Canon 70-300mm zoom...help.

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Kell
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#1
A little while ago I bough a Canon 70-300mm on the advice of people on here.

Now I'm beginning to wonder if I bought a dud as I cant seem to get anything sharp at 300mm, but it seems very sharp at 70mm.

Alternatively (even probably) it could be poor technique or bad choice of settings.

I assume the IS is working as I can hear it whirring away. But at the minute, there's not a lot in it in terms of sharpness from shooting at 70mm and cropping in or shooting at 300mm.

So my question is what COULD I be doing wrong and how would I correct it? I haven't done an exhaustive test, so it may work on a tripod for example, but if I can't rectify this, there's not much point in having a zoom at all.

Couple of sample images...(all SOOC - just converted to JPEGS in Photoshop).

Shot at 70mm:

IMG_7342
by Kell Lunam-Cowan, on Flickr

Shot at 300mm:

300 mm crop
by Kell Lunam-Cowan, on Flickr

Shot at 70mm and cropped to same size as 300mm.

70mm crop
by Kell Lunam-Cowan, on Flickr
 
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Dominic
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#2
1/400 at 300mm is maybe a bit slow (even with IS) it all depends on how steady you are and your technique. Also at 300mm the lens will most likely be a little softer than 70mm. Shooting at f/7 or 8 would probably help.
 
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Tony
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#4
Actually, what focus pattern did you use?
Centre point, expanded, group area..............????

I've found to my cost that canon cameras tend to be heavily weighted to "closest object" focusing.
 
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Kell
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Kell
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#5
I think I switched everything over to full auto for this test - to try and eliminate me using the wrong settings. But when I've used it before I've used centre spot. And still had failings with it. Looking back however, it might have been better to try and only change one thing at a time.

was the clock dial the point you focused on?
It was - and it looked like it acquired that as a focus point.

1/400 at 300mm is maybe a bit slow (even with IS) it all depends on how steady you are and your technique. Also at 300mm the lens will most likely be a little softer than 70mm. Shooting at f/7 or 8 would probably help.
Of course - I'd forgotten about the focal length/shutter speed rule.

This particular lens has two axis IS, so I had it switched to mode 2 which doesn't allow panning and should provide the most stabilization.

I didn't remember to try one with no IS though.

Things to try then:

Faster shutter speed at 300mm to compensate.
 
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Kell
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#7
When it goes to full auto - I don't have that option.

however, I have it set to centre spot on AV and M, so I will look to take some shots at a faster shutter speed to see if that helps.

As said above, this lens gets great reviews, so it's likely to be me ballsing it up rather than the equipment.
 
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Tony
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#8
Just briefly looking at the technical data, it is not as sharp at 300mm as it is at 70mm.
To get the best from the lens at 300mm it needs to be stopped down to f/8.
 
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#10
Just to clarify........................there are or were two versions of the 70-300mm a 'standard' one and an L one, which one do you have???
 
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Alistair
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#12
I've had 2 copies of the Canon 70-300 IS, one I used on my old 60D and found it ok and I now have another one on my 6D. This one I have now I find it a bit soft (the problem is that by comparison, I have sharper lenses ;) ), so I've used the camera's lens micro-adjustment to try to compensate.
At 70mm I've set it to about -5 and at 300mm it's up to maximum +10.
I do try not to use the maximum aperture unless focusing on something close.
Higher shutter speeds will help. But you might also have faulty IS, so do test shots with and without IS too.
 
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Kell
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#14
I did go back out the following day with my 'go-to' lens (Tamron 24-70 2.8) and stood in the same place to take another shot at 70mm, but appreciate that there are too many variables for this to be a good test. When I next have time (and it's daylight) I'll take a variety of lenses out to compare them, and try to remember to put it into manual so I'm comparing like with like.

But thank you for the couple of pointers so far, at least it gives me something to 'focus' on.
 
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Gary
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#15
I think I switched everything over to full auto for this test - to try and eliminate me using the wrong settings. But when I've used it before I've used centre spot. And still had failings with it. Looking back however, it might have been better to try and only change one thing at a time.



It was - and it looked like it acquired that as a focus point.



Of course - I'd forgotten about the focal length/shutter speed rule.

This particular lens has two axis IS, so I had it switched to mode 2 which doesn't allow panning and should provide the most stabilization.

I didn't remember to try one with no IS though.

Things to try then:

Faster shutter speed at 300mm to compensate.
Mode 2 is for panning. It disables IS in the horizontal plane. Mode 1 gives IS in both Horizontal and Vertical planes.
 
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Jim
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#17
I think you should be using mode1. Canon's description isn't very clear but I believe mode 1 is the standard for normal shooting.

Ah, beaten to it by Gaz.
 
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Kell
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Kell
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#18
I'll check the lens when I get back in as it will still have the same settings, but I'm pretty sure it was on 2.
 
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Alistair
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#19
Mode 2 is for panning shots, mode 1 is for normal use.
One theory also suggests you should turn off the IS if you are shooting beyond the reciprocal of the focal length; ie if you're at 1/300 or more on a 300mm lens, then you might actually catch the IS moving the image across the sensor and thus it'll not be sharp.
Also, you need to press and hold the shutter briefly to let the IS start working and settle before you take the image otherwise you get the same problem, ie the IS mechanism is still moving.
 
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#20
Some good advice from people for you there. (y) Do keep us updated on your tests and results with that lens at 300mm, as I'm thinking of buying one as a stop-gap until I can save up for a 100-400 L Mk2. :D
 
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Richard
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#21
Mode 2 is for panning shots, mode 1 is for normal use.
One theory also suggests you should turn off the IS if you are shooting beyond the reciprocal of the focal length; ie if you're at 1/300 or more on a 300mm lens, then you might actually catch the IS moving the image across the sensor and thus it'll not be sharp.
Also, you need to press and hold the shutter briefly to let the IS start working and settle before you take the image otherwise you get the same problem, ie the IS mechanism is still moving.
Not quite, the theory is when the shutter speed exceeds the sampling frequency of the stabilisation system, but it's only a theory and I've never seen any hard evidence that image-stabilisation is detrimental at high shutter speeds, and no manufacturer has ever supported that view. The reason some professionals switch off IS with long lenses is because they're using a monopod or tripod when it's unnecessary and drains the battery.

The point about letting the IS spool up before tripping the shutter is very valid though - takes about half a second.
 
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Kell
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#22
OK, so first off, thank you everyone for your input.

Secondly, yes I was a div and mis-remembered the bit about the dual stabilization. I did have it set to 2 which, in a typical stupid way only offers 1 axis stabilization. Whereas 1 offers 2 axis stabilization. Still, my fault and a reminder to RTFM.

I didn't actually take any shots with IS off, but just looking through the viewfinder with it on and off, you can see how much more stable the image was.

So onto the results. Everything was much sharper - both at 70mm and 300mm. Certainly enough to make a convincing argument that the dud in question wasn't the lens, but the bloke stood behind it.

I took a couple of shots with the 70-300 at both 70 and 300, then swapped to my Sigma 18-250 and took one at 18mm (to give an idea of the distances involved here) plus one at about 70 (73mm according to the data) and then one at 250.

As before, I've blown them all up to match the one taken at 300mm and can now confirm that the 300mm version looks to be the sharpest to me.

Oh, and just for a laugh, I cropped into the 18mm version too.

Pics below (for some reason the BB Code isn't working, so these don't link to the Flickr images - and because these are exported JPEGS from Photoshop, the EXIF data isn't there, but they were all shot at f/8.0, 1/125, ISO 100.

If you wanted to view the 300mm full version it's here: https://www.flickr.com/photos/119343618@N08/28317258798/in/dateposted-public/

18mm Sigma Shot for reference:



Canon 300mm



Canon 70mm shot blown up to 300mm



250mm Sigma shot blown up to 300 mm


Sigma 73mm blown up to 300mm



And finally, Sigma 18mm blown up to 300mm

 
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Kell
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Kell
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#23
For the record despite ALL that, I put the camera into aperture priority to ensure it stayed at f/8.0 and forgot about the bloody shutter speed. These were all taken at 1/125, so it's probably remarkable they're as sharp as they are.

But in short, the lens is OK, I'm the faulty part...
 
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