Saturday, May 30, 2015

Primes vs Zooms and Why I Use Both


As with most things on the internet, there is a cyclical buzz that runs round and round about prime lenses vs zoom lenses.   Everyone seems to want to discuss which one is better.  If you know me at all you know that I do not subscribe to which one is better overall, but to which one is the best tool for the current job at hand.


I do realize that not everyone has the luxury of being able to own full compliments of both types of lenses.  You may need to make a choice between the 2 or have a combination of both types.


Let’s look at the characteristics of each lens and why you may find one type an advantage over the other. These are not meant to be all inclusive or an end all be all. The examples are used to make a point and not be comprehensive.


Primes


Speed
With few exceptions, primes have the benefit of having fast apertures.  The potential benefit to you is that you have a larger degree of subject isolation from the background as well as the ability to get faster shutter speeds or use lower ISO values.  This is good news if you are shooting in poor light and need to keep your shutter speeds high for hand holding or capturing fast moving action.  These apertures commonly run between f/0.85 and f/2.8.

Handheld, no image stabilization
ISO 800, 1/50, f/2
Image Quality
Historically, primes have had an image quality advantage.  This is because they tend to be less complex to build.  Also, compromises don’t need to be made for the glass elements to cover a range of focal lengths - they just need to be good at one focal length.

sharp, clean for portraits and shallow depth of field
ISO 200, 1/125, f/2.8
Physical Size
Without the complexity of zoom rings and additional glass elements to cover multiple focal lengths, the size of the lenses can be downright small.  All this is really dependent on the max aperture size and the size of the sensor that needs to be covered.  Even with that, primes still have the potential to be small and light.


Convenience
The big negative to primes, in my opinion - and it is not THAT big, is the fact that if you need another focal lengths, you need to change lenses.  This can provides a bigger risk of introducing dirt on the sensor and the possibility of a missed shot while changing lenses.

It can also be a struggle for those not used to using them to remember to “zoom with their feet” and not rely on the zoom ring of a zoom lens.


Price
Prices can range from bargain basement sub $100 to $10,000 for some prime lenses, depending on focal length and maker.  The more common focal lengths tend to be less expensive, while the more exotic or specialized focal lengths go to the expensive side.  The big thing to remember here is that since the prime lenses can be less expensive and very sharp, which you don’t always find in a bargain prices zoom lens.


Zooms


Speed
The majority of fast zoom lenses run with a fixed aperture in the f/2.8 range.  There are some that have variable apertures like f/2.8-4.  There are some zoom lenses that have faster aperture ranges, but those are not common.  For most people’s shooting needs, they could comfortably use an f/2.8 lens and get the exposure and isolation that they need.  The only times that a faster aperture would be more beneficial is extreme low light and when you need a faster shutter speed to freeze action and f/2.8 isn’t going to cut it with an acceptable ISO value.


Image Quality
Long gone are the days when primes were far superior to zoom lenses.  Technology and experience have shown that many professionals have entrusted their businesses to zoom lenses.  Unless you are looking at 100% crops, pixel peeping you are not really going to see a difference.
Image quality also tends to suffer somewhat on zooms teh wider range of focal lengths it has - again, more compromises to cover the various focal ranges can cause compromised IQ.  It can come in the form of overall sharpness, edge sharpness pincushion or barrel distortion.


Physical Size
Zooms can tend to be quite bigger, and depending on their construction, may increase in length as they are zoomed out to longer focal lengths.  The front element needs to be big enough to cover the widest and longest lengths - and the faster the aperture, the bigger the glass needs to be.
This image below shows the difference in lenses. The one to the left is a variable aperture f/4-5.6 and the one to the right is a constant f/2.8.

©CameraSize.com
Convenience
Here is the real benefit of a zoom.  Have a 24-70mm and need 24mm, you got it.  Need to get to 50mm, just twist the zoom ring and you are there.  Have to shoot in dusty or wet conditions?  Danger to dirt or water getting to the sensor is greatly reduced because you don’t need to swap out lenses.

The convenience of the zoom takes us from the image immediately below and then to the second one after that with the twist of the wrist. Could have missed shot 2 if I had to swap from a wide to telephoto prime.

ISO 200, 1/200, F/2.8 @ 86mm

ISO 200, 1/320, f/2.8 @ 200mm
Price
Just like primes, the prices can range from a few hundred to a few thousand dollars for all the same reasons.

©CameraSize.com
From Left To Right
12mm f/1.8, 45mm f/1.8, 12-40mm f/2.8


©CameraSize.com
2 primes and a pancake zoom(not extended)

My Bottom Line

Repeating my statement from the beginning of the article, use the right tool for the job.  Sometimes zooms are best, other times primes are….or perhaps there is a need for both.  The more experience you have shooting, cultivating a style and determining what you like to shoot and how you like to shoot it will help you get the to the right decision of which choice in lens is right for you.


I use both primes and zooms because I shoot a wide variety of subjects and need the versatility of both types of lenses.  It is really that plain and simple.  Nothing fancy or philosophical about the whole thing.

No magic bullet, review from another person should make the decision for you.  Reviews are helpful in giving you information about the things you might care about like focus speed, focus ring throw, and image rendering before a purchase is made.  The rest is up to your personal requirements.

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