Archived posting to the Leica Users Group, 2015/01/05
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]People always spoke of the sanctity of never cropping their pictures. People in Magnum even did that. But I suspect it was all about the precious thin black borders. A print in the stack with no black border stood out as weak. On 1/5/15 8:46 PM, "Ken Iisaka" <ken at iisaka.com> wrote: > Yes, Mark, been there done that. > > Also, when using shorter lenses, such as Zeiss Hologon, the actual exposed > area on the film was slightly larger than the actual aperture of the > shutter, since the rectangular aperture was a millimeter or two in front of > the film surface itself. > > On Mon, Jan 5, 2015 at 5:23 PM, Mark Rabiner <mark at rabinergroup.com> > wrote: > >> Most people I knew in the 90's and before filed out their negative >> carriers >> of their enlargers so they'd both get black borders from the clear edges >> of >> the film before the sprocket holes; and also insure the people looking at >> it >> that not cropping had been done. We did this with our medium format negs >> as >> well. And our 4x5 sheet film. Full frame black borders. Soon at least the >> Omega company started making the neg carriers already wide enough so we'd >> not have to file them. >> On the paper we'd leave ample white borders. Minor White said if you don't >> leave am inch border you're print was not archival. >> So no your image size or magnification was not determined so much by paper >> shape. We printed the entire neg. if we were shooting with a Nikon F and >> other flagship cameras which gave us 100% viewing then we were seeing >> exactly what we'd be getting at the edge. >> >> >> On 1/5/15 6:06 PM, "Ken Iisaka" <ken at iisaka.com> wrote: >> >>> When comparing sensors with different aspect ratios, the use of the >>> diagonal to calculate the factor is overly simplified. >>> >>> With the diagonal measurement of roughly 21.6mm, the FourThirds sensor is >>> often said to have a crop factor of 2.0, compared to a "full frame" 35mm, >>> which has a diagonal measurement of 43mm. This implies that a 25mm lens >> on >>> FourThirds is thought to work like a 50mm lens on a "full frame" 35mm. >>> >>> But it's not quite that way. >>> >>> What you should be comparing is NOT the diagonal measurement of the >>> sensors, but the dimensions of the actual area of the sensor that will be >>> used for the final image. >>> >>> So, if you are creating an image with an aspect ratio of 4x5, you are not >>> using the full area of the sensor, but only a smaller area of 24x30mm, >> and >>> 13x16.25mm. When doing so, the "crop factor" is not 2.0, but is merely >>> 1.846. The different is not all that big, but is not insignificant >> either. >>> A 25mm lens on FourThirds works more like a 46mm lens, not 50mm. There >> are >>> some of us, who split hair between smaller than that. >>> >>> If you're creating an image with an aspect ratio of 5x7, the situation >>> changes. You'd be using an area of 24x33.6mm from a 35mm sensor, but >>> 12.38x17.33mm. Here, the effective "crop factor" is 1.9386. >>> >>> Want to make it more complicated? Sure, I can do that. >>> >>> We didn't really use the full 24x36mm area of the 35mm camera. The slide >>> mount or enlarger negative carrier usually cropped the image to 23x35mm >> or >>> so. So, if you are creating an aspect 4x5 image, the effective crop >> factor >>> was only about 23/13 = 1.77, since you only used an area that measures >>> 23x28.75 to create your image. >>> >>> So, a 12mm lens on FourThirds behaves more like a 21mm lens instead of a >>> 24mm on a 35mm film camera (12*1.77 = 21.24) >>> >>> With hidden complexities such as this, I find all the discussions about >> the >>> crop factor, etc. to be absolutely absurd. Sorry, Mark. >>> >> >> >> >> >> -- >> Mark William Rabiner >> Photographer >> http://gallery.leica-users.org/v/lugalrabs/ >> >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information >> > > -- Mark William Rabiner Photographer http://gallery.leica-users.org/v/lugalrabs/