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04-23-2010, 01:22 PM   #1
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Sharpness with DAL 55-300mm

I'm having some issues getting really sharp images with my DAL 55-300. I'm a newbie, so I thought I would ask for some advice.

When I take the photos and look at the tiny picture in the viewfinder they look pretty crisp, but once they're loaded on the computer and I zoom in on the subject I realize that they are very soft. I have shake reduction turned on and am trying to be as still as possible, but I'm not seeing the results I'm hoping to.

For others that use this lens, is this a common problem when shooting with this lens and not mounting to a tripod? I've even noticed some similar issues when I use my 18-55 kit lens, so maybe it's just my unsteady hands?

Any advice would be helpful. Thanks!

04-23-2010, 02:03 PM   #2
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I've got a DA 55-300/F4-5.8. It's not bad, but when you start heavily cropping on 300mm FL shots (say 25% or less of the original 14.6Mpx shot) you can notice a reduction. You're down to about 3.5Mpx so the reduction could be purely pixel related, but I think with this amount of crop-produced "'magnification" you'll also see lens problems.

I do weekly Saturday morning U8 soccer (half-length fields) and a tripod with K20D and the 55-300. I follow the action, by panning, throughout the game. If I close-frame (zoom in to concentrate on just 1 or 2 players) I face problems when they kick (the ball may already have moved out of the frame - I don't like an action shot of a player who had just given a great kick and you can't see the ball in-frame.). If I use medium-framing, I can keep the ball in-frame more easily and see approaching players on an intercept path, so I can get more dramatic shots, but I end up cropping more often, sometimes a lot.

Have you tried it on a tripod (with SR off)? It could also be a B/F focus issue. Try:

https://www.pentaxforums.com/forums/pentax-dslr-discussion/46793-moire-patter...djustment.html

Dan

Last edited by dosdan; 04-23-2010 at 02:34 PM.
04-23-2010, 02:30 PM   #3
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There are several possible reasons for this, so it's very hard to say without seeing some samples. Could you upload some pictures you're unhappy with? Preferably full size.
04-23-2010, 02:33 PM   #4
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BluBubble Boy, have you considered the other factors that cause soft results? If not, have a look at the shutter speeds used to capture those shots you claim are soft. Even with SR on, ensure that Tv does not exceed 1/focal length, i.e. keep shutter speed faster than 1/300 for a shot at 300mm.

Also ensure that SR engages before you release the shutter - this involves keeping the shutter button half-depressed after locking focus momentarily until the SR symbol lights up in the viewfinder. When shooting on a tripod, use both SR off and the 2-sec shutter release delay function to avoid inadvertent camera shake from mirror slap.

If your tripod isn't rock-solid, that is a more obvious cause of camera shake and thus soft results.

Focus points are important as well, and any slight movement of the camera towards or away from the subject at high focal lengths can dramatically affect the sharpness of the subject in the image.

Overall, the 55-300 is an excellent lens (for a slow telezoom) and can give you great results. Some of my examples at full-stretch:




04-23-2010, 02:39 PM   #5
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QuoteOriginally posted by Ash Quote
Even with SR on, ensure that Tv does not exceed 1/focal length, i.e. keep shutter speed faster than 1/300 for a shot at 300mm.
Ash, that's for FF. For Pentax APS-C, multiply the shutter speed by 1.5 i.e. minimum of 1/500s at 300mm. If the SR operates correctly, you'll be able to go slower than that.

Dan.
04-23-2010, 03:01 PM   #6
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A lot of things look crisp on the viewfinder, but you can set the magnification so when you crank the wheel in review mode, it zooms in to a preset magnification. I use this for checking focus on critical shots in the field.

And a lot of shots look soft if zoomed in to 100%, though they might in fact be perfectly fine when viewed reasonably. I agree with Eric that we need to see pictures to tell what is going on.
04-23-2010, 03:04 PM   #7
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QuoteOriginally posted by dosdan Quote
Ash, that's for FF. For Pentax APS-C, multiply the shutter speed by 1.5 i.e. minimum of 1/500s at 300mm. If the SR operates correctly, you'll be able to go slower than that.

Dan.
They say the SR can get you 3-4 stops but I do not count on that much. My rule of thumb is to use the old full-frame rule and then take off 2 stops. This is conservative but means I take extra care in borderline situations.

So if I'm shooting a 100mm I start with 1/100s, then go to 1/50 and 1/25. I would not shoot slower than that.

(And of course this does not help with subject movement.)
04-23-2010, 03:12 PM   #8
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QuoteOriginally posted by rparmar Quote
use the old full-frame rule and then take off 2 stops.
Yes, I only expect about 2 stops. With 300mm on APS-C, that's about 1/125s. Stabilisation-in-lens (e.g. new Sigma) on a Pentax may get 3-4 stops improvement.

Dan

04-23-2010, 03:19 PM   #9
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QuoteOriginally posted by dosdan Quote
Yes, I only expect about 2 stops. With 300mm on APS-C, that's about 1/125s. Stabilisation-in-lens (e.g. new Sigma) on a Pentax may get 3-4 stops improvement.

Dan
Any scientific proof that in-lens stablization is better by 3-4 stops instead of 2-stops? Just curious....
04-23-2010, 03:27 PM   #10
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QuoteOriginally posted by aleonx3 Quote
Any scientific proof that in-lens stablization is better by 3-4 stops instead of 2-stops? Just curious....
There's empirical proof in tests of the performance of stabilized lenses at Digital Camera Reviews and News: Digital Photography Review: Forums, Glossary, FAQ compared to the SR performance in cameras. Although I think the SR performance of the top-end Sonys is very good.

Dan.
04-23-2010, 03:32 PM   #11
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QuoteOriginally posted by dosdan Quote
There's empirical proof in tests of the performance of stabilized lenses at Digital Camera Reviews and News: Digital Photography Review: Forums, Glossary, FAQ compared to the SR performance in cameras. Although I think the SR performance of the top-end Sonys is very good.

Dan.
Thanks, Dan, but I don't really read too much into DPReview...
04-23-2010, 03:42 PM   #12
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QuoteOriginally posted by aleonx3 Quote
Thanks, Dan, but I don't really read too much into DPReview...
I don't either, but the SR differences seem consistent on their tests.

Dan.

Last edited by dosdan; 04-23-2010 at 04:03 PM.
04-23-2010, 08:06 PM   #13
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Aside from shake, it's also possible the problem is as simple as the camera not focusing at the same exact sport where you are lookuing at 100%. Not sure how familair you are with DOF (depoth of field) and how to control how deep it is and where the focus is, but I'd say failure to dequate control focus is the main mistake people make that leads to a perception of soft images.
04-23-2010, 09:16 PM   #14
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Technicalities aside, the lens is simply brilliant at rendering detail. Have a look at these images with 100% crops to show you how sharp it is:



and 100% of above:




100% crop:




100% crop:




100% crop:


My originals are tack-sharp even if they don't appear that way here. And the apparent colour/sharpening noise seen on the 100% crops are also hardly as visible as they are here. The image hosting site must be playing tricks with me...

Last edited by Ash; 04-23-2010 at 09:26 PM.
04-23-2010, 10:01 PM   #15
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Da(l) 55-300

Hi B,
DA 55-300 only autofocus Ive ever bought, it and 18-55II only ones I own
when I first started using, I slapped an old, low quality 58mm UV filter on it,with somewhat same expirence as you, removing was improvement.
Also broke original hood,noticible difference without hood,
it hurt, but I bought another OEM hood

As good as that lens is at min/max zoom, I think its way better in ranges exclusive of
high/low end

Last edited by BillM; 04-23-2010 at 10:11 PM.
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