Opnions needed about halos on Canon 100mm macro images
hermanzaum
Registered Users Posts: 6 Beginner grinner
Hi all,
I asked the same question on Fred Miranda forums, but I guess people here may have more experience with my specific setup. Sorry if this is the wrong place.
Yesterday I've been trying out new lighting schemes with my new flash bracket and got what looked like very nice pictures on the camera's LCD. After opening those pictures at my computer, I was very disappointed because they showed a flaw I've already seen (albeit not as obviously) in previous pictures of mine: halos around lighter objects against dark backgrounds.
At first I tough the problem was caused by the position of the flash head/diffuser. However, after a batch of test pictures where I did change the flash's position (and many other parameters), I came to this conclusion: it's a lens limitation.
My testing comprised of pictures at varying apertures (mostly f/8, f/11 and f/14), magnifications, optional use of tubes (a Kenko set), all at different positions of the main light (flash). The subject was a piece of white felt against a black background (my camera bag). The camera was on a tripod and I focused manually on the felt fibers using live view at 10x. Timer and MLU were used.
What I observed was the same haloing I've got in the field. The halo intensity varies depending on some factors:
- Flash position didn't alter halos. Even with the light emitting surface completely behind the lens front element, the halos were still there (which discarded some kind of flare caused by the flash).
- Aperture also didn't have any effect.
- Higher magnification amplified the halos. The lens is at it's worst at 1:1, being already much better at 1:1.5.
- The use of extension tubes to achieve greater magnification made the problem a lot worst. Using a full set of Kenko tubes (68mm) and putting the lens at 1:1 gave me the worst pictures (very bad lost of details).
Below is a 100% crop of an image taken with the lens set at 1:1 without any tubes (tripod, 1/250s, f/11, ISO 200):
And this one is a 100% crop of a image with the 68mm of tubes added (tripod, 1/250s, f/11, ISO 200). It is so bad that one can think that I missed the focus entirely (it wasn't the case, I assure you):
The picture below, reduced for web, was taken at similar settings: 68mm of tubes, lens set at about 1:1 (magnification at around 2:1), 1/250s, f/11, ISO 400, monopod. It looks OK at web sizes, but it isn't printable as it doesn't carries much more detail than what you can see at this size:
Now the question: such "haloing" is expected from the Canon 100mm macro at 1:1? And it really gets that bad with extension tubes? It's time to save for a MPE-65?
Thanks in advance.
Cesar "Herman" Carvalho
Florianopolis / Brazil
PS: Sorry about my bad English.
I asked the same question on Fred Miranda forums, but I guess people here may have more experience with my specific setup. Sorry if this is the wrong place.
Yesterday I've been trying out new lighting schemes with my new flash bracket and got what looked like very nice pictures on the camera's LCD. After opening those pictures at my computer, I was very disappointed because they showed a flaw I've already seen (albeit not as obviously) in previous pictures of mine: halos around lighter objects against dark backgrounds.
At first I tough the problem was caused by the position of the flash head/diffuser. However, after a batch of test pictures where I did change the flash's position (and many other parameters), I came to this conclusion: it's a lens limitation.
My testing comprised of pictures at varying apertures (mostly f/8, f/11 and f/14), magnifications, optional use of tubes (a Kenko set), all at different positions of the main light (flash). The subject was a piece of white felt against a black background (my camera bag). The camera was on a tripod and I focused manually on the felt fibers using live view at 10x. Timer and MLU were used.
What I observed was the same haloing I've got in the field. The halo intensity varies depending on some factors:
- Flash position didn't alter halos. Even with the light emitting surface completely behind the lens front element, the halos were still there (which discarded some kind of flare caused by the flash).
- Aperture also didn't have any effect.
- Higher magnification amplified the halos. The lens is at it's worst at 1:1, being already much better at 1:1.5.
- The use of extension tubes to achieve greater magnification made the problem a lot worst. Using a full set of Kenko tubes (68mm) and putting the lens at 1:1 gave me the worst pictures (very bad lost of details).
Below is a 100% crop of an image taken with the lens set at 1:1 without any tubes (tripod, 1/250s, f/11, ISO 200):
And this one is a 100% crop of a image with the 68mm of tubes added (tripod, 1/250s, f/11, ISO 200). It is so bad that one can think that I missed the focus entirely (it wasn't the case, I assure you):
The picture below, reduced for web, was taken at similar settings: 68mm of tubes, lens set at about 1:1 (magnification at around 2:1), 1/250s, f/11, ISO 400, monopod. It looks OK at web sizes, but it isn't printable as it doesn't carries much more detail than what you can see at this size:
Now the question: such "haloing" is expected from the Canon 100mm macro at 1:1? And it really gets that bad with extension tubes? It's time to save for a MPE-65?
Thanks in advance.
Cesar "Herman" Carvalho
Florianopolis / Brazil
PS: Sorry about my bad English.
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www.theanimalhaven.com :thumb
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Canon 30D, some lenses and stuff... I think im tired or something, i have a hard time concentrating.. hey look, a birdie!:clap
It could be blur on the spider shot, but every shot from that spider with that specific lighting turned up with those halos (and I was using a monopod).
Also, the test images taken from the piece of felt were done with a (solid) tripod, MLU, timer, etc., so it wasn't camera shake.
I have no idea of what it is.
www.theanimalhaven.com :thumb
Visit us at: www.northeastfoto.com a forum for northeastern USA Photogs to meet. :wink
Canon 30D, some lenses and stuff... I think im tired or something, i have a hard time concentrating.. hey look, a birdie!:clap
Moderator of the Cameras and Accessories forums
Yes, I did. I've been using this combo (100mm macro + tubes) for some time. The lens is sharp when the subject have a flatter lighting, as seen on this shot taken a few minutes after my spider shots (full set of tubes, 100% unprocessed crop):
Now, compare with the 100% (unprocessed) crop from the spider shot:
So far, light hairs + darker background =ugly haloing
On the attached felt fiber pictures the diffuser was behind and above the lens (I've tried to put the flash at different positions but the halos were always there). On the spider shot the diffuser was above the subject. Both, however, show the same problem so I'm confident it isn't just a common lens flare but something else. It looks like some kind of spherical aberration, pretty much like the dreamy look one gets when using a Canon 50mm f/1.4 wide open. The question is why does it get so much worse when using the extension tubes?
I have no idea of what's going on