how to choose a lens?

[Charliedelta]

Hello everybody,

I was wondering, when choosing a lens, how to tell which lens gives best pictures? Let's say there's two lenses, same focal length, same speed, and maybe even same image stabilization features. How can I tell which one is best?

 

[Overread18 6]

Few thoughts:
Lens choosing is based on two factors:

1) Your needs and situation.
a) Budget - how much you can justify and afford for the expense - note I often encourage people to look at things outside of their price bracket as well. Sometimes you might spot that if you wait a little longer you can save up and get something significantly better.

b) What you want/need the lens to do - sure you can get lenses "because they are good" but doing that is oft a recipe for lenses that sit on the shelf. So have a use in mind (even if its only rough). This will also help you make key choices as to which lens might suit you best (eg you might go with a slightly lower optical quality lens that has IS because you're going to use it for hand held video work so the IS is a very important feature to you).

2) The lens's optical and general performance
a) Read reviews - ask opinions and look at sample shots. In short research the lens. Note if you're looking at samples you really want as close to un-edited ones as possible taken by the same person on the same day with the same settings - they will often be of things like test charts and be very boring - but they'll show you the performance in a very comparable way (just looking for general shots is far too varied).

b) Date of design - typically an older lens in the same price bracket as a newer one will have reduced performance (esp on newer high density MP cameras). Although typically most newer releases have higher prices today.



So once you've got your lenses just read up on them. Chances are if they are as comparable as you say there will be a good few articles on the matter.

 

[Gary A.]

There are websites which tests lenses. I use Welcome to Photozone! to reference lens performance. This site performs and provides results for objective, laboratory tests. No internet lens testing site has tested every lens ever made.

Good Luck and Good Shooting,
Gary

 

[KmH]

Two lenses - same focal length, same speed, same image stabilization features - from the same lens maker?
Or 2 lenses - same focal length, same speed, and maybe even same image stabilization features, from different lens makers?

Camera Lens Quality: MTF, Resolution & Contrast

 

[Ido]

I use DxOMark.com, but it took me a long, long time to figure out what I should pay attention to and what I shouldn't.

Let's take this one for example: Tests and reviews for the lens Canon EF 50mm f/1.2L USM - DxOMark
First and foremost, never look at the scores. Go straight to the Measurements tab.
Then click on Sharpness, and move over to the "Field map" option. Select the focal lengths and apertures you're most interested in, and look at the colors there. It's best to look at it in comparison to a lens you already own.
I've found that, for me, if red is showing up at the focal lengths and apertures I'm interested in, it's unacceptable. Anything else is totally fine for me.
Then I do the same thing with chromatic aberrations, though here I typically accept some red popping up in the corners, because it's pretty easy to eliminate in processing.
Distortion I only worry about if it's severely off.

YMMV. I also look at AF speed and the weight of the lens before I even think about its optical qualities.

 

[Charliedelta]

thanks for your replies.

Keith, does it make a difference? I am interested in understanding what to look for that would tell me if a lens will give me a better image than another one. Something that applies to different manufacturers and to same manufactuter as well.

Thanks

 

[KmH]

There can be some variation between two lenses - same focal length, same speed, same image stabilization features - from the same lens maker.
Camera maker lenses tend to have the least variation. Third party lenses, particularly the less expensive ones, can have a lot of variation.

Two lenses - same focal length, same speed, and maybe even same image stabilization features, from different lens makers is a different story.
The quality and type of glass used can make a big difference in cost and performance.

The bottom line is to put both lenses on your camera and make some photographs that you can compare.