# Zoom lens quality and problem



## shinares777 (Nov 15, 2011)

Hi guys,

Im new around here and new to photography also. I have 1000d with 18-55 and 55-250mm....so far im pretty happy with the lenses but I noticed when I take picture with maximum or minimum zoom, the quality of the result seems to be not very good. My question is:

1. Is it normal for zoom lens to have less quality for maximum and minimum zoom ?
2. if so, what is the best range to get the best result for the zoom lens ? is it probably around 25-45 zoom for 18-55 lens and around 70-185 for 55-250mm lens ?

Any suggestion ? Thanks...


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## SCraig (Nov 15, 2011)

It is not at all uncommon for any lens to be less sharp at minimum or maximum aperture.  Zoom lenses are more prone to that problem, especially at full zoom.  Whenever possible keep your aperture (f-stop) 1 or 2 full stops from the minimum or maximum setting and you should notice an increase in sharpness.

Also keep in mind that:
1)  At maximum aperture (lowest f-stop number) your depth of field becomes limited.  What you are seeing may not be a sharpness issue but a depth of field issue.

2)  At longer zoom levels it takes a faster shutter speed to maintain a sharp image due to camera movement.  The rule of thumb is the reciprocal of the focal length.  If you are shooting at 55mm then use 1/55 second (round up to 1/60) as the slowest shutter speed you can use hand-held.  At 200mm 1/200 (or 1/250) should be the minimum.  If your lenses have optical stabilization you can exceed those limits by 2-4 full stops.  These are just rules of thumb though.  Your mileage may vary.


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## Big Mike (Nov 15, 2011)

Welcome to the forum.



> 1. Is it normal for zoom lens to have less quality for maximum and minimum zoom ?


Yes, and also at minimum and maximum aperture.  This is especially true with cheap 'kit' zoom lenses like you have.  

If you had the Canon EF-S 17-55mm F2.8 IS and the Canon EF 70-200mm F2.8 L IS II, you see much better quality across the board, and the drop-off at the minimum and maximum would be much less.  
But of course, you have to pay for that level of quality.


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## shinares777 (Nov 15, 2011)

Thanks for all the replies. Thats very helpful 

Well, the lenses were bundled with the body when i bought it  Im aiming for 100mm macro but need to save some money first :meh:


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## 2WheelPhoto (Nov 15, 2011)

I had a 55-200 and it won't take you long to find its "sweet spots" and you will get sharp pics.


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## Stryker (Nov 15, 2011)

for non "L" lenses, my own rule of thumb is the shutter speed must be at least 1/double your focal length.  If you have an 18-55mm lens, the shutter speed must be 1/110 or faster to have a clean, crisp output.  

Try it.  You'll have better output


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## MReid (Nov 15, 2011)

Don't shoot them wide open or at smaller than F14 for maximum sharp.
Sweet spot for sharp should be 5.6 or 8 somewhere in there.


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