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06-30-2010, 06:11 AM   #1
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Is this much green and purple fringing normal ?

Hi,

Someone has recently given me a Tamron AF SP 90mm Di F2.8 Macro to look at and test a bit so I've tried to take a couple of pictures to see how it behaves and I've also tried to check for front/back focus defects.

The lens focuses spot on but I've noticed quite a bit of purple/green fringes in the pictures and I was wondering if it's normal.

Most of these pictures have been taken at 2.8, one of them at 3.2.
Little bit of fringing: a small cactus (1), the same cactus (2).
water drops with purple fringing.
Nikon D70 focus test chart with green above and purple below: here and here.

The fringing improves once I step down a bit, as you can see here vs this.

I haven't been able to test this very much and I don't have that much experience anyway. Any comments are appreciated

Sorry about the slow loading of the pictures, it's a small server.

06-30-2010, 06:45 AM   #2
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QuoteOriginally posted by eblis Quote
Hi,

Someone has recently given me a Tamron AF SP 90mm Di F2.8 Macro to look at and test a bit so I've tried to take a couple of pictures to see how it behaves and I've also tried to check for front/back focus defects.

The lens focuses spot on but I've noticed quite a bit of purple/green fringes in the pictures and I was wondering if it's normal.

Most of these pictures have been taken at 2.8, one of them at 3.2.
Little bit of fringing: a small cactus (1), the same cactus (2).
water drops with purple fringing.
Nikon D70 focus test chart with green above and purple below: here and here.

The fringing improves once I step down a bit, as you can see here vs this.

I haven't been able to test this very much and I don't have that much experience anyway. Any comments are appreciated

Sorry about the slow loading of the pictures, it's a small server.
That's about average at a 2.8 aperture. As usual, stopping down for a macro is necessary both for DOF and aberration control.

It's only marginally noticeable unless pixel peeping. On the water drops, I don't see much PF at all, but I do see blue or purple reflection in the drops themselves.

On the cactii it's more obvious because you have white fronds against a green backdrop. That's probably the most likely colour contrast to see PF for any lens in any shot.
06-30-2010, 08:14 AM   #3
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Thanks a lot, now I can tell my friend the lens is a keeper
06-30-2010, 10:55 AM   #4
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QuoteOriginally posted by eblis Quote
Thanks a lot, now I can tell my friend the lens is a keeper
Yes it is. I don't see any true PF in those images.

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