If its under $200 it isn't likely to be the IS version.  Personally if you want to go that low and don't want IS the Sigma APO one is a better bet. 

I would spend a bit more for the IS if you can afford it.  It's really important and 300mm.  At least I definitely need it.

Talanis, the 30-700 is out of question, as it must cost here at least about US$1000 (the simpler model - the DO already costs more than that in the USA), if they have it in stock.  But it is important to know it isn't good.

Lisa, I saw the Sigma in the store's list, but it's out of stock.

Thanks for your asnwers.

Jerry,
I have never seen an ad for photo equipment rental here (I'm in Brazil).

Eco,

I saw the Sigma 70-300 APO in another store's website and I emailed them last night.  Hopefully they will reply me by monday.

I am a bit uncertain however about the usefullness of such slow lenses in wildlife photography, as most observations are done early in the morning and late in the afternoon, when sunlight is not quite bright.  But then my 28-135 is also f/5.6 max at 135mm.

The Sigma 70-300 is not available. I saw an ad for a second hand Tamron 70-300mm f/4-5.6 LD Macro 1:2 AF - any experiences with this lens?  It's not the Di model.

mantonino,

Had I planed this in advance, I would have tried to get a good lens imported.  This is not the case however, this trip appeared suddenly (and I am still waiting for confirmation).  I have no expectation that these lenses would be good for stock image.  I only wished I could take more advantage of the photo opportunities I may have in this trip.

I checked many sample images from these lenses at Pixel Peeper, it is difficult however to get a good evaluation, with so many photos taken at ISO 800 or more and often at larger aperture.  I picked many images taken at 300mm and CA was often very high.  Sometimes focus is decent, although certainly not sharp.

The 300mm length would mean an image 2x bigger than my 135mm gets (in dimensions; 4x in area).  If I think of personal use - building a presentation to show to my friends - in fact I could crop the photo from 135mm to get a "zoomed" version.  Hmm.

What about a converter, if I can find one, to use with my 28-135mm IS, would it be better?  Again, it may be an item that is not in stock.

A choice I got: Canon EF-S 55-250mm f/4-5.6 IS.  Good reviews.  I'm still looking for test shots.  Thoughts?

What is actually the "problem" with EF-S lenses?  I understand it doesn't work with full frame cameras, but mine is a 400D/XTi, so they are compatible, right?

Thanks for one more source of info (I use slrgear, fred miranda, photozone, pixel-pepper for samples) , I only regret that the images are not at full resolution.   I know Nilesh from SP, I'll write him and ask for his feedback.

Madelaide

The never 70-300 IS is something totally different though. Optically it is comparable with my 100-400 IS L lens, but with slower focussing (no ring-USM focussing motor) and a lower built quality (no weather sealing). It is more expensive than the cheap 75-300 versions, but you get what you paid for. The DO version (also with IS) is also not too bad, but it is the most expensive of them all.
  

WOW! You must have really gotten a crap copy of the 100-400 if it's as bad as a 70-300.

DO lenses may have some unusual internal lens flare if you are shooting lights.

Since Madelaide doesn't say what she's trying to shoot or requirements, it's pretty hard to guess what other options may be. If the goal is a cheap lens that's as good as an expensive lens, keep wishing. You only get what you pay for, and sometimes less than that.

Very sharp lens, not over the top expensive, $500+ used (same price as a new 70-300 IS),  70-200 Non-IS f/4. Reviews are high on quality and personally the f/4 without IS can be lived with unless you shoot surveillance most of the time. Sharp, nice size, good value, good photos. Both cost about the same, but one has a much better build and quality construction. True ring USM on the 200, rotating zoom, not trombone, which may be unimportant. Quality will last a long time after the kit lens has become wobbling and loose. Do you need 300mm over a sharp high quality lens?

Something to consider is how long you plan to use the lens. If it's only a few years, then you'll want to replace it, get the kit lens 70-300. If it's long term and you want reliability, get the "L" lens.

70-300 review
http://www.bobatkins.com/photography/reviews/ef_70_300is_review.html

70-200 review
http://www.fredmiranda.com/reviews/showproduct.php?product=14&sort=7&cat=27&page=3

If the question was just the 75-300 and not all the side information. Please save your money. I've paid more for a good polarizing filter than the 75-300 is worth.

How did you like the 55-250 Adelaide? 

I don't shoot a lot of tele images for stock so something inexpensive and adequate for vacation pics would probably do the trick for me too.

I have purchased the canon 70-300 is usm  and i am very happy with it. A number of images i took with it are now selling .This is a pic my newspaper  published  taken with the lens http://farm4.static.flickr.com/3569/3648205528_0087b90b63_b.jpg

I have uploaded one of my bird images, so you can have a better idea. 

http://www.shutterpoint.com/Photos-ViewPhoto.cfm?id=733200

Those are really helpful.  I think for my purposes the 70-300 would be better.  More detail in that one, I think.  Check out the freckles on the biker's shoulder.  Very well defined.

Thanks Adelaide and Chas! 

PixelBytes,

The 70-300 IS had good comments, however at over 2x the price of the 55-250 and not available in our stores other than by order, it was out of question.  Had I had the opportunity to buy it in the USA, I would certainly have bought the better lens for about the price I got the 55-250mm here. 

And you guys complain!