Why does my 24-105 have a different magnification (macro ratio) from a 105mm macro lens at same MFD?

Started 5 months ago | Questions thread
Monicaa
OP Monicaa Junior Member • Posts: 42
Re: Why does my 24-105 have a different magnification (macro ratio)

ThrillaMozilla wrote:

the magnification is determined by the distance from the front focal point, not from the sensor. The front focal point can be almost anywhere

Right. This made it click in my head, I've connected the dots from the other replies now. At infinity the difference is negligible beween "a 105mm focal length" lens where that focal length is measured starting from 5cm or 15cm in front of the sensor, but if the subject is 30cm away from the sensor that's going to have a significant impact on the appearance of the image.

I have felt this difference in focal points before but I never really made the connection to how it would affect the image. In fact, even using the 24-105 at macro distances it "feels" off compared to some other lenses. You have a very tight image but the way the focus and framing changes as you move doesn't feel quite consistent with other lenses.

Of course it makes sense that the focal length is relative to the focal point and not from the sensor, so different focal point placement will make a different image... I'm surprised I didnt make that connection.

I now see this exact thing written in the other replies, but worded in a way that didnt quite click in my head. Reading is hard

 Monicaa's gear list:Monicaa's gear list
Fujifilm X-E3 Panasonic Lumix DC-S5 Panasonic S 24-105mm F4 Macro OIS Sigma 105mm F2.8 DG DN Macro Sigma 35mm F2 DG DN
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