by MiserereEver noticed how many things in life come in threes?
The 3 Stooges,
the 3 Musketeers,
the 3 Tenors,
the 3 Wise Men...and your friends will always give you 3 cheers. So too do primes come in threes.
Last week I wrote about
my love of primes, and hopefully I got some of you to put away your zoom lens for an afternoon and go shooting with a prime instead. Did you have fun? Did you enjoy shooting at lower ISOs? Did you show off to your friends because their primes weren't image-stabilised while yours were thanks to Pentax's in-body IS? I hope you replied "yes" to all of the above.
Let's make it clear that I am not advocating that you throw away your zooms, only that you broaden your horizons...and your tools. There is a time for zooms, and a time for primes. When you've spent enough hours shooting both you will know exactly when you need, or want, either of them.
But how do you go about setting up a 3 prime lens kit? With zooms, you just choose a wide angle zoom (18-55mm, 16-45mm, 16-50mm...) and a telephoto zoom (50-200mm, 55-300mm, 50-135mm...), with the depth of your pocket being the determining factor as to which ones you pick. How could that be easier!? Primes are another story, because there are many focal lengths and apertures to choose from.
Superman says 28mm is normal.Back in the day it wasn't so difficult. Most photographers had a wide, a normal and a telephoto lens. Wides were usually 24mm or 28mm; normals were somewhere between 35mm and 55mm (depending on what "normal" meant to each photographer) and telephotos were between 100mm and 135mm. The rule of thumb was to pick focal lengths that were about 1 stop apart in length, such that each lens had half the field of view of the preceding one (which is double the focal length). Possible combinations following this rule could be 28mm, 55mm and 105mm; or 24mm, 50mm and 100mm. Then, as now, which particular flavour you chose of each lens depended on your pocket. If you could afford it, you would have picked a 28mm f/2 and a 50mm f/1.4. More thrifty photographers would have gone for the more affordable 24/28mm f/2.8 and a 50mm f/2.
In 2001 Pentax made the choice of a prime trio easy for those who could afford it by issuing the 31mm f/1.8 Ltd., last of the three FA series Limited primes. Those who wanted the very best in construction and image quality could buy a 31mm f/1.8, a 43mm f/1.9 and a 77mm f/1.8. While these numbers might seem like they were pulled out of a bingo ball after too much sake was drunk at a Pentax New Year's party, they actually do make sense. 43mm is the length of the diagonal of 35mm film, which makes this limited the epitome of "normal" lenses. 31mm offers a FoV that is about 1-1/3 times wider than 43mm, while 77mm is a little over 1-2/3 narrower than 43mm.
50mm is the king of primes.The problem is that all these focal lengths I'm quoting are for 35mm film. What about those shooting digital Pentax? Fret not, there is still hope. Pentax thought of us APS-C guys and introduced a line of DA Limiteds: 15mm, 21mm, 40mm and 70mm; and all but the 15mm are pancake lenses! While the 40mm and 70mm lenses are longer than their FA Ltd brothers (61mm and 107mm 35mm equivalents), the 21mm is a 32mm-equiv. However, the DA Ltds. are actually closer to the classic 28/55/105mm trio (in FoV, when mounted on APS-C) than their FA counterparts and are more versatile for it. The upcoming 15mm f/4 Ltd will provide a 23mm-equiv. FoV in a small package, for those that want something wider than the 21mm f/3.2 Ltd.
OK, but how about those who are on a budget? Again, Pentax is here to help you, because you can use Pentax's backwards compatibility to your advantage. There are literally tens of thousands of K, M, and A prime lenses out there in the used market looking for a new home, and unlike with other brands, they will work on your Pentax DSLR (although some functionality might be lost, you will never lose the ability to meter, even if it means pressing an extra button). Claim a 28mm f/2.8 for well under $100 and use it as your normal lens. Get a 50mm or 55mm as your short tele lens, ideal for portraits on APS-C. If you don't want to jump for a new FA 50mm f/1.4, get an M series version. If you want the versatility of being able to use Av or Tv, why not try the crowd favourite SMC-A 50mm f/1.7? (Just be sure to enquire as to the health of the aperture ring, because they tend to break easily for this particular lens.) If you want wider angles than 28mm or 24mm, Pentax can offer you the K or M series 20mm f/4. And don't be shy, there are also plenty of 3rd party options available. And remember, while these older Pentax primes might be old, they are made of metal and glass, have long focus throws, and are a joy to use. Once you get one, you might find yourself sitting in front of the television turning the focus ring this way and that, just because it feels good.
135 is not just an abstract number.And what's my prime trio of choice? 24/28mm, 50mm, 135mm. Yup, I might be shooting APS-C, but I still like the old classics. I guess I'm not really a wide guy when it comes to photography. I can't sing much either.
To finish off, I want to remind you all that Pentax has always been known for its marvellous primes. You will find many photographers who will tell you the only reason they chose the Pentax system was because of their prime line-up. Even today, Pentax are continuing to release primes while other brands are busy churning out only zooms.
So be true to tradition and start doing your math: figure out which is your normal focal length, then divide and multiply by 2. Now get on the internet or visit your local pawn shop and get yourself a nice trio. They may not sing like
The 3 Tenors, but they might make
you sing when you see what you can do with them.
When you're done with your photography session, don't forget to give yourself 3 cheers.
Thanks for reading.
Miserere
AF Lenses for Digital (APS-C): 
PENTAX DA 10-17mm F3.5-4.5 ED (IF) Fish-Eye - $429.95
PENTAX DA 21mm F3.2 AL Limited - $424.95
PENTAX D FA 50mm F2.8 Macro - $394.95
PENTAX FA 50mm F1.4 - $199.00
We took advantage of the situation and took many pictures. In some areas, the sun was piercing through the thick fog, and projecting rays of light. The atmosphere was almost magical. Of course, with pictures, you can capture the visual, but the birds chirping, the wind whistling through the trees, the smell of fresh mountain air cannot be expressed with any pictures. For us, every time we look at the photographs, we hear the sound and we smell the smell in our minds. 
