Welcome to another session of Photography in 90 seconds. In this episode I will introduce you to a cheap method for doing macro photography, the practice of taking close-up photographs of small objects, like insects, coins, flower petals, or any number of things.
The standard practice is to use something called a ``macro lens'', which allows you to focus at close distances, and achieves a magnification of at least 1:1 or greater (i.e., the object photographed is projected as life-size on the sensor). Such lenses, however, are very expensive.
Fortunately, there are some much cheaper options. One such option is to use what is called a "reversing ring." A reversing ring does what it sounds like, it allows you to attach a lens in reverse, by screwing the lens onto to the camera using the filter ring, instead of the standard mount. For this to work, however, you will need two things:
1. A 50mm lens with a manual aperture ring. Almost 50mm lens from the 35mm film days will work (except for a Canon EOS mount).
2. A reversing ring which matches the filter size of the 50mm lens. This will normally be 52mm or 49mm. Make sure you buy an adapter with the same filter size as your lens, and one that fits your camera type (i.e., for Canon, Nikon, Pentax, etc).
To use this setup, simply (a) attach the lens to the camera in reverse, i.e., using the filter ring; and then (b) move the camera closer or further relative to your subject to achieve proper focus. This is manual focussing at its purest. Voila! You have a cheap but effective macro lens. Now go have fun. Just be mindful of the shallow depth of field. Stopping down the aperture somewhat is essential.
You can purchase reversing rings and old 50mm lenses on ebay.
Custom White Balance is the process of setting the neutral gray reference point manually, rather than relying on your camera’s Auto White balance (which typically only approximates neutral grey.) Custom WB is an important step for anyone who is serious about achieving accurate colours in their images. If you are shooting RAW single images, then you can just take a picture of a spectrally neutral grey card and set the WB in post-processing. However, if you are shooting JPEG or Video, it is important that you set the custom WB in your camera before shooting. How you do this is dependent on your particular camera, but it will involve taking a picture of the gray card (fill the frame as much as you can) and then telling the camera (via its menu system) to use that image as the neutral reference point. You will have to read your camera’s instruction manual for the particular details of those simple steps. Now, once you have the Custom WB set, you will likely have to manually rotate the WB dial or indicator from AutoWB to Custom WB. (Again, the specifics will vary for each camera manufacturer. Once you have that stuff set, you are good to go shoot your videos without having to worry about trying to do onerous colour correction in post-processing. Good luck!
I discuss ISO and other related topics (aperture, shutter speed, histogram, and so on) in my recently completed an introductory photography book: "A Concise Introduction to Photography."
ISO is a measure of the sensitivity of your film or digital sensor. In this episode I discuss the basics of ISO and how it relates to exposure and noise.
In this 90 second tutorial I show how you can create a black and white image by copying the luminosity channel in LAB mode and pasting it into each individual channel in RGB mode. I find that this generally produces good black and white results from a colour image.
If you're image is too light or dark after completing this process, duplicate the layer and change the blending mode to multiply or screen and then adjust the opacity to suit your needs.