Today’s Post by Joe Farace
A crop sensor refers to any sensor smaller than a full frame sensor or a 35mm film frame.—Wikipedia.
It used to be called the “multiplication factor” but “crop sensor” caught on, I think, because it has fewer syllables, It’s a term I hate because it’s based on the assumption that the only relevant sensor size is 24x36mm, the same format that Oscar Barnack developed for the original Leica in 1925. You can read my rant on that subject here. But there are different size sensors in different cameras; case in point…
Leica’s Summilux-M 24mm f/1.4 ASPH ($7,495) is a fast prime lens that was designed for digital and film-based M-mount cameras, including Leica rangefinders and cameras like my Zeiss Ikon SW. The lens incorporates a series of anomalous partial dispersion glass elements and one aspherical element to control color fringing and aberrations to improve sharpness. Floating elements are used to maintain image quality throughout the focusing range, which is from 2.3-feet to infinity.
How I made this shot: The top photo of the below comparison was made with a borrowed 24mm Summilux-M f/1.4 lens that was mounted on a (borrowed) Leica M8.2 digital rangefinder camera producing an angle-of-view but not necessarily the perspective of a 32mm lens. Exposure for the photograph was 1/250 sec at f/11 and ISO 160.
For the bottom image, a similar exposure was made while I was standing in the same spot but the lens was now mounted on my Leica M6 TTL film camera that was shooting a roll of Fujicolor Pro 160S color negative film from my freezer. When shot this way, the lens produces the full 84-degree angle-of-view.
There are some differences in color tonalities between the two images but I tried to get them as close as possible in Photoshop so you could focus on the differences in the angle-of-view when mounted on different cameras. With the M8.2 you get a nice photo of the tractor but when shot with the M6 TTL you will also see part of the truck the tractor is sitting on as well as part of the event grounds in the background.
The Leica M8.2 had a 1.33 crop factor, while the newer Leica M (Typ 240) features a 24MP full-frame CMOS sensor so the field-of-view would exactly be the same for my M6 TTL and that newer digital camera.
And if you’ve ever wondered about the whole “equivalency” thing, now you know the rest of the story.
If you enjoyed today’s blog post and would like to buy Joe a cup of Earl Grey tea ($2.50), click here.
Along with photographer Barry Staver, Joe is co-author of Better Available Light Digital Photograph that’s now out-of-print but new copies are available from Amazon for $21.88 and used copies are four bucks. For some reason, the Kindle price is really high.