Disappointed with Tamron 17-50

Bluelion

Bluelion

Bluelion

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I bought a Tamron 17-50 f2.8 lens earlier in the year to pair up with a D300. This was the first time I've bought/used a non-Nikon branded lens, but the encouraging reviews and the fact that it cost 1/3 the price of the equivalent Nikon convinced me to give it a go.

At first I was satisfied, the slow and noisy AF wasn't a concern, or was the (very) plastic build quality. It was an f2.8 lens which focuses quite close which has come in handy. However, I've never been "blown away" by any of the pictures it produces. Furthermore, just recently I've been noticing a lot of off-centre softness, and in some cases even a bit of distortion. Is this normal for these lenses, or have I just picked up a poor one?

For example, the following pic of this weekend's sunset in the New Forest looks ok at first:

dsc_4131_1024x768.jpg


Lets take a closer look using a 1:1 crop. The centre duck is ok, relatively sharp:
dsc_4131_sharpDuck.jpg


But just look at the edge duck :(
dsc_4131_fuzzyDuck.jpg


I'm quite disappointed with this, the two ducks are roughly the same distance from the lens so I don't believe it is a depth of field issue. Also, the right hand side of the image is still sharp - its only the left. Am I expecting too much from this lens, or have other people reached similar conclusions with their Tamron/Sigma lenses?

(oops lost the exif somewhere, details are: 17mm at f5.6, 1/124 second exposure ISO 200)
 
Well for a start your shooting a landscape shot at F5.6. This is quite shallow depth of field your working with and will provide about 70% softness throughout a landscape shot. You should be shooting around the F16/F22 range.

I dont know this lens but if its a budget lens you can expect plastic built quality, slow & noisey AF and the image quality wont be up there will professional labled zoomed and primes but you will still get results that are satisfying.
 
Well it was getting a bit dark, and bananaman here forgot to bring the correct tripod head to attach the body to. I didn't realise at that distance I'd get so much variation at f5.6, should have upped the ISO :( (also doesn't really explain why the background trees are sharpish, or the right hand side of the pic is sharp)

ps. the lens is about £300, so not budget budget but not up to the £1k for the Nikon equivalent.
 
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Well the simple fact remains that you wont get in focus photos on a landscape photo at f5.6
I personally think its a fine photograph colour/contrast wise for the light in the scene.
You will get quality fall off towards the end of pretty much any lens but what you have showed in your 100% example is just softness due to aperture.

Would try n do some photos bolted to a tripod and using maximum depth of field (F22+) and look at your 100% examples :)

Dom
Closest F. to zero is shallow.
Up the scale F8, F11, F16, F22, F46 etc wider the DOF yes (maximum Depth of field)
 
The problem with getting the Fstop to 22, that it lets less light in.

So if i take landscape shots and there is something moving they will be blurred as my Shutterspeed obviously lower.

One day i will understand proper Exposures :P
 
looks like that soft duck has slight motion blurring around its head , like it has turned its head just as you shot, it is a little oof too

also with stopping down to f22 you will start getting diffraction and the shots will get softer all over
 
You won't need to stop down as far as f/22. Between f/8 to f/16 is generally the lenses sharpness sweet spot, whatever the cost and manufacturer of the lens. f/22 onwards as JBuk said, you will start getting diffraction because of the limitations of your cameras resolution, you will also see drops in contrast. You can only really get away with low apertures when you shoot on medium and large format (precisely the reason why most landscape photographers shoot on LF) because the film has a larger surface.
 
EnglishMack said:
You won't need to stop down as far as f/22. Between f/8 to f/16 is generally the lenses sharpness sweet spot, whatever the cost and manufacturer of the lens. f/22 onwards as JBuk said, you will start getting diffraction because of the limitations of your cameras resolution, you will also see drops in contrast. You can only really get away with low apertures when you shoot on medium and large format (precisely the reason why most landscape photographers shoot on LF) because the film has a larger surface.
Click to expand...

Its nothing to do with the camera resolution simply a limitation of the rules of physics. A larger sensor would help.

I would never go above f/11-f/16. And all leneses are noticibly softer at f/16 than f/11. F/22 is never acceptably sharp.
 
EnglishMack said:
The higher the resolution per mm on the sensor, the sharper the image.
Click to expand...

No, the softness due to refaction has nothing to do with the sensor. Infact, the higher the pixel desnity the worse the softness will be. The softness is due to refacrtive properties of light going through the small aperture opening which defines the max possible resolution. Only at large apertures do you gain some shrpness with increased resolution, otherwise the 2 are exlcusive of each other.
 
domthecondom said:
god dam it you lot :P i should never go above F16 then?
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Never, and if you hvae a high resolution crop sensor (e.g., 12-15mp), f/14 might be a limit.

check here for an example: http://www.slrgear.com/reviews/showproduct.php/product/355/cat/23

Image softens slightly from F/11 to f/16 buit still good at all focal lengths. Going from f/16 to F/22 makes the image unacaptably soft throughout. Therefore for this lens on this camera, f/11-f/16 gives the smallest acceptable aperture.
 
The Tamron unfortunatly has a large field cureture as described in the review here:
http://www.photozone.de/nikon--nikk...pherical-if-nikon-test-report--review?start=1

Basically this means that the plane of focus is not flat so if you focus at 10m in the centre then the plane of focus will curve in at the edges placing stuff at say 6m in focus but at 10m out of focus. To avoid this you will need to shoot at a smaller apeture f/11-f/16 as said avoid f/22 and above as they are noticably softer due to diffraction.
 
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D.P. said:
No, the softness due to refaction has nothing to do with the sensor. Infact, the higher the pixel desnity the worse the softness will be. The softness is due to refacrtive properties of light going through the small aperture opening which defines the max possible resolution. Only at large apertures do you gain some shrpness with increased resolution, otherwise the 2 are exlcusive of each other.
Click to expand...

Refaction? I can only assume you mean refraction. Refraction doesn't come into it and it's something totally different to diffraction.
 
Here is a useful link:
http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

In general these should be the max F-stop/ min aperture on Nikon Cameras

6mp class (D50, D70, D100, etc): F/16
10mp class (D200, D80, etc): F/13
12mp class (D2X, D300, D90): F/11

12mp FF (D3, D700): F/16


On Canon crop sensor the the sensor is smaller, pixel density higher and so the minimum aperture is larger. On the 4/3rds system You might find Diffract from F/8.

Hence landscape photographers rely upon medium or large format.

I learnt this the hardway by shooting 18 month at F/22 in landscapes wherever possible and was disappointed with soft images throughout. Some experimentation and high-school physics I determined the Optimal Aperture to be quite different. I shoot F/14 on my D70.


On luminous landscapes there is a similar article about max theoretical resolution. http://www.luminous-landscape.com/tutorials/resolution.shtml
Look at Table 3 in particular:
"take the green-yellow light and f/8-f/11 aperture values as a reference. It represents a realistic, not too demanding case. Consider a 35mm system with a lens at f/11. At best, the maximum resolution you will get is equivalent to 16 MP, even if your camera has 22 or 25 MP. In the case of an APS-C based system the limit goes to 7 MP, and 4 MP considering a Four Thirds format. Stopping down to f/22 the limit of the effective resolution of the 35mm based system goes to 4 MP!"

SO the 1DsMK3 at F/11 shooting a green england landscape can't resolve more than 16MP with even a theoretically perfect lens
 
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