Macro Problem with SIGMA 35-70 2.8-4 Macro 1:6.7

neofg · Joined: 27 Oct 2012 Posts: 5

Hi all.
I buyed a "SIGMA 35-70 2.8-4 Macro 1:6.7".

http://www.ebay.it/itm/261106276867?ssP ... 1497.l2649

The problem is that it focus max at 0.5 meters. Where are the 1:6.7?
Someone could help?
Thanks... Sad

sichko · Joined: 20 Jun 2008 Posts: 2475 Location: South West UK

neofg · Joined: 27 Oct 2012 Posts: 5

Really?
Didn't it works at contrary... 1mm object result 6.7mm on the film/sensor?
So this is not a Macro. The minimal Macro isn't 1:1?

berw · Joined: 20 Oct 2012 Posts: 38

There are no 1:1 macro zoom lenses. Every 1:1 macro lens is a prime lens. A "macro" designation on zooms means absolutely nothing. There are lenses with 1:3 magnification without a "macro" stamp on it, and there are lenses with 1:10 magnification with a shiny letters saying MACRO. That's just stupid.

berw · Joined: 20 Oct 2012 Posts: 38

By the way, sichko is right. 1:6.7 means that a 6.7 cm object will be 1 cm on the sensor.

sichko · Joined: 20 Jun 2008 Posts: 2475 Location: South West UK

WolverineX · Posted: Sat Oct 27, 2012 1:11 pm Post subject:

WolverineX

sichko · Joined: 20 Jun 2008 Posts: 2475 Location: South West UK

WolverineX · Posted: Sat Oct 27, 2012 1:33 pm Post subject:

buerokratiehasser · Joined: 12 Jun 2011 Posts: 470

Just to add more irrelevant information, there seems to be one Sigma 70-300 1:2 AF, or was it 28-80 1:2 AF? Among myriads of Sigma (and rebrands) 70-300 and [24,28]-[70,80] without these features, of course

I suppose the 300 is soft at 300 anyway, as nearly all of these tele zooms are. Or let me put that like, "optimised for common enlargement film".

The monster Macro from Minolta AF (extremly rare and expensive) goes bigger than 2:1 and is technically a zoom (though the magnification changes with focal length). It's also hardly useful in the field.

berw · Joined: 20 Oct 2012 Posts: 38

OK, i stand corrected, there are zooms with almost 1:1 magnification (thanks for the info), but what's the point of putting a "Macro" designation on a lens with 1:6,7 magnification? There are a lot of zooms (especially from Sigma) saying that it is a macro lens. Cheating?

Pancolart · Expire: 2013-11-18

Cheating no more then putting "Cholesterol free" label on vegetable oil.

iangreenhalgh1 · Expire: 2014-01-07

Sigma use terms like apo and macro as mere marketing.

buerokratiehasser · Joined: 12 Jun 2011 Posts: 470

In this case it may simply remind you that it's 1:6.7, not f/6.7.

But yes, 1:5.3, 1:4 MACRO etc. are silly marketing - 1:5 isn't quite good and the long end usually sucks anyway

Sony kit lens SAL 1855 does 1:3.3 or something without even mentioning it (improved by 1.5 crop)

Some lenses (like Minolta AF 35-70/49 have extra "macro" switch, doesn't help very much.

neofg · Joined: 27 Oct 2012 Posts: 5

Ecuseme, but, that's from wikipedia:

"Likewise, a macro lens is classically a lens capable of reproduction ratios greater than 1:1, although it often refers to any lens with a large reproduction ratio, despite rarely exceeding 1:1"
[http://en.wikipedia.org/wiki/Macro_photography]

So? Please, answers only from who really know them...

berw · Joined: 20 Oct 2012 Posts: 38

Wikipedia is right. A macro lens is a lens that is capable of reproduction ratios 1:1 or greater. 2:1, 3:1, 4:1 ... Good example is a Canon MP-E 65mm. It has a max of 5:1 reproduction ratio, or a 5x magnification. So, your Sigma, with 1:6.7 reproduction ratio is not a macro lens.
To fill a frame of an APS-C sized sensor, you will need an object that is 23(mm - size of the sensor)X6.7(reproducton ratio). That is 154mm. On the other hand, with my EF-S 60mm macro lens (1:1 RR), i can fill the same sensor with an object that is 23mm "big". With the MP-E 65mm, you can fill the same sensor with a 4.5mm object.