Full frame has 61 MP and can crop in 2x down to 30 MP and they still have as many pixels in the result photo as what I started with on my APSC shot. If I do the same crop on the APSC shot, it would make a 16 MP image. For the same focal length of 50mm FF equivalent, the full frame camera has double the detail. It also depends on the type of camera. That’s because, for APS-C cameras, you have to apply the crop factor. So, a 35mm lens on a full-frame camera is like having a 50mm lens on a cropped sensor. What focal length is best for family portraits? The short answer would be to get a focal length. Something that ranges from 35mm to 85mm or so. 85mm portrait lens. A short telephoto is typically the portrait photographer's favourite focal length - with a something around 56mm on a camera with an APS-C sensor or a 85mm on a full-frame I've got a question regarding focal length conversion of lens to/from APS-C sensors: Full frame lens to APS-C: 1.5(ish) X focal length. I get that since we're taking a larger area, and cropping it down by (theoretically) making the focal length of the lens longer, to bring down to the smaller sensor size of APS-C cameras For the full frame this value is 45mm but usually rounded up to 50mm for convince. For the compact digital (APS) this value is about 33mm. One last point: Over the years camera sizes have shrank due to technological improvements in film and imaging sensors. This trend will continue. The focal length of the lens consigned also reduced APS-C Effective Focal Lengths. Now that you know the crop factor of common sensor sizes, you can compute the effective focal length of any lens you may use. Assuming the 18mm focal length of the original topic, its effective focal length on a Canon APS-C sensor (i.e. 550D, 60D, 7D) would be: effectiveFocalLength = 1.6 * 18mm = 28.8mm, or 29mm Full-Frame vs APS-C Sensors. Focal Length Differences. How Focal Length is Measured; Full-Frame vs. APS-C Images; Cropped Full-Frame vs. APS-C Images; Crop Factor and Wide Angle Lenses; Body Size Differences; Megapixel and Image Quality Differences. Advantages of Larger Full-Frame Pixels; Comparing Megapixels in Full-Frame vs APS-C Sensor Log-log graphs of focal length vs crop factor vs diagonal, horizontal and vertical angles of view for film or sensors of 3:2 and 4:3 aspect ratios. The yellow line shows an example where 18 mm on 3:2 APS-C is equivalent to 27 mm and yields a vertical angle of 48 degrees. The rule of thumb, “expensive usually means better” doesn’t exactly ring true with full frame sensors – there are great benefits to full frame sensors but that doesn’t make them intrinsically “better” than APS C crop factor sensors. To better understand the pros and cons of full frame sensors, we have to ask: what is a full frame sensor? Introduction A 50 mm lens on an APS-C format (crop factor 1.6) images a slightly smaller field of view than a 70 mm lens on a 35 mm camera. The terms crop factor and focal length multiplier were coined to help 35 mm film format SLR photographers understand how their existing ranges of lenses would perform on newly introduced DSLR cameras which had sensors smaller than the 35 mm film format lOTuANw.