Canon 600d & Teleconverter

Hi,

Am I correct that if I use a teleconverter with my camera I will only have manual mode?

Not Manual MODE but you loose Auto focus with some I think and there is a trick to put tape over some of the contacts .

David

Jonno1964 wrote in post #15119310
Hi,

Am I correct that if I use a teleconverter with my camera I will only have manual mode?

First with what lens do you want to use it ?

Depends on which teleconverter and which lens.

More specifically, it depends upon the maximum aperture of your lens....

A teleconverter reduces the amount of light reaching the AF sensors in the camera. How much depends upon how strong a teleconverter. A 1.4X TC costs one stop of light. A 2X teleconverter costs two stops.

If you have an f2.8 lens and put a 1.4X on it, the combo is an f4 lens. If you put a 2X on it, the combo is an f5.6 lens. In both cases, they will focus on your camera, though in the case of the 2X it will be with the center AF point only.

If you have an f4 lens and put the same TC's on it, it becomes an f5.6 and an f8, respectively. Your camera isn't supposed to be able to focus with an f8 lens, so the lens + 2X TC shouldn't work. Canon has designed the camera to turn the AF off, when this kind of combination is detected.

However, you might be able to fool the camera, tape up a couple pins on the teleconverter so the camera doesn't know it's there. It then might try to focus, though it will probably be slow and is more likely to fail when light isn't ideal. If the combo of lens + TC ends up f11 or smaller aperture, it's very unlikely you'll get any AFing at all.

Also the loss of each stop of light progressively makes your viewfinder dimmer, so that makes manual focusing more difficult, too.

Note, too, that some teleconverters simply won't fit onto some lenses. Canon TCs have a protruding front element, which basically mean they'll only fit onto the 135mm and longer telephotos, and on the 70-200mm zooms, but not the 100-400 or any of the other zooms.

Amfoto1 gave a great job of explaining when you keep and lose autofocus on a lens for your camera.

So to sum it all up and address manual mode, again for your camera when the lens combination has an aperture of above f/5.6 -

- then you only lose AF.

- you still have automatic metering (aperture and shutter) if you want.

You can still put it in Auto (automatic everything mode), P (program mode), A/Av mode (aperture priority mode), Tv/S (shutter priority mode) and the camera will do things automatically (which things depends on the mode chosen) - it just will require you to manual focus

You can always with any combination of lenses choose M (manual mode), where you the shooter picks everything letting the camera use only your choices.

I use my 1.4x TC (original Mk.i version) on my 300mm f/4L IS and my 70-200mm f/4L IS lenses.

It works quite well with either of these lenses. I have not used it on my 400mm f/5.6L lens because the lens will lose autofocus caqpability when used with a Canon TC on a 1.6x camera. I have been planning to test out the 400mm f/5.6L with the 1.4x TC on my Canon 7D camera in manual focus mode. But, due to laziness, I have never done so...

However, the Canon TC has a protruding element and will not physically fit many Canon and some third party lenses.

There are 3rd party teleconverters (Tamron, Kenko and others) which do not have a protruding element and which will fit some lenses that the Canon TC will not fit.

However, using a TC on less than a top performing lens will often reduce the image quality significantly. Using a TC which will reduce the effective maximum apewrture below f/5.6 will also cause loss of A/F on 1.6x cameras.

Normally most 2x TC's will not achieve significantly good image quality. However, the IQ that they achieve might be good enough for some users. It all depends how fussy your are about IQ.

OTOH: although I have not been fortunate to use the combination; I have heard from many sources that the combination of Canon 70-200mm f/2.8L IS ii lens and the Canon 2X Teleconverter Mk.iii produces very good to excellent mage quality. The price of that combination is pretty steep but having a 140-400mm f/5.6 lens would be quite nice...

also just a note, as everyone has covered almost every point...there are no teleconverters that are compatible with EF-S lenses...so if you're looking to extend the range of a 18-55IS, or 55-250IS, you're out of luck

Sorry for not clarifying earlier.

I have a 100-400 IS USM L lens which I am more than happy with. I will be doing a trek which may let me use the manual zoom ( read feet) and was wandering if this may be an option to gain the extra reach?

I understand that it will reduce the f5.6 to f8 as well as will on work in manual focus mode but was uncertain if it would actually work on the entry level camera I have at present. I do intend upgrading at some point however as I am still learning I will persevere with what I have at present.

amfoto1's comments about in not working with the lens in question seems to answer my question though. That is that it does not work.

Thank you all for the replies.

The older 1D series lenses will AF to f/8.. All newer cameras in the other series, including Rebels (yours included ) and even the better cameras- like the 5D3 & 1DX - are limited to f/5.6... Yes, you can trick the AF system into trying- but it is outside of specifications..

So, yes, manual focus will work.. You should also be able to put the camera into Live View mode- and use Live View to focus... When manual focusing, I tend to use 5x or 10x in live view...

TCs work with the 100-400 just not the 70-300.

Thanks for the response.

I now need to decide whether to take the plunge?

Jonno1964 wrote in post #15128077
Thanks for the response.

I now need to decide whether to take the plunge?

I would try to borrow a TC and try it on your 100-400 first. That way you won't lose any money when you decide it's too much of a PITA. Personally I reckon you're better off shooting without the TC and cropping a bit more. At least you retain usable AF that way.

I tried the Kenko 1.4x TC with the Tamron 70-300 f/4-5.6 VC lens. In bright sunlight it was working fine, even though the IQ degraded noticeably. In the shade, the AF was extremely poor, it hunted in and out all the time. Manual focus was hard to do because of low light. Eventually I just gave up.