Do you use your favorite medium format lens to shoot digital?

NiallerM · 2025-09-18T15:23:56-0400

Alexander6x6 said:
The format factor comes from the diagonal length ratio between the frames resulting in 1,5-fold and 2,5-fold factors for full-frame and medium-format compared to Fuji X (APS-C).

That's the crop factor. Sensor size is distinct from focal length. My observations with the etup aren't restricted to the image size, although it is generally considered to be a good indicator.

I think you may also be making the mistake that effective focal length is based on a full-frame comparison as a baseline, not on the sensor or film size for which the lens was originally designed..

Alexander6x6 · 2025-09-18T15:28:01-0400

NiallerM said:
Also, why do you insist on referring to aperture stops as "speeds"?

Your question must be re-addressed to a native speaker. who introduced the term "fast lens":
"A faster lens means the maximum aperture is larger, and more light will hit the sensor compared to a “slower” lens. This is usually expressed in an “f-number.” The smaller this number is (like F2. 8), the “faster” the lens is, and vice-versa."

NiallerM · 2025-09-18T15:32:16-0400

Alexander6x6 said:
Your question must be re-addressed to a native speaker. who introduced the term "fast lens":
"A faster lens means the maximum aperture is larger, and more light will hit the sensor compared to a “slower” lens. This is usually expressed in an “f-number.” The smaller this number is (like F2. 8), the “faster” the lens is, and vice-versa."

You said:

speed (f-stop wide open)

Alexander6x6 · 2025-09-18T15:38:58-0400

NiallerM said:
You said:

> speed (f-stop wide open)

It has the same meaning:

"Lens speed is the maximum aperture diameter, or minimum f-number, of a photographic lens. A lens with a larger than average maximum aperture (that is, a smaller minimum f-number) is called a "fast lens" because it can achieve the same exposure as an average lens with a faster shutter speed."

Alexander6x6 · 2025-09-18T15:48:00-0400

NiallerM said:
That's the crop factor. Sensor size is distinct from focal length. My observations with the etup aren't restricted to the image size, although it is generally considered to be a good indicator.

I think you may also be making the mistake that effective focal length is based on a full-frame comparison as a baseline, not on the sensor or film size for which the lens was originally designed..

I spent about eight years actively participating in the projects to adapt medium-format lenses for digital mirrorless cameras. In all those years, you are the first person to tell me that I am wrong.

MattKing · 2025-09-18T16:17:09-0400

Moderator hat on:
Gentlemen - please!
Hat off.
Be cautious about any such analysis where the sensor/frame sizes being compared have different aspect ratios.
When those aspect ratios differ, there are actually four different equivalencies:
1) short dimension of the frame;
2) long dimension of the frame;
3) diagonal of the frame; and
4) area of the frame.
So you can have four different answers, all of which are right, even though their appropriateness depends on the use being made of them.

Do you use your favorite medium format lens to shoot digital?

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