"The Numbers, Mason!! What Do They Mean??" My Personal Focal Length Guide

Hey guys, first of all I want to apologize for the corny reference from a Call of Duty quote on the title, but today I want to explain about the different focal length and how to utilize them to your photography in my personal way. It's all about the numbers on your lens!

75mm (150mm full frame) focal length.

Focal length, as we know, is the "zoom" of the lens. It's how far or how close can the lens cover a certain image. It's measured in milimeters. Basically the more "zoomed in" the lens is, the higher the number of the focal length, vice versa. You can identify the focal length on your lens with the indicated millimeters number printed on it.

Both understanding and choosing the right focal length are very critical to the composition of a picture as the focal length does impact an image in a few different way. That's why, I hope that by the end of this post, you will be able to utilize the focal length on your lenses to their maximum potential.

Let's start

Different focal length exhibits different characteristics on the same camera, regardless of the aperture, shutter speed, ISO, sensor size, etc. The most obvious one is how "zoomed in" or "zoomed out" the picture is; we call this "Angle of View". But in reality there are three image aspects that are being affected by the change of focal length. They are:
1. Angle of View
2. Depth of Field
3. Perspective(Distortion/Compression)

Angle of View
As mentioned before, angle of view is how zoomed in or how zoomed out the composition of the picture is from a certain position. The wider the angle of view, the more zoomed out the picture is, vice versa. As you may already figured out, the smaller the number of the focal length, the wider is the angle of view, and the higher the number of the focal length, the narrower and tighter is the angle of view.

Very tight angle of view, courtesy of ultra telephoto focal length

Depth of Field
Depth of field is the amount of focused field on the picture. The shallower the depth of field, the less focused area appear in the picture and you will see a lot of blur or bokeh in the picture. The wider the depth of field, the more focused area appear in the picture, everything else beside the focused part of the picture will appear sharper. Smaller focal length will give wider depth of field naturally while larger focal length will give shallower depth of field.

Relatively blurred background, courtesy of mid-telephoto focal length.

I know, I know, you will say "I can stop down my aperture to get more depth of field or shoot wide open to get more defocused background, regardless of the focal length.". That is true, but have you tried photographing an object using 300mm focal length at f/16? The background still looked somehow blurred, isn't it? Or have you tried photographing a landscape using 14mm lens at f/2.8? Everything still looks sharp, isn't it? You'll get the idea.

Perspective
Perspective is the relationship between the objects(foreground and the background) and the eye. It's how big and small the objects are in the image relative to our vision. As an example, we know that the size of a certain pencil physically isn't changing whether it's close or far. If we see a pencil pointing at us from far away, visually the size of the rear part of the pencil and the pointy front part of the pencil will look almost the same. however, when we move the pencil closer to our eyes, the rear part will visually look a lot smaller than the front pointy part; this is called perspective distortion. Try it!

Perspective distortion, courtesy of ultra wide angle focal length

As you already guessed, smaller focal length will exaggerate the perspective distortion, meaning that the object on the background will look a lot smaller. The bigger the focal length, the object on the background will get more perspective compression, meaning that the object background will appear a lot larger.

Focal Length Characteristics and Crop Factor

At this point, I want to clarify some things regarding crop factor and focal length conversion because the standard measurement of focal length are often being mentioned in terms of 35mm full frame sensor size/film size. Here are some of my observation:

1. The angle of view gets affected by the crop factor. This means that when you use a 50mm lens on a Nikon D7000 or Sony A6000, it will give you the same angle of view of a 75mm lens on a full frame 35mm camera.

2. The depth of field isn't exactly affected by the crop factor, but it does sort of get "affected" indirectly. Let me elaborate using an example, a 50mm lens on a Micro Four Thirds body will give you the same depth of field of a 50mm lens on a full frame body. The part where people get confused is that in Micro Four Thirds, we treat and use 25mm to achieve the full frame 50mm angle of view; 25mm and 50mm isn't the same focal length even though they give the same angle of view on their respective bodies, therefore it won't give you the same depth of field.

3. The perspective distortion and compression are affected by the crop factor, but it sort of "doesn't get affected" indirectly. We use 25mm in Micro Four Thirds to match the 50mm angle of view on the full frame body. Because the angle of view between those focal lengths on their respective sensor, we get the same compression or distortion between 25mm Micro Four Thirds and 50mm full frame. On the same note, when we put 50mm Micro Four Thirds, it will have the same compression or distortion of 100mm full frame.

And now, my thoughts for each focal length

I will explain how I treat some of the commonly used focal lengths. All are mentioned in full frame terms with equivalent field of view focal length terms:

18mm (12mm APS-C, 9mm Micro Four Thirds) and lower

Ultra wide panoramic landscape photo

This is an ultra wide angle focal length, good for wide landscape, wide architecture, interior, and wide astrophotography. I've done some close range street photography at this focal length too and it gives a very unique result.

Given the small focal length, the depth of field of this focal length are generally very wide, which makes everything looks relatively focused and sharp even at big aperture(small F numbers). This means that this lens isn't the best choice when it comes to blurred background picture or bokeh, even when you could afford big aperture lens for this focal length.

Please note that at this focal length the perspective distortion is very pronounced and also the vertical lines will get very tilted if you are not careful. This is my go to focal length when I want to include as many objects in a single photograph, with the exception of a group photo.

24mm (16-17mm APS-C, 12mm Micro Four Thirds)

Very wide semi landscape photo

This is a very wide focal length. As far as I can tell, this focal length generates the same field of view of human eyes, meaning that if you can see everything in that scenery, chances are you can fit the same scenery into a picture using this focal length. I use this focal length for general landscape, architecture, general scenery, cityscape, wide-field street photography, and environmental portrait.

Where this focal length really shines is when you you use it for travelling, because it is wide enough to capture most sceneries of the places that you visit during your travel and it's also a good enough focal length for vacation portraits to include your family members and the scenery in the same frame.

The perspective distortion is still pronounced at this focal length, but not too bad. This is not really my favorite focal length to be honest, but I will treat this as sort of my ultra wide angle lens when I didn't carry my ultra wide with me. I may consider this focal length for a group photo if I must but I will usually go to 28mm or 35mm if I have the choice.

28mm (18mm APS-C, 14mm Micro Four Thirds)

Moderate wide angle focal length

This is a moderate wide angle focal length. This is usually the focal length of the rear camera of your smartphone. Anything from iPhone to Android to Windows phone uses this fixed focal length for the rear camera of the phone.

If you are used to a smartphone camera, you're already familiar with this focal length. It's best for general landscape, architecture, cityscape, street photography, environmental portrait, group photo, and full body portrait. It's good for travelling too, as 28mm is still wide enough for most scenery that you want to photograph but I still prefer 24mm for travelling sceneries as sometimes I will find an object that's too big for the 28mm to cover especially when there's space restriction.

It's pretty similar to 24mm but the extra few millimeters will help to reduce the perspective distortion and making it easier to photograph things without having the vertical lines look too tilted exaggeratedly. I always use this focal length to take a group photo too as it doesn't make the people on the edges of the frame to look stretched due to distortion.

35mm (22mm APS-C, 17-18mm Micro Four Thirds)

Classic street 17mm MFT(35mm full frame) focal length

This is a normal wide angle focal length. Good for tight landscape, 3/4 body portrait, tight group pictures, general walk-around lens, environtmental portrait, and documentary.

This is also happens to be one of the classic street photography focal length. Many people swear by this focal length and it could be the only focal length that they need when doing street photography. This lens will require you to get a bit close to your subject when doing street photography, but on the contrary, you will need to back up a little bit when you're photographing wide sceneries as now your focal length is a bit tighter compared to 28mm or 24mm.

I've survived a few days using this only lens to photograph half body and 3/4 body portraits as well as group photos without using any other lens. This shows how versatile this lens is. Granted, the distortion can still be visible sometimes especially when you are photographing something close, but it surprisingly gives me very acceptable results most of the time.

50mm (33-35mm APS-C, 25mm Micro Four Thirds)

Classic 50mm street focal length

This is what most people consider to be the normal focal length. It's good for very tight landscape, 3/4 to half body portrait, documentary, and product photography. This focal length also happens to be the standard fixed focal length on the kit lens in the old days of film cameras.

As with 35mm, this is also one of the classic street photography focal length. This focal length is what many photojournalists use on their cameras to produce some of the most iconic photo of all time. One notable person who is the master of 50mm is Henri Cartier Bresson, who was(and still is) the grand master of photojournalism; he uses only 50mm for his street photographs and never really use any other focal length except for a few occasions when he need to do landscape stuffs.

There is a debate going on about 50mm being "what the eye sees"; my personal opinion is that it's not what the eyes sees, it's just that there is no longer distortion and there is only a very slight compression happening on the picture yet at this focal length so the pictures look very natural and "normal" to us. I personally don't really love or hate this focal length but I extensively used this focal length when I started photography in 2013 for a few months to discipline myself with just a single focal length.

At this focal length, big aperture starts to translate into shallower depth of field, meaning that you can use this focal length for some blurred background pictures. But you can still stop down the aperture if you want everything to look sharp without stopping down too much.

85mm(50-56mm APS-C, 42-45mm Micro Four Thirds)

Portrait with 45mm MFT(90mm full frame, close to 85mm)

Many consider this focal length as a telephoto focal length. For me, I treat this focal length as sort of a good start for normal portrait focal length. I use it for half body portrait and I always get a very good result using this focal length. This focal length is also good for product photography, but depending on the lens, you might not be able to get close to the product due to close focusing distance limit, so you might need to consider about that.

I've done street photography with this lens too, but it looks more like a candid portrait rather than a proper street photo and it's not revealing much environment on the picture so it's not as useful as 50mm or 35mm. But sometimes you are too far from your subject when you are on the street, and when you can't get closer; on that matter, this lens can still deliver a street photo.

Not a focal length that I use everyday, but once I need it, this focal length will give a pleasing compression to the picture. Depth of field is already shallow with this lens, even on smaller sensor like Micro Four Thirds, so treat it carefully. You can stop down to get more depth of field but at this focal length, it's not going to be easy to get everything in focus.

135mm(90mm APS-C, 60-67mm Micro Four Thirds)

Notice the background compression of this focal length.

As a telephoto focal length, this is my choice when 85mm just doesn't cut it. Sometimes you need more compression for your portrait and you want to flatten face features to make your subject looks more flattering. This makes 135mm the logical choice if 85mm isn't enough. This is a good choice for shoulder portrait as well as a headshot portrait.

I love the super shallow depth of field inherent from this focal length. This makes this lens also ideal for full body portrait or product photography in a crowded space that has cluttered background, since the inherently shallow depth of field of this focal length will make it easy to blur the background without much effort.

I don't use this focal length for anything else, not even street photography. But sometimes 135mm can be used for close range sport where you can get closer to the action without the need of a longer focal length.

200mm(135mm APS-C, 100mm Micro Four Thirds)

Ultra compressed perspective, a classic signature of a telephoto lens of this focal length.

This telephoto focal length is the ideal headshot portrait focal length, and also a good start for wildlife focal length to shoot animals in the distance as well as for sport photography. The compression of this lens is perfect for flattening facial features of a head, and it also has the ideal tight field of view to photograph objects in the distance.

This focal length isn't easy to wield and is probably not gonna be used that much for day-to-day regular use. But for special purposes that the focal length is capable to deliver, picking up a lens of this focal length to photograph those special objects will definitely reward you with a good picture. Just make sure that you are using sufficient shutter speed, as at this focal length, lens movement is very pronounced.

300mm(200mm APS-C, 150mm Micro Four Thirds) and above

Super telephoto focal length.

This is considered as super telephoto focal length, which is what you will need for wildlife photography; bird photography in particular. Many wildlife photographer will also extend the focal length even further by applying a Tele Converter which multiplies the focal length to get a longer focal length and a much tighter field of view.

I personally only use this focal length for wildlife, and sometimes for distant big objects like the moon, planes, etc. I don't use this focal length for general purpose and I rarely carry a lens with this focal length except when I purposefully want to have this focal length covered.

Now this brings us to another popular debate: Zoom Lens vs Prime Lens

After discussing all about the focal lengths themselves, many will automatically start to think about the application. This brings us into the world of lenses and you basically have two choices for your preferred focal length: zoom lens and prime lens.

I don't worship one more than the other. I love both, and I use both differently for my photography needs. Granted, neither one can deliver everything and I need both of them for different reasons.

That being said, I love prime lens because they are small, they are sharp, they tend to have a large aperture, and they are very portable. I can just stick a prime lens if I know what I'm about to photograph to get a very good and predictable result. I usually attach a prime lens on my E-PL6 to reduce the overall size of the camera so I can carry it in my short's pockets or in a small bag for ultimate portability.

However, when I am travelling, I usually rely on zoom lens, because I don't know what I'm about to photograph; sometimes I may need to take a picture of an object that requires the flexibility to change the focal length constantly and that's where the strength of the zoom lens lies. Zoom lens is generally bigger than prime lens, so I need to have a bag to carry a zoom lens attached to my camera. It also doesn't work too well in low light situation because of the relatively small aperture(except for the f2.8 zooms) so I tend to use it only during daylight.

So, be sure to choose the right focal length for the right job!

I hope this post will help you to understand more about focal length and hopefully that will help you to utilize all the different properties of the focal lengths to your advantage as well as to help you determine which focal length that you should use for what you need to photograph. Thanks for reading and God bless you :)