Help Needed with my Kenko 2x convertor

wegotitugetit

wegotitugetit

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alex
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ok so i bought a kenko 300 2x convertor for my canon lens from a tp member got a really good price
so i put it on last night went out and it was struggling to get focused cant remember the exact term any way this version is the pro 300 white body one and i just realised it is tele plus version

should this work fine with my lenses
28-135 is usm lens
nifty fifty and
70-300 usm lens

i had it mainly running on my 28-135

i think this is for the L lens and i didnt realise can any one confirm this it is also running slow one of my batteries at the time might not of been fully charged but the other 1 was

im using a battery grip

so can anyone tell me if i have a made a big balls up and if so what do i need to be looking for and can the 2x convertors work with my lenses

looks eactly like this one but mine is white LINKY
 
Hey mate.

I dont think they will focus on this lens, especially at the larger focal lengths.
A 2x TC adds 2 stops of aperture onto u're lenses.

A Canon 30D is only capable of focussing at F5.6 as a maximum (you have a 5.6 Lens, putting the 2x TC on it will make it a F8 lens, meaning it wont auto-focus)

If you want to manually focus it'll work however :D
 
The slow running will be because of the problem in focusing. With a 2x on a lens less than f/2.8 you will really only get reliable results with manual focus (as Jamie above says. All he says it correct except its even worse - f/5.6 with a 2x is f/11)

Paul
 
Ahh, sorry I thought it went F5.6 -> F6.3 -> F8 -> F11

Sorry, but F11 is slightly bad :(
 
f/6.3 is a third darker than f/5.6. Then there's f/7.1 and then f/8. Two stops always doubles, halves the number. 1-stop is 1.4x the number
 
Dont think that would auto-focus either mate :( sorry

Think you need to get yourself a F4L lens - for a 1.4x TC
and a F2.8L lens - for a 2x TC
 
Your 30D has got £100 split prism focus screen in it....this should allow you to manually focus better than most folk on here. Practice Alex, you'll be surprised how quickly you get the hang of it.

Bob
 
A 30D might be able to focus when you combine an f/5.6 lens with a 1.4X teleconverter but it is not supposed to work at all - according to Canon's specs. If the camera is aware that you have the teleconvter fitted it will simply disable AF - it won't even try to AF. Some teleconverters are "non-reporting", which means they do not reveal their presence to the camera. With such teleconverters the camera will attempt to AF. Maybe it will work. Maybe it won't. If it does work it will probably be slow and unsure. It might be OK for static subjects but not for tracking motion.

If you have a "reporting" teleconverter you will need to tape some pins to conceal the presence of the teleconverter from the camera. I need to do this on my Kenko Pro 300 DG teleconverter. It's easy enough to do. Sellotape will be fine. There is an illustration of what to tape on this web page....

http://www.michaelfurtman.com/taping_the_pins.htm
 
tdodd said:
A 30D might be able to focus when you combine an f/5.6 lens with a 1.4X teleconverter but it is not supposed to work at all - according to Canon's specs. If the camera is aware that you have the teleconvter fitted it will simply disable AF - it won't even try to AF. Some teleconverters are "non-reporting", which means they do not reveal their presence to the camera. With such teleconverters the camera will attempt to AF. Maybe it will work. Maybe it won't. If it does work it will probably be slow and unsure. It might be OK for static subjects but not for tracking motion.

If you have a "reporting" teleconverter you will need to tape some pins to conceal the presence of the teleconverter from the camera. I need to do this on my Kenko Pro 300 DG teleconverter. It's easy enough to do. Sellotape will be fine. There is an illustration of what to tape on this web page....

http://www.michaelfurtman.com/taping_the_pins.htm
Click to expand...
i persume you mean error codes which is a no nothing at all i can get it to focus some times but 75% it wont but this wasat around 7 ;30 ish and had a similar problem tonight without it on

and then was great again after that
 
wegotitugetit said:
i persume you mean error codes which is a no nothing at all i can get it to focus some times but 75% it wont but this wasat around 7 ;30 ish and had a similar problem tonight without it on

and then was great again after that
Click to expand...

You won't see any error codes. Quite simply if the camera sees a lens combination that is slower than f/5.6 it will not try to AF. If it thinks your "lens combination" is f/5.6 or faster it will try to focus. Depending upon how big a lie you are telling the camera its success at AFing beyond f/5.6 will vary.

e.g. the Canon 100-400 lens is f/4.5 wide open at the 100mm end. If you combine a 1.4X teleconverter with the lens at 100mm you will end up overall with an f/6.3 lens. If the camera sees f/6.3 it will not AF at all. If you tape the pins it will attempt to AF. As f/6.3 is only a little outside spec it might do quite well. However, as you begin to zoom the lens and increase the focal length the native lens aperture will decrease, first to f/5.0 and finally to f/5.6. When combined with the 1.4X teleconverter you will go from f/6.3 through f/7.1 and end up at f/8. f/8 is a fair way outside spec and you can consider yourself fortunate if you get worthwhile AF performance when "cheating" like that.
 
You might get away with manual focus but with your lenses and a 2x extender the results will be woefully shocking
 
tdodd said:
You won't see any error codes. Quite simply if the camera sees a lens combination that is slower than f/5.6 it will not try to AF. If it thinks your "lens combination" is f/5.6 or faster it will try to focus. Depending upon how big a lie you are telling the camera its success at AFing beyond f/5.6 will vary.

e.g. the Canon 100-400 lens is f/4.5 wide open at the 100mm end. If you combine a 1.4X teleconverter with the lens at 100mm you will end up overall with an f/6.3 lens. If the camera sees f/6.3 it will not AF at all. If you tape the pins it will attempt to AF. As f/6.3 is only a little outside spec it might do quite well. However, as you begin to zoom the lens and increase the focal length the native lens aperture will decrease, first to f/5.0 and finally to f/5.6. When combined with the 1.4X teleconverter you will go from f/6.3 through f/7.1 and end up at f/8. f/8 is a fair way outside spec and you can consider yourself fortunate if you get worthwhile AF performance when "cheating" like that.
Click to expand...
Great answer. I think that's the best explanation of the AF limits with teleconverters that I've seen.

Gary Coyle said:
You might get away with manual focus but with your lenses and a 2x extender the results will be woefully shocking
Click to expand...
I'm surprised nobody has mentioned this before in this thread, to be honest. There is a reason why Canon Extenders won't fit any of these lenses and it's because the results will be rubbish.
 
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