Why are Tele-Convertors sooooooo expensive?

Naboo32

Naboo32

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I was just toying with the idea of adding a 2xTC to the kit bag, for occasional use with my Nikkor 70-300mm ED VR lens (although it will be a mega-'slow' max aperture at the 300m end). My specific problem is that the lens is not great (ie. is soft) at anything over about 200-240mm and so I have to hold back on the zoom to get the best out of it. With a 2xTC, I could still get a focal length of up to around 4-500mm without going into the soft zone of the lens (although the max aperture would be quite feeble). At least, that was my thinking :thinking:.

Having Googled around, I'm absolutley astonished at how much these things cost :eek:. What's inside them, apart from 5 static lenses and a bit of air? Is the glass especially thick, or hard to grind or something? Or, is it just that most people who buy them are adding them to 'pro' lenses and consider the cost to be in proportion to what they paid for their 3-4,000GBP glass?

In my case, the Nikon TC costs about the same as the lens that I was going to put it on (i.e. 300GBP+). I see that Kenko make them too, for about half that price, but I don't know how good they are :|!?

Any views on the cost:benefits ratio of Tele Convertors in general?
 
My first thought are back away from the 2x and consider a 1.4x instead

Your soft zone on you 70-300mm will be negated by a 2x which inherently cause a loss of sharpness. The 1.4 doesn't cause nearly as much sharpness loss, in fact I bet 300mm + 1.4x would be sharper than 200mm +2x

As for cost, the kenko pro series are very highly regarded and are much cheaper - just make sure whatever TC you buy is compatible with your lens.
 
Nikon TC will not work on the 70-300 VR unless you want to regrind some glass.

Kenko will but AF and image quality will suffer.
 
Quite interested in this thread as I've been considering a TC for my 70-300VR as well...
 
RichardtheSane said:
My first thought are back away from the 2x and consider a 1.4x instead

Your soft zone on you 70-300mm will be negated by a 2x which inherently cause a loss of sharpness. The 1.4 doesn't cause nearly as much sharpness loss, in fact I bet 300mm + 1.4x would be sharper than 200mm +2x

As for cost, the kenko pro series are very highly regarded and are much cheaper - just make sure whatever TC you buy is compatible with your lens.
Click to expand...

:agree:

1.4TC = + 1 stop
1.7TC = + 1.5 stops
2.0TC = = 2 stops

I would use a 1.4 or at a push (in good light) a 1.7 TC on a f4 lens.

I would only use a 2.0TC on a f2.8 lens.

Cameras struggle to focus automatically past f5.6 max aperture, sometimes they will sometimes they will not, depends on light and subject contrast, however you can still manual focus.

You would also need to check that your zoom will actually take a TC, sometimes the rear lens element can hit the TC element.
 
You would also need to check that your zoom will actually take a TC, sometimes the rear lens element can hit the TC element.
Click to expand...

That's what I said:)
 
Nikon and Canon TCs are expensive and they don't fit a lot of lenses, including yours. But they are built to pro standards. With the right lens, 1.4x is usually okay, but nobody rates 2x of any sort; you can usually get better results by cropping, which shows how naff they can be.

I paid £100 last year for a Kenko Pro 1.4x and that seems like a decent buy if you can get somewhere near that at today's new exchange rate prices. It also fits a lot more lenses, including yours probably. It might be worth trying, but if you're disappointed with the lens as it stands at the long end, I doubt very much if shooting at 200mm with a TC will be any better. Note the comments about AF not working, too.

Sigma 1.4x TC is also quite well rated, but stay away from cheapies. They are rubbish.

From what you're saying, I think you should be looking at a longer lens.
 
In my case, the Nikon TC costs about the same as the lens that I was going to put it on (i.e. 300GBP+).

The Nikon TC will not fit, so don't waste your money. Its for Pro AF-S lenses only. You won't be able to mount the lens.
 
Naboo32 said:
In my case, the Nikon TC costs about the same as the lens that I was going to put it on (i.e. 300GBP+). I see that Kenko make them too, for about half that price, but I don't know how good they are :|!?
Click to expand...

If the T/C is about the same cost as the lens you're going to use it with then it's pretty certain that the lens isn't good enough for it.

Bob
 
OK, thanks everyone - a lot of valuable information there :).

It seems as though my homework has been done for me and I should just shelve any ideas of a "cheap fix" to my long-range lens dilemma ;). I really don't have the budget for the kind of lens that I'd most like (but then, do any of us :p?), hence "toying with" the TC option.

From what some of you have said, I guess that the reason for the apparently steep price on the Nikon versions is that they are accessories designed for lenses costing 10x the price of the TC (as opposed to 1x, in my case).

Anyway, as always, I've learnt a lot from a few hours worth of helpful responses, so I'm very grateful :thumbs:.
 
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