Sunday 18 November 2012

Lens Aberration - that can't be good…

I've been putting my camera through it's paces for a few months now, trying new things, having some successes (along with plenty of failures), but one thing that's really starting to bug me is the performance of the kit lens.


I mentioned it in the last post, so I'd like to elaborate a bit here so other users will know what to look for - but the same problems seem to crop up regardless of the lighting conditions and don't seem to be exclusive to the extremes of the focal length.

Now - don't get me wrong here - compared to the majority of compact cameras this is still a great lens and I've found it great for learning the craft and how to use my equipment. And I've captured some great images, but the lens has introduced the same 2 flaws consistently, that - now my eye has become more critical - is really doing my head in!

This shouldn't come as a surprise really as I've noticed quite a few adverts offering the camera body on it's own or with the lens and the price increase is now only £30. When you look at it that way - even factoring in the problems - it's an incredibly cheap lens and pretty good value for money.

But you do only get what you pay for in this life of toil and it shows here

Some things that are bad, sometimes sound nice - binge drinking, joy riding, friendly fire - they all sound nicer than they really are. Lens aberration just sounds straight up nasty though, and here's what to look for if your lens is exhibiting flaws:

1 - colour fringing - this is the number one gripe I have with the 18-55 kit lens. You would expect some colour fringing at the focal length extremes (18 or 55) - or maybe if you shoot straight into the light source, but it seems to happen under most circumstances.

2 - colour noise - this is the equivalent of the grain you would get in some high iso films, and would show as grain in the print. Here it shows as noisy pixels and is most often seen in the sky areas of an outdoor image

An example of both can be seen in this image of the Sagrada Familia in Barcelona…



This shows the camera raw image opened in Adobe Camera Raw, for processing into photoshop (this is a great tool and I'll cover it more in a future post). Zoom into the detail though and all is not well!



If you check out this enlargement - you can see the colour fringing clearly along the edge of the building. It shows as a green colour fringe along the edge.

Also the sky areas are fairly noisy. You can see this as a dithering of the pixels across the flat blue of the sky.




On the plus side, there doesn't appear to be any vignetting - that's where the edges of the lens barrel cast a dark halo around the image corners like you're looking down a tube - so it's not all stick and no carrot!


So - time for a top tip here, brace for impact…

Check your images at true 100% magnification on a proper monitor or laptop screen


Never judge the quality of an image by looking at it on the camera LCD screen - everything looks great on there! The true acid test, for all images, is to open the file in your preferred processing application (there are loads - the Nikon "View NX 2" software that is supplied with the camera is great), and view the image at 100%. I usually zoom in to 400% to check mine and that's when all the badness floats to the surface - but at least then you can correct it.

It makes the difference between a good image and a potentially great image.

I'm planning to break up the posts going forward with some diary type posts, some tips and some gear or magazine or book reviews. In addition, my passion is for landscape photography, and I will be posting links to other established photographer's work that I find inspirational, so you can explore their fantastic imagery yourself - kind of a "put you on it"

If you're enjoying the post to date though - please link to follow (I need some followers!) and I will always welcome your feedback.

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