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06-27-2012, 04:43 PM   #1
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Tamron SP AF 90mm F2.8 Di Macro 1:2 magnification

Could someone please tell me at what focus distance the Tamron 90mm macro achieves 1:2 magnification?


Last edited by luftfluss; 06-28-2012 at 08:37 AM.
06-27-2012, 05:18 PM   #2
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Do you have the lens in front of you, there should be a macro magnification scale just above the distance scale. On the 52BB, the closest focus mark at 1.3ft or 0.39m correspond with the 1:2 magnification.
06-27-2012, 05:40 PM   #3
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Thanks for the info. I don't yet own the lens, am currently looking, though.
06-27-2012, 09:45 PM   #4
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There's one being offered for sale on the marketplace with an original lens hood: https://www.pentaxforums.com/forums/photographic-equipment-sale/190691-sale-t...ptall-2-a.html I am tempted to buy this one to acquire the lens hood (something I've done a few times when my wallet wasn't so anemic). It's a very good lens, it's the best handling macro lens from Tamron imho, even if the magnification max out at 1:2.

06-27-2012, 10:21 PM   #5
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QuoteOriginally posted by excanonfd Quote
On the 52BB, the closest focus mark at 1.3ft or 0.39m correspond with the 1:2 magnification.
I can confirm this is also the case with the earlier 52B model, no surprise really
06-28-2012, 07:45 AM   #6
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just keep in mind a couple of simple thoughts here.

these distances are measured from the sensor plane, and are total distances, not working distance from the front of the lens.

to consider working distance,
-if you assume the nodal point of the lens is approximately at the front element, and
-for 1:2 you need 2 times the distance subject to lens and lens to sensor, and also
-at 1:2 the lens is extended to 150% of the focal length, (i.e. 90+45 mm or a total of 135mm from the focal plane for a simple lens) then
-the front of the lens would be about 270 mm from the subject,
06-28-2012, 08:37 AM   #7
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QuoteOriginally posted by Lowell Goudge Quote
just keep in mind a couple of simple thoughts here.

these distances are measured from the sensor plane, and are total distances, not working distance from the front of the lens.

to consider working distance,
-if you assume the nodal point of the lens is approximately at the front element, and
-for 1:2 you need 2 times the distance subject to lens and lens to sensor, and also
-at 1:2 the lens is extended to 150% of the focal length, (i.e. 90+45 mm or a total of 135mm from the focal plane for a simple lens) then
-the front of the lens would be about 270 mm from the subject,
Great info, thanks!
06-28-2012, 08:39 AM   #8
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I should have been more specific in which Tammy 90mm I'm referencing. I'm considering the current model, Tamron SP AF 90mm F2.8 Di Macro Lens Reviews - Tamron Lenses - Pentax Lens Review Database

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