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I'm an aspiring photographer of fish. So the implication is that, I have a segemented working distance:

  • 1st Between me and the aquarium, that I can adjust
  • 2nd The breadth of my aquarium

The 2nd is sadly a limiting point, and this has me asking, is an Internal Focusing macro lens a bigger benefit for me?

The Tamron 90mm's flagship version has IF, but the older, cheaper one doesn't. But they both achieve 1:1 at relatively the same distance. So is there really any impact?

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  • Which older, cheaper one? There are at least three different Tamron 90mm Macros that have been offered in the fairly recent past. – Michael C Mar 10 '16 at 16:27
  • Right now, at least in the U.S., the newer version is listed cheaper ($649) than the immediately preceding one ($749). There is currently a $150 mail-in rebate offered on the older one, but getting rebates from Tamron's third party rebate fulfiller is reportedly very spotty. – Michael C Mar 10 '16 at 16:56
  • @MichaelClark-apologies for not being clear. Yes I meant the Latest and the 2nd oldest one. Wasn't planning on the oldest :) Thanks for the head's up, I'm in Europe though. – Chai Mar 10 '16 at 21:56
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Keep in mind that the focus distance is measured from the sensor plane to the subject. The distance from the front of the lens to the subject is called the working distance. You might have two lenses with the same Minimum Focus Distance that have widely varying Working Distance.

The Tamron SP AF 90mm f/2.8 Di Macro Lens (Tamron lens ID 272) has a working distance of only about 3.6 inches.

The Tamron 90mm f/2.8 Di VC USD Macro Lens (Tamron lens ID F004) has a working distance of about 5 inches.

The Tamron 90mm f/2.8 Di VC USD Macro Lens (Tamron lens ID F017) has a working distance of about 5.5 inches.

The Tamron 180mm f/3.5 Di Macro Lens (Tamron lens ID B01) has a working distance of about 9.6 inches and might be better suited to your use case.

Also keep in mind that the refractive properties of the water in the aquarium and, to a lesser extent, the glass of the walls of the aquarium will affect focus distance, working distance, and maximum magnification. In this case the water should work to your advantage.

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  • Thank you so much! A brilliant answer, very clear! I've seen the words thrown around but never appreciated their meaning until now. – Chai Mar 10 '16 at 21:53
  • @michaelclark- I have a follow up question about working distance, I hope you can still see this. Delighted that you mentioned the new Tamron, saw it a few days ago on ebay, was wondering why I had never seen this before. Do you know where I can get proper updates on new lens releases to avoid this in the future? :) As for my question. I've been reading some and the biggest flaw it seems is that the extending barrel obstructs illumination from behind the camera. Are there any other disadvantages? :) – Chai Mar 11 '16 at 15:05
  • I've not used the Tamron 180mm Macro. But I would think in your use case any light from the camera direction is going to cause unwanted reflections off the front glass of the aquarium anyway. Normally your lighting in such a situation would need to be from overhead with the aquarium's hood removed (or mounted inside the hood - just don't place anything in there you don't mind being ruined by getting wet). – Michael C Mar 11 '16 at 17:52
  • @Michaelclark- Thank you! Yes I heard overheard from a pro-fish photographer. Even heard of 2 additional to the sides. But could you tell me about my question regarding the drawbacks of the extending barrel? :) – Chai Mar 11 '16 at 19:42
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    Apart from working distance (addressed in the above answer) and flash vignetting (addressed in the comment above) there really aren't any. – Michael C Mar 11 '16 at 22:57
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Do you want to say that aquarium limits the magnification? If it is the case you might want to prefer an objective with bigger focal length or the one which has more focus breathing (the rear focal length gets bigger at smaller focusing distances).

And, from these two, the older 90mm Tamron seems to have more breathing. Review page, search in Google for related information.

Normally focus breathing is considered as a drawback but if the choice is limited you might actually want to prefer an objective with more breathing. If your choice is not limited you'd better search for objectives with bigger focal length.

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  • Thank you, I'm going to look more into this, I'm a bit lost, a lot of jargon that I'm not so sure about. Thank you for your time! :) – Chai Mar 10 '16 at 21:54

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