Ah yes, this can get confusing. Looks like these lenses defy the optics laws but they do not. Here is my thinking.
The sensor in both cases is withing the max circle otherwise you would see dark corners.
The 1/2" lens is at 2f with optical magnification close to 1:1 based on the size of the image. The 1/2.5" is not. Its focal center is not at 2f, it is further away and thus lower optical magnification. Here are the calculations:
As you can see both lenses' backs are at 65mm from the film but the lens center of the 1/2.5" lens is more than 32" from the film.
With the black housing like that, you do not know where the center is unless you find the info from the manufacturer.
What you can try is bringing the 1/25"lens closer in and then you will get the same image size and there should still be no black corners.
The sensor in both cases is withing the max circle otherwise you would see dark corners.
The 1/2" lens is at 2f with optical magnification close to 1:1 based on the size of the image. The 1/2.5" is not. Its focal center is not at 2f, it is further away and thus lower optical magnification. Here are the calculations:
As you can see both lenses' backs are at 65mm from the film but the lens center of the 1/2.5" lens is more than 32" from the film.
With the black housing like that, you do not know where the center is unless you find the info from the manufacturer.
What you can try is bringing the 1/25"lens closer in and then you will get the same image size and there should still be no black corners.
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