tamron70-300 and kenko x2 converter

[glider64]

Following my other post i`ve been having a quick play with my tamron 70-300 and kenko 2 x converter and all the shots are over exposed know i believe due to the converter this should happen(?) and it only works in manual focusing , can anyone help me overcome this ie technique or whatever , and if i purchased a canon 300mm lens and canon 2x converter would it work on autofocus and high quality photos or isn`t it worth hte spend , sorry for all the questions, Harvey

[MX5]

Re: tamron70-300 and kenko x2 converter

Well we (the older ones) will all have done manual focusing on 35mm SLRs for donkeys years, but we had a focusing screen that helped. On the EOS digitals and if I recall correctly focus confirmation in manual only functions if the lens (or lens plus extender) would Autofocus if set to AF rather than MF. If you understand.

I'd go for a Canon f5.6 400mm which will AF ... and an optional 1.4x extender (which wouldn't AF on anything but a Series 1). If you want AF to be maintained with an extender then use a 300 f4 plus 1.4x. The 2x should (IMHO) be regarded as emergency use only, whereas the 1.4x can be used without a second thought. [I'm assuming you aren't planning getting a 300 or 400 f2.8].

You seem to need a lot of reach (been there done that). So good luck.

[glider64]

Re: tamron70-300 and kenko x2 converter

What is it about the 2 x converter that makes it a last resort?

[MX5]

Re: tamron70-300 and kenko x2 converter

You'll find that the f4 or f5.6 lenses the viewfinder is darker with an extender (more so with the 2x) ... which makes focusing harder.

The image quality will suffer unless you have a really high quality prime lens. i.e. one of the £4k plus super telephotos.

So it will work on the 300 f4 and 400 f5.6 but the drawbacks means IMHO it is an emergency bit of kit. Then there is using it ....

And don't forget that 300 x 1.6 (Crop Factor) * 2 (extender) equates to 960mm (that's about 19x magnification) and the 400 to 1280mm (nearly 26x) will make these a handful and even require care on a tripod (mirror lock up / remote cable). Combined with narrow aperature and you are into lower shutter speeds (or winding the ISO up).

I use to experiment with extremes, like 500mm (an old mirror lens) with stacked teleconverters ... but results were never much cop.

[Neilly]

Re: tamron70-300 and kenko x2 converter

Hi Harvey,

I have a x2 TC as well as a x1.4 TC . The x2 makes the AF very slow, even with a top of the range lens like the Canon 300mm f2.8. Even with a 1D iv on, it ain't that quick - the 7D is almost arthritic, I'm sad to say. So, unless you're taking pictures of something reasonably slow I wouldn't bother. I only use the x1.4 now because it doesn't seem to make any difference to the AF speed. Having said that, I believe the next generation of TC are very good, but they come at a steep price.

TTFN,
Neil

[glider64]

Re: tamron70-300 and kenko x2 converter

In autofocus it works but won't lock on to the subject, I must admit I don't want spend money on another 300 mm lens unless there's going to be a noticable increase in quality especially as I could get a nice macro lens for my budget