2x lens converter info please

Ive just seen a 2x lens converter on ebay. Just wondered if anybody uses these and if the picture quality drops when using these.Any info would be appreciated.
Thanks,
Dave.

Picture quality drops and you lose 2 stops of light. Really only any good on f2.8 and faster. 1.4x is a better bet but it depends a lot on the lens being used and the quality of the converter.

I'm using TAMRON SP 2x TC occasionally - IQ drops by a margin (maybe dependant on quality of lens as well) but to my experience I can still get nice sharp pictures and lot of details. You're going to loose 2 f stops when shooting with 2x TC.
If you have money, better invest in telephoto lens and you will not loose those 2 f stops, but if you're decided on teleconverter....better get a good one. Consider also the lenses you will be using with it - you want to use fast lenses with 2xTC, something like M150/3.5 or A*300/4 for example will be too difficult to focus, unless you have a lot of bright light.

I have a Teleplus 7-element 2x converter, supposedly fairly good optical quality, but the performance varies wildly depending on the lens I partner it with.

- With Sigma 50mm f2.8 macro, shots are still sharp, IQ suffers only a little

- With DA L 55-300mm forget it - shots are blurred and rubbish

- With SMC Takumar 135mm f3.5 (very sharp lens) it's somewhere between the two

I'm less concerned about the loss of two stops have good eyesight and the ISO can be whacked up (depends on camera of course, K-x is very good at high ISO). All in all, I use the 2x converter only rarely as I don't like the loss in image quality.

Regards
David

I took this with a 2x TC
link unsharpened version

This is the sharpened version

I would seriously suggest that you do a Search on this forum (and others!) for tele-converters (TC) and read the relevant threads.

As has been said, the results vary a lot between TCs due to the optical quality,and it is unfortunately difficult to get many KA mount TCs that are really good - except when they are purpose-designed to go with specific lenses e.g:
- The Pentax 1.7x
- (some say!) some of the older Tamron units
- the Sigma EX 1.4x and 2x for use with certain, but not all, long focal length Sigma lenses (I have both, but prefer the 1.4x)

The good ones are not cheap, and will cost you over £100, sometimes £200 - at which point that begs the question as to whether it would be better to out the money towards a decent quality longer focal length zoom or prime (i.e. non-zoom).

The rest of the post!!

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I really would not bother with cheap (less than £70 s/h!) TC's and would put the money towards something else. However,decide what lenses you will, or would, use a TC with and then do some searches to see what others have found with these combinations.

Note: I agree with the comment that the image quality of the Pentax 55-300mm zoom is a lot worse with a TC than without it - certain borne out when I tried an older Kenko 1.4x with mine.

The Pentax-A 1.4X-S works well with the 55-300mm almost
no loss in quality. link

The Pentax-A 2X-S is also a decent converter and will work with the
55-300mm with a slight drop in quality. link

These are both manual focus only, but the A Series electric
contacts function OK on digital.

I'm glad to hear that some TC's do work with the 55-300 lens, but I won't be buying one anytime soon as I already have a Sigma 100-300 F4.0 and the matching TCs (as above) for when I need some real reach - and for focusing speed, because the 55-300 (even without a TC) can't match that Sigma + autofocusing 1.4x or, even more so, the faster 70-200 F2.8 Sigma that I also have

OTOH: the 55-300mm is a very good/sharp lens for normal use, and is what I take on holiday, etc., as the Sigmas are too damned large and heavy and I would not have any weight allowance left!!!


BTW: those TC's that you linked are going for £99 each, and are probably relatively rare - so anyone who wants one had better move quickly!!

It's a hell of a lot easier carrying around the 55-300mm and a TC rather than something like a Sigma 150-500mm or Bigma

You can also almost take macros with the the 55-300mm and a TC.
The lens also seems to let more light through than any of my others so the light loss isn't a noticable.

[quote:3496ace15f="Algernon"]It's a hell of a lot easier carrying around the 55-300mm and a TC rather than something like a Sigma 150-500mm or Bigma quote]

That's why, at my age (64 today! ) I never serious considered buying one of those big/heavy lenses, whereas I can (just about!) carry a backpack with both the smaller Sigmas in it because I can put the backpack, with the lens not in use, down (and keep a careful eye on it!) when I am taking photos. Even then, the 100-300 + TC + K-5 combo is only bearable provided I drop it on to the strap and keep my grip on it. Oh for the idea of being 20yrs younger, fitter and stronger.

The main problem I have with the Bigma is that it won't lock focus at 500mm. The bulk doesn't bother me too much aside from the fact that trying to hold it steady and focus manually is a bit of a tall order and I generally find a tripod handy.

Not a camera fault as both bodies tested are fine with a selection of Pentax AF lenses, I think it's due to the f5-6.3 nature of the beast. I know my K-m is fine with an f2.8 zoom in any lighting conditions, switch to an f5.6 and it can end up hunting unless you have a contrasty subject and good light. Newer bodies may be better as I would assume Pentax have upgraded the AF sensor to go with the wider ISO range (not a lot of point in outstanding high ISO if the thing can't focus in low light).

My 50-500mm has had no trouble locking focus since I got it (second hand). Has been used with K10D/K20D/K-7 and now K-5.

I've never had a problem with my Bigma either. Used it on the Ds, K20D and K-5.

I don't even mind carrying it.

Well, the 150-500mm here definitely isn't right then!

It won't lock focus without a lot of fiddling about. It actually goes past the right point then stops and flashes the green hexagon as if to say "I'm stumped, you try!"

I have read about similar problems with other brands of camera which were solved with firmware updates, but I've no idea how to do this with a lens. My K-m is fine with everything from the DA* 50-135mm to an old F 35-70mm, and focus confirm works perfectly with lenses going back to the original K series. I therefore think it has to be the lens.

Anyone know how long the Sigma guarantee is?