pendennis

I added a 1.4x TC to my Nikon 200-500 f/5.6, and there was noticeable softening of the images. I compared the images from a cropped D500 to those of a FX D750 w/1.4x TC, and the D500 images were better. Even cropped, with no TC, the D750 images were better than with the TC.

Billnikon is spot on!

mwsilvers Loc: Central New Jersey

First not every lens works well with an extender. Second the best images are captured with a 1.4 extender rather than a 2x extender. 2x extenders are very problematic and only give good results on certain lenses and certain cameras. Depending on the maximum aperture of the lens you use it with, a 2X extender may not allow you to auto focus. In any case a lens without an extender will always produce a better image than that same lens with an extender. With 1.4x extenders the loss of image quality may be minimal but under controlled conditions you were still see it. 2x extender are a whole different story and generally have a noticeable negative impact on image quality with all but a few lenses that work very well with one. Further I have never heard of a 4X extender. I think the people the camera shop were referring to a 1.4 X extender.

BlueMorel Loc: Southwest Michigan

I want to thank everyone for this discussion. I'm rather frugal with my (Canon) lens purchases, and have only three: 18-55mm kit lens, a 50mm f1.8, and my latest, EFS 55-250mm IS, the last to give more reach. I was toying with getting an extender for the 55-250 ($82.50 at B$H), but the more I read here and other online gurus, I think I would be way disappointed. Even the Canon manual for the extenders give downsides for them. My birthday is in April. Maybe a decent long lens would be a good present to myself. I, of course, will do my due diligence and search here for advice then.

JimBart Loc: Western Michigan

I checked with another camera store this afternoon and yes they confirm what each of you have to say. In addition they mentioned that Sigma will be coming out with a new sport lens before the end of the year to replace the sport.
Currently I believe the old one is 150-600 and the new one should be a 50-600 range with costs still being about the same. Costs for the old sport lens should be significantly reduced at that time to reduce inventory. They have a Sigma rep onsite in Nov whom I will be talking to and inquiring if the contemporary lens will also be changed.
I will try and keep you posted

rmalarz Loc: Tempe, Arizona

Here's something to keep in mind. Whatever the power of the extender, any flaw in the lens will be multiplied by that factor. Will it be noticeable? Maybe, maybe not. That's the gamble one takes. You also reduce your maximum aperture by the same factor.
--Bob

amfoto1 Loc: San Jose, Calif. USA

"Discussions at the local camera shop" are wrong.

Teleconverters and "extenders" are the same thing. Canon calls their teleconverters "Extenders". But they are the same as what the rest of the world refers to as "teleconverters".

The most common teleconverter "strengths" are 1.4X, 1.7X and 2X... I have seen 3X too (but they are awful and should be avoided. Never seen or heard of a 4X.

Weaker 1.4X teleconverters (TCs) do the least "harm" to image quality. There's more with 1.7X and 2X, though they can work well with some lenses.

It really depends upon the lens, too. Primes work better than zooms... Zooms with narrower ranges do better than those with wide ranges. Telephoto to telephoto zooms do better than wide to normal to telephoto zooms.

Of your lenses, probably the best one to try with a teleconverter is the 55-300mm.

However, there's another problem. Teleconverters "cost" light... a 1.4X TC costs one stop, a 1.7X costs one and a half stops, and a 2X costs two stops. So your f4.5-5.6 zoom with 1.4X added would "become" an f/6.3-f/8... Or with a 2X added it would "become" an f/9-f/11. There's a good chance your camera won't be able to autofocus... or that at best AF slows down considerably and hunts a lot more... with these reductions in light. TCs work best with f/4, f/2.8 and faster lenses.... which none of yours are. As I understand it, D7100 has at least partial capability to focus as slow as "f/8 equivalent" lens and TC combo. So a 1.4X TC might work on that 55-300mm... giving you an effective 77-450mm. A 2X on that lens would be manual focus only... and your viewfinder will be dimmed down, making that more difficult, too.

Image quality is also effected... and it varies depending upon the particular lens and TC that are paired up. And there are near infinite possibilities, so it's always hard to predict. The better the quality of the lens, the better it will work with a quality TC. I'd predict that a kit zoom with a slow aperture like your 55-300mm would make for pretty poor IQ.

In fact, Nikon's own teleconverters have a protruding front element that needs to fit inside the rear barrel of the lens. For this reason (as well as focus issues and image quality issues), they have a lens/teleconverter compatibility chart here: https://cdn-5.nikon-cdn.com/Assets/Common-Assets/Images/Teleconverter-Compatibility/en_US_Comp_chart.html

None of your lenses are listed.... so that rules out any of the Nikon TCs.

Sigma, Tamron and Kenko make teleconverters, too. Theirs may physically fit your lenses, but it's anyone's guess what they'll do to image quality.

Sigma might have a compatibility chart too... though I wouldn't expect much using even a weak 1.4X on a 28-300mm zoom (10X zoom range, plus it's technically a wide to normal to telephoto zoom).

You would probably be better served saving your money and simply getting a more powerful telephoto.... Either Sigma or Tamron 150-600mm or one of their 100-400s. Or Nikon 200-500 or 80-400. Any of those is likely to out-perform all but the best (and most expensive) lens/TC combos.

ecurb1105

Teleconvertors are notorious for light loss and degradation of image quality. Avoid them at all costs.

abc1234 Loc: Elk Grove Village, Illinois

Two points. As Sigma and Tamron have now shown, Canon and Nikon no longer have a lock on quality. Be open minded. Second. I recommend renting both the OEM and third-party lenses and shooting them side-by-side. I start will a lens target and camera on a tripod under very carefully controlled conditions. This maximizes the likelihood of seeing differences. Then, shoot your favorite subjects, again side-by-side, and see if any differences really matter. If you really want to be anal, ask someone to look at the pictures without knowing which lens was used and tell you if he sees a differences. I have done that with pictures posted here. Cannot have better judges than that.

wdcarrier Loc: Eureka, California

For my bird photography I use a 500mm Canon f4 on my 7DII, often with a 1.4X extender. I find very undetectable differences in detail with or without the extender except the DOF is much more critical, especially at wide-open settings. However, using a 2X extender reduces feather detail to the point I have eliminated it from use. A friend has gone to the Tamron 150-600 lens and is getting excellent results.