jerjane

I recently up graded to a Canon EOS 80D with a 18-135mm lense and have my old Canon 75-300mm Image Stablizer. I dont want to spend the money on a longer lense and was wondering if just putting the 2.0x teleconverter on my 75-300mm would do for long distances. I want to get out there to the 500-600mm range. First time poster and am eagerly waiting to hear your response. You folks have probaly already had this discussion so hope not a rerun. Thanks Jerry McGillivray

blackest Loc: Ireland

You may lose autofocus with it. A 2x teleconverter loses 2 stops of light so an f4 becomes a f8 which is slower than needed to focus (f5.6) a 1.4x teleconverter loses 1 stop of light taking an f4 to f5.6 which will still focus ok. 300mm to about 420mm (focus breathing may make it a bit less).

speters Loc: Grangeville/Idaho

I don't know if the lens you're talking about is compatible with a TC ( I have a feeling it is not), but even if, most likely the IQ would suck with that lens and a 2x. It would be manually focusing only and that would suck as well with such a dark viewfinder image! Better get a longer lens!

robertjerl Loc: Corona, California

The Sigma converter is a dedicated design made to work well with only a limited number of Sigma lenses. The same for the Canon extenders. Also you will lose auto focus with a 2.0x on your lenses.
Try Kenko, they design theirs to work with a much bigger list of lenses by several makers. Their Pro 300 line (I have the 1.4x & 2.0x) is for EF lenses. They have a new HD model line that works with EF and EF-S lenses.

I would recommend you use a 1.4x, on your 80D it should still AF and your 75-300 (use only at the 300 mm end) and will give you an Angle of View of a 672 mm.
But I would recommend you buy a longer lens, if you can't afford the $2K for the Canon 100-400L (I use this one with a Canon 1.4x III extender), then look at the Tamron or Sigma 150-600 (1K to 2K depends on version), or the Tamron or Sigma 100-400 ($800 or so-Tamron available for preorder the end of this week) and possibly then add a 1.4x later.

CHG_CANON Loc: the Windy City

You cannot physically mount a Canon 1.4x (nor EF 2.0x) to an EF 75-300 lens. End of discussion for this lens and a Canon extender. For a 3rd party model extender, I seriously doubt they can be used either, but I defer to the vendor documentation or someone with hands-on experience. If you don't want to spend money on a longer lens, you probably shouldn't be wasting your money on 3rd party extenders either ...

jerryc41 Loc: Catskill Mts of NY

I don't know the cost, but I'd look at Kenko.

https://smile.amazon.com/s/ref=nb_sb_noss_2/140-4563474-5873666?url=search-alias%3Delectronics&field-keywords=kenko

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

You will probably loose auto focus, and if not your focusing speed will be greatly diminished, your camera may HUNT for a focus(can be very frustrating when out in the field), IQ (image quality) will be greatly compromised.
Yes, it is alluring because of the price, most folks don't want to fork over extra money for a longer telephoto.
So, on the plus you can get out further and on the negative you loose or lesson your focusing speed and greatly sacrifice IQ.
Personally I would suck it up and buy the Canon 100-400 II lens, I wish Nikon made one this nice.
Best of luck to you and keep on shooting until the end.

CHG_CANON Loc: the Windy City

Repeat - If you don't want to spend money on a longer lens, you probably shouldn't be wasting your money on 3rd party extenders either ...

(Read the * / ** / *** star reviews and note the loss of AF and the soft images from other users all reporting they returned their product ....)

Robert Bailey Loc: Canada

You not only lose light, but you lose quality when you use a teleconverter.
I don't use them with zoom lenses, only with prime lenses.

Notorious T.O.D. Loc: Harrisburg, North Carolina

Probably not physically possible to use a TC and not the sort of lens that you would want to use with at 2x TC. Save your money toward a longer lens.

Best,
Todd Ferguson

dsmeltz Loc: Philadelphia

Actually the 80D keeps AF at f8. However, when out at 300 (600) with the 2x you will have a maximum working aperture of f11 so AF will fail. The 1.4 TC, however will give you 420mm (672mm equivalent) at the long end at F8. That is not bad.

For more, see this article "What's new: EOS 80D - AF at f/8 max. apertures" from Canon
http://learn.usa.canon.com/resources/articles/2016/eos-80D/af_at_f8.shtml

Zooman 1

Don't buy it. Stick with Canon TC's it is worth the money to do so. Depending on how long of lens you want to work with I would suggest getting a different lens. I am very pleased with the Canon 70-300, the newer lens. It has become my most used lens and is lighter than the Canon 100-400L, which I also use. I also use the 80D as well as the 77D. You might want to take a look at the Tamron 18-400mm, it is a new lens, so far the reviews have been positive. Waiting for mine to be delivered.

Haydon

Consider a used bridge camera. You might be able to find a SX50 for $150 and get the equivalent of 1200 mm.

jerryc41 Loc: Catskill Mts of NY

I posted shots I took with and without a Kenko 1.4TC, and people couldn't tell which was which. (No, they weren't both terrible. ) I'd gladly spend $150 rather than $2,000. A 2.0 is too much for my comfort zone, though.

CHG_CANON Loc: the Windy City

Jerry - from browsing 2-pages of your topics created, I didn't see an obvious title that would include these example images...

I too have posted repeatedly with examples of images using Canon's 1.4x and 2.0x extenders along with images without the extenders. I'd challenge anyone to say: this is obviously from the extender as it's 10% or 25% worse (or any crazy stupid percentage regularly trotted out on UHH as some sort of known fact ...)

However, none of these comments nor example images apply to the equipment presented by the OP. Their problem is the EF 75-300 that cannot be extended with Canon equipment and 3rd party options are not of the same quality as the Canon versions as well as disabling auto-focus even if the quality drop did not exist. The OP has one of Canon's most recent models including the ability to AF at f/8 across multiple focus points, a very new feature that did not exist even in the 1DX. Rather than spending smaller increments on trying to extend a lesser zoom in Canon's line-up, the OP should be looking at lenses from Canon and 3rd parties that have the desired target focal length.