Regular readers may know that I have a 7.5mm Fisheye Lens for my Micro 43 cameras. Whilst it doesn’t get used all that often, it’s a great lens, very well priced and is incredibly well made. If you haven’t seen one check out this link on Amazon (http://amzn.to/1QyJzUJ) and take a close look at the focus scale in the picture of the lens.
This lens is certainly one of the sharpest lenses I have and the depth of field is incredible which you can see from the depth of field scale. With the aperture wide open at f/3.5, I can easily achieve a depth of field from 12 inches to infinity. In fact the depth of field is so great that I tend to forget about it when shooting landscapes. I simply set the aperture to f/5.6, set the focus on infinity and shoot away without bothering to focus any further.
This is a useful approach as the lens is manual focus and you don’t need to worry about zooming in on the back of the camera to check the focus before shooting. And this was my downfall. You see I decided to use the lens on my Infrared camera. What I forgot is that infrared light focuses closer than infinity and this lens doesn’t have any IR focus markings to remind me. What made me feel even sillier is that I was also shooting IR film in my XPan at the same time and using the IR focus scale on that cameras lens.
By the time I realised my mistake most of my shots had been lost. In the end, the one you see here was manually focussed by setting the focus scale to (very spookily) what you see in the amazon picture. If you look at this, although I had been shooting at f/8, there is no way the image would have been in focus when I had the focus set to infinity.
So lesson learned. When shooting infrared using a manual focus lens, focus on the back of the camera and don’t rely on depth of field markings.
In case you’re wondering, the image here did start of in focus but has been deliberately blurred using Nik Analog Efex. You can’t do that when the image is out of focus.
The Lightweight Photographer 