Lens focal length terminology

[RABaker]

I have to apologize for the (very) lengthy and probably overly-detailed response I provided earlier. I fear I may have added to the confusion by providing more information than was needed.

Just in case it might help, here are a couple of examples of the lens information available from a popular online retailer (B&H), and I'm pretty sure B&H got this directly from Nikon literature. To find this data, simply click on the "Specifications" tab on the B&H web page for a lens:
http://www.bhphotovideo.com/c/produc...mm_f_1_4D.html
http://www.bhphotovideo.com/c/produc..._70_300mm.html
Note that I own Nikon equipment so I don't normally look at other lenses and I'm not sure if other manufacturers routinely provide exactly the same information - but I would be very surprised if the information isn't available from their websites, if nowhere else.

The first lens is a Nikon 50mm f/1.4 and you will notice that it lists Format Compatibility as as "Nikon FX/35mm Film" [full frame] along with "Nikon DX" [APS-C]. The next row down is Angle of View which shows "46°" for the FX, and "DX Picture Angle: 31°."
The second link is to a Nikon 70-300mm zoom lens. Again the Format Compatibility lists both FX and DX. The Angle of View shows 34°-8° for FX and 22°-5° for DX. All the cameras specify whether they have FX or DX sensors. If you review more Nikon lenses, you will find many that list Format Compatibility as DX only, so these will have only the DX AOV figures shown.

As stated by others, what really counts is what you see when you look in the viewfinder. However, sometimes in order to make a decision about what lens you might want to consider (when you don't already have one in that focal length range), it can be useful to know the angle of view as well as other specifications. Hopefully, having this information readily available to you will simplify things for you.

Good luck,
Richard Baker

[rtrsr]

Thanks to all. I have enough to go with. Richard Baker's comments were especially hrelpful.
This was my first chat room experience with PopPhoto. I learned a few things: Be very clear about the question or the subject. But if replies come in from left field, be patient - eventually someone will figure out what you really mean.