The .666 Factor

For photographers, “666”, this isn’t the sign of the devil, it’s a number to know when you are buying a lens or planning a photoshoot with your DSLR. You may not realize it but the focal length of your lens isn’t always what is advertised.

The 0.666 factor comes into play if you have a DX style camera. That’s a camera (both Canon and Nikon) with an APS-C sensor. Most entry level & advance amateur DSLR’s tote an APS-C sensor. An APS-C sensor is 66.6% the size than old school 35mm film – remember film? Although most people, at least the photographers I know, shoot digital the industry still uses the 35mm film size as the standard when calculating focal length for lenses.

Now, what does this mean for those photographers with an APS-C sensor DSLR? It means your 50mm F/1.8 lens actually has approximately a 75mm focal length. Your 18-70mm kit lens is actually a 27-105mm.

In many cases this is a good thing. It gives you extra reach with your lens. A mid-range zoom becomes quite long on the far end. However, it also means your wide angle lens isn’t so wide angle.

The simplest way to figure it out is to divide the focal length of your lens (again this only applies to an APS-C sensor DSLR, a DX camera in Nikon speak) by 0.666. Examples of a few common lens focal lengths:

Primes

• 28mm = 42mm
• 35mm = 52mm
• 50mm = 75mm
• 60mm = 90mm
• 85mm = 128mm

 Zooms  

• 18-55mm = 27-83mm
• 18-135mm = 27-202mm
• 24-70mm = 36-105mm

Of course, if you want to avoid all this then get a “full-frame” or FX camera. These are cameras with sensors whose size is equivalent to 35mm film. I won’t get into a discussion about which sensor is better, but at minimum you can expect to pay more for an FX camera than a DX camera. OK, personally I think an FX is better.

It should be noted many lenses are classified as “digital” and therefore are tuned for an APS-C sensor. Also, some lenses are considered a full-frame lens. I’ve used these types of lenses interchangeably, but a purest will likely call me out for the evils of my ways.

So remember, when purchasing a lens or planning your photoshoot think about the focal length you need and then plan your lenses choice appropriately. Either way, get out there and shoot!

Fast Glass

OK, I decided to finally purchase some faster lenses!

Since I switched to digital about 5 years ago I've used the traditional advance amateur lenses. I've relied on my Nikkor 18-70mm DX, 18-135mm DX and a recently purchased 70-300mm ED VR (replacing a non-VR version). I also use a Tokina 10-17mm AT-X DX Fisheye and a Tokina SD 12-24 AT-X DX wide angle lense. Except for a prime Nikkor F/1.8 50mm lens, none of my lenses are very fast. Most have F/3.5 at the fast end. I like to take lots of handheld street scene photograph and late night photoshoots. With my lenses I struggle with blur and/or noise unless I use a tripod.

I finally decided to buy a couple of F/2.8 lenses. I've been drooling over the F/2.8 Nikkor lenses, and have researched them for some time. Honestly, if it wasn't for the cost I would have only Nikkor lenses. Since I'm only an advance amateur I couldn't justify approximately $1,700 for a new Nikkor 70-200mm VR F/2.8, and the $1,000 plus cost of a shorter zoom lens with the same speed.

After much research and consideration I decided to purchase a Tamron SP AF70-200mm F/2.8 DI LD Macro, and an SP AF 28-75mm F2.8 XR Di LD Macro. Both were more in my price range, although I realize "you get what you pay for". So far I'm happy with the purchase. I purchased both at Roberts Camera. Both lenses combined were approximately $500 less than the Nikkor AF 70-200mm VR F/2.8. Again, if money wasn't an issue I would be a proud owner of two new Nikkors.

Here is the AF28-75mm lens. This will become my "keep on the camera" lens that I will use most of the time. I will regularly interchange this with my Nikkor 18-135mm lens for most of my shots. What I like about this lens is the F/2.8 speed, it's clean lines and it's sturdy build. Also, it has a slightly longer zoom range out to 75mm, although not a huge plus, but nice. I took some test shots and so far I like this lens.

The lens weighs in at 510g with a filter size of 67mm. The lens comes with a Bayonet type lens hood because the lens is IF.

The SP AF70-200mm F/2.8 Di LD Macro is a beast. It weighs in at about 1150g and is very sturdy. Its not as elegant as it's Nikkor higher end brother. The BIGGEST drawback is that it does not have VR, but please note my comment above about price. I took several test shots at different focal lengths and the lens shake isn't as bad as I expected. With the faster speed I am confident that I can use it in most hand held situations. I normally use a tripod with all my night photoshoots so this won't be an issue.

The lens comes with a huge bayonet type lens hood and a 77mm filter size. I really like the feel and the look of this lens when mounted. Also, if I ever get hassled in any of my late night photoshoots I can use the lens as a club...

So far, I'm really happy with these 2 lenses and I'll post a few shots using the lenses in the near future.

Hats off to Roberts Camera for helping me with these purchases. I knew what I was looking for and what I needed, so the sales guy let me do my thing. He provided help when I had a technical question and when I wanted to try out all the other F/2.8 lenses including the Nikkors.