Magnification ratio calculation and how to choose the best macro lens

Magnification ratio and how to choose the Best macro lens

Magnification Ratio – What are they?

You may see the 0.5:1, 1:1 or 2:1 marking before but may not really know their meaning. Or how to choose the right one to use when shooting? Don’t worry! Today, we are here to share some tips on this “must-know” macro photography knowledge and give you some advice for picking the right lens.

Before start, for those who don’t want to get into details (such as calculating the magnification ratio), here are the quick steps for you to determine which macro lens fits you the best:

1. Know your sensor size and camera

  • Full Frame 36 x 24mm | APS-C 25.1 x 16.7mm
    • It helps you to understand how much area would the subject cover
    • Camera system (Mirrorless or DSLR? Which mount does it use?)

2. What are you going to shoot?

  1. Small objects such as insects (full-body shot for something over 10mm?)
    • A Macro lens that can magnify up to 2X Macro would be perfect.
  2. Anything super tiny? (less than 10mm or your want to have an extreme close up to a bug’s head)
    • 2X or above. Something like the Laowa 25mm f/2.8 2.5-5X Ultra macro.

3. Would you also shoot things that are in a distance?

  • Not all macro lenses can focus infinity. Especially one with an ultra-high ratio.
  • If A and B in Q2 are all “yes” to you, then you will need to have at least 2 lenses.
    One for Infinity to 2X and one for a higher magnification ratio.
Same magnification ratio under Full frame and APS-C
1X magnification ratio to 5X
Infinity focus

To put it simply, 1X magnification means: if the object is 1mm long, it would be exactly 1mm long when projected to the sensor. Let’s say you are shooting 1X magnification with a full-frame camera (36X24mm), an object with the size 18x12mm would take 1/4 area of your photo.

You can record the whole insect and keep a little bit of the environment. It’s quite handy for most of the situation but if you want to get closer to the subject, Or get much more details of the insect, you have to get a lens at least able to do 2X macro. Take a look at the illustration below. assume you want to fill the frame with the whole insect, you can know how much magnify power may need by guessing the size of the target:

So does it mean getting a lens with the highest magnifying power is always the best? Yes and no. Take the Laowa 25mm f/2.8 2.5-5X Ultra Macro as a sample, this is a great option for small subjects such as aphid and ant. The details reveal under the 5X magnification are unbelievable. You can not do the same with a 1X or 2X lens. However, the 25mm does not has the ability to focus infinity which means you can only use it for extreme macro photography.

On the other hand, if you need to record different species in the field. The 100mm f/2.8 2X Ultra Macro APO would be your best choice. It allows you to capture larger subjects like a butterfly and relatively smaller Jumping spiders. You can either photograph the whole insect or get a close-up shot of it. The lens is also able to focus infinity which means you can also use it for even larger subjects or use it as a portrait lens. It’s really a matter of choice whether you need that extra magnification ability or wants to keep that flexibility instead.