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01/14/2004 12:36:07 AM · #1 |
We all know about and read up on the 1.x crop factor with the D-SLR's, but has anyone compared a 35mm film print to a D-SLR print of the same subject at the same focal lengths between film and digital.
I have not seen any comparisons so I did a little test over the weekend with a film 35mm Canon EOS rebel and my Canon D60, using the same lens on a tripod and using the same focal point on my subject. I had 4x6 prints made of the film shots and will have my 4x6 prints from the D-60 tomorrow to see what the "crop" factor actually means and does to the subject.
I will scan in the 35mm film prints and post the results tomorrow night.
James
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01/14/2004 12:44:39 AM · #2 |
You should find that the linear magnification of objects in the 4x6 prints from the D60 is 1.6x that in the film prints. In other words, the distance between the same two points will be 1.6x larger for the D60.
It will be off slightly though (should be lower) since the film camera print is slightly cropped from the full negative.
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01/14/2004 12:50:44 AM · #3 |
Just a question, are the 4x6's full frame? Even though the aspect ratios of 35mm film and 4x6 prints are the same (2:3), most minilabs still crop some around the edges. You might want to look at the negatives as well.
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01/14/2004 04:23:31 AM · #4 |
I understand the need to compare to the 35mm, because so many photographers understand it. But, I don't care! I can see exactly what I just shot and the histogram, to judge if I need to change it somehow. What is the big deal? If not already versed in this rheoteric, then it doesn't matter, right?
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01/14/2004 08:25:28 AM · #5 |
my reason for this is purely out of curiosity. I have no intention of going to film, I used my girlfriends sisters camera and my D60 for the test.
I did not want to shake things up and cause a huge debate, I just wanted to see the difference I have been reading about over the last few years with my own eyes. I tend to not 100% believe something unless I can SEE it with my own eyes
James |
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01/14/2004 08:30:04 AM · #6 |
this months photographic magazine has an article on choosing lenses, and one of the things they mention is the 1.x crop factor on digital slr vs 35mm
and they show you how the digitals sensor compares to the same shot on 35mm - sort what you are taliking about i think.
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01/14/2004 08:32:42 AM · #7 |
Many people misunderstand what the crop factor does. They think that this factor multiplies the focal length of the lens. Really, this factor multiplies the FOV (field of view) of lens focal length not focal length itself. What happen is that you achieve an image with the FOV equivalent to a lens with the Focal lenght of your (Lens * Crop Factor). This will not magnify your subject, only crop it in a way equivalent to a FOV of the resulting Focal Lenght.
IE: You have an 80mm lens with the 1.5 crop factor. This gives you a FOV equivalent to (80*1.5)=120mm. The subject will be croped by the FOV like a 120mm lens, but won´t be magnified like it. To magnify a subject by a factor you will need a teleconverter attached to your lens. In this case you will have the equation (Lens Focal Lenght * Teleconverter Factor) to give the total Focal Lenght, magnification, and ((Lens Focal Lenght * Teleconverter Factor) * Crop Factor to achieve the Focal Length equivalent FOV.
In your test you will achieve a photo with more detais around your principal subject in 35mm than your digital version. It´s the same that you put a frame to cover the borders of 35mm photo. It´s because the sensor size is shorter than a film exactly a the same Crop Factor.
I´ll wait to your posts, but from now you had a vision of results. |
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01/14/2004 09:03:23 AM · #8 |
Rob Sheppard had a good article entitled "Is Digital Magnification Real?" in the November 2003 issue of Outdoor Photographer.
Basically, he says that when you talk focal lengths, you must also include some info about the "imaging area" of the camera. If somebody says "my camera has an 80mm lens", you really don't know what that means unless you know something about the format of the camera in question. If it is a 4x5 camera, that's a very wide-angle lens. If it's a 35mm film camera, it is a mild telephoto. And if a tiny digicam could have a lens that long, it would be an ultra-mega-telephoto.
So if you say that a 1.5X crop-factor (compared to 35mm film) DSLR is "just cropping", you are ignoring the fact that the size of the sensor is very important. You'd never say that an 80mm lens is really a wide-angle lens that is "just cropped when you use it on a 35mm film camera." But that is exactly the case when you compare 4x5 and 35mm because the "imaging area" of those camears are a different size. So why should we treat a smaller-sensor DSLR any differently?
A DSLR with a smaller-than-35mm-sensor isn't a "cropped 35mm" any more than a 35mm is a "cropped medium format".
Bottom line: subjects are magnified in the final image when using different formats, and a small-sensor DSLR is the same as a different format because the size of imaging area is different. |
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01/15/2004 08:53:49 AM · #9 |
| Hi Jabb19, have you done that scan? I´m curious about results. EddyG puts some noise in my theory, then... I´m more curious now. |
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01/15/2004 09:30:50 AM · #10 |
| For those interested, the article in Outdoor Photographer that EddyG mentioned is the best that I have read on this topic. After reading it I finally got around the term "crop factor" and started underting the relationship between imaging area and focal length. It's definitely worth looking up if you have access to the magazine. |
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01/15/2004 10:32:56 AM · #11 |
Originally posted by GoodEnd:
Hi Jabb19, have you done that scan? I´m curious about results. EddyG puts some noise in my theory, then... I´m more curious now. |
No I ran out of time last night, but I did compare the photos side by side and there does appear to be a little magnification difference between the 35mm print and the digital print. but you can definatelly tell the difference that the amount of subject mater is greater in the 35mm print over the digital.
James
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01/15/2004 11:15:09 PM · #12 |
Here are the scans from the 35mm prints and the D60 prints
the top image was taken with a canon D60 @ 28mm.
The bottom photo was taken with a Canon EOS Rebel (35mm film) @ 28mm
the top image was taken with a canon D60 @ 200mm.
The bottom photo was taken with a Canon EOS Rebel (35mm film) @ 200mm
James
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