Sigma 100-300 F4 + Teleconverter ?????

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Rodintee

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Name
Russ
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Morning All

A rare post by me seeking some advice if anyone can help.

I have recently rationalised my collection of mediocre lenses and for a bit of reach have purchased a Sigma 100-300 F4 EX that I am very pleased with.

For this years airshow season I am thinking fo ading a Kenko Pro 1.4 teleconverter for a bit of extra reach. My question is this, will the quality of cropped images from the raw lens equal the uncropped equivalent field of view of the lens + converter or will the converter give a real advantage.

Anyone with any experience of this combo?????

All suggestions welcomed.

Cheers

Russ
 
I did some testing with Canon, Kenko and Sigma T/C's last year...the 1.4x and 2x of each. I found that the Sigma T/c's had comparable quality but gave a very different colourcast on a Canon 300/4...the Canon and Kenko were pretty closely matched.
I can only assume that this is due to some interaction between the lens coating and the T/C coating and think the reverse may also be true....Sigma lens with Kenko converter may give a similar result.
I think a Sigma T/C may be a better option for you.

Bob
 
Hi,

I have used both the Sigma 1.4 and Kenko on the Sigma 100-300 F4 and couldn't really tell much difference, I think the Kenko is better over the whole image than the Sigma but the Sigma is supposed to be sharper in the centre if that makes sense. One thing I did notice though and it put me off using a TC on this lens was it increased the CA ( Chromatic Aberration ) when used in bright conditions, but this was only on rare occasions. It also tended to hunt a fair bit if the light was poor, but that's common to all TC's with a lot of lenses.

Try one and see, they hold their value S/H, but don't buy a brand new one as they lose about 1/2 their value right away. A good used one will be about £65 - £75 or thereabouts.

Mike.
 
I use a Sigma 100-300 f4 and a Sigma TC. Work quite well together, I use mine for motorsports and I notice focussing is a bit slower than without it. Slight degrading of IQ as well - but thats par for the course with TC's
 
Mike,

If I understand things correctly then this is how it would come about.

Any CA inherrent in the lens would remain constant but appear on the image as being magnified by the T/C.....ie, if the CA spans x pixels, then it would be 1.4 x pixels wider using a 1.4x T/C.
If there is CA where it wasn't visible without the T/C then the T/C must be responsible for the CA.

Bob
 
Canon Bob said:
Mike,

If I understand things correctly then this is how it would come about.

Any CA inherrent in the lens would remain constant but appear on the image as being magnified by the T/C.....ie, if the CA spans x pixels, then it would be 1.4 x pixels wider using a 1.4x T/C.
If there is CA where it wasn't visible without the T/C then the T/C must be responsible for the CA.

Bob
Click to expand...

Hi Bob,

that sounds about right ;), it was a while ago that I had this combo but I do think the lens had some CA at times, but it was very slight and as you say the TC would/did just exaggerate it.

Here is a quote from Photozone which covers the same subject ...... "CAs (color shadows at harsh contrast transitions) are very low in the native 100-300mm range with a maximum of 0.64 pixels on the average at the image borders. The situation deteriorates significantly when adding the EF 1.4x II resulting in already noticeable CAs widths of around 1 pixel.

Verdict
The AF 100-300mm f/4 EX HSM is the most impressive Sigma lens tested to date. It is capable to deliver a near flawless performance with great resolution figures, low vignetting, low distortions, low CAs and as a nice whipped cream on top the build quality feels just right. It also mates pretty well with the Canon EF 1.4x II converter at costs of relatively high CAs and a somewhat lower but still high resolution. All in all ... highly recommended! "

Mike.
 
Thanks for all the replies.

I may take your advice Mike and pick one up either secondhand or new from HK and see how the combo works..

I'll be at the show at RAF Cosford in a few weeks to give it a testrun before RIAT......

I'll post up how I find it.

Russ
 
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