I used my 55 – 300mm Pentax zoom lens set at 107.5mm, f/5.6, ISO = 400, and 1/200 sec. to take the above picture.  This was a clear case where I needed the zoom’s focal length to reach across the pond.  The conditions were also such that I didn’t want to be changing lenses while out in the field.  Conditions like this, along with the potential of seeing wildlife, have made this lens one of my favorites except for when it isn’t.

There are many situations when the 55 – 300mm f/4-5.8 zoom is not my preferred lens.  These are when I find it too heavy to carry long distances, when I desire greater image quality such as sharpness, when I desire a faster lens, and when I’m working among people who don’t like to be “shot with a cannon.”  For those times, I prefer to use a prime lens.  I will occasionally use my 18 – 55mm zoom lens, but not often.  I don’t like the quality of the images as well as those taken with a prime lens so I generally only use the 18 – 55mm f/3.5-5.6 lens during inclement weather since it is weather resistant as is my K-5 camera.

But, the decision process of which lens to use is sometimes foggy since I can’t see into the future.  My preference when going out to take pictures is to decide which lens I’ll need before I go and then put it on the camera and not take any other lenses.  I usually manage with my decision, but not always.  I have three prime lenses for the Pentax K-5 … the 21mm f/3.2 (on order), the 35mm f/2.4, and the 50mm f/1.8, which give me effective focal lengths of 31.5, 52.5, & 75mm.  A big difference between Pentax and Nikon or Canon is that Pentax decided to produce small light-weight primes rather than fast primes; therefore, the Pentax primes are lighter and create a more discreet camera-lens combination than its competitors.  I love the smaller, lighter size of the system when using primes, but I still have to decide which one to use.  I try to error on a slightly wider focal length than I think I’ll need since I can then crop-zoom to get the composition desired.

I’m going to change my setup in order to decrease the chances of having the wrong lens with me.  If I know that the odds are high that I might need different lenses, I’m going to start taking a camera bag with an extra lens or two in it.  I have mostly avoided this in the past since I didn’t want to carry any more weight than necessary.  Since my circumstances have changed … my back is doing better and the weight isn’t as much of a problem, and I’m not out in the field for long periods of time any more … I am going to take a bag and multiple lenses.  But, this also means that I need to get familiar with changing lenses while out in the field.  I’ll let you know how it works for me and tell you a little about my bag setup as well as different strap arrangements at some later date.  My desire is to work the kinks out and have my techniques perfected before spring so that I can concentrate on taking pictures.

BTW … if you aren’t using prime lenses, try them.  I really prefer the image quality, the lower weight, and greater ease of carrying a more discreet system.  I’m looking forward to my new 21mm prime lens and will use my primes more than my zooms if I take less wildlife pictures.