Macro Lenses - I found this unusual?

[Paradox]

It is quite interesting to note that the lenses looses between 1.5 to 2 f-stops in speed when set to the min. focus distance. This is in line with other macro lenses featuring an internal focusing (IF) mechanism. The focal length will also be affected here (aka reduced).


I didn't know about this feature - This was on the review of the Sigma 150mm f/2.8 Macro. Is this typical of macro lenses as the review says? If so, I'm curious as to the mechanics behind it - Why so?

[Rooz]

yepp, as reviewer says, common to many macro lens'. my old tammie did the same thing. coldrain provided a clear explanation of why this happens a while back but i cant remember where it is unfortunately.

[TheWengler]

Does this mean that you actually wouldn't be able to shoot at f/2.8 or that you get more of the feel of a lens that's stopped down (i.e. DOF)?

[Paradox]

Thanks Rooz - And I second TheWengler's question. Does this cause the lens to physically reduce the aperture, or does it just emulate this effect?

[Rooz]

i wouldnt be too concerned about it to be honest. its never been an issue for me or restricted my shots on either the tam or the sigma.

correction: just tried it again, it does not physically restrict aperture. so i think its what lukas said. i wish i could remember where that post was.

[AdamW]

Does this cause the lens to physically reduce the aperture, or does it just emulate this effect?

Where's Razr when we need him?


;)

:p

:D

:rolleyes:

[Razr]

Where's Razr when we need him?




Lurking...

[JTL]

Lurking...Wow, that just creeped a lot of people out...

[AdamW]

Lurking...

Now what have I done? I'd sworn to use my powers only for fighting evil....

[downtrodden]

Now you've gone and done it this time!!!

I think i'm going to sleep with all the doors and windows locked tonight...

You never know who is lurking...