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Aboudd · 06-14-2011, 04:43 PM

Originally posted by Digitalis

no on a 24X36mm sensor the Pentax 150-300mm f/5.6 @ 300mm it will behave like a 300mm lens, a slow 300mm lens.

In other word,it's roughly 80% of the length to equal a FF 35mm perspective on the 645 D

jwjohnson · 06-14-2011, 04:49 PM

The crop factor is around .75 - .80 relative to FF 35mm depending on if you are concerned about horizontal or vertical size since the form factor is different. The 300 would behave as a 300 on a full frame 35mm camera, but putting it on the 645D would give you the equivalent of about the 234mm on FF 35mm.

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06-14-2011, 04:43 PM	#16
Aboudd Senior Member Join Date: Jun 2011 Location: Arlington, VA Posts: 187	Originally posted by Digitalis no on a 24X36mm sensor the Pentax 150-300mm f/5.6 @ 300mm it will behave like a 300mm lens, a slow 300mm lens. In other word,it's roughly 80% of the length to equal a FF 35mm perspective on the 645 D

06-14-2011, 04:49 PM	#17
jwjohnson Junior Member Join Date: Jan 2011 Location: United States Posts: 36	The crop factor is around .75 - .80 relative to FF 35mm depending on if you are concerned about horizontal or vertical size since the form factor is different. The 300 would behave as a 300 on a full frame 35mm camera, but putting it on the 645D would give you the equivalent of about the 234mm on FF 35mm.

Crop factor of the 645d

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