Hey, how’s it going? I’m Andy Jones and this is episode 122 of the Photography Side Hustle podcast.

This week I received an audio question from Joel Silver. This by the way is his second time on the podcast. So let’s listen to Joel’s question.

* Audio *

Okay, so he has an old Pentax lens that has a maximum aperture of f/1.2, which is manual focus. He didn’t say what the focal length is but that is fine.

So I’m going to answer his questions while I give you a rundown of things you need to know about lenses.


What you need to know about lenses

There is some basic stuff you need to understand about lenses. The different types and what they do, plus what makes a good lens good. So let’s get started with some of the basics and start with … 

Zooms & Primes

A zoom lens allows you to zoom in and out, changing the focal length so you can fill the frame with your subject. I’ll go over focal lengths in a minute.

There is a good chance that your first camera came with an 18-55mm zoom lens. You will hear them called kit lenses, this is because they are sold in a kit, camera body, and lens. None entry-level equipment sells separately, you buy the body and get the lenses you need to shoot your chosen genre. 

Anyway, zoom lenses come in lots of sizes, such as 16-35mm, 24-70mm, 24-105, 70-200, 100-400, 100-500, 150-600

The best maximum aperture you can get on a zoom lens is f/2.8, although Canon has a new 28-70 f/2 lens which costs over $3000.

The best maximum apertures on prime lenses are better than zooms. They open up to f/1.8, 1.4, and 1.2. 

Prime lenses don’t zoom though, if you need to fill the frame with your subject you need to move closer or move away.

These have fixed focal lengths, like 24, 35, 50, 85, 135, 200, 300, 400, 500, 600, and 800mm.

So there are pluses and minuses to both zooms and prime lenses. 

Focal Length

Now lens focal lengths can go from 4mm to 1200mm. 

A 50mm lens gives a similar view to our own eyes. Focal lengths lower than 50mm give a wider view, so 24mm or 35mm would be perfect for group shots or landscapes.

Over 50mm the view narrows and brings the subject closer to you.

So let’s look at the focal length groups and what they do. First up is …


They range from 4mm to 15mm and give the bulging effect. You might have seen photos of dogs where their noses are closest to the lens and the nose is bulging out of proportion with the rest of their body.

This type of lens is for creative and abstract work. The front element of the lens is domed, unlike a flat normal lens.

Wide Angle

Wide Angle lenses range from 10mm to 35mm and are used for Landscape and architectural photography. The lower the number the wider the view.


A standard lens is in the range of 35mm to 85mm and is suitable for portraits, studio work, and anything that needs a regular view.


These lenses are used to fill the frame with subjects that are further away from you. The focal lengths in this group range from 85mm to 1,200mm. 

If you are shooting sports like football a 600mm lens might be needed to capture the action at the far side of the field. For action closer, you might only need a 400mm lens to fill the frame.

When shooting ice hockey at the rink you can use a lens in the 70-200 range.

Bird photographers often use 500 to 800mm lenses and there is even a 1200mm lens they can buy. The problem is the Canon RF 1200mm f/8 L IS USM Lens has a price tag of $19,999. 



These lenses allow you to magnify your subject. The focal lengths used go from 15mm to 200mm. I use a 100mm 2x macro lens and can fill the frame with a ladybug.


What do all the text and numbers mean on the lens?

So let’s start with the name of the lens. I’ll use the Canon RF 70-200mm f/2.8 L IS USM Lens as an example.

The first part, Canon RF means it is a Canon lens that fits its RF mount. All manufacturers have two mounts, one for DSLR models and one for mirrorless models. Canon has EF for DSLRs and RF for Mirrorless.

Next is the focal length, this one is 70-200, so it is a zoom lens. Prime lenses have just one number, not a range.

The f/ number is next and is its maximum aperture. That is the widest the aperture blades in the lens can open. In this case, it is f.2.8, and because there is only one f/ number it means that whatever aperture you choose won’t change when you zoom in and out.

An 18-55 f/3.5-f/5.6 lens changes the aperture as you zoom, in fact, any lens with a range of f/numbers will change as you zoom. So at 18mm, the maximum aperture is f/3.5, and at 55mm it’s f/5.6.

Joel asked how important the maximum aperture is. Well, it’s really important, because the more light the lens lets in the better it is. So his f/1.2 lens was once a quality product. 

I was just on the B&H website and searched for Canon 85mm lenses. Now these prices are for EF mount lenses. The 85mm 1.8 was priced at $500, the 1.4 at $1600, and the 1.2 at $2000.

So the optics and build quality of the f/1.2 lens are superior to the 1.4, which in turn is more advanced than the 1.8 lens.

The lower the f/ numbers on a lens the better it is, and of course more expensive.

Okay, so after Canon RF 70-200 f/2.8 is the letter L. That means it is an L lens and L stands for Luxury. These are the best lenses Canon produces, with the best optics, autofocus, and build quality, and can be identified by a red ring around the lens body. Sony has GM lenses, the GM stands for Gold Model, and are its best lenses.

After the L comes IS USM. IS stands for Image Stabilisation and allows you to shoot at slower shutter speeds without getting blurry images. On Sony lenses, OSS is its version of Image Stabilisation, and Nikon has VR which stands for Vibration Reduction.

USM stands for Ultrasonic motor. This is the motor that drives the autofocusing. On some Canon lenses, you will see STM instead of USM, STM stands for Stepping Motor. This type of motor is very quiet when focusing, which is what you want if you are shooting videos.


What else is on the lens?

So let’s look at some other things you will find on a lens.


Filter Size


On the front of a lens, you will find a number, and in front of that number is a ᴓ which means diameter. So if it is ᴓ58, then that means the lens has a 58mm filter size. The lens has a thread in front of the front element and a filter can be screwed onto it.


Minimum Focus Distance


Somewhere on the side of the lens, you will find the word macro, a small flower sign, or the infinity sign followed by a measurement. That measurement is your lens’s minimum focus distance. That is the closest the front of your lens can be to the subject. Any closer and it won’t focus. ∞ – 0.10m/0.33ft

This doesn’t mean it’s a macro lens. It is just the minimum focus distance. I know, it’s confusing.



Another switch you will find on the barrel of a lens is the AF/MF switch. AF is Autofocus and MF is Manual Focus. Autofocus does the focusing for you, if you choose MF you will have to use the focus ring at the front of the lens barrel to bring your subject into focus. Nikon users might have to also choose MF in the camera’s menu settings.

Now this was one of Joel’s questions. Is it practical to focus manually when working professionally?

I’m going to say no because in most circumstances you need to be fast. Manual focus is labor intensive. If you are working in a studio I can see it being possible, but still way slower.

There is one area in which I always use manual focus, and that is shooting macro. My lens is manual focus so I have no choice. 

When shooting professionally I would stick with autofocus, it is so fast and accurate and you can take ten shots while you are composing one manually.


Choosing a lens

So when you are thinking about buying a new lens think about the focal length you need to shoot your genre. Then look for one that lets in as much light as possible in your budget. So the lowest f/ number possible, again within your budget.

Remember, if the lens you want is too expensive, think about buying a used version. You can save yourself a bundle. I would rather buy a used 24-70 f/2.8 zoom instead of a brand new 24-70 f/4 version. 

Okay, that is everything I have to say about lenses.

If you need someone to give you an appraisal of your work or website, you can contact me through Facebook Messenger. You can also join the Facebook group and get answers to anything photography.

Okay, I’ll be back next week with a bag full of waffle. Talk to you soon, Bye.