> If this lens is a bad example
It's hard to render an opinion without a sample shot, referably raw.
- DL
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Camera locked down on tripod, main focus was supposed to be corner of the roof.I PM-ed ARD and offered to put it up on a web page I control, and here it is:
........tried to attach a raw file but can't get it to work
You need to take a classic brick wall photoWhy are so many photographers testing with a brick wall?
Why are so many photographers testing with a brick wall?
Brick walls are notoriously difficult to see details and contrast in. (I've tested with one, too.)
That being said, I have problems finding any area in the posted image that was sharp, even though you could identify roughly where the plane of focus might have been.
It is likely that the long exposure is a problem here (1/15s is a bit too optimistic when photographing flowers).
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I'll take a brickwall shot, and also anything else that might help in finding if the lens is defective or not.
Could you tell me what a good subject is for this, and what focal length and shutter speed.
I really appreciate everyones help on this one, and look forward to finding out if the lens is defective.
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Tried emailing the brick wall shot, but it is too big for my email, 8.2meg
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48MB PSD (http://beautiful-photo.com/300f4l/bricks.psd)
(The file will be removed later, "later" being subject to my bandwidth utilization, the positions of the planets, tea leaves, and quantum mechanics)
The color space is ProPhoto RGB, but I saved it with 8 bits per pixel to make the file smaller than 16 bits per pixel would.
I downloaded ARD's brick shot and did my best to duplicate it with my own 300 f/4 L IS lens. His shot is at the top, mine is at the bottom. Aside from the obvious difference of being different brick walls, his shot, at top, was made with a 1D Mark II (8.2 megapixel, 1.3x crop factor) while my shot, at bottom, was made with a Rebel XT (8.0 megapixel, 1.6x crop factor). Adobe Camera Raw auto-adjusted his shot +0.85 exposure, mine -0.55 exposure (I exposed at +2/3). I applied Photokit capture sharpening to both captures, medium edge sharpening. I set the white balance of each from the mortar, and they are both just above 4000 Kelvin. My lens was tripod mounted with the collar and I used self timer and mirror lockup. He'll have to comment on his capture technique.
My preference is not to shoot bricks, but rather books, CDs, or DVDs because I find judging the sharpness of text written on the spines easier and there are many more colors present to judge. Shelves of such media are typically indoors, too, so the light can be controlled from shot to shot, or even duplicated at a later date. But in this case, bricks it is.
Judge for yourselves.
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I don't think there's anything wrong with your lens. Sharp corner to corner, and focus appears good (autofocus was better than fore/aft). If I get a chance I'll take a similar shot with mine for another comparision. The 300 is a sharp lens but doesn't compare to the 70-200 for instance. Yours looks within normal range.
- DL
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Thanks for the reply, I thought that the 300 would be sharper than the 70-200 as it is a prime lens?
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I haven't reviewed the uploaded files but my 300 f/4 IS is very nearly as sharp as my 500 f/4 IS and both of them are as sharp or sharper than samples I've seen from the 70-200 f/2.8 IS and as sharp or sharper than the 70-200 f/4 I used to own.
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The 500 f/4L IS is much sharper than any pixel pitch can currently take advantage of, so unless you start comparing it to lenses like the 300 f/4L IS with the same amount of stacked TCs, you're going to experience equalization by a coarse recording medium.
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I haven't reviewed the uploaded files but my 300 f/4 IS is very nearly as sharp as my 500 f/4 IS and both of them are as sharp or sharper than samples I've seen from the 70-200 f/2.8 IS and as sharp or sharper than the 70-200 f/4 I used to own. [a href=\"index.php?act=findpost&pid=72752\"][{POST_SNAPBACK}][/a]No way is the 300/f4 as sharp as the 70-200 (one of Canon's sharpest lenses, zoom or not). Check Photodo, 300/f4 mtf = 3.4, 70-200 mtf = 4.1. Note that the non-IS version of 300/f4 tests 4.3. My own feeling is that photodo's rating on the 300/IS may be a little pessimistic, but it would be an exceptional example that would be sharper than the 70-200.
No way is the 300/f4 as sharp as the 70-200...
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The more significant question, Don, might be, 'Is the 70-200 with 1.4x extender sharper than the 300/4L IS?'
I wouldn't know, but I suspect even the rather poor copy of the 300/4 IS that Photodo tested would be at least equal to the 70-200 with 1.4x extender, as the test charts below would suggest. Add an extender and those curves for the 70-200 will probably drop by 10-20 MTF percentage points.
[attachment=881:attachment]
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I wonder though how many people never realise they have a copy of a lens that is not as good as it should be.
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I have long thought to trade my 300 for the 100-400 but just cannot part with this lens. It comes into its element at f/4 and as I have never used a tripod, the IS is handy.
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No way is the 300/f4 as sharp as the 70-200 (one of Canon's sharpest lenses, zoom or not). Check Photodo, 300/f4 mtf = 3.4, 70-200 mtf = 4.1. Note that the non-IS version of 300/f4 tests 4.3. My own feeling is that photodo's rating on the 300/IS may be a little pessimistic, but it would be an exceptional example that would be sharper than the 70-200.
- DL
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The EF400mm f5.6 LUSM might be another option as this is supposed to be the unsung hero of Canon
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Got a replacement lens today, and still have the original. I took a few shots at the same settings. I think the new lens is better, sharper and more contrast.
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Of course, it could be that your target does not contain fine enough detail. I generally find that the written word is a useful target. Arrange the distance to target and the size of the lettering so that at least some of the words are almost illegible. If the better lens makes them legible, then that can be considered a meaningful improvement.That's the point I was trying to make earlier:
My preference is not to shoot bricks, but rather books, CDs, or DVDs because I find judging the sharpness of text written on the spines easier and there are many more colors present to judge. Shelves of such media are typically indoors, too, so the light can be controlled from shot to shot, or even duplicated at a later date.I could've been clearer, I suppose, by saying a shelf of books, CD cases, or DVD cases. CD and DVD cases work particularly well at close distances because their depth is consistent. Book spines don't tend to be all on the same plane so focus and depth-of-field issues overshadow lens differences. There is also almost always some white somewhere on some of the spines to set white balance from.