2x Telephoto Lens Converter

I just bought one of these...
http://www.ebay.com …ev4exp=true&for​ceRpt=true

The idea was to take my EF-S 18-200mm lens and effectively make it a 36-400mm lens. Can't say I'm thrilled with it, at full zoom I can't attain sharp focus and quite honestly, the subject seems further away. Am I not using this properly or should I get my money back?

Yeah, get your money back and chalk up this endeavor as an experience. When you use a x2 teleconverter, your lose two full stops at the minimum. Now if you tried using your T.C. attached to a constant aperture zoom (70-200 2.8), your results would be much better. I understand what you were trying to do, but image quality will suffer. Also, auto focus does not work at the long end of your combo, hence the focus issues. I hope this helps.

These "teleconcerters" are not the best way of getting a longer lens. They are actually the most inferior way of trying to achieve that.
First of all, the Canon 18-200 lens is not really suitable for teleconverters. Not for the classic ones (that mount between the lens and the body, most of them won't even mount physically), and not for these kind. It's a slow lens to begin with which means that with a 2x converter it will be even slower (you lose 2 stops), so at the long end of the zoom you have an f/11 lens essentially. No camera will autofocus with that little amount of light.

Now, what you said about the subject appearing further away... that's odd. I never used these things but it should appear much closer than with the bare lens.

Bottom line is, these screw-on converters are not worth it, it's clever marketing that sometimes tricks people thinking they can double the reach of their lens in an inexpensive way.

Very much so. Thanks.

Now I have a 2x converter that fits between the lens and camera that I've used with my EF 75-300 lens with great results. I think in the future I'll save up for better lenses.

I'm amateur at best right now, much to learn.

DannyC71 wrote in post #15143283
Very much so. Thanks.

Now I have a 2x converter that fits between the lens and camera that I've used with my EF 75-300 lens with great results. I think in the future I'll save up for better lenses.

I'm amateur at best right now, much to learn.

The T.C. isn't a total bust, saying you will use it in the long run. Also, you can cheat many lenses with a T.C., just not the lens you tried it with. There are some lenses south of a cool grand that you will have quality photos with.

Are you photographing wildlife? If so, you have a couple of options. You can buy better quality glass and not utilize a T.C., or buy lenses which are very compatible with a T.C. Either way you have to upgrade to a higher quality lens. Honestly, don't do what I did and buy a bargin zoom. Buy "L" glass right off the bat. Also, third party lens manufactures are a good source to.

We all started off at one time, as it's not a big deal. Happy Trails!

Wildlife in the Zoo for the time being.

i do use a 2X teleconverter, but mine is a canon 2X II (not the latest) using on a relatively expensive canon 300mmf2.8. This combo gives me an effective 600-mm f5.6.

Yours (I think) is a Canon 18-200 f3.5-5.6, meaning at 200mm your max aperture is f5.6. so adding a 2X will lose another 2 f stops, meaning your max aperture with 2X converter would be f11. It is certainly not worth the money.

I have had decent photos with the 300f2.8 and 2X ii combo on a Canon 5D3 (see attached), so it is an economical way to get to 600mm without spending 5-figure on a lens. A 300f2.8 + 2X, however, will never match a 600mm f4 in terms of IQ, AF performance, etc.

I'd suggest for zoo picture, you might want to look at a 70-300 f4-5.6 IS for a little more reach or a used copy of a 100-400 IS. You will not be happy with any of the teleconverter for your existing 18-200.

Nice hummingbird.

I've already sent back the converter for my 18-200. Here's my lens lineup, I have a T3i....

EF-S 18-200 1:3.5-5.6 IS
EF 75-300 1:4-5.6 (Came with camera)
EF 40 1:2.8
EF-S 18-55 1:3.5-5.6 IS (Came with camera)
EF 28-80 1:3.5-5.6 (Came with my Rebel 2000 film camera)
Tamron 2x AF Teleconverter

save up for a sigma 150-500OS...it's the cheapest way to go long with stabilization...and it'll be a lot better than the 75-300mm with a 2X TC on it...

Thanks, checked it out and looks like a good option for me.

quite honestly, the subject seems further away. Am I not using this properly or should I get my money back?

You have it mounted backwards?;]

What are you suggestions for 70-200/4 L IS USM? Is it advisable to buy teleconverter or rather a new lens for 300mm?

jasio wrote in post #15222530
What are you suggestions for 70-200/4 L IS USM? Is it advisable to buy teleconverter or rather a new lens for 300mm?

if you buy a 1.4TC you'll get to 280mm and still retain autofocus...a 2X TC will likely leave you with MF...

are you sure 280mm is going to be long enough?

Sometimes one has to do a bit of research before hitting the buy button. These screw in converters rarely do a particular good job. Secondly, most 18-200mm are just OK, nothing special. They don't even take a TC of any magnification all that well.

What you are seeing is, this screw in converter being of poor quality is effecting your image quality, then multiply this with some image quality problems with the 18-200mm, and you have a recipe for disaster.

If you have $1000 dollar lens, then you screw in a $70 converter, you have a $70 lens. Makes sense?

jasio wrote in post #15222530
What are you suggestions for 70-200/4 L IS USM? Is it advisable to buy teleconverter or rather a new lens for 300mm?

A "REAL" teleconverter fits between the lens and the camera body. Normally, most 1.4x teleconverters (Canon, Kenko, etc) do a pretty fair job on a lens like the 70-200mm f/4L or f/4L IS. You lose one stop but, the image quality and autofocus is not deteriorated to any great degree.

This is not so even if you used a "REAL" 2x TC. You lose two stops which will make autofocusing impossible with any 1.6x crop cameras which cannot autofocus when the lens has a maximum aperture smaller than f/5.6. Additionally, most 2x converter/lens combinations lose a lot of image quality. A marked exception to this is a 70-200mm f/2.8L IS ii lens combined with the Canon 2x TC ii.

The OP is talking about a tele lens attachment which is good for nothing except to fatten the wallets of those who sell it...