Teleconvertor

steelerdean

steelerdean

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Dean
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I'm relatively new to photography (currently own a Nikon D3100) and am about to purchase a Sigma 70-200mm f2.8 for some indoor sports shots. It got me wondering about whether a teleconvertor may be worth the investment too for the extra reach, but must admit it is completely new to me.

Could anyone give me a basic explanation on how they work, and how the effect things like the Aperture, shutter etc?

Thanks in advance :thumbs:
 
Basically, very...............it is like putting a magnifying glass between the camera and the lens. They effect aperture and shutter speed because they add another resistor between the light and the camera sensor. Simply , a 1.4 TC will lose you a full "stop" of light, for example your lens is F2.8 wide open, if you put a 1.4 TC on it, it will become F4 wide open.This also affects your shutter speed because of the light loss.

I have kept it as simple as I can for you, but if I have oversimplified it then please ask away........:thumbs:

I`m sure somebody will be along to baffle us all with science soon...........:D
 
Thanks Fracster, that's just how simple I needed it to be!

Is the multiplier as simple as it sounds i.e. a 1.4x teleconverter would increase a 70-200 up to a 98x280 - or is it not as simple as that?
 
steelerdean said:
Thanks Fracster, that's just how simple I needed it to be!

Is the multiplier as simple as it sounds i.e. a 1.4x teleconverter would increase a 70-200 up to a 98x280 - or is it not as simple as that?
Click to expand...

Hang on, i`ll get my calculator out...................
 
Yes it does. .............:)......your 70-200 does become a 98-280 F4 lens.

A 2x convertor will lose you two full stops, so your F2.8 becomes a F5.6. I have never used a 2x, so have no idea on the quality of them. However, I did have a sigma 1.4tc on my 120-300 f2.8 and it was excellent. I now have the Nikon 1.4 and 1.7, both work very well on the lenses I have tried them on.
 
So, again, just keeping it as simple as possible, a 1.4x teleconvertor would basically change my 70-200 f2.8 lens to a 98x280 f4 lens?

Other than the obvious loss of light and the effect that would have, does there tend to be any other side effects like loss of quality anywhere else?
 
steelerdean said:
So, again, just keeping it as simple as possible, a 1.4x teleconvertor would basically change my 70-200 f2.8 lens to a 98x280 f4 lens?
Click to expand...
....Yes.

steelerdean said:
Other than the obvious loss of light and the effect that would have, does there tend to be any other side effects like loss of quality anywhere else?
Click to expand...

I can only go off my own experience, and I have never used a Sigma 70-200, the Sigma 1.4 on the 120-300 was like a match made in heaven. The Nikon ones on my prime lenses are superb with no noticeable loss of IQ, TCs do work better on primes though. I have not tried them on my 70-200 so can`t offer any help on that one i`m afraid.
 
Thanks for the advice fracster, really appreciate it.

Just out of curiosity, (apologies if this is a daft question) is the only option if I get a Sigma lens to get a Sigma-produced TC, or can you mix and match? i.e. Sigma lens but Nikon TC?
 
steelerdean said:
Thanks for the advice fracster, really appreciate it.

Just out of curiosity, (apologies if this is a daft question) is the only option if I get a Sigma lens to get a Sigma-produced TC, or can you mix and match? i.e. Sigma lens but Nikon TC?
Click to expand...

I tried the Sigma 1.4 on my nikon 300 prime, they did not like each other at all...........:lol:...........autofocus was all over the place. Never tried the nikon TCs on the sigma lenses after that debacle.

I would be inclined to stick with the same brand to be honest. Saying that, the Kenko pro series TCs get very good reviews, I have never used one so can`t say one way or t`other though bud.
 
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fracster said:
.....Saying that, the Kenko pro series .....
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Won't I get coffee granules all over the place?

I know, terrible, i'll get my coat.

Seriously though, thanks very much for the advice - much clearer with what i'm doing now. First step is the lens then based on you're advice, a TC could be the next purchase.
 
steelerdean said:
Won't I get coffee granules all over the place?

I know, terrible, i'll get my coat.
Click to expand...
...Close the door on the way out..............:lol:

steelerdean said:
Seriously though, thanks very much for the advice - much clearer with what i'm doing now. First step is the lens then based on you're advice, a TC could be the next purchase.
Click to expand...

Try and borrow one or buy a secondhand one first, I honestly have no idea about the Sigma 70-200 or how it takes the TC. Mind you, the tcs are pretty cheap so could be worth a punt. Your choice , so don`t blame me if it`s a right marriage from hell............:D
 
On a sensible note, I was advised some while back not to shoot tcs wide open, give them at least another full stop, so try shooting at F5.6 rather than F4, some tcs also need good light to become sharp and contrasty. Just practice with it and try varying apertures and you`ll see what I mean.
 
steelerdean said:
So, again, just keeping it as simple as possible, a 1.4x teleconvertor would basically change my 70-200 f2.8 lens to a 98x280 f4 lens?

Other than the obvious loss of light and the effect that would have, does there tend to be any other side effects like loss of quality anywhere else?
Click to expand...

Apart from the loss of light there can be some reduction in image quality especially softer images. Depends on the quality of the convertor and how well it pairs with the lens. The option of rent before buying is a good idea.
 
The Sigma lens will not physically fit onto the latest Nikon TCs, there is a small tab on the mounting plate of the TC that only allows Nikon AF-S lenses to fit.

Having said that the tab can be removed, which of course will invalidate your warranty on the TC, and involves a slight element of risk on your part in removing the plate and grinding the tab off.

My Nikkor 1.4TC has no tab ... :naughty:

Here is a link if you are interested, also has some other useful info on TC's LINK
 
If your camera is ok at handling high iso you can get the best out of a teleconverter by using the camera on manual, setting it on f/8 choosing whatever shutter speed is appropriate and putting the camera on auto iso to sort the exposure

1.4x is as high as I'd go on a sigma zoom though, the 2x is terrible
 
Martyn... said:
The Sigma lens will not physically fit onto the latest Nikon TCs, there is a small tab on the mounting plate of the TC that only allows Nikon AF-S lenses to fit.

Having said that the tab can be removed, which of course will invalidate your warranty on the TC, and involves a slight element of risk on your part in removing the plate and grinding the tab off.

My Nikkor 1.4TC has no tab ... :naughty:

Here is a link if you are interested, also has some other useful info on TC's LINK
Click to expand...
Thanks Martyn - not sure how much i'd trust myself to start carving and a TC - I think i'd better keep it safe and go for the easier option of an actual Sigma branded one!
 
wack61 said:
If your camera is ok at handling high iso you can get the best out of a teleconverter by using the camera on manual, setting it on f/8 choosing whatever shutter speed is appropriate and putting the camera on auto iso to sort the exposure

1.4x is as high as I'd go on a sigma zoom though, the 2x is terrible
Click to expand...

I tend to do most of my shooting in Aperture priority. I've not seen an option in that mode for auto ISO so will have to have a play around. Thanks for the tip :thumbs:
 
Have a look in the shooting menu... there's an option to activate auto ISO. On my D300 you can then fine tune the settings to suit :)
 
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