How to fully test a 24-70mm f2.8?

Started Jan 18, 2013 | Discussions thread
joneil Regular Member • Posts: 176
Re: How to fully test a 24-70mm f2.8?

I dropped my 24-70 on the ground last year and noticed right away it wasn't as sharp as it should of been.  Eventually it went back to Nikon for repair.

anyhow, very simple to test a lens, especially if you have another lens or lenses in the same focal length.

Get a tripod, mount the camera, and setup and focus on something interesting.  "Interesting" can be anything you like - a spider on a web, a big landscape, etc, but I find you stick with a topic you "normally" like to shoot, as long as it "static" - that is, not normally moving.  A moving train - no good for example - but a train that is parked and not moving - that works.

Now get yourself an old fashioned notebook an pencil  if you don't have one, 2 buck at a local dollar store will fix you up.

Setup your 24-70 zoom first, since it is the lens "in question."  Make sure you have some kind of manual setting on the camera too.   What you want to do is take a set of shots at different focal lengths.  What the settings, that is up to you, but the focal lengths should be at ranges you can duplicate on your 24-85.  by that I mean, you do NOT compare the 70mm on one lens to 85mm on the other lens.  That ain't gonna work too good 

Make up the settings yourself as I said, but as a suggestion do three shots at 24mm, three at 40mm, three at 55mm and three at 70mm.   The first shot of each series should be wide open at the maximum opening - but here's the catch - I thnk the 24-85 max is - what F3.5?   So your wide open shots on each lens will not be a perfect comparison.

Anyhow, your second shot at each focal length should be around F5.6 or F8 on both (or all lenses) and the last one stopped down pretty good at F16 or F22, etc.   You pick your own settings, but make sure the settings are the same lens to lens.  Same camera body, same tripod, and make sure the weather is the same from shot to shot - all sunny, all cloudy, all foggy, whatever.

If you can add more lenses into the mix, do so. the "trick" is to record each shot.  i reccommend paper and pencil because it is simple, but hey, you wanna use your iPad or smart phone, etc, instead, whatever works for you.

After you done all your shots, you bring them in, dump on your computer using whatever software you use, the the other "trick" is to arrange all the photographs so that all your 24mm, F2.8 (or wide open shots) are together, all your 55mm F8 shots on different lenses are together in your software.

Once you done that, take a beak, go get yourself a coffee, iced tea, bottle of soda, can of red bull, a glass of 12 year old scotch - whatever makes you relax.  Sit down, and start comparing your shots side by side.

One of the first things ANY photographer has to do is trust themselves, their own vision.  I don't give a darn if you shot film or digital, if you use a point and shoot 3mp camera or an 8x10 view camera with sheet film - you have to learn to trust your own judgement.  You might have to teach yourself to trust yourself (I know, sounds weird, but that's how it goes some days), but do so.

Take your time, then take some more time.  Do not rush. Take time to enjoy what you are doing.  Compare your shots side by side.  Look them over again and again.   You will be doing more that one thing here, even on a subconcious level.

first you will obviously be looking at your lens quality.  You will be looking at edge sharpness, lens distortion, etc.   if your 24-70 has an obvious flaw, it should come to you here.

but the other thing that will happen is you will see the difference between your lenses, and if you learn to trust your own gut instincts, you will figure out what lens is best for your.  for example, the "best" zoom lens is the one you will be using more often that not.  Optically the 24-70mm is one of the finest out there, any brand, any time, but it is also big and heavy.  If you find it is easier for you to use the 24-85, then that is the "best" lens for you.

so bottom line is, you do not need a degree in optics or expensive software to figure out if your lens has an issue, but you do need time, patience and effort.

good luck

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