Picjoe

I have never had a tele-converter or know anyone who has one. What are the pluses and minus to using one?

JohnFrim Loc: Somewhere in the Great White North.

Depending on the power you will lose light, so your largest f-stop may end up smaller than that on an equivalent telephoto lens.

Coupling of lens information (electronic) and function (mechanical) may be lost unless the converter takes care of all those things.

You are adding more glass into the light path, so unless you have high quality optics in there you may degrade your final image.

There may be other factors, but these are the first that come to my mind.

elliott937 Loc: St. Louis

On the negative side, you will lose some light which can equal one f-stop. You already know the plus side in that you will get increased magnification. Is there more you are asking? Yes, decrease in sharpness due to additional glass. Does that mean you should not consider a tele-converter? Definitely not, you should consider one.

Now here's my major recommendation and it's based on experience. Don't cut corners and go on the cheap. You will simply not use your converter after a while. I'm an all Canon kind of guy, and the third party converter was a major disappointment. It was about $150. The one made by Canon was more like $395. Yes, I finally bought the Canon $395(?) and never regretted it. Off of the coast of Dover, England, I saw a very distant castle. I captured a shot with my 100-400 L, and happy with it. Just for the heck of it, I attached my Canon 2.0, so my 400 became 800. The resolution was amazing.

I don't use it often, but when the need comes up, I don't hesitate a bit. I simply remind you and other, but top quality.

orrie smith Loc: Kansas

one thing to check before you buy, a teleconverter will not fit on all lenses, even if you buy a Nikon teleconverter, it will not fit on all Nikon lenses, and it will not fit on any 3rd party lenses. I am unaware how canon does theirs, but I would expect it to be the same situation.
other than that, they are nice to gain extra reach without adding the weight and expense of a longer lens. you will lose some light and the photos will be a bit softer, but they are workable.

Gitzo Loc: Indiana

Elliott937 pretty well nailed it; when it comes to optics, quality always comes out on top;

When it comes to TCs, they come in many different magnifications; the more magnification, the more light loss, less contrast, etc.

Are high quality TCs offered by camera makers worth the big difference in cost? that would all depend on how good of a result you're ready to settle for; (the expensive ones will ALWAYS give far better results.

Used properly, TCs can vastly increase your capability.

CHG_CANON Loc: the Windy City

I'll speak from experience over past month with Canon lenses and the 1.4x and 2.0x extenders. The quality of the lens with extender is most dependent upon the native quality of the lens with no extender. I've found the longer the lens, the less the quality impact of the extender. You can see some degradation: if nothing else, you've just placed more glass between the sensor and the subject. The degradation can be immaterial to slightly noticeable but acceptable.

For other things to consider, does your camera auto-focus with the candidate lens + extender combination? The extender causes a loss of light changing the maximum aperture of the lens. An f/5.6 native lens with an 1.4x extender becomes an f/8 lens. In the Canon line-up, only the 1D series bodies, the 5DIII and 7DII cameras can auto focus with an f/8 lens. In Nikon line, I'm unsure of the bodies that support this combo. (The just announced 80D will also autofocus at f/8, but maybe not all lenses I think I've heard.) So, do you have a body that can auto focus with the lenses and potential extenders? With a f/2.8 lens and a 1.4x extender that becomes f/4, do you like the results of the out of focus areas? You can manually focus if your camera doesn't support the lens + extender that pushes to f/8 or smaller, but did you invest in an extender to turn an auto focus lens into a longer manual focus lens?

I've shot the Nikon combo of a D7100, 70-200 f/2.8G, 1.4x extended. The image quality is superb and you can't see any degradation. I'd say the same with a 100-400LII and the 1.4x from Canon. But, there's other combinations where the differences with the 1.4x is noticeable, but still acceptable, particularly when stepping down the lens.

Finally, in all cases with cost excluded, the longer native lens will always outperform a short lens with extender. Is the difference material? Here you might include cost, size and weight in judging 'material difference'.

Oh yes another thing - not all lenses even allow for the use of an extender. Be sure to carefully ready the compatibility chart before making a purchase.

LoneRangeFinder Loc: Left field

Concur. IF you use Nikon, they have a lens compatibility chart with various teleconverters. It would be advisable to verify compatibility before you buy.

;-)

rmalarz Loc: Tempe, Arizona

Joe, one of the inescapable aspects of using a tele-converter is that you multiply issues with the lens and divide the amount of light available to expose the image.

If, for instance, you are using a 2x converter. Sure, you've doubled the lens' focal length, but you are also multiplying any defect the lens itself may have by a factor of two. At the same time, if you have a lens that is a f/4.5, you've reduced the the f-stop to f/9.

So, depending on you acceptance of possible flaws and lower light, a converter may work.
--Bob

wotsmith Loc: Nashville TN

You use it when you need more "reach" and have enough light. I routinely use a 1.4X and a 2X doing bird photography added to my 300mm f2.8 or my 600mm F4. Elliott is correct. Quality of the tele-converter is critical. The latest version of the canon ones I think is version III (that's what I have) and you can get very sharp photos using them. Understand that keeping a 1200mm lens rock still while you shoot is a challenge and will require much improved technique.
Another way to get more reach is to use a crop factor camera like a Canon 7Dmk2 which has advanced focusing and does very well in bird photography.

mcveed Loc: Kelowna, British Columbia (between trips)

A Nikon 300mm f2.8 lens and a TC20E III converter will give you a 600mm f5.6 lens for $5944. A 600mm f4 lens will run you $12,296. That is one of the big factors (for me, anyway). When adding a TC to a lens you have to multiply the speed of the lens by the strength of the TC to determine the effect on your auto-focus. A 300mm f4 lens with a 2X TC will give you the same amount of light onto the sensor as an f8 lens. Some cameras will not autofocus with that amount of light - some require a minimum of f5.6. A zoom lens that goes from f4.5 to f6.3 with a 1.7 TC will give effective light levels of f7.6 to 10.7 and so will function on some cameras at its shortest range only, but not on others. If you have a specific combination in mind you will get more specific info.

Mickey Jetpur Loc: California

What if you have a Tamron 70-300 VC. I am thinking of getting a Tamron teleconverter to match it to my Canon 70D, instead of getting the Canon teleconverter. Any opinions on this, would like to know.

SteveR Loc: Michigan

Teleconverters are best used with prime lenses. A good combination would be a 300mm f4 with a 1.4x, for instance. This combination is used quite a bit by Swamp Gator, using Canon equipment.

sterrill Loc: missouri

There is no cheap substitute for close. That being said I have the nikon 1.7 . In the right situation it helps bit focus is slower and there is some loss of sharpness.

Mickey Jetpur Loc: California

Yes I agree, but should I get the Tamron 1.4 teleconverter or the the Canon 1.4 teleconverter, for my Tamron lens. The camera store here suggested I get the Canon, but I went back on another day and the salesperson suggested I get the Tamron! So I am confused!

orrie smith Loc: Kansas

if you decide on the canon, be sure it is compatable to your lens. I am unfamiliar with canon, but Nikon teleconverters will not work on 3rd party lenses, as well as a good deal of their own lenses.