Thu 09-Aug-12 02:55 AM | edited Thu 09-Aug-12 03:07 AM by ZoneV
>Ok, I think I got it. I had been thinking that if I used a >FX lens and set a crop factor, it would have magnified my >image. Sort of like using a 100mm FX lens and achieving the >results of approximately 150mm. The same as putting the 100mm >FX lens on a D300.
No. You are stuck with the number of pixels in the DX sensor size. You cannot make new pixels by using the crop mode. The DX frame will always have less pixels than the FX frame when shot on the same camera using the highest resolution. But if the number of pixels in DX mode is enough for you, then you do get a final result that is equivalent to having extra magnification in DX mode.
Example: shoot FX. Resize for web to 800 pixels.
Example 2: Shoot DX. Resize for web to 800 pixels. It's sort of like getting more relative magnification for the output size.
Example 3: shoot FX and crop in post to DX format. Then resize to 800 pixels. Same result as #2.
It's really down to personal preference whether you want to use FX or DX framing mode when shooting with an FX lens. You can use either. But in DX mode, the cropping is permanent.
Basically, these are multi-format cameras. You get to choose your sensor size. But the result is the image will look different.
In conclusion, the DX image (lower resolution, cropped, smaller frame format) has to be magnified more when printing a certain size image. This is where the magnification comes into play...in the printing. So it's not free magnification. You have to sacrfice image quality to get it (less pixels per inch at the given output size)...it's just as if you'd used a camera with a smaller (DX) format sensor. But in the real world, this may be a small, un-noticeable sacrifice in image quality. For all intents and purposes, the extra magnification step (when printing) might come along as a free rider, and no one will ever know. In that case, it's like getting free magnification (sort of)...and the effect would be for all intents and purposes like you said...a 100mm lens acting as a 150mm (in terms of field of view and image size. I hesitate to say "magnification", because "magnification" is acutally a process, not a result of a process).