Teleconverter 2x macro

[dengalejoker]

Nead help finding a teleconverter 2x for Tamron sp 90mm f 2,8 a mount

 

Sendt fra min LON-L29 med Tapatalk

[Username]

Can't point out one TC but here's what I've found.  

   

My old A-mount TCs are somehow incompatible 

with my newer digital A-mount cameras, even tho  

all my equally ancient Sigma and Tokina A-mount 

lenses are fully compatible with the digital bodies.  

    

If your Tamron 90 has a stationary rear element 

[like my Sigma 90] then, optically, you would use 

any typical 2X TC, IOW not a TC that is optically 

configured for typical macro and tele lenses, cuz 

the latter TC type has a protruding front element  

that will crash into any stationary rear element. 

   

@@@@@@@@@@@@@@@@@@@@ 

 

There is no magical optical breakthru in so-called

"Matched" TCs. The key to optimal IQ is reducing

the empty space between the front TC elements

and the rear primary lens elements. This is hard 

to deal with in terms of which generic TC dares to 

build with less recessing of its front elements but 

is still safe for the rear of various primary lenses. 

So ... generic TCs will have generously recessed 

front elements where a "matched" TC is sold by 

the same company that knows the exact location 

of the rear element of the matching primary lens. 

That allows it to be built to minimize empty space. 

Sometimes this means "no recessing" or maybe 

just "minimal recessing" but in some cases it will 

mean "protruding front elements". 

   

Only "matched" TCs can safely market less-than-

typical recessing of front elements. So if your 90 

does have a stationary rear element, seek out  

"matched" TCs marketed for other lenses and buy

the one whose front element is as far forward as 

possible WITHOUT actually protruding past the 

front flange of the TC. Such a TC is optically as 

well matched to your 90 as it is to the lens that it 

is designated as matched to ... assuming your 90 

has a stationary rear element ... or even if its rear

element does move, that it "parks" at infinity just

inside the rear lens flange.  

   

===================================  

   

This could well mean ordering multiple "matched" 

TCs and then returning all but one. Forget all the 

guilty feelings. The demise of helpful well stocked

local photo shops was not your doing. Now you've  

just gotta deal with the existing marketplace.   

   

Or .... just settle for a typical 2X TC. And specify 

the 7-element design [rather common] and avoid 

the 4-element designs. The 7's are almost always 

marked as such in their model name and/or in the 

marketing info [website, packaging, etc]. Also, 4's 

self-identify by their very low prices even tho, for 

obvious reasons, they won't be boldly marked as 

4's. 7 elements is for bragging, 4 is for "hiding".

   

Rotsa Ruck !

[Username]

You may hear from lens geeks that the whole idea of 

a TC on a macro lens is a horrible idea. The definition

of "horrible" is verrrry subjective. Geeks will be geeky. 

It's what they do :-) 

[Username]

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

  

    

Look at these TCs. Protrusion is minimal, but 

requires careful checking for safety. I usually 

put a very thin soft wad of tissue on my rear 

element and then carefully attempt to mount 

the TC to the lens to perform a safety check. 

  

If your 90 has a slightly recessed rear element 

then order one of the above and safety test it. 

   

I don't know the street price but these will cost 

somewhat extra cuz they limit their own market 

range by being  definitely NOT safe for generic 

universal applications. But for lenses that will 

fit safely, they will reduce the empty space that 

exists between the TC element and the primary 

lens rear element. That is beneficial and benefit 

is NOT tied to the so-called "matching" lenses. 

ANY and EVERY lens that can SAFELY fit will

equally benefit by that reduction. 

[Username]

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

   

Above is an example of seriously protruding front 

elements. I do not know the design of your macro 

lens. If it appears to have enuf recess, at all focus 

settings, of its rear element ... then if this TC does  

safely fit, it will be as well matched to your macro

lens as it is to its designated "matching" Sony lens. 

   

BTW, as per explanations in earlier posts, this TC 

is a fine choice for SLR lenses on SLR-to-E-mount 

adapters. An adapter creates an enormous recess 

behind the rear elements of the SLR lens, and this 

TC helps to bridge the empty distance in there. 

   

I'm noticing one other aspect of "matching" TCs. I 

see a small diameter front element. This warns us 

that the TC's front element ought to be pretty darn 

close to the rear element of the primary lens so as 

to prevent vignetting. Prolly matters far more on FF 

than on APS-C. 

[Username]

oO0Oopz .... the white TC is not A-mount. 

  

I've just noticed the engraving on the front 

flange says it's E-mount. Still, solid visual 

example of really protruding elements .... 

[Username]

`    

    

Finally realized, no ooopzology owed. 

  

You posted an A-mount lens query in the

APS-C lens forum. I can stop banging my 

head on the wall now. Anywho, rotsa ruck.