A question (or two) about crop factor and field of view.

**Madaboutpix** · 01-04-2020, 03:11 AM

The number that you entered on being prompted is the focal length, which is indeed 50mm, not a diameter. And the lens will behave like any 50mm on Pentax APS-C, namely as a short telephoto lens. The FOV will be basically the one you would get with a 75mm (50mm x 1.5 crop factor) short telephoto lens on FF.

Enjoy shooting your nifty-fifty. They're fun on APS-C.

Last edited by Madaboutpix; 01-04-2020 at 06:01 AM. Reason: Illustration added

Penview52 · 01-04-2020, 07:37 AM

The digital crop sensor was invented because the full frame sensor ( old type ) is very expensive in the making. Since any crop sensor can display image by up scaling the object as seen on lcd or viewfinder there is no increase or decrease of size of captured image. The focal length rule is just to make the object move closer or further as viewed. There are also smaller sensor than type -c which do the same function. A curious mind needs input to fill up his ... and be happy.

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01-04-2020, 03:11 AM	#16
Madaboutpix Site Supporter Join Date: Dec 2011 Location: North Rhine-Westphalia Posts: 1,448	The number that you entered on being prompted is the focal length, which is indeed 50mm, not a diameter. And the lens will behave like any 50mm on Pentax APS-C, namely as a short telephoto lens. The FOV will be basically the one you would get with a 75mm (50mm x 1.5 crop factor) short telephoto lens on FF. Enjoy shooting your nifty-fifty. They're fun on APS-C. Last edited by Madaboutpix; 01-04-2020 at 06:01 AM. Reason: Illustration added

01-04-2020, 07:37 AM	#17
Penview52 Veteran Member Join Date: Apr 2017 Photos: Albums Posts: 327	The digital crop sensor was invented because the full frame sensor ( old type ) is very expensive in the making. Since any crop sensor can display image by up scaling the object as seen on lcd or viewfinder there is no increase or decrease of size of captured image. The focal length rule is just to make the object move closer or further as viewed. There are also smaller sensor than type -c which do the same function. A curious mind needs input to fill up his ... and be happy.