APS Size Digital Sensor: Crop or Multiplier?

[kai_griffin]

SF CA, the only thing "imaginary" about it is that the term "crop factor" assumes that a 35mm film frame is the standard by which all things should be judged. To a person who has never used 35mm film, the term has little meaning, because as far as they are concerned what they see through their digital camera with a particular lens mounted is "normal & standard". Crop factor? What crop factor? They might ask... and they'd be right, from their point of view.

 

From the point of view of someone who is used to 35mm film, the crop factor manifests itself by reducing the field of view they get from their lenses. If they're used to their 50mm lens providing a certain field of view on their 35mm film cameras, they'll be more acutely aware of the significance of the crop factor when they use the same lens on a digital body. There are other subtle issues, alluded to by others above, but the major issue that hits most people straight away is that reduced -- cropped -- field of view. Personally, I think you get used to it quickly enough... though the need to buy ultra-wide lenses to achieve moderarly wide FOV's does hit the wallet a bit harder! And that, of course, is precisely why we now see cheaper digital-only lenses on the market that don't require the same expensive optical hoop-jumping that you find in full-frame ultrawides. It brings wider angle lenses at a more economical price to smaller-sensor cameras.

[greg_whitten1]

Thanks to all of you for chiming in. Here is a link from luminous-landscape.com that explains this and, more importantly (to me), has comparison pictures:

 

http://www.luminous-landscape.com/tutorials/understanding-series/dslr-mag.shtml

 

Greg

[John Crowe]

What it also means is that certain x-factor DSLRs can actually challenge the full frame DSLRs for super telephoto duties where perhaps the super telephoto you have is not long enough to fill the frame of the full frame camera in particular situations. In these cases you may end up cropping the full frame image for display purposes. The already cropped image of the x-factor camera may have just as many pixels as the cropped image from a full frame DSLR. Now, if you actually manage to fill the frame with the full frame DSLR or whip out a 1.6 times bigger lens, then it's another story.

 

 

I do lots of sport photography with a 400mm f2.8 and a 1.4x converter and I could see many instances where this combination will not fill the frame of a full frame DSLR but it would fill the frame of a 1.6x factor DSLR. I have crunched the pixel numbers, and I don't feel too bad about not being able to afford a full framer for a few years yet. Of course at the other end of the spectrum my 14mm would be absolutely wasted on a 1.6x DSLR, so I will have to continue with film for awhile.

[topher]

<i>...because the perspective of the lens (eg 'telephoto compression' effects) doesn't change.</i>

<p>

Mostly because there is no such thing as perspective of a lens.

<p>

Perspective is totally determined by subject to camera distance. Please look it up in any introductory camera book.

[jcuknz]

"Greg Whitten , mar 14, 2005; 05:37 p.m.

Thanks for helping me with that. Now that I know my 70-200 is still a 70-200 and not a 120-320, I realize I need a 300mm or 400mm prime!"

 

Only if you want a 480 or 640 equivalent lens.

I fear that you are still confused :-) .....While your 70-200 is still a 70-200 with respect to aperture and focus you have effectively turned it into a 120-200 by using a smaller than full frame sensor behind it with respect to the angle of view.

It has been pointed out the DoF will be different as well due to the greater magnification required to produce a given print size. [less DoF]

 

Which is why my Nikon 8.9-71.2mm lens is effectively a 35-280 lens with regard to it's angle of view in SLR terms ... but with the DoF of a shorter lens.

I run a x2.2 converter on my Pansonic 6-72mm lens which turns it into a 950mm SLR equivalent for angle of view.