Teleconvertors- what's the opinion?

dinneenp

Hi,

I'm just wondering what's the opinion on teleconvertors?
I've read a wee bit on them, says they decrease light 4 times and resolution (factor of 2)
Do they increase possibility of camera shake a lot? Pentax K-X has body stabilisation.
Mainly used for sports? What else?
Aperture changes so if I used it on Pentax 55-300 4.5-5.8or 18-250 Tamron 3.5-6.3 zooomed out fully (or at long length) with 2X convertor I guess I'd end up with a very low aperture?
Would you recommend one? What other options for sports for close shots? (besides dedicated lens) Or just use what I have and crop?

Cheers,
Pa.

Borderfox

Most popular would be a 1.4/1.6x teleconverter, makes an f2.8 a f4 so not too bad. Personally I shy away from the 2x variety (I dont have a teleconverter anymore, had two and got rid of them) even on good glass the 2x looks meh. Anything over f5.6 unless you tape pins means you lose autofocus except on pro bodies.

Pro's - Extend reach
- cheap(ish) for the extra range
- when used with good glass IQ is not hit too bad on the 1.4x

Con's - Poor IQ (2x)
- if you use them on poor quality glass the results are not great
- lose a stop or 2 of light

pete4130

It depends on what TC you want to use on what lens. Some lenses CANNOT be used with TC's as the rear element extrudes too far and will make contact with the front element of the TC and FUBARing both elements so be careful.

A 1.4 TC will lose you 1 stop of light, so a 2.8 lens will still be a 2.8 but the extra glass reduces the light to the equivelant of an f4 lens.

A 1.7 TC will lose you 1.5 stops of light making a 2.8 as "bright" or as "fast" as a f4.5-f5 lens.

A 2x TC will lose you 2 stops of light maing a 2.8 lens as fast as an f5.6 lens.

Depending on brand and compatability the bigger the TC is the more it will affect image quality. A 1.4 is usually seen as good in terms of focal length gain and quality drop off. A 1.7 is acceptable and a 2x TC its noticeable in most cases. Again it depends what glass you are starting off with before the TC's are attached.

I shoot Nikon and the Nikon TC's don't retain all the infor form the lens like VR on some lenses (I think) while the Sigma APO TC's do (I think???). Then there are other 3rd party TC's like Kenko (spelling?) that also retain VR (I think) and are good quality.

The last time I borrowed a 2x TC (Sigma version) on my Nikon 80-200 2.8 the quality was just rubbish tbh so it wasn't worth it.

You also have to keep in mind that if you put a 2x TC on an f/4 lens its going to be equivelant to an f/8 lens in terms of speed and the AF will really struggle at best to focus. So your AF is affected using TC's as well.

It's a trade off really with focal length and image quality. I wouldnt realluy recommend using one on a lens that isn't fixed aperture (like a 50-200 3.5-5.6 or something). because of focusing issues and a lens that isn't stunning to start with being made less stunning with a TC attached.

Camera shake will bein creased as your focal length is increased and it gets amplified. I'm not sure how well internal VR/IS works so I can't comment.

pixbyjohn

I recently bought a secondhand 2X Nikon telconverter in Berminghams for €260 and I have used it a couple of times with my 70-200 f2.8 VR lens. Shots are reasonable on both my D700 and D80. On the D80 its 35mm equivalent to 600mm cos of the cropped sensor. I think the VR works with it ok cos I took shots handheld and they are reasonably sharp.
Like another poster said, I think you need a fixed aperture of 2.8 to gain full advantage of a teleconverter really. Its a nice addition to my kit.

http://www.kenrockwell.com/nikon/tc20e.htm

pete4130

As Borderfox posted the lenses can lose AF, I wasn't sure/couldn't remember if it was VR or AF...or both in some instances. It is alot cheaper than buying a 400mm or 600mm lens too for most purposes.

soccerc

I use a 1.7tc on the Nikon 300mm 2.8 bringing it to 4.8. It is only ever used at football games and while not as fast it provides more than acceptable images.

For example this was used in last week's Irish Sun, wouldn't have captured it @ 300mm.

ThOnda

Got one second hand and for the money it's grand. Doubling the focal length of my 24-70 creates is wonderful for headshots. It takes almost no space in the kit bag and does great service.

pete4130

ThOnda wrote: »

Got one second hand and for the money it's grand. Doubling the focal length of my 24-70 creates is wonderful for headshots. It takes almost no space in the kit bag and does great service.

Headshots.....thats what the 24mm is for!!!!

Xiney

pete4130 wrote: »

Headshots.....thats what the 24mm is for!!!!

At such a wide angle you would be likely to introduce perspective anomalies - giving a person a large protruding nose etc.

pete4130

*sighs*

Xiney

ThOnda

@pete4130 - But I am not you to risk being hit by a peg or a tire to get the shot

pete4130

XINEY.....I'm more a fan of street/in your face portraits of random people and usually use wider angle lenses for it so I can stick it right in there like this....



Thonda knows I shoot BMX and shoot wide angle sometimes andput myself at risk of being hit by a bike tire of an axle pegs because I try to get so close! The closes I ever came was a wheel brushing against my petal hood on a fisheye....but now we've gone WAY off topic....back to TC's!