Focal Length Comparisons

With the advent of digital SLR with APS-C sensor, 10 and 12mm have become common focal lengths for wide-angles. 10mm lenses (e.g. Canon 10-22, Sigma 10-20) offers a pretty wider angle than 12mm (e.g. Tokina 12-24, Sigma 12-24, Nikkor 12-24).

The Sigma 12-24mm is the only 12mm that works on fullframe (24x36mm) cameras - it offers an amazing and unparalleled angle of view. A 14mm lens - the widest rectilinear wide-angle in Nikon and Canon lineup - has a pretty narrower angle of view than Sigma 12-24, and 16mm (e.g. Canon 16-35 f/2.8) does not come even close to the amazing angle of view of a 12mm.

The Canon 17-40mm is the widest wide-angle for fullframe cameras in the same price range of the Sigma 12-24. The Sigma lens has an huge advantage!

17-55, 17-85 and similar zooms, created for APS-C cameras, offers a pretty wider angle of view than standard zooms for FF cameras, as the Canon 24-105 L IS. Even though I prefer the latter, it is necessary to combine it with a good wide-angle lens if you want a good wide-angle coverage. 

24 and 28mm are common focal lengths for mid-range zooms. Whenever possible, I'd recommend a lens that starts at 24mm, unless you already have a lens that covers the widest focal lengths.

In wildlife photography, the 300 f/4 is often compared with the 100-400 and 400 5.6. Unless you photograph very collaborative subjects, you would often use the 300 f/4 with 1.4x, to compensate for the much shorter focal length.

The difference between a 280mm (70-200 + 1.4x), a 300mm (as the 70-300 VR or a 300 f/4 without TCs) and 420mm (300 f/4 +1.4x). If you have Nikon, in my opinion the 300 f4 AFS + 1.4x TC is the best choice for wildlife in its price range - the 70-200 VR is too short, and the only other lens that offers a comparable focal length (the 80-400mm VR) has very slow AF and average image quality.

The f/4 supertele comparision - 420mm f/4 (300 2.8 + 1.4x TC) in comparison with 500 f/4 and 600 f/4.

One of the most common doubts of wildlife photographer that are trying to choose a big lens: 500 or 600? The 600 offers a considerably higher magnification, that is great for small or shy subjects.

The 600 f/4 supertele with teleconverters - 840mm (600+1.4x) and 1200mm (600+2.0x). Of course, this comparision holds true for every lens with 1.4x and 2.0x teleconverters.

How to create your own comparisons

If you want to create your own comparisons, you can use this simple calculator. How to use it:

1) First, choose a photo that you want to use as sample, and resize it to a given format - personally, I always use 720x480px. 

2) Put the measures of the resized image in the Height and Width box in the first row of the table. By default, these values are set on 480 and 720 pixels. 

3) Enter the two focal lengths that you want to compare in the Focal (mm) fields. The shortest FL should be in the upper field.

3b) If you want to compare two lenses on cameras with different sensor sizes, select the appropriate value in the "Sensor Size" box.

4) Click on "Calculate". The script calculates the height and width for the second focal length.

Open the sample image in Photoshop and click on Image>Canvas Size; enter the new values of height and width (in pixels). The photo will be cropped to simulate the FOV of the longer lens. Now, you just need some basic PS skills to create the comparison using layers and transparencies.

Do you have comments or questions?

If you have comments or questions about this article, feel free to ask in the Juza Nature Photography Discussion Forum!