why can't i get a sharp edge?


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Jun 5, 2006
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#1
In this shot with S3 IS, f5.0, 1/60, focal length 12.1, AWB, Aperture Priority, how come I can't get sharp edges on the can?

Can anyone advise?

 

catchlights

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Sep 27, 2004
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#2
two things.

#1, increase the f stop

#2, place two black cards at each side of the can, just outside the frame, to add dark edge to the can.
 

Jun 5, 2006
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#3
Thanks for quick reply...I've some shots in f8, but still have the hazy edge. will try out your suggestion. will black paper, or any black surface do?? will it matter if it is shiny black surface or matte black surface?
 

Robbo73

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#4
MooneyedWileECoyote said:
Thanks for quick reply...I've some shots in f8, but still have the hazy edge. will try out your suggestion. will black paper, or any black surface do?? will it matter if it is shiny black surface or matte black surface?
Must admit when I first saw this I thought it was a depth of field issue as well but if it's hazy at f8 or f11 it's a funny one. May be worth doing a quick calculator as distance to subject is also a factor.

http://bobatkins.com/photography/technical/depth_of_field_calc.html

Manual...
http://bobatkins.com/photography/technical/depth_of_field_calc.html

Agree that it may also be the background causing the "lack of sharpness" - if you can post a 100% crop with both white & dark b'ground it may be easier to see if it's something to do with CA (chromatic aberration). Clutching at straws a bit I confess.

Even better, if you know someone else with the same camera you could compare the same shot.

Cheers
 

Robbo73

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#5
Just realised the top of the can is relatively sharp all the way round so d.o.f. unlikely to be the cause. May well be the large contrast difference causing fringing (often seen when taking pic of trees & buildings with very bright skys).

Cheers
 

Artosoft

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#6
Robbo73 said:
Just realised the top of the can is relatively sharp all the way round so d.o.f. unlikely to be the cause. May well be the large contrast difference causing fringing (often seen when taking pic of trees & buildings with very bright skys).

Cheers
Agree with you...

Regards,
Arto.
 

VR2

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Dec 17, 2005
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#8
rather soft at side of the can.
 

sk.images

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#9
I don't really think that is softness, I think it is more that there is insufficient contrast combined with writing being on a curved surface.
 

Jun 5, 2006
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#10
Hi, I've done some experimenting. This is the same exposure, but I have changed the background to grey colour art paper, with black paper on the right. I also moved the can forward away from back wall. I think improved!



I then used EmoblitzDS328AZ with home made diffuser. here is the setup and result with f8, 1/250, in-built flash at 1/3 output, slave at max output (sensor taped up)





I still don't get the sharp edge, though improved!! Further explanations?
thanks in advance.
 

Jun 5, 2006
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#12
cyber m0nkey, I'll try more contrast with black background, and direct flash only...
 

Robbo73

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#13
The more I look at this, the more convinced I am that it is a function of contrast and maybe flash-related shadow - the background is also still a bit too light (light bounce back?). I also note that the position of the can isn't helping... the bottom left of the can at the side is one of the white Coke "ribbons" which gives an illusion of softness as well. As mentioned, the top of the can seems fine so lets assume it's CA or PF.
A few things you could do (in order...if you have the time/can be bothered)
Post a 100% crop of the middle of the RH edge of the can (to look for PF/CA which lead us to believe it's a lighting/contrast thing) - maybe for each of the pics above to see differences?
Repeat with black background & play with lighting types (dir flash, daylight...)/angles (1 side, above, front) as mentioned by cyber m0nkey.
Repeat the same shot with a different lens (some lenses suffer from CA more than others)
Repeat the same shot with same lens, different body (PF can be as a result of sensor issues - not always linked with CA)
 

Jun 5, 2006
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#14
Robbo73 said:
The more I look at this, the more convinced I am that it is a function of contrast and maybe flash-related shadow - the background is also still a bit too light (light bounce back?). I also note that the position of the can isn't helping... the bottom left of the can at the side is one of the white Coke "ribbons" which gives an illusion of softness as well. As mentioned, the top of the can seems fine so lets assume it's CA or PF.
A few things you could do (in order...if you have the time/can be bothered)
Post a 100% crop of the middle of the RH edge of the can (to look for PF/CA which lead us to believe it's a lighting/contrast thing) - maybe for each of the pics above to see differences?
Repeat with black background & play with lighting types (dir flash, daylight...)/angles (1 side, above, front) as mentioned by cyber m0nkey.
Repeat the same shot with a different lens (some lenses suffer from CA more than others)
Repeat the same shot with same lens, different body (PF can be as a result of sensor issues - not always linked with CA)
unfortunately I use a S3IS, and can't change lens/body. Only can play around with 1 slave flash, and my table lamp. will try to find time to get 100% crops.

thanks
 

alexj

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Apr 10, 2004
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#15
my guess is its just the nature of the reflective metallic can. since the dictionary is just beside, have a quick shot of it and see if u cant get a sharp edge.

edit: if that's the case, you might want to isolate the sides of the coke can relative to your image and spray with a dulling agent; something like hair spray would do okay. remember to cover your lens and similar optics nearby. the other way is to kill some degree of light hitting the sides.
 

alexj

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Apr 10, 2004
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#17
thought it might be something like that. you might want to take the idea of putting the black card as close to the can.

the use of a dulling spray is usually a quick fix. ur lighting setup can be tweaked further. if you're frying your brains at the moment, try to work with one light first to try to establish the mood. examine the lighting of the coke can - the silver rims at the top and bottom of the can have clues to where the key light is.
 

chunger

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Mar 12, 2004
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#20
Could it be due to the limitation of S3 optical that cause these? No matter how you do it, it feel kinda soft and no contrast at all. Did you photoshop it ?
 

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