How to prevent vignetting or diffraction problem


kianisme

New Member
Mar 23, 2009
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#1
Hi, i am using a 550D with 17-50mm tamron lens. I realise that my picture when enlarge , they don't seem sharp. What can i do to prevent it?
 

wdEvA

Senior Member
Sep 1, 2006
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etanphotography.com
#2
enlarged as in view at 100% or more?
on your camera's LCD or computer LCD?

to prevent vignetting caused by the characteristic of the lens, stop down your aperture (different lens will have different apertures when vignetting improves)
to prevent diffraction, dont shoot like very small apertures like f18-f22 (different lens will have different aperatures where diffraction kicks in)
 

kianisme

New Member
Mar 23, 2009
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#3
on my camera lcd and computer too.. is 150% or more.. I tried using f8, but still can slight blurish on the edge..
 

Rashkae

Senior Member
Nov 28, 2005
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#4
on my camera lcd and computer too.. is 150% or more.. I tried using f8, but still can slight blurish on the edge..
Aiyo. Anything more than 100%, your computer is interpolating and guessing where the edges are. Don't go above 100%. Or better yet, stop pixel peeping.
 

wdEvA

Senior Member
Sep 1, 2006
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etanphotography.com
#5
yup,
actually, even with the sharpest lens and a good fullframe sensor, at 100% it won't be razor sharp.
 

kianisme

New Member
Mar 23, 2009
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#6
oh i seee.. cause sometimes just want to check whether the face is sharp when taking model...but realise when zoom in is blur..
 

wdEvA

Senior Member
Sep 1, 2006
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etanphotography.com
#7
actually if you don't print, and only view on your computer / share online.
the image is sharp when viewed at 1024 resolution would nomrally be sufficient.
 

kianisme

New Member
Mar 23, 2009
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#8
but what if i need it for print? Lol
 

catchlights

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Staff member
Sep 27, 2004
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#9
check sharpness you need to see your image at 100% zoom factor, larger than this is not accurate.
for doing touch up, you can go 200% or more for some details work.

for printing, if your original image is sharp, any paper size smaller then your image dimension will be fine.
larger print usually don't see at close distance.
 

kianisme

New Member
Mar 23, 2009
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#11
ohhh.. thanks guys!!! now i understand... =))
 

Octarine

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Staff member
Jan 3, 2008
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Pasir Ris
#14
Another point: focus accuracy. If your camera focus is not spot on then this will also contribute to soft images. Have you verified this point?
 

kianisme

New Member
Mar 23, 2009
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#15
yea that i know.. been trying alrdy..

oh well.. NO CASH! hahhaha...
 

#18
pardon me asking... vignetting is the one with "black shadow" at the sides of the pic right?

If so, i personally like that "black shadow" sometimes becoz basically it gives mood to some of the pictures. Why are people trying to avoid it at all costs?
 

Rashkae

Senior Member
Nov 28, 2005
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#19
pardon me asking... vignetting is the one with "black shadow" at the sides of the pic right?

If so, i personally like that "black shadow" sometimes becoz basically it gives mood to some of the pictures. Why are people trying to avoid it at all costs?
Because some people believe that perfect edge to edge exposure and sharpness are what make a picture "good". This pixel-peeping mentality is common here in SG. :)

Sadly, the artistic part of photography gets ignored too often.
 

catchlights

Moderator
Staff member
Sep 27, 2004
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Punggol, Singapore
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#20
pardon me asking... vignetting is the one with "black shadow" at the sides of the pic right?

If so, i personally like that "black shadow" sometimes becoz basically it gives mood to some of the pictures. Why are people trying to avoid it at all costs?
technically speaking, this is the flaws of the lens design, or mistakes during creating the images, we should avoid it.
some time, we can use it to enhance our photos, however, not all images work well with vignetting.
 

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