Tamron SP 90/2.5 and extension tube for 1:1

[mladen_g]

Can someone please tell me more about this combination Tamron 90/2.5

(apparently AF) and extension tube especially designed for it to go

1:1(since the lens itself goes 1:2 without it)? I can send a photo of

this combination if you like!I have searched for this combination at

photo.net but did not find anything. How is it optically?Effective

aperture will be 5.0 with the tube, right?

 

Thank you all!

[bruce_hamm]

The Tamron 90mm f2.5 has a good reputation, as does most of the SP line. I'm sure that this lens with the matched tube (or any extension tube, for that matter) would give good results. The effective aperture with extension tubes remains the same; it is only with teleconverters that it is multiplied.

[harry_akiyoshi]

Actually, the effective aperture does change, due to the bellows effect. For macrophotography, it won't matter unless you plan to use non-TTL flash.

[douglas_green1]

That Tamron is a Manual focus lens, and it is a great lens. (Their Autofocus lens is a later 90mm f2.8) I prefer the 90mm f2.5 Tamron SP to the 105mm f4 Micro Nikkor because of the added speed, and small size, and it is VERY well made and compact. IMHO, it's the best lens Tamron ever made.

[bruce_hamm]

With any extension, bellows or tubes, the only thing that changes is the distance between the lens and the film plane. The focal length of the lens remains unchanged with extension, as opposed to the use of teleconverters. Therefore the aperture, that being the ratio of light gathered vs. focal length, remains unchanged as well.

[al_kaplan1]

The "aperture" marked on the lens is figured at infinity. At any closer distance you're dealing with "effective aperture". At 1:1 you lose two stops. No way out of it. It's right up there with the Law of Gravity, inviolate!

[david godfrey]

Really, really good lens. The dedicated extension tube awkward as you must remove the mount, attach the tube then re-attach the mount. In terms of quality I have no complaints stunning- Certainly the lens I use most.

 

The lebns is now avaliable as a f2.8, 1:1 version, so no tube is needed, and is avaliable in AF or MF(AD2) mounts.

[tony_gorell]

I bought this lens over twenty years ago. It used an SP 2X Teleconvertor to make it effectively a 180mm F5. The Teleconvertor had to mount between the lens and the Adaptall mount - not the most convenient. It was not specifically dedicated to the 90mm Macro lens - working with other Tamron Adaptall-mount lenses.

 

Results with the lens were superb - less so with the convertor.

 

I still have the lens, and it sees occasional use - though I rarely have the need for a Macro lens these days. The Teleconveter died several years ago - it became very cloudy - probably some of the glued element groups separated; a problem I also had with a much cheaper Tamron lens many years ago.