Teleconverter (Page 2): It does happen and a quick check on the exif information on the picture I posted will verify that...

chikid68 Loc: Tennesse USA

nadelewitz wrote:

The only thing "Better" with a teleconverter is less cost than a long lens. In every other way, a lens is better than the extender. Plain and simple.

Assuming, of course, that your lens can even work with a teleconverter, which in your case, doesn't happen.

It does happen and a quick check on the exif information on the picture I posted will verify that

amfoto1 Loc: San Jose, Calif. USA

RBal wrote:

I have a Canon Zoom lens EF75-300 1:4-5.6 with my Canon EOS and would like use it to get to 600 mm. This would be better then getting a fixed lens and lower cost. Some of the places I asked said that it would not fit my camera. Any suggestions.

First, I assume that's the EF 75-300mm "III" lens. If so, it has marginal images quality at 300mm to begin with. It would be simply awful further magnified by a 2X teleconverter.

None of the Canon teleconverters (which are very high quality) will even fit that lens. They all have a protruding front element that has to fit inside the rear barrel of the lens they're used upon, and the 75-300mm and 70-300mm lenses do not have large enough diameter.

Cheaper and likely lower quality third party teleconverters can fit, but there are still further problems.

Teleconverters not only change the effective focal length of a lens, they also change the lens' maximum aperture. You "lose" a stop of light with a 1.4X and two stops of light with a 2X.

Your lens is already f/5.6 at 300mm (as well as some shorter focal lengths). Many Canon cameras require f/5.6 or larger to be able to autofocus. You didn't mention which camera you have, but unless it's an 80D, 7D Mark II, 77D, T7i, 5D Mark III, 5D Mark IV, 6D Mark II or one of the 1DX or 1D-series models, you will have no autofocus with an effective f/8 lens (f/5.6 with a 1.4X teleconverter).

It's even worse with what you want to do... you'll have an effective 600mm f/11 lens, which no Canon DSLR will be able to focus. The only cameras able to AF with that combo are the new EOS R and EOS RP mirrorless models.

Your viewfinder will also dim down, making manual focus difficult or impossible. Live View with exposure simulation or the electronic viewfinder of one of the mirrorless cameras can help with manual focus, but it's still manual focusing and will be slow. No good for sports or wildlife, for example.

Teleconverters work best with high quality prime lenses, instead of zooms. There are some exceptions. Canon's 100-400mm lenses, especially the newer "II", work well with them. So do the EF 70-200mm f/2.8 II and the EF 70-200mm f/4 (with a 1.4X, which makes it only a 98-280mm f/5.6). Those lenses sell for around $800 used to $1800 new, plus another $250-$400+ for a quality teleconverter. What sets these zooms apart is that they all use fluorite, which makes them exceptionally sharp to begin with, and more tolerable of using a teleconverter. (Canon uses fluorite in many of their higher performance telephoto primes and zooms.... none of the third party lenses do.)

Honestly, once you get beyond 300mm, there are no really cheap options. Expect to spend $700 or more, if you want usable images. Maybe a little less if you can find a decent, used copy of an older, less sharp lens like Sigma 120-400mm OS HSM or 150-500mm OS HSM. Currently Sigma offers a 100-400mm that sells for $700. Tamron has one that costs $800 and has option of fitting a tripod mounting ring (an additional $129), which is something I'd want with any lens that weighs 3+ lb. and is over 300mm focal length. Some better lenses cost between $1300 and $2000.

RBal

orrie smith wrote:

The ef75-300 lens is not compatible with a telecon... (show quote)

Thank You

RBal

amfoto1 wrote:

First, I assume that's the EF 75-300mm "III" lens. If so, it has marginal images quality at 300mm to begin with. It would be simply awful further magnified by a 2X teleconverter.

None of the Canon teleconverters (which are very high quality) will even fit that lens. They all have a protruding front element that has to fit inside the rear barrel of the lens they're used upon, and the 75-300mm and 70-300mm lenses do not have large enough diameter.

Cheaper and likely lower quality third party teleconverters can fit, but there are still further problems.

Teleconverters not only change the effective focal length of a lens, they also change the lens' maximum aperture. You "lose" a stop of light with a 1.4X and two stops of light with a 2X.

Your lens is already f/5.6 at 300mm (as well as some shorter focal lengths). Many Canon cameras require f/5.6 or larger to be able to autofocus. You didn't mention which camera you have, but unless it's an 80D, 7D Mark II, 77D, T7i, 5D Mark III, 5D Mark IV, 6D Mark II or one of the 1DX or 1D-series models, you will have no autofocus with an effective f/8 lens (f/5.6 with a 1.4X teleconverter).

It's even worse with what you want to do... you'll have an effective 600mm f/11 lens, which no Canon DSLR will be able to focus. The only cameras able to AF with that combo are the new EOS R and EOS RP mirrorless models.

Your viewfinder will also dim down, making manual focus difficult or impossible. Live View with exposure simulation or the electronic viewfinder of one of the mirrorless cameras can help with manual focus, but it's still manual focusing and will be slow. No good for sports or wildlife, for example.

Teleconverters work best with high quality prime lenses, instead of zooms. There are some exceptions. Canon's 100-400mm lenses, especially the newer "II", work well with them. So do the EF 70-200mm f/2.8 II and the EF 70-200mm f/4 (with a 1.4X, which makes it only a 98-280mm f/5.6). Those lenses sell for around $800 used to $1800 new, plus another $250-$400+ for a quality teleconverter. What sets these zooms apart is that they all use fluorite, which makes them exceptionally sharp to begin with, and more tolerable of using a teleconverter. (Canon uses fluorite in many of their higher performance telephoto primes and zooms.... none of the third party lenses do.)

Honestly, once you get beyond 300mm, there are no really cheap options. Expect to spend $700 or more, if you want usable images. Maybe a little less if you can find a decent, used copy of an older, less sharp lens like Sigma 120-400mm OS HSM or 150-500mm OS HSM. Currently Sigma offers a 100-400mm that sells for $700. Tamron has one that costs $800 and has option of fitting a tripod mounting ring (an additional $129), which is something I'd want with any lens that weighs 3+ lb. and is over 300mm focal length. Some better lenses cost between $1300 and $2000.

First, I assume that's the EF 75-300mm "III&q... (show quote)

Thank you for your response. I am now going to start looking at the new Tamron lens. the one I am referring is the one that is 18 to 400mm. This lens just came out and the cost is about $600.