IS problems on Canon 100-400mm with Kenco 1.4 TC

[crrlb001]

Thanks to everyone who has responded to my recent flurry of queries - you have been really helpful.

I would be grateful if anyone could advise whether there are reports of problems with the IS on the 100-400 when using a Kenco 1.4 TC. I am beginning to believe that there may be. I have taped the Kenco pins to allow AF (thanks guys - works fine using a diagonal focus point) which may be a contributary factor, but I am becoming convinced that my images are disproptionately worse in terms of blur than would be caused by the additional zoom factor. It could simply be my poor technique but i would like to eliminate any technical issue just in case.

I've searched this forum and Googled extensively without luck

Thanks in advance

Barry

[kevindurose]

One problem with using a convertor is that shutter speed is reduced in AV mode due to the the reduced amount of light, unfortunaltly the higher magnification requires a faster shutter speed!

A rule of thumb is you need the same fraction of a sec for each mm of mag. eg a 500mm lens needs at least 1/500th sec, a 650mm lens will need at least 1/650th sec. Normally with IS this should be reduced by about half, lets say about 320th sec with a 650mm lens. However the IS will be less effective on your setup with the TC on because of the increased magnification will magnify the motion.
I'm guessing that you will need 1/500th of a sec to stop motion blur.

[Roy C]

Which Camera are you using Barry?

[crrlb001]

Yeah, sorry Roy, forgot a pretty salient piece of information - it's a 40D

[djprest]

i have the same problem and exactly the same set up,but i also found some of my images to over-expose.
i got the converter nov 07 when it was used with the bigma,this was near useless.
march 08 got the 100-400 and taped the pins.
up to just before christmas i had given up using the converter due to the above problems.
i gave it a go at moore nr in cheshire on christmas eve after removing the tape and using live view found it works perfectly(though no af).
i carry tape just in case i get a sunny day.

[Duck_Pond]

I have the same kit as you (40D, Kenko TC and 100-400mm) and I've given up using the TC now. Aside from the AF issues, even with taped pins, the IS made the image jump worryingly around when shooting, so much so I switched it off, for fear of damaging the lens.

I have reached the conclusion that the extra reach gives a worse image than cropping that bit more. The images are just blurred or terribly soft.

It's annoying because it used to work well on the 350D with the same lens.

[crrlb001]

Thanks for the responses guys.

Duck pond have you tried using one of the the diagonal focussing points - AF is much more reliable and using a tripod and timer release I have managed to get some fairly sharp images - not of birds of course which is the object of the exercise. The trouble is every hand held shot seems to suffer motion blur which, as I say, may be down to my technique but I wanted to eliminate the possibilty that taping the pins was knocking out the IS. From your and djp's responses it appears that may be the case. While TC does cause some IQ issues I have seen images on here taken with 1 series cameras, TC and 100-400 that are extremely sharp. Anything from "marise" is superb. My wife has a 450D so I might give the TC a try on that over the weekend. Has anyone tried untaping one of the three pins to see if this brings back the IS - or do all three need to be taped to ensure AF works? Any more thoughts on this isuue would be welcome.

Cheers

Barry

[Roy C]

You could always use manual focus mode with the tc on board although this is a bit difficult without using a tripod. IQ should be pretty good if the results I get from my 400/5.6 + tc is anything to go by.

[postcardcv]

I have the same kit as you (40D, Kenko TC and 100-400mm) and I've given up using the TC now. Aside from the AF issues, even with taped pins, the IS made the image jump worryingly around when shooting, so much so I switched it off, for fear of damaging the lens.


I found this same problem when testing this lens/tc combo on a 400D, if it was leaping about like mine did I'd certainly advise against using it. The extra reach of a tc might be nice, but it's not worth risking the lens for.

[paul goode]

While TC does cause some IQ issues I have seen images on here taken with 1 series cameras, TC and 100-400 that are extremely sharp. Anything from "marise" is superb.
Cheers

Barry

Marise does indeed take superb images but uses a 400mm f4 DO, not a 100-400. ;)

[crrlb001]

Thanks Roy - you are quite right. I guess I will hang on to the TC in case I ever find myself in a position to fork out for the DO or need to take pictures at midday in the Sahara. Same conclusion as my thread about the 1.4 TC and AF really - although the diagonal focus point tip helped a lot with AF

[Roy C]

Thanks Roy - you are quite right. I guess I will hang on to the TC in case I ever find myself in a position to fork out for the DO
Or maybe even the 400/5.6 prime which is even cheaper than the 100-400 ;););)

[shoshone]

I have slagged of the quality of the Canon 1.4 II with my 100-400 on several fora before now.

Then I was using it with either the 5D or 40D.

I have to say that on the 1d MKIII the shots are much more acceptable both manual focus and AF. So it may be a body thing?

Jamie

[djprest]

the kenko 1.4xconverter works with IS when not taped