Image is not sharp at 105mm


ahjie86

New Member
Dec 13, 2010
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#1
Hi, I'm currently using a D3100 paired with a 18-105mm. Images are pretty sharp at 18-55mm but at 105mm they are mostly not sharp. VR is turned on. Can I get some help on this? Thank you :)
 

tecnica

Senior Member
Dec 26, 2004
3,660
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#2
sorry but i cant imagine how your pictures look like by just reading 37 words.
 

ahjie86

New Member
Dec 13, 2010
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#3
Lol, you actually counted the number of words I wrote. Oh, then to put it simply, does the IQ degrade from 55mm onwards or is it supposed to be approximately the same as at 18-55mm.
 

Jun 14, 2010
973
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Admiralty
#4
In other words, please post a pic so we can analyze the situation more better and help you out.
 

tecnica

Senior Member
Dec 26, 2004
3,660
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#5
i'm not sure how you define "degrade", as everyone has their own threshold levels.

seriously, a picture speaks not just 37 but a thousand words. ;)
 

Aug 31, 2010
78
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#6
don't expect the best from this lens. u want sharpness, set your aperture between f8 - f22.
 

tecnica

Senior Member
Dec 26, 2004
3,660
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#7
stay away from the extreme end of the aperture range to avoid diffraction.

most lenses are normally sharp at between f8-f11(or f16). but there are lemons around too, so yeah.

kit lenses are good but dont overly expect from them.
 

Rashkae

Senior Member
Nov 28, 2005
19,105
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#8
don't expect the best from this lens. u want sharpness, set your aperture between f8 - f22.
Incorrect. After f16 diffraction sets in.

TS, most lenses, especially the "zoom" lenses, are not at their sharpest when at maximum aperture. try setting to f/8-f/11 and try again.
 

ahjie86

New Member
Dec 13, 2010
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#9
Thank you for all the positive feedbacks and help. I'll try em and maybe post some pictures tmr :)
 

daredevil123

Moderator
Staff member
Oct 25, 2005
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lil red dot
#10
Hi, I'm currently using a D3100 paired with a 18-105mm. Images are pretty sharp at 18-55mm but at 105mm they are mostly not sharp. VR is turned on. Can I get some help on this? Thank you :)
Without samples to look at, I would say it comes down to improper technique. You need to make sure that your shutter speed is at least 1/focal length when not on vr. On vr you need to calculate what is the minimum shutter speed for your focal length. For 105mm minimum shutter speed will be 1/100s. With vr minimum shutter speed will be around 1/15 assuming you get a real 3 stop vr advantage. To be safe I would say keep minimum shutter speed to 1/30s. And you need to learn proper handholding techniques as well.
 

#12
...I would say it comes down to improper technique...
It would help much if you could show a photos of the same subject taken under 55mm and at 105mm. I have a feeling it might be due to what bro daredevil mentioned.
Having VR on is one thing, using it correctly is another issue. When you attempt to focus on a subject by half depressing the shutter button, you will hear the "click" of the VR mechanism kicking in, hold steady and leave about half to a second for the VR system to balance out to steady state. This is when you can fully depress the shutter button to make the exposure. A better test would be to mount the camera on tripod with VR off to test the IQ at 55mm and 105mm, this should give some conclusive results. :)
 

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MRSAMO

New Member
Nov 17, 2008
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Australia->Japan
#14
105mm is not as sharp because quality falls off the greater the zoom length, 18-55mm is usually sharper across all the kit lenses within that range.
 

Jan 27, 2010
809
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#15
So what is the best aperture to take landscape for instance on a tripod? Some mentioned f8-f16. But which will provide the sharpest? f8? f11? f13? f16? Does it differ for different lenses?

Also TS, perhaps your VR is not off when set on a tripod. The VR will try to compensate, but since the tripod is too still, it introduces unnecessary compensation, hence the blur.
 

daredevil123

Moderator
Staff member
Oct 25, 2005
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lil red dot
#16
So what is the best aperture to take landscape for instance on a tripod? Some mentioned f8-f16. But which will provide the sharpest? f8? f11? f13? f16? Does it differ for different lenses?

Also TS, perhaps your VR is not off when set on a tripod. The VR will try to compensate, but since the tripod is too still, it introduces unnecessary compensation, hence the blur.
It really depends on what you are trying to achieve.
 

daredevil123

Moderator
Staff member
Oct 25, 2005
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lil red dot
#17
Lousy? Is that so?

http://www.flickr.com/photos/tinatwo/3246668679/
http://www.flickr.com/photos/alemdag/4009238218/
http://www.flickr.com/photos/zs-photography/4222075333/
http://www.flickr.com/photos/zs-photography/3410777642/
http://www.flickr.com/photos/resouzaesouza/4614098402/
http://www.flickr.com/photos/fromzeotherside/3282603748/

This is a quick 2 min search in Flickr and I grabbed a few links at random...

Most people who complain lens is lousy, are people who can't produce good pictures and blame it on the equipment.
:think:
 

#18
So what is the best aperture to take landscape for instance on a tripod? Some mentioned f8-f16. But which will provide the sharpest? f8? f11? f13? f16? Does it differ for different lenses?
You want star shaped lights on your night shots use a smaller aperture. You have moving subjects and you don't want them too blurred, use larger apertures. You want to blur out moving elements but you don't have a ND filter and your ISO is already at lowest then use a smaller aperture. Depends on situation really, the settings are all about compromise.
 

daredevil123

Moderator
Staff member
Oct 25, 2005
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lil red dot
#19
Jan 27, 2010
809
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#20
You want star shaped lights on your night shots use a smaller aperture. You have moving subjects and you don't want them too blurred, use larger apertures. You want to blur out moving elements but you don't have a ND filter and your ISO is already at lowest then use a smaller aperture. Depends on situation really, the settings are all about compromise.
Okay i got it. But usually i just want to achieve maximum depth of field for sharpness. To paraphrase what you said, for general landscapes, a smaller aperture up to f16 will yield better results? But what if im already at hyperfocal distance?
 

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