Author Topic: Out of focus images with UV filter...Updated!!  (Read 1838 times)

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Offline Glank27

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Out of focus images with UV filter...Updated!!
« on: February 07, 2010, 01:49:11 PM »
Lately have been complaining with my A300 images which was suffering a lot to get a picture with right focus. Most images, almost always resulted  soft or out of focus. Also noticed that the camera was taking more time to focus.
I noticed that all this had stopped when i removed my Hoya UV filter. I don`t know if this may have nothing to do at all, but images are more successfully focused. When UV filter was on, i was always deleting 3 out of 5 pictures taken due to bad focusing, whilst without the UV filter i now rarely delete a picture due to bad focusing.
I`d like to ask if a UV filter may make the camera suffer to focus correctly. For your information, the lens used is the kit basic 18-70.
« Last Edit: February 18, 2010, 06:44:25 PM by Glank27 »
Sony A300 Dslr, DT 18-70 lens; SAL75300 lens.

Offline Asher

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Re: Out of focus images with UV filter
« Reply #1 on: February 07, 2010, 02:18:20 PM »
It probably isn't worth using a filter on the kit lens.

Is it a "digital" filter?
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Offline Glank27

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Re: Out of focus images with UV filter
« Reply #2 on: February 07, 2010, 04:19:43 PM »
no its not
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Offline Stef.

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Re: Out of focus images with UV filter
« Reply #3 on: February 07, 2010, 05:20:51 PM »
I have protection filters on all my lenses and never a problem.
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Offline AScot

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Re: Out of focus images with UV filter
« Reply #4 on: February 07, 2010, 08:25:23 PM »
Hoya filters come in various grades and in regular and digital. The cheapest Hoya (In the green box I think) is still a very good filter and would not cause even a kit lens to focus poorly, at least I don't think so. Unless of course it is dirty or scratched. :D

Like Stef, I use Hoya or B+W UV or clear protective filters on all my lenses. Can't say I don't have problems though, It's usually me at fault, not the filters. 
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Offline zekewhipper

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Re: Out of focus images with UV filter
« Reply #5 on: February 08, 2010, 05:03:14 AM »
Lens filters should not be causing AF issues.  I would try a different filter.
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Offline jesseclarke

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Re: Out of focus images with UV filter
« Reply #6 on: February 09, 2010, 12:46:17 AM »
I usually use a filter as a lens protector, without a problem so far.

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Offline keithf

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Re: Out of focus images with UV filter
« Reply #7 on: February 09, 2010, 11:44:05 AM »
Stupid suggestion was the filter screwed in 100% right, if it was off slightly then the light would be coming through at an odd angle, which could be confusing the metering/focusing systems....Or if there is the merest hint of a smudge on the filter that could also affect it or if you have cleaned the filter with anything like washing up liquid which may have stripped any protective layers off. or you could have got a dodgy one....have you got a mate with a same size filter thread, get them to try it on their lens/camera kit if they get the same result then it's likely to be the filter, if not then it could be the camera....
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Offline Asher

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Re: Out of focus images with UV filter
« Reply #8 on: February 09, 2010, 02:28:56 PM »
I never use a filter as protection and I haven't had any problems either. :)
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Offline Madraykin

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Re: Out of focus images with UV filter
« Reply #9 on: February 17, 2010, 12:46:32 PM »
I have a UV on my lens pretty much all the time and havent suffered any problems.... I don't want to come across as patronising, but have you checked the lens and filter are clean, inbetween them? I.E, you didnt accidentally put a smudge on the filter or lens when you put it on?

Failing that I'd get a new filter and see if you get the same problems....
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Offline Madraykin

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Re: Out of focus images with UV filter
« Reply #10 on: February 17, 2010, 12:47:36 PM »
OH, I also notice with my a300, if the battery is below 45% then the images are almost always blurry.... (maybe because it takes longer to react in AF mode?)
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Offline Glank27

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Re: Out of focus images with UV filter....Updated!!
« Reply #11 on: February 18, 2010, 06:43:51 PM »
Had some shots today with wife and kid, and didn`t ue the UV filter as to see how the camera performs. Unfortunately many images are soft and a bit blurry. Battery was ok, so shouldn`t be a slow reaction due to a not charged battery. I tried various AF methods.... centre, wide, and also continous AF-C, AF-A, but the problems seem to persist in most settings.
Might this be a lens problem?
To say it all, i notice this blurring in images only when viewing them in full resolution. Image sized to fit screen, images all look fine. Am i perhaps expecting too much from my DSLR?
Sony A300 Dslr, DT 18-70 lens; SAL75300 lens.

Offline Mike (Senior)

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Re: Out of focus images with UV filter...Updated!!
« Reply #12 on: February 18, 2010, 06:53:53 PM »
Not sure what you are asking exactly.
There is no way for us to know what is causing your images to be soft or out of focus.
It could very well be faulty equipment, could be you, could be your subjects, could be your post processing or lack there of, could be a combination of all of this.
Where are the sample images with detailed camera settings, detailed post processing procedure etc, etc?

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Offline Stef.

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Re: Out of focus images with UV filter...Updated!!
« Reply #13 on: February 18, 2010, 09:18:29 PM »
Glank27- some questions first:
a) did you shoot in RAW? If yes than the reason might be that raw images need to be sharpened in post-production
b) which lens did you use - what length- what aperture and exposure speed? It might be that what you see is camera shake. If you have used a longer lens i.e. or the shutter speed was too slow than this is obviously possible. If nothing at all is sharp in the image than it is very likely camera shake.
c) was sss turned on or off?
d) to check whether the lens is sharp or not: mount your camera onto a tripod- turn sss to off- set the camera to self-timer - focus onto something such as a bookshelf - make sure you keep the minimum distance and then shoot at different apertures.

If you used a kit lens than do not expect razor sharp images. Nevertheless- even with kit lenses if you stop them down i.e. use a higher f stop they should give you a reasonable sharp image. Lastly- how old is the computer monitor? Can you trust its resolution and sharpness?
If you could post an image with the data (f stop and shutter speed) this might help to determine where the fault is. Hope we can figure it out.
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Offline Glank27

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Re: Out of focus images with UV filter...Updated!!
« Reply #14 on: February 20, 2010, 08:06:59 AM »
SSS is always on. I should try with it at OFF position. Lens used is the kit lens, so it could be that i am expecting a bit too much.
Which popular alternatives are there as for sharp lenses for the A300?
Sony A300 Dslr, DT 18-70 lens; SAL75300 lens.