There is no magical size/weight advantage

Started 5 months ago | Discussions thread
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Re: What "exactly" is an equivalent lens as regards to the sensor size?
In reply to nigelht, 5 months ago

nigelht wrote:

olyflyer wrote:

That's exactly it. Not only to you, but to everybody else. Those lenses are not equivalent, only equivalent to the half... or one third if you are generous, ignoring other, sensor and IQ related issues, like same ISO = more noise if the sensor is smaller.

This is false and assumes that the sensel sensitivity is identical across large and small sensors. There are 1" BSI sensors in production consumer cameras. Are there FF BSI sensors in production consumer cameras?

I have no idea what a BSI sensor is, nor am I very much interested in. I have what I have in my cameras and that's what counts.

The LENSES are indeed equivalent in terms of exposure or the ISO would be different.

Yes, no one is arguing that. But that is only ONE part of equivalence. If you want ALL parts equivalent then things become more complicated than just exposure. In the end, photography is about taking images, and if you compare two cameras using images then you can only do that if you compare them on equal terms, not just by the exposure.

The fact that noise changes at the same ISO is true if I stuck the same lens on a 1" Nikon camera vs 1" Sony camera.

LENS equivalence never has anything to noise performance of a sensor since what sensor it is paired with changes over time or between manufacturers.

Otherwise no lens is rarely ever even equivalent with itself whenever it is placed on a different body and that's just silly.

What is silly is this sentence. Of course you will see differences if the same lens is used on different systems, but mostly because you probably not compare them the right way. It is perfectly possible to compare the V1 with the D800, using the same lens and the same scene, even though one is a 36MP FX and the other is a 10MP CX. You can indeed take identical images with those cameras and come up with results where no one can see the differences unless one looks at the EXIF or both are displayed at 100%.

Some examples from today:

I took the above images using the 50/1.4 on both the V1 and the D800. Composition is almost exactly the same, exposure is almost the same, DOF is almost same and I am convinced that no one can see which camera took which image unless looking at the EXIF. Looking at the images at higher magnification in the shadow areas show actually a difference in ISO noise, even though one is ISO100 and the other is ISO500. The V1, taken with ISO100, which is the base ISO of the camera, is clarly the one displaying more noise.

The cropped images above show a 100% crop of the V1 image and a 52% crop of the D800. Why 52%? Because the D800 is a 36MP camera and the V1 is a 10MP camera, so to equalize the two, you must look at them at different size to get the same magnification. It is very clear that the ISO noise is substantially less in the D800 than it is in the V1 image, even though the ISO is much higher. Not before we look at the D800 image at 100% also that the noise becomes similar.

I have to admit that in my example I made one mistake, I let the D800 use Auto ISO and the camera selected ISO500 with that aperture while ISO640 would have been more right and in that case I think noise would have been equal as well. On the other hand, the selected aperture was f/7.1 while it should have been f/7.6 to get a higher equality between the images, but f/7.6 is not possible to select with the camera, so I had to use f/7.1. Perhaps I should have selected f/8, but that would have been wrong the other way.

To me photography is about taking images and unless I can take the same image with two cameras they are not equivalent. Having equivalent focal lengths means only partial equivalence, using the same aperture means nothing, since it will result in different images, even if the ISO will be the same.

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