Zoon lens minimum focus

With a zoom lens, does the minimum focus remain the same at all zoom ranges? i.e.; is

the 5.9 foot min. focus for the 100-400mm IS the same at 100mm as it is at 400mm?

Thanks, and thanks to Ming Kuo and Isaac Sibson for their previous answers in this forum. They

were a great help to me.

Depends on the lens....some lenses do change, some don't.

<p>

For example, the Canon 35-350L has its highest magnification ratio

at 135mm, after which it can not focus so closely. As far as I'm

aware, this is not the case with the 100-400IS, but the answer to

your general question is that it depends on the lens.

<p>

Another example of this was my old Sigma 70-300mm APO Macro. It had

a close focus of 1.5m throughout the range, but at 300mm you could

move a switch, which would allow it to focus down to 0.95m. This

locked the zoom mechanism, however, because the lens was not capable

of this at shorter focal lengths, so to zoom back out, you had to

focus back to a point 1.5m or further away, and move the switch back

to the normal position.

hmm... i didn't know that. thanks for clearing that up, isaac. all

zooms i've ever used had constant minimum focus throughout their range.

Upon testing, my EF 100-400mm L IS USM is parfocal (i.e. no

focus change when zooming) at all focus distances. My other

EF zooms are varifocal: e.g. the EF 28-135mm IS USM is able

to focus closest at around f=80mm, closer than the 50 cm

Canon spec.

<P>

<blockquote><small><i>'Tis better to remain silent and be

thought a fool, than open one's mouth and remove all doubt.</i>

<br>

<b><a href=

"http://quotationspage.com/search.php3?homesearch=remove+

doubt"

>Samuel Johnson</a></b></small></blockquote>

Thanks for the information on zoom lens min. focus. Since that one

foot difference in min. focus between the 300f4IS and the 100-400IS

is so little, I have pretty much made up my mind to go for the 100-

400 as my next lens, even though the 300 is apparently a little

sharper.

By the way, I assume the 300f4IS & 100-400IS don't have the third

sensor mode to detect tripod use as do the big primes. or do they?

Yes, unfortunately the Image Stabilizer does not have a tripod

sensing mode on the EF 100-400 (and the EF 300 f/4 L too, from

what I read).

<P>

I was told by a Canon sales rep in a store I was visiting to try

Mode 2 (panning) on the 100-400 when shooting from a tripod.

Anyone had any success with this strategy?

Neither the 300 F4L IS nor the 100-400 have the tripod mode.

<p>

There are several generations of IS technology. The first generation

is the single-mode, 2 stop gain, as found in the 75-300 IS and the

28-135 IS. The second generation is the 2-mode, 2 stop gain, as

found in the 300 F4L IS and 100-400 IS. The third generation is 2-

stop gain, two mode with tripod, as found in the 300 F2.8 IS, 400 F4

DO IS, 400 F2.8 IS, 500 F4 IS and 600 F4 IS. The latest generation,

found only on the 70-200 F2.8 IS is two-mode with tripod, three-stop

gain.

<p>

Using mode 2 on a tripod might work, but there's less reason to use

IS on a tripod.

<p>

Charlie- If you go for the 100-400, I doubt you'll be disappointed,

but do remember that, although it is similar weight to the 300F4L

IS, the weight is at the front, and when the lens is zoomed, it is

quite long, and can seem heavier than it is (it's acting as a

lever). My advice would be to go to a shop that has both, and handle

both on your own camera body.

<p>

Whichever lens you buy, you'll get some great shots, and happy

shooting!