Teleconverters

Paul J Gans wrote:
G.T. wrote:

"Roger N. Clark (change username to rnclark)"
wrote in message ...
wrote:
In message ,
Paul J Gans wrote:


I'd like to buy a 1.4X telextender for a Canon
telephoto lens. My choice comes down to the
Canon 1.4X or the Kenko 1.4X.

Any reason to buy the more expensive Canon other
than brand name?


Nope. The Kenko Pro 300 1.4x is about as good as they get. I
use
one with my 100-400IS, and there is no visible loss of contrast,
or any kind of distortion. It is good enough that I opt to zoom
out instead of removing it, unless lighting gets really low and I
need that stop back. The Canon TC is only useful with select
Canon
telephotos; you can use the Kenko with almost any lens, although
it starts to get soft and distorted in the corners of a 1.6x-crop
if you use wide-angle lenses, wide open, with it. You can use
the
Kenko with macro lenses, too, to get more magnification

I second this. Be sure you get the pro 300, not just any kenko.


I should have asked this earlier and directly to JPS but what does
he mean by "The Canon TC is only useful with select Canon
telephotos"? What are the benefits of using the Canon TC on those
select lenses?

I can provide one answer (JPS will, I'm sure, give his). Canon
has a page (sorry, no URL) somewhere that lists the lenses that
their TC will work with. It is not large and does not include
much below a 70-200 mm lens, if I recall correctly.

---- Paul J. Gans

I've never found it at Canon USA; always at B&H:
http://www.bhphotovideo.com/FrameWor...xExtender.html
There's another for 1.4x, but I think it differs only in the resulting
effect on f/l and magnification. There may be a difference in some
notes.

--
Frank ess

http://www.bhphotovideo.com/FrameWor...xExtender.html

In message ,
"Thomas T. Veldhouse" wrote:

Better be careful that the rear glass element of your lens doesn't smash into
the teleconverter glass for wide angle lenses. Most documentation suggests
not to use a lens shorter than, IIRC, 50mm.

I use it with the Tamron 28-75 f/2.8, mainly because I don't like to
take the TC off the camera for dust reasons. The zoom has plenty of
room, I believe. I wouldn't try it with wider lenses, because I really
don't need the effect.
--


John P Sheehy

In message ,
Paul J Gans wrote:

Thanks. My intended use was with a telephoto, but it is good to
know that I could use it with a 50mm or longer. That could save
me having to carry too much when just "walking around".

The manufacturers generally recommend 90mm+ or 100mm+. That's probably
based on FF, though, so going a little bit lower with a 1.6x crop should
be OK.

Better to have a faster lens in the range that you want, though, if
possible. As I said in another post, I mainly use the 28-75 with the TC
only because I don't like to expose the chamber to the air. My 20D has
recently started to get a greasy sensor that grabs dust. Have to clean
it with a dry wipe; Eclipse doesn't help pick it up.
--


John P Sheehy

wrote:

The Kenko Pro 300 1.4x is about as good as they get.

The Canon TC is only useful with select Canon telephotos; you
can use the Kenko with almost any lens

Thank you for this! I've been interested in getting a teleconverter for
my Digital Rebel, but was discouraged when I saw information about
converters only working with a small set of lenses.

I'll start looking into doing this again, now.


--
www.ericschreiber.com

wrote:
In message ,
"G.T." wrote:


I should have asked this earlier and directly to JPS but what does he mean
by "The Canon TC is only useful with select Canon telephotos"? What are the
benefits of using the Canon TC on those select lenses?


You get to use it.

The Canon 1.4x protrudes in the front, and only attaches to lenses that
have a wide hollow for the protrusion to fit into. These is generally
only "L" telephotos.


So it's a physical compatability issue.

Thanks,
Greg

--
"All my time I spent in heaven
Revelries of dance and wine
Waking to the sound of laughter
Up I'd rise and kiss the sky" - The Mekons

"G.T." wrote in message
...
wrote:
SNIP
The Canon 1.4x protrudes in the front, and only attaches to lenses
that have a wide hollow for the protrusion to fit into. These is
generally only "L" telephotos.

So it's a physical compatability issue.

Yes, although most generic TCs are optimized/intended for longer
focal-lengths as well.

In my experience with a Kenko Pro 300 2x, compared to the Canon 2x
one, the Canon extender is quite useful while the Kenko one loses huge
amounts of contrast with the only lens of mine I tested (EF 200mm
f/2.8) which allowed the Canon extender to be mounted for a direct
comparison.

Bart

wrote:
In message ,
Paul J Gans wrote:

Thanks. My intended use was with a telephoto, but it is good to
know that I could use it with a 50mm or longer. That could save
me having to carry too much when just "walking around".

The manufacturers generally recommend 90mm+ or 100mm+. That's probably
based on FF, though, so going a little bit lower with a 1.6x crop should
be OK.

Better to have a faster lens in the range that you want, though, if
possible. As I said in another post, I mainly use the 28-75 with the TC
only because I don't like to expose the chamber to the air. My 20D has
recently started to get a greasy sensor that grabs dust. Have to clean
it with a dry wipe; Eclipse doesn't help pick it up.
--

Thanks.

The rest of the story can now be told. Went to B&H today and
bought a Canon 70-200mm f/2.8 IS L today. I wanted to also get
the Kenko 1.4 extender with it. Sadly, B&H was out of them...

By the way, the few shots I've taken with the new telephoto
have been just great!

---- Paul J. Gans

In message ,
"Eric Schreiber" eric at ericschreiber dot com wrote:

wrote:

The Kenko Pro 300 1.4x is about as good as they get.

The Canon TC is only useful with select Canon telephotos; you
can use the Kenko with almost any lens

Thank you for this! I've been interested in getting a teleconverter for
my Digital Rebel, but was discouraged when I saw information about
converters only working with a small set of lenses.

I'll start looking into doing this again, now.

Just realize that some of the lenses that won't work with Canon's TCs
don't, for good reason; they aren't sharp enough to warrant a TC.

A TC, at best, can only magnify what the lens itself is resolving. A
lens that is more of a limit to resolution than the sensor is not a good
candidate for a TC.
--


John P Sheehy

wrote:
In message ,
"Eric Schreiber" eric at ericschreiber dot com wrote:


wrote:


The Kenko Pro 300 1.4x is about as good as they get.

The Canon TC is only useful with select Canon telephotos; you
can use the Kenko with almost any lens

Thank you for this! I've been interested in getting a teleconverter for
my Digital Rebel, but was discouraged when I saw information about
converters only working with a small set of lenses.

I'll start looking into doing this again, now.


Just realize that some of the lenses that won't work with Canon's TCs
don't, for good reason; they aren't sharp enough to warrant a TC.

A TC, at best, can only magnify what the lens itself is resolving. A
lens that is more of a limit to resolution than the sensor is not a good
candidate for a TC.

For those that know would the Kenko Pro 300 1.4x provide decent results
with the 70-200 f/4 L?

Greg

--
"All my time I spent in heaven
Revelries of dance and wine
Waking to the sound of laughter
Up I'd rise and kiss the sky" - The Mekons

The Sigma APO 1.4x has a protruding front element. Would you mind
measuring the diameter of the protruding front for me? I am trying to
measure if it will fit.

Thanks in advance!

Cheesehead wrote:
Most of the 3rd-party TCs tend to be pretty soft.
The exception is the Sigma APO 1.4x.
After that, go with the brand name.
The other respondent's comments are also worthy of note.
(I've never tried a Kenko Pro 300.)

Collin
KC8TKA