Before I get into the nitty gritty, I think it’s important to state the following:
Photography is about the end result and not about gear, numbers or other attributes. You don’t need equivalents to take good photos.
-OPEN FILMMAKER
Imagine a camera that generates random values for focal lengths, f-stops and isos. What will those numbers mean to you? The answer:
These numbers don’t mean anything without establishing a reference (to sensor size). This information is needed to understand what the photographer used. Otherwise, the information is not of value.
Different sensors, different settings, but the same result
The following photo was taken on a MFT camera. The settings used are displayed in the photo:
Look familiar? Yes, it’s the same orange in both pictures. This time I have listed MFT values in the photo. So now we’re getting somewhere. Again, if you don’t own an MFT camera and aren’t aware of the crop, what do these numbers mean? Not much!
Here’s another photo taken on an APS-C camera:
Wow! More numbers! We’re not done yet, there’s more!
I’ve listed the values here from the above photos:
| MFT | APS-C | Full Frame | |
| Focal Length | 50mm | 62.5mm | 100mm |
| f-stop | f/5.6 | f/7 | f/11.2 |
| ISO | 200 | 300 | 800 |
Wow, how does anyone understand this stuff? The point here to understand is that various cameras produce nearly the same photo using different settings. In order to do that, you should understand the relationship between the numbers and their camera sensors.
About full-frame
For both film and photography, the 35mm Full-Frame sensor has been used as an industry standard. I’m calling for this to be continued with respect to not only focal lengths, but also aperture and iso values. The tables below list the equivalent values.
Equivalent Focal Lengths for different sensor types
| Full Frame | APS-C | Micro Four-Thirds |
| 25mm | 15.63mm | 12.5mm |
| 50mm | 33.25mm | 25mm |
| 100mm | 62.50mm | 50mm |
| 200mm | 125mm | 100mm |
| 600mm | 375mm | 300mm |
Equivalent F-stops for different sensor types
| Full Frame | APS-C | Micro Four-Thirds |
| f/1.90 | f/1.19 | f/0.95 |
| f/3.60 | f/2.25 | f/1.80 |
| f/7 | f/4.38 | f/3.50 |
| f/8 | f/5 | f/4.0 |
| f/11.2 | f/7 | f/5.6 |
Equivalent Isos for different sensor types
| Full Frame | APS-C | Micro Four-Thirds |
| 50 | 128 | 200 |
| 100 | 256 | 400 |
| 200 | 512 | 800 |
| 400 | 1024 | 1600 |
| 800 | 2048 | 3200 |
| 1600 | 4096 | 6400 |
Supporting videos
Please take a few minutes to watch the following videos:
To reiterate from the videos, there is a crop applied to non full-frame cameras to get to full-frame equivalents. Shown below.
The magic (crop) factors
| Full Frame | APS-C | Micro Four-Thirds | |
| Focal Length | 1 | 1.6 | 2 |
| F-stop (aperture number) | 1 | 1.6 | 2 |
| Iso | 1 | 1/(1.6)^2 or ~2/5 | 1/(2)^2 or 1/4 |
The case for a standard scale
Photographers that transition from MFT -> APSc -> Full-Frame, may care more about equivalents than those that are content with one sensor-size.
Or perhaps you’re using a speed booster like the Viltrox EF-M2 or the Metabones. If this is you, you’re likely also aware of the crop factor (not to mention the additional light) and likely think in full-frame equivalents.
Having a standard scale for these attributes is like having one photography language across different sensor types. I personally think that not only should one list the camera’s values, but also the ff-equivalents.
The camera values and ff-equivalents would eliminate the need for calculations to understand equivalent lens and camera settings. That is, if you’re even aware of the crops to begin with.
Community research
I decided to take a poll to find out what other MFT users were doing.
50% of the MFT users convert their numbers to FF-equivalents. Remember, this was in a MFT user-group. I have a hunch that I would get different results in APSc user groups… If 50% of the group is doing it, these users may consider the full-frame as a standard. So there you have it. Evidence that full-frame equivalents matter (to some).
What do you think? Agree? Disagree? This article makes no sense? Let me know in the comments! Thanks!