Easiest way to measure magnification of your macro lens

in steemstem •  3 months ago 

Hello everyone! Today I will show you easy equation on how to measure magnification of your lens. For my example I will use lens called Sigma 28-70 with macro reverse adapter and my crop sensor Canon 600D.


CameraLensShutter speedF-stopISO
Canon 600DSigma 28-70 @70mm + macro reverse adapter1/160 sec.f/8100

So what you will need for this experiment:

  1. Camera body
  2. Macro lens of any sort
  3. Measuring tape, ruler or similar

IMG_20190601_155203 (1).jpg

So first you need to see what size of sensor do you have, if it's a full frame sensor your dimension would be 36mm by 24mm. If you use crop sensor it would be 22.2mm by 14.8 on Canon or Nikon 24mm by 16mm. Our focus will be on length of a sensor, so 36mm for FF and 22.2mm for APS-C sized sensor.

Now, after we've seen sizes of sensors you will need to know one more thing. You need to place ruler or measuring tape and take photo of it at closest distance so we can count how many millimeters are shown in our photo. To get 1:1 macro magnification your lens should show 36mm of a ruler, or ~22mm on crop sensor.

Let me show you how much millimeters I got after using my equipment that is on focal length of 28mm on APS-C sized sensor.



I got 38mm on this first example, so I have magnification of about ~ 1:2 which I get by dividing 22.2mm of a sensor length and 38mm that I got in focus. So 22.2/38 is around ~0.5 which is 1/2 of a real magnification.

Next example is at around ~55mm focal length.


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At this focal length I got around 12mm of a measuring tape which leads to equation of 22.2/12 and result is 1.85 which is slightly less than 2:1 magnification that shows that is 2 times bigger that it really is in real life.

And at highest focal length that this lens can have, 70mm, I got 10mm of a measuring tape which gives me 22.2/10 and result of 2.2 that is a slightly more that 2:1 magnification.


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This is the highest magnification that I can get by using this equipment, which is a lot when you compare price of lens and adapter. I already mentioned in other posts, price of lens and adapter is at around 10$ and I got highest magnification of more than 2:1. That is just unbelievable when you compare real macro lens that has 1:1 magnification and costs around 300+$ for cheapest of all.

What I can do to make magnification even higher is buying macro extension tubes that would give me astonishing magnification of more than 3:1 surely. It costs around 10$ at amazon, but you can find even cheaper on other sites. So when I combine it with my 10$ equipment I would get around 20$ worth and magnification higher than 3:1. That is A LOT!


I will share with you some photos that I took with this equipment, you already seen it at the beginning but there are more under this text.


CameraLensShutter speedF-stopISO
Canon 600DSigma 28-70 @70mm + macro reverse adapter1/160 sec.f/8100


CameraLensShutter speedF-stopISO
Canon 600DSigma 28-70 @70mm + macro reverse adapter1/200 sec.f/8200


CameraLensShutter speedF-stopISO
Canon 600DSigma 28-70 @70mm + macro reverse adapter1/100 sec.f/8200

To recap. This is really amazing what you can get for such a cheap price that everyone can afford. There is few cons tho, which are changing aperture and you will need a lot of light for this kind of photography. I placed my aperture to be fixed to f/8 and I have flash to give it more artificial light. So for me, those cons are fixed. F/8 doesn't give me a lot of depth of field to work with but it's acceptable, especially when you take photos at around ~30mm then depth of field is pretty good. At highest focal length you can get in focus only eyes of a subject but that is also pretty great for me. All in all, I'm amazed by the results and I can recommend to every photographer to try it.

Thank you for stopping by! Have a nice weekend! :)

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