Hmm to my eye the shot still lacks critical sharpness, but the image is fine in all other respects.
Posted by Andy Astbury on March 1, 2008 at 5:08 AM
Comp-wise it works Ian
Here's my input FWIW - if I look at the image I can see more sharpness between the subject and camera than beyond the subject - I'm looking at the grass stalks and the ground in general.
There's a lot of sharpness in the grass in the left bottom corner of the frame and across the frame at that distance. But if you look between the birds legs the grass behind the bird is soft, even though it's closer to the subject than the sharp stuff in the foreground.
It doesn't matter whether you are Old Skool DoF third in front two thirds behind, or New Skool DoF half in front half behind - neither seems to apply here.
Either you've suffered from 'pilot error' in focusing or you may have a calibration problem - I'd fancy the first option, especially with the 2x 'in play'
It would be better trying to judge on the full res tiff without any sharpening, but judging from this small jpeg your focus point is actually infront of the subject.
Also curious as to why you used f10 - at these distances all that will give you is a less OoF BG which is never really a good thing as it fights the lens' bokeh, removes smoothness and makes the BG look more 'busy'.
Try doing some shots at f4 of a static object at a distance of say 40x the focal length both with and without the TC, so 24 meters without and 48 with - as long as you shoot along the same line the subject should be roughly the same size in both images - this will show you if there's an error in your lens cal and also what effects the tc is having.
Looks like Andy has covered everything! I'll just add that when I get a new lens or body I go into the garden with various items (of different materials and colour) to test focus and exposure at varying distances. Then examine the results on a big screen. This also helps in understanding your equipment and knowing how it'll react in various situations.
Posted by John Chapman on March 1, 2008 at 6:22 AM
Hi Ian the overall setting is nice but the Curlew is not critical sharp on my screen.
John
Aberdeen
I'm terrible at assesing sharpness on a small jpeg, so I won't bother, but the composition, subject and warmth of the scene work a treat.
I do similar to Paul and assess a lenses sharpness by mounting everthing on a very sturdy tripod,locking all the controls on the head solidly, locking the mirror up, focusing and exposing very carefully and attaching a remote release. Overcast conditions work best with identical light for each shot. I then do a series of shots at all apertures, with and without extender's,etc, perhaps using auto focus and manual focus as well. I find buildings make great testing material with the wealth of fine detail and texture being an excellent test for sharpness. Plus they don't move, so that cuts that issue out of the equation. Churches are my favourite, lovely and peaceful so you can really concentrate on what your doing without disturbance
Checking the results in Breezebrowser by comparing up to four images works superbly in evaluating the results and the ability to zoom to 100%, 200% and 400% shows even the slightest difference between shots.
Once this test has been done and the results are acceptable you then know any images that don't shape up are either through poor technique, subject movement, atmospheric conditions or the type,direction and quality of the light, to a lesser extent.
Posted by eric weight on March 1, 2008 at 10:45 AM
Nice colours and comp.
Plus some excellent advice. Useful post for me. Eric
Dont know about anything else but an equivelent focal length of 1560mm only takes a small vibration to take the edge of the sharpness.I like the comp and the light and also the slightly less difused bg.
Stu.
Posted by Andy Astbury on March 1, 2008 at 1:40 PM
Stu is dead right - but it doesn't apply in this case.
Vibration would soften the entire frame, not just the subject
It's a focus issue Ian, plain and simple - DO THE TESTS matey
Many thanks to everyone for the very useful advice! I have tried the lens indoors with stable subjects and there is no doubt it makes sharp images. It is clearly a technique issue and I need to keep practising. I have a few more images to post and I thank you in anticipation!
Discussion
11 repliesThe sun shone for this one, giving me a better shutter speed. How is it for sharpness this time?
Here's my input FWIW - if I look at the image I can see more sharpness between the subject and camera than beyond the subject - I'm looking at the grass stalks and the ground in general.
There's a lot of sharpness in the grass in the left bottom corner of the frame and across the frame at that distance. But if you look between the birds legs the grass behind the bird is soft, even though it's closer to the subject than the sharp stuff in the foreground.
It doesn't matter whether you are Old Skool DoF third in front two thirds behind, or New Skool DoF half in front half behind - neither seems to apply here.
Either you've suffered from 'pilot error' in focusing or you may have a calibration problem - I'd fancy the first option, especially with the 2x 'in play'
It would be better trying to judge on the full res tiff without any sharpening, but judging from this small jpeg your focus point is actually infront of the subject.
Also curious as to why you used f10 - at these distances all that will give you is a less OoF BG which is never really a good thing as it fights the lens' bokeh, removes smoothness and makes the BG look more 'busy'.
Try doing some shots at f4 of a static object at a distance of say 40x the focal length both with and without the TC, so 24 meters without and 48 with - as long as you shoot along the same line the subject should be roughly the same size in both images - this will show you if there's an error in your lens cal and also what effects the tc is having.
Looks like Andy has covered everything!
John
Aberdeen
I do similar to Paul and assess a lenses sharpness by mounting everthing on a very sturdy tripod,locking all the controls on the head solidly, locking the mirror up, focusing and exposing very carefully and attaching a remote release. Overcast conditions work best with identical light for each shot. I then do a series of shots at all apertures, with and without extender's,etc, perhaps using auto focus and manual focus as well. I find buildings make great testing material with the wealth of fine detail and texture being an excellent test for sharpness. Plus they don't move, so that cuts that issue out of the equation. Churches are my favourite, lovely and peaceful so you can really concentrate on what your doing without disturbance
Checking the results in Breezebrowser by comparing up to four images works superbly in evaluating the results and the ability to zoom to 100%, 200% and 400% shows even the slightest difference between shots.
Once this test has been done and the results are acceptable you then know any images that don't shape up are either through poor technique, subject movement, atmospheric conditions or the type,direction and quality of the light, to a lesser extent.
Plus some excellent advice. Useful post for me.
Stu.
Vibration would soften the entire frame, not just the subject
It's a focus issue Ian, plain and simple - DO THE TESTS matey
It does appear to be front focused, f10 despite what andy says should be optimal with the 2x.... looks like it could be a gorgeous image.
Major.