IkarusJohn Posted October 30, 2015 Share #61 Posted October 30, 2015 Advertisement (gone after registration) Thanks for trying. It's a nice try. I agree that it's not rocket science. It's about the meaning of terms. Anyway, those who have not understood by now are not likely to do so in the further course of this thread. I'm not so sure about that, Phillip. When people ask about crop factors, they're usually wanting to know what the resulting image is going to look like. They will have worked out that a 50mm lens on an APS-C camera will produce an image that looks like one taken with a 75mm lens on a 35mm camera. None of this was a problem with film, but when smaller sensors came along, things were confused further by zooms being marked with full frame equivalent focal lengths. When you introduce a system camera with a cropped sensor and mount adapters, people quite reasonably start asking what the crop factor is. With a camera with a larger sensor, like the S, to say the crop factor is 1.25x is confusing because the question is asked, not because the person wants to know if the image from the SL will be "cropped" compared to the image from the S (I hope), but how the S lens wil perform in terms of image coverage by reference to 35mm format. The answer is that a 120mm lens for the S camera will perform like a 120mm lens on the SL. The field of view of that lens (in 35mm terms) on the S equates to 96mm (applying a factor of 1.25x), but on the SL, it will give a 120mm field of view. Just saying the crop factor of an S lens on an SL is 1.25 confuses - if you put any S lens on an SL, there won't be any cropping in 35mm terms. Link to post Share on other sites More sharing options...
Advertisement Posted October 30, 2015 Posted October 30, 2015 Hi IkarusJohn, Take a look here What's this "crop factor" (OT from Leica SL sensor). I'm sure you'll find what you were looking for!
mjh Posted October 30, 2015 Share #62 Posted October 30, 2015 Just saying the crop factor of an S lens on an SL is 1.25 confuses - if you put any S lens on an SL, there won't be any cropping in 35mm terms. Just like there is no cropping in APS-C terms if you use a FF lens on an APS-C camera. In fact there is never any cropping if you view it this way; the crop factor is always 1. Now of course this is a perfectly valid way of looking at things but quite obviously it is not the perspective taken by someone asking for a crop factor. Answering his question by saying that the crop factor was 1 would be confusing indeed. Link to post Share on other sites More sharing options...
pop Posted October 30, 2015 Share #63 Posted October 30, 2015 (...) Just saying the crop factor of an S lens on an SL is 1.25 confuses - if you put any S lens on an SL, there won't be any cropping in 35mm terms. Well, yes, it depends on the frame of reference of the person posing the question, as has been said here before. If you normally use the 35mm film format, you certainly can use any lens you can attach to the body, provided the lens has been made for a frame which is at least as large as the 35mm film format. Even though the image projected by the lens is cropped, you don't have to take that into account because the lens and the resulting image will be exactly as expected from a lens of that focal length. Well, perhaps you have to take measures so that the light of the part of the image which lies outside of the sensor area does not produce flare or other artefacts, but that's another issue. If you normally use the S which has a slightly larger frame size, you might want to know what FOV you are to expect when using your S lenses on a FF body. In that case, you would speak of a crop factor. Link to post Share on other sites More sharing options...
Jeff S Posted October 30, 2015 Share #64 Posted October 30, 2015 Yikes....late to this thread...and glad that I didn't worry about 'crop' terminology when I alternately shot film in 35mm, 6x6, 6x7, 2 1/4, 4x5 and 8x10 formats over a few decades. But I sure knew the lens I wanted for each camera and desired image. My 'frame of reference' changed regularly, without any attempt or need to compare. Given this, I'm always amused at the concept of 35mm being 'full frame'. Simpler to just know one's camera....film or digital. Jeff Link to post Share on other sites More sharing options...
IkarusJohn Posted October 30, 2015 Share #65 Posted October 30, 2015 Just like there is no cropping in APS-C terms if you use a FF lens on an APS-C camera. In fact there is never any cropping if you view it this way; the crop factor is always 1. Now of course this is a perfectly valid way of looking at things but quite obviously it is not the perspective taken by someone asking for a crop factor. Answering his question by saying that the crop factor was 1 would be confusing indeed. Of course! The skill in answering a question helpfully is understanding the question and the person asking it. If asked what is the crop factor of an S lense on the SL, saying 1.25 is probably saying more about the person providing the answer than actually giving the information asked for. That person would understand from the response that on an SL, a 70mm S lens is going to behave like a 87.50mm lens designed for the SL camera. The question itself shows (1) a need for assistance, based on (2) a fundamental lack of understanding of focal length based on a life time of thinking in 35mm terms. To say 1.25 or 1 is equally unhelpful, if accurate. Link to post Share on other sites More sharing options...
Daedalus2000 Posted October 30, 2015 Author Share #66 Posted October 30, 2015 Yikes....late to this thread...and glad that I didn't worry about 'crop' terminology when I alternately shot film in 35mm, 6x6, 6x7, 2 1/4, 4x5 and 8x10 formats over a few decades. But I sure knew the lens I wanted for each camera and desired image. My 'frame of reference' changed regularly, without any attempt or need to compare. Given this, I'm always amused at the concept of 35mm being 'full frame'. Simpler to just know one's camera....film or digital. Jeff I am sure you understand that the crop factor is done as a shortcut for people who do not necessarily use many different formats to be able to calculate the field of view for a specific focal length and a specific sensor size. So if I ask you what is the field of view of a 20mm lens on the Fuji X20, I am sure you will find it difficult to calculate. If I tell you that the crop factor is 3.6 then it becomes extremely easy (I am sure you know how a 72mm lens behaves on the 35mm sensor). So to say that you to know your cameras is simpler, sort of misses the point. But at least I know that you are a man of great photographic experience! :-) Link to post Share on other sites More sharing options...
Jeff S Posted October 30, 2015 Share #67 Posted October 30, 2015 Advertisement (gone after registration) So if I ask you what is the field of view of a 20mm lens on the Fuji X20, I am sure you will find it difficult to calculate. If I tell you that the crop factor is 3.6 then it becomes extremely easy (I am sure you know how a 72mm lens behaves on the 35mm sensor). All you'd need to tell me is the size of the sensor (or negative)....and the specific lens characteristics (coverage, etc). I wouldn't be all that interested in comparison terminology. Experience would dictate the rest. YMMV. Jeff Link to post Share on other sites More sharing options...
Daedalus2000 Posted October 31, 2015 Author Share #68 Posted October 31, 2015 All you'd need to tell me is the size of the sensor (or negative)....and the specific lens characteristics (coverage, etc). I wouldn't be all that interested in comparison terminology. Experience would dictate the rest. YMMV. Jeff My point is not everyone has your experience and you still need two pieces of information, whereas the crop factor is just one number that everyone can use even without experience... Link to post Share on other sites More sharing options...
BerndReini Posted October 31, 2015 Share #69 Posted October 31, 2015 The 70mm S-lens will have the same field of view as the 70mm summicron M lens on the SL. On the S medium format sensor, the 70mm S-lens has approximately the field of view of a 50mm lens on an M or SL camera. Link to post Share on other sites More sharing options...
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