[BrianR]

So what's the rounded thingie on the side?

cheers

Paolo

AFAIK, the knob on the FA50 macro adjusts the friction of the focusing ring, and can act as a focusing clamp when fully turned (I've never had one in my hands though!). The newer dfa50 macro has a focusing clamp (like the non-WR dfa100mm) whose operation is a bit different - it's either off or on to lock down the focusing ring and prevent it from moving. These can be handy to keep the magnification at a certain setting, but in practice I don't find the rings move much on their own. The clamp on the DFA macros also disables AF, which means you can use them for catch-in-focus.

I wouldn't call either of them a focus limter in the usual sense

[angerdan]

Too lazy to check the reviews on my phone According to my failing (and fallible) memory, one of the few differences between the Pentax-F 50mm macro I own, and its Pentax-FA counterpart, is the presence of the focus-limiter. The older one doesn't have it.

No focus limiter on any 50mm lens from Pentax. Some macro lenses only do have a focus clamp do fix the current distance/focus setting.

So what's the rounded thingie on the side?

Regarding the D FA 50mm macro, it's written on the barrel. You just have to read and understand the meaning of the latin letters CLAMP.

Missing focus clamp on F/FA 50mm macro is also mentioned here:
FS: SMC Pentax-FA 50mm f/2.8 Macro.
LensTip.com - lens review, lenses reviews, lens specification - LensTip.com

[cyberjunkie]

No focus limiter on any 50mm lens from Pentax. Some macro lenses only do have a focus clamp do fix the current distance/focus setting.


Regarding the D FA 50mm macro, it's written on the barrel. You just have to read and understand the meaning of the latin letters CLAMP.

I wrote that my memory is fallible. Thanks for the clarification. It's a clamp, not a limiter. Got it.
If i had a D FA i suspect i would be perfectly capable to read "CLAMP"... but never say never
If you have one for lend, i'd be happy to try and see if i can.... you know, you start with a fallible memory, then with dyslexia, then you never know what can happen
Btw, i referred to the FA. I've never seen the D FA in the real world, only in picture.

EDIT:
let's make this post a little useful. One lens i own that has a focus limiter (and that has not been mentioned), is the AF version of the old Tamron 2.5/90mm macro. The model # is 52E.
Nothing else comes to my mind. The big Sigma AF zooms have locks, not limiters.

Missing focus clamp on F/FA 50mm macro is also mentioned here:

FS: SMC Pentax-FA 50mm f/2.8 Macro.

LensTip.com - lens review, lenses reviews, lens specification - LensTip.com

Btw, the Pentax-FA 50mm macro DOES HAVE a focus clamp. The Pentax-F doesn't.
I remembered the FA had a knob on the side of the barrel that my F doesn't have. I wrongly assumed its nature but I was sure that difference existed

cheers

Paolo

[angerdan]

Who knows the limiter distance steps of the FA* 600mm and 250-600mm ?

[angerdan]

FA* 300mm 2.8 offers following settings:
..2m - ..4m
..4m - 15m
15m - ..∞

[cmohr]

Who knows the limiter distance steps of the FA* 600mm and 250-600mm ?

SMC Pentax-FA* 600mm F4 ED [IF] Lens Photo - Pentax Lens Reviews & Lens Database

The focus limiter on the FA*600/f4 is variable, you can set whatever limit from infinity to a minimum distance or from minimum distance to a maximum distance. You cannot set a range inbetween ie 100ft to 30ft. ( I believe it is the same exact system on the 250-600, and the same system on both the F* and FA* lenses) . It's the collar just infront of the distance window on the lens with the locking screw in it. In the photo in the lens review, you can see it there.

You simply set the lens to manual focus, (pulling the focus collar backwards to the manual position ) set it to infinity, then unlock the screw and rotate the limiter collar to the distance you want. so if yo only want to go from infinity to 30ft, lock the limiter at 30ft, then put the lens back into AF and it's right to go. Inversely, to set from minimum distance to 30ft ect, start with the limiter at full. put the focus collar at minimum distance, then rotate the limiter back to 20 or 30ft, put the lens back into AF and you will only have the range from min to 30ft.

They give you a caution about setting the limiter, it can seize up if you try moving the limiter when the lens is not at either infinity of minimum focus, because you would be forcing the limiter against the focus collar.

[angerdan]

Very intersting to see that back in 1988 pentax constructed all mechanical working focus limiter.
Canon did everything electronic back in 1987 with the ED 300mm 2.8 L USM.
Canon EF 300mm lens - Wikipedia

[stevebrot]

Very intersting to see that back in 1988 pentax constructed all mechanical working focus limiter.

Perhaps because it is still useful, even when doing manual focus?


Steve

[angerdan]

Now the D FA 70-210mm 4.0 ED SDM WR can be added to the list:
HD Pentax-D FA 70-210mm F4 ED SDM WR Reviews - D FA Zoom Lenses - Pentax Lens Reviews & Lens Database

0.95m-2m / 2m-∞

[angerdan]

For 645, the FA 120mm f4 macro also offers a focus range limiter.

SMC Pentax-FA 645 120mm F4 Macro Reviews - 645 Telephoto Primes - Pentax Lens Reviews & Lens Database

[StigVidar]

FA*300/2.8

∞ - 15m
15m - 4m
4m - 2m