Originally posted by Albermarle Just wonder if anyone can describe how they believe the FF will work in crop mode.
1. in crop mode, the viewfinder magnification does not change in the literal sense. However, viewfinder magnification are based on 50mm lenses compared to the naked eye. Not 50mm-equivalent lenses.
This is why with the same field of view and the same magnification, a full frame viewfinder looks much bigger.
However, if you use a crop lens, this advantage goes away and you are back at comparing literal viewfinder magnifications.
In the case of Nikon, a few examples:
- D810, crop factor corrected: 1.06x
- K3-II: 0.95x
- D7200: 0.94x
- D3300: 0.85x
- D810: 0.70x
Therefore, you see the cropped image in the viewfinder appears smaller than in even the worst entry level SLRs. To compensate, the Pentax FF would have to have a viewfinder almost as big as Pentax MX, i.e., more like 1.0x. Unlikely to happen as even the most expensive full frame cameras have no VF bigger than 0.76x, not anymore
So yes, the cropped viewfinder image is a bit like a view into a tunnel.
2. Nikon is able (in some of their full frame cameras) to shade / mask the area in crop mode which won't be captured. This helps with the composition. Alternatively, Nikon has red guides to highlight the cropping region. Useful as it supports a 1.2x crop mode too.
Both features are absent in Pentax viewfinders. It remains to be seen what Pentax does to highlight the cropping region. My guess is just an engraving on the matte screen.
3. The rear screen LV shows the cropped region in crop mode.
4. The AF module in APSC cameras is actually more or less the same as the one in full frame cameras. I.e., the AF points cover a relatively small area all within the cropped area. That's because the full frame mount and mirror and AF sub mirror don't allow to cover a larger portion of the full frame view.
It is more extreme actually with the 645Z which still has the same AF module, covering the innermost portion of its frame only.
5. With fast moving subjects like birds in flight, it is much easier to frame full frame even in crop mode. Because you can still track a subject when outside the frame.
6. In practice, you won't use the crop mode but crop in post processing. Based on subject detail inthe corners and vignetting which depends on aperture, zoom and distance. The standard DA-crop mode from Pentax won't do most DA lenses justice on a full frame camera.