Beginner Teleconverters

DaleJ

DaleJ

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Good morning!

I'd like some advice on teleconverters, please. I've recently bought a new lens, EF 70-300 IS USM II. Really happy with it so far. I did originally buy a 70-200 f4L but it lacked range and I thought I'd benefit more from an IS system. I took the 70-300 out at the weekend for some trial images of birds, for the most part really happy with the results. I would have loved a 100-400L but my sales pitch to the other half failed so it's the 70-300.

I noticed while I was out that a little more range would be useful so I'm not relying on cropping so much, could a teleconverter be a solution until I develop my stalking skills?

I know this lens isn't compatible with the canon teleconverters but I watched a youtube video of a reviewer that had used a Kenco TC with it. He didn't go into much details about results just that it did work.

So I guess what I'd like to know are the pros and cons, or if a TC is a complete waste of time and money could you offer me any other solutions?

Thanks, DaleJ
 
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I have the Nikon version of that lens and a Kenko 1.5x telecon. IMO I get better results from cropping into a "naked" image than using the one from the teleconverter. It works but not very well - a teleconverter will magnify any shortcomings in any lens.
 
Remeber that a teleconverter decreases the aperture, so at the long end IIRC a 1.4TC would make your f5.6 lens into an f8 lens. This can affect the auto focus accuracy and means either a slower shutter speed or higher ISO, both of which could lead to lower image quality. So TCs are more useful on faster (e.g. f2.8) lenses but become a bit limiting on slower lenses.
 
No free lunch with a teleconverter. Although you can often get something to 'work' eg with a Kenko, only a few cameras will autofocus at f/8 and I'm not sure your 70D is one of them. Again, there may be a workaround for that (taping the pins trick) but AF will never been either fast or reliable, at best. That's aside from optical performance which will be significantly degraded with that lens.

For wildlife, especially small birds, there's no substitute for the longest lens you can get hold of, good field-craft (ie get closer), a fair amount of skill and endless patience.
 
It can be handy to have, I wished I had mine with me at the weekend for birds resting on the cliff edge, but remember it's not a solution to everything. You can lose some optical quality and then of course it increases the f number so can affect shutter speed etc in poor light, autofocus capabilities etc
 
Sometimes a TC can just help you to get the shot because you just can't get closer but it can only do well on a good lens.
I had the opportunity of watching a new Crane chick last year, mostly from a distance over a large lake and my TC-17 EII boosted my 500 f4 enough to get me some decent shots ... well you judge if it would have been worth it for you :)



New Crane Chick Slimbridge 2017 by Roger, on Flickr
 
gramps said:
Sometimes a TC can just help you to get the shot because you just can't get closer but it can only do well on a good lens.
I had the opportunity of watching a new Crane chick last year, mostly from a distance over a large lake and my TC-17 EII boosted my 500 f4 enough to get me some decent shots ... well you judge if it would have been worth it for you :)



New Crane Chick Slimbridge 2017 by Roger, on Flickr
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That's just misleading. You have an £8k 500/4 lens on a £3k camera - not the same thing at all.
 
Generally a TC doesn't really help compensate for distance... the lens has already done it's job of collecting/creating the image, the TC simply magnifies that (good and bad) as well as probably introduce some errors of it's own (i.e. CA)**. It can help in terms of resolution if the original scene, as transmitted by the bare lens, exceeds the resolution capability of the sensor (not typically these days).

The primary benefit of a TC is in choosing the FOV angle/magnification for managing BG's... it's really just an extension of choosing FL to control perspective/separation.



** a well matched TC which is designed to be an extension to a specific optical formula/arrangement does become more a part of the lens rather than simply "magnification"... but IMO that doesn't really change much.
 
HoppyUK said:
That's just misleading. You have an £8k 500/4 lens on a £3k camera - not the same thing at all.
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It's not misleading at all!
I stated the lens used and that the lens makes a great difference ... and all further exif is intact on the Flickr link.
Oh and if you paid those prices for the same equipment I used then you have been diddled!
 
Wow, guys thanks for the feedback. Gamps that's an amazing shot!

Ok so a TC will not be this magic piece of equipment I was hoping for... to be honest, i didn't think it would be.

From what you've said though it may sometimes be of use and worth getting one to have a go with, I should just be expecting slower speeds and a dent in quality.

Thanks again! DaleJ
 
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Get a good one, the cheap ones are usually rubbish, a good one will cost but it's worth it.
 
DaleJ said:
Wow, guys thanks for the feedback. Gamps that's an amazing shot!

Ok so a TC will not be this magic piece of equipment I was hoping for... to be honest, i didn't think it would be.

From what you've said though it may sometimes be of use and worth getting one to have a go with, I should just be expecting slower speeds and a dent in quality.

Thanks again! DaleJ
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Before you dash off and buy one see if you can get one to try.
It is highly unlikely that your lens/camera combination will autofocus with a 1.4 TC attached.
It MAY do if you resort to the pin taping trick( http://www.michaelfurtman.com/taping_the_pins.htm), this basically tries to fool the camera into thinking it is not at f8, but despite what the article says it does not always work.
I had it working on a Canon 5DMk1 and a 100-400 with a 1.4 kenko Plus but it would not work on a 7D or a 5DMk2.
Personally I would put the money towards a used Canon 400 L f5.6.
 
You cannot trick the AF system into working at smaller apertures... you can only trick it into trying to work.
If the virtual image areas used are masked off by the lens aperture there is nothing the AF system can see. There is a "transition" where a virtual image is partially masked but still exists to some extent, so the AF may be able to lock on a particular feature/in certain situations (i.e. the lens hunts a lot). I.e. my D5 will lock focus at f/11 max aperture... occasionally.
 
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Nod said:
I have the Nikon version of that lens and a Kenko 1.5x telecon. IMO I get better results from cropping into a "naked" image than using the one from the teleconverter. It works but not very well - a teleconverter will magnify any shortcomings in any lens.
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This is very likely applicable to the OP's Canon lens too. There is a reason why Canon decided to make the EF 70-300 IS USM II incompatible with Canon Extenders, and I'll bet that image quality was at least a big part of it.
 
It's quite rare that the Fuji X-T2 can't achieve AF when the 100-400 and 2x TC are fitted. It might not be rapid AF but it almost always manages and that combo is f/11 at full stretch. Shame that even using fairly well matched lens and TC, I get better results if I crop into a 1.4x converter image (unless I want/need all the pixels that using the 2x telecon gives me without cropping.)
 
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