steps in your post processing work flow is all that it takes to generate wonderful emotionally high impact images that will wow your viewers each and every time!
The final two images show the difference between using a Polarizing Filter and not. The first is without it and the 2nd is with. Both were taken at the same location on the same day.