Pentax-DA 560mm F5.6 ED AW

Started Mar 28, 2013 | Discussions thread
viking79
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Re: Pentax-DA 560mm F5.6 ED AW
In reply to Tom Lusk, Mar 28, 2013

Tom Lusk wrote:

From the intro:

With a focal length of 560mm (840mm equivalent in the 24x36 mm format),

Huh?

24x36mm is 135 format or "full frame". I imagine he brings that up since it is a DA lens.

So an 840mm lens used on full frame would look the same as this lens used on APS-C (field of view).  The lens is still a 560mm lens

I utterly despise the idea of "equivalent focal length" (too much confusion).  Spec sheets for C mount lenses list field of view for the various sensor sizes which is more logical to my Vulcan self.

I frequently see people misusing focal length and will say things like I have to have my 35mm lens for my crop sensor, when they really mean they want a 23mm lens, not a 35mm lens.  They leave off the term "equivalent", which is really confusing.  This is really bad in the Fuji forums or even on NEX forums sometimes, where there might be a lot of shooters more used to film, or somehow figure the only proper format is 135.

I think the Pentax forums are the only sensible ones regarding this, and likely because they lack a full frame model and have excellent support for APS-C lenses.

Sorry, I will get off my soap box now.

Eric

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