Should I Buy A Telephoto Lens Or Use A Teleconverter?

This post is a part of our Q&A section. If you want to submit your question, please use the form in the Contact page.

Oliver (Auckland, New Zealand) asked: I like doing nature and wildlife photography and considering my options whether to buy telephoto lens or teleconverter. Please suggest what should I do?

Hello Oliver! If the budget is not an issue, getting telephoto lens for your need is the best choice by all means. If you are serious into sports photography or nature and specially wildlife photography, telephoto lens will make its way into your camera bag sooner or later. And if you can't afford good telephoto lens yet but have mid-range zoom lens, 70-200mm for example, your option is to get teleconverter and extend its range.

Why do we need a Telephoto Lens?

Telephoto lens is a specific type of long-focus lens and an essential tool to have if you are into wildlife photography and considering to make it your profession or serious hobby. You cannot always get closer to your subject and telephoto lens is the only way to capture them. But good telephoto lens comes with big price and might be bulky for some of us to carry around all day long. As of today, the most expensive and long range Nikon super-telephoto lens (AF-S NIKKOR 800mm f/5.6E FL ED VR) costs around $16,299.95 and weighs around 10.1 lbs (4.5 Kg) and mid-range telephoto lens (AF-S NIKKOR 200-400mm f/4G ED VR II) costs around $6,999.95 and weighs around 7.4 lbs (3.3 Kg). Not everyone needs and can afford these beasts but that doesn't mean we should give up.

What should we do then?

Where there is a will, there is a way, and, this is where teleconverter comes into our discussion. Teleconverter is a cheap way to extend your lens range from its normal range. As name suggests itself, teleconverter multiplies your lens range by its x factor. Let's say you have a 70-200mm lens with f/2.8 max aperture and you bought 2.0x teleconverter. Once you fit this teleconverter to your lens, it will extend range from 70-200mm to 140-400mm and reduces maximum aperture to f/5.6, by half, allowing only half amount of lights and hence slowing down the speed which might be crucial for wildlife photography specially for capturing birds and fast moving animals. If you were thinking little earlier why telephoto lenses were that much expensive when you can achieve the same range with cheaper teleconverter, you may now have the answer. Yes, it not only extends the zoom range by x factor but also decreases the aperture by same factor. So, if your goal is to get greater range with maximum aperture possible (to produce nice bokeh effect in the background and faster shutter speed) then you may have no choice but buy expensive telephoto lens. Sometimes you may be able to get nice blurry background even with smaller aperture if your focusing distance is greater because depth of field is affected by your distance to subject as well. Another disadvantage of using teleconverter is distortion effect. Your image might be little distorted because teleconverter adds different sets of glasses behind your lens adding an external components to the lens whereas telephoto lens is made up of same quality glasses incorporated inside single barrel to produce better result. Distortion might be little less noticeable or even unnoticeable if you use teleconverter from same manufacturer as your lens.

To summarize our discussion into points,

1. Telephoto lens can be heavy and expensive but it is the best option if the budget is not an issue and you do not want to compromise with quality of pictures.

2. Teleconverter is the best alternative and cheaper option to get extended range from your normal zoom lens.

3. Teleconverter extends the range of your lens but also decreases the max aperture by same factor and slow down your lens by allowing only half of the lights than the lens without the converter.

4. And that is why getting telephoto lens or using teleconverter depends on what you want to achieve and how much money you are willing to spend for it.

Understanding Depth Of Field Preview

Depth of Field (DoF) is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in the image. It is widely used term in all types of photography and specially popular in Portrait and Landscape photography. We use small DoF (small aperture value), also called shallow depth of filed, in portrait photography to emphasize the subject and throw an unwanted background away from viewer's attention by blurring it; whereas, large DoF (larger aperture value), also called deep depth of filed, is widely popular in Landscape photography where everything from the foreground to the background should be in focus.

What is Depth of Field Preview and When do we need it?

Let's say your lens's widest aperture is f/2.8 and you want to shoot with f/11. In this particular case, when you close down your aperture value to f/11 from f/2.8, your camera will not close down aperture blades, also called diaphragm, immediately after you change an aperture value. This is because all camera bodies focus at the widest aperture of the lens and then stop down to the chosen aperture (f/11 in this case) when you press the shutter release button all the way down to take the picture (after focusing your subject obviously).

Note: I noticed that if you are using Nikon D90 and the D lens which has an aperture ring on it's barrel, you have to set the ring to f/22, lock it and set the actuator (at the end of the lens) which allows opening the aperture from the camera body.

DOF Preview Button on Nikon D90 and D80

Today's most advanced DSLRs come with a dedicated button (DoF preview button) to preview the Depth of Field and allows you to close down your aperture to the selected value by stopping down the lens's diaphragm. So, when you set an aperture to f/11, pressing DoF preview button closes down the aperture to f/11 and darkens your viewfinder by allowing the less light through an aperture. It is a really helpful tool when you are doing Landscape photography, and most importantly if you are using Hyperfocal distance formula. In often cases, you will get deceived by the widest open aperture and will be difficult to judge what is in focus and what is not through the viewfinder.

DOF Preview Button on Canon EOS 40D

Canon EOS 40D has a Depth of Field Preview button right below the lens release button. Every camera manufacturer has a different body design and their choice of placement for this button also differs by camera models (even on the camera from the same manufacturer).

What Is Depth Of Field (DoF)?

This post is a part of our Q&A section. If you want to submit your question, please use the form in the Contact page.

Manjit Singh (Delhi, India) asked : Can you please explain me about Depth of Field and it’s relation to the camera settings?

This is what Wikipedia says about DoF - In photography, depth of field (DoF) is the distance between the nearest and the farthest objects in a scene that appear acceptably sharp in an image. Although a lens can precisely focus at only one distance at a time, the decrease in sharpness is gradual on each side of the focused distance, so that within the DoF, the unsharpness is imperceptible under normal viewing conditions.

Sometimes you want to focus everything inside the frame (for example you are doing landscape photography), and a large DoF is appropriate. And in other cases where you are doing macro photography or portrait photography and want to blur the background, a small DoF may be more effective, emphasizing the subject while de-emphasizing the foreground and the background. Usually, a large DoF is often called deep focus or deep depth of field, and a small DoF is often called shallow focus or shallow depth of field. Now let’s discuss briefly about these terms.

Shallow depth of field: When you selectively focus one part of the image and let rest of the image go out of focus, you will get shallow depth of field. This is pretty famous when you are shooting macro or portrait and want to blur the background or produce nice bokeh in the background.

Shallow depth of field

Focal length : 28mm     Aperture : F/4.5     Shutter speed : 1/40 sec     ISO : 200

Deep depth of field: When you want to keep everything inside the frame from the foreground to background in focus using correct combination of camera settings, it is called deep depth of field or larger depth of field.

Deep depth of field

Focal length : 32mm     Aperture : F/8     Shutter speed : 8 sec     ISO : 200

Now let’s take a look at the camera settings that affect depth of field. The DoF is determined by an Aperture, lens Focal length and the physical distance from the subject.

1. DOF and its relation to an Aperture

To get shallow depth of field, you need large opening of the Aperture. And please keep in mind that large opening of Aperture means small f-stop value. Smaller the f-stop value, larger the lens aperture opening will be (allows more light and faster shutter speed) and larger the f-stop value, smaller the lens aperture will be (allows less light and slower shutter speed).

In another word, we can say: for a given subject magnification, increasing the f-number (decreasing the aperture diameter) increases the DoF; decreasing the f-number decreases DoF.

If we keep the focal length and the distance from the subject fixed: larger the opening of Aperture (small f-stop value), shallower the depth of field you will get and smaller the opening of Aperture (large f-stop value), deeper the depth of field you will get.

2. DoF and its relation to the Focal length

Focal length is something that depends on type of the lens you are using. If you are using zoom lens, you can zoom in and zoom out to increase and decrease lens focal length.

If we keep an Aperture and the Distance from the subject fixed: larger focal length will give you shallower depth of field and smaller focal length will give you deeper depth of field.

3. DoF and its relation to the Distance

Physical distance from the subject to the camera also affects depth of field.

If we keep an Aperture and the focal length fixed: closer you are to the subject, shallower your depth of field will be and farther you are from subject, deeper your depth of field will be.

Conclusion: Larger aperture opening (small f-stop value), closer to the subject and larger focal length will give you the shallowest depth of field possible.