Canon 7D Front Focusing Problem

Whilst I have had some reasonable pictures with the 7D I haven’t been totally satisfied with the results. At first I thought it was my technique that was wanting because the lens I purchased (Canon 400mm f5.6) does not have IS. I had also read somewhere that the 7D requires a heavier hand on the sharpening to get the desired results and indeed I have had to resort to this on most of the images I have  posted on Flickr.  Whilst heavy sharpening can often improve the image the results are never the same as a  picture that started off sharp and heavy sharpening increases the noise quite markedly .......... but that’s another problem.

A month or so ago on a rainy day with the Slavonian grebe in Dover marina I did a side by side comparison of the Sony and the Canon and without doubt the Sony was the best. As I'd only just got the Canon I attributed this to the lack of IS on the Canon and the slow shutter speeds I was experiencing.

On one of my days on the cliffs with the perched peregrine I did another side my side comparison and on this occasion although the Canon produced the superior images I was still a little disappointed with the results especially when cropped in close. As before there was a softness to all the images even though this time the pictures were all were taken using a tripod and I had good shutter speeds.

The outcome of these comparisons and problems made me reluctant to take the Canon out on dull days and if/when I did I was resigned to using a tripod and high ISO (to keep the shutter speed high).

Having spent so long in deciding what to buy to replace the Sony I didn’t want to admit to making a mistake in purchasing the Canon - not just because of the money wasted but because I had no idea what to change it for.  So had I wasted my money? Today I set out to find out.

My first test on the accuracy of the focusing was to use a method suggested by Steve Ashton whereby you set up at ruler at 45 degrees then focus on one of the central numbers. I took a number of shots at different shutter speed and every single one suggested I had a front focusing issue i.e. the number I was focusing on was not the sharpest it was several centimetres down the ruler..

I searched the internet and found a test target (published by Tim Jackson) that I printed off, set up and ran some more test. The test chart is marked up to show how bad the back/front focusing is - with the right hand side being further away from the camnera This test showed I had a significant  front focusing problem - of the order of 10-20mm.(I did a lot of shots at different shutter speed but I needn’t have bothered – they all showed the effect):

Focus was on the thick black line

 Out with the manual and after several changes to the autofocus microfocus adjustment I think I have overcome the problem:

Post adjusting

Fingers crossed.

Sunday. As the sun was shining I went along the cliff tops from South Foreland to Langdon Hole looking to find something to point the camera at (hoping for a peregrine) to test whether the adjustments would have an effect in the field.

There was a not a lot going on but mippit numbers have increased over the last few days and were singing/displaying with gusto but the first test subject was a male stonechat. He never let me get really close but the results were far far sharper than I had grown to expect (I’ve put an uncropped version up so you can see the level of cropping done on the close up):

Uncropped

Stonechat

When at Langdon Hole I spotted 2 peregrines circling just above the cliff top back towards Fan Bay so I returned to near the rock fall and waited. I didn’t have to wait too long before one did several passes:

Peregrine

Whilst waiting for the peregrine to come close one of the herring gulls seemed to take exception to the presence of the peregrines and pestered one of them for about 5 minutes but sadly always distant:

Herring gull attacking peregrine

On the return leg there was a male wheatear down in Fan Bay but I couldn’t be bothered to climb down to try and get some pictures but a mippit did let me get reasonably close and again the shots are much better than I’ve experienced previously.

Meadow Pipit

So not an exciting day bird wise but it’s a relief that the camera is now operating how I’d hoped it would.

(Click on any image to get them all at a larger size)