teleconverters

donalglackin

i have a kenoko teleconverter and when i use it on my 70-300 nikon lens the autofocus doesnt work. i was just wondering if i used a nikon teleconverter would the autofocus work or does autofocus not work when teleconverters are being used.

sasar

As far as I know it will only work on fast lenses 2.8 or below

DaireQuinlan

sasar wrote: »

As far as I know it will only work on fast lenses 2.8 or below

Yeah, that lens is already f/5.6 at the long end. A 1.4 tc turns the long end into an F/8 440 (or so), and a 2x tc turns it into an F/11 600. Highly unlikely the af will work, normally AF operation is guaranteed only to F/5.6 and even at that it tends to hunt a little.

-edit- The reason most literature states 2.8 or below is that with a 2x TC a 2.8 lens gets turned into a f/5.6 lens, and runs into the caveat above about AF operation. -edit-

Anouilh

There is a lot written about teleconverters and it is important, as Sasar says, to choose the correct one for the lens in question.

Although this does not reference Nikon, it explains a lot about teleconverters:

http://photo.net/canon-eos-digital-camera-forum/00BS9v

Are you pleased with the one you have when used in manual?

I'm thinking of getting one and since Canon is so expensive I may do fine with the brand you mention.

donalglackin

im not mad about it i find i use it less and less it could be just they way it performs with my lens though. its a 2x converter that i use. i find the qulity and sharpness is slightly reduced with it. was thinking of getting a 300 2.8 and using the new nikon 1.7 converter on it anyone ever use this set or that converter.

soccerc

donalglackin wrote: »

was thinking of getting a 300 2.8 and using the new nikon 1.7 converter on it anyone ever use this set or that converter.

Yep, that's my set up for field sports

donalglackin

and does the autofocus work fine ?

CabanSail

I have just started (today) to use my Nikon TC-17 with the new 70 - 200 f2.8 VR. All the functions of the lens work through the TC, but I believe that third party TC's don't offer that.

When I process some photo's I may post some but the Internet is quite flakey at the kip I am staying at. It's supposed to be a 5 star Intercontinental Hotel, but it's not that flash.

Arciphel

CabanSail, it's nothing to do with whether the TC is third-party or not. The Nikon 70-200 f/2.8 VR will work with a Sigma or Kenko 2xTC as well (I have tested it), including the AF & VR. It's just as others have said that the lens has to be fast enough to give a combined max aperture of 5.6 or lower when the TC is added

soccerc

donalglackin wrote: »

and does the autofocus work fine ?

Sorry, I should have added that the AF works fine if maybe a little slower.

It can also tend to back focus or hunt but you can anticipate it and adjust accordingly. It brings the 300mm 2.8 to f4.8 and have had no issue even shooting under floodlights

Reoil

I also use the 1.7 TC with my 70-200mm. Everything works fine- though the image is significantly softer than without. And the f/2.8 then becomes a f/4 of course.

Anouilh

I know that this question shows my utter bewilderment, but what is the difference between a teleconverter and extension tubes? The first lengthens the zoom. The latter magnifies, but does it also help if one wants to make portraits by standing back from the subject. Any links to the tech details would be really appreciated.

A teleconverter seems to be usuable only with a minimum focal length of 100m and I cannot work out whether extension tubes would be useful with prime lenses of 50mm or less.

charybdis

Anouilh wrote: »

I know that this question shows my utter bewilderment, but what is the difference between a teleconverter and extension tubes? The first lengthens the zoom. The latter magnifies, but does it also help if one wants to make portraits by standing back from the subject. Any links to the tech details would be really appreciated.

A teleconverter seems to be usuable only with a minimum focal length of 100m and I cannot work out whether extension tubes would be useful with prime lenses of 50mm or less.

A teleconverter is a lens that magnifies the centre portion of a lens by a given factor.

Extension tubes are a way of moving the rear element of a lens further from the focal plane to reduce the minimum focusing distance of the lens when mounted in this fashion.

Anouilh

Ever so often I have found references to the low cost of tubes for macro work, as here:

http://www.boards.ie/vbulletin/showpost.php?p=60685101&postcount=2

Is this a reference to second-hand, as every site I have found lists a set of Kenko tubes for well over 100 euro.

Can they be used with a 50mm prime on a crop body?

Nforce

@ Anouilh : You'll get them for around a tenner on Dealextreme.com or Ebay. The 50mm f1.8 is an excellent choice though you'll lose the ability to autofocus,naturally.

Here's a quick and dirty example of a shot that I took using the 50mm on a D80..

DutchGuy

Anouilh wrote: »

Ever so often I have found references to the low cost of tubes for macro work, as here:

http://www.boards.ie/vbulletin/showpost.php?p=60685101&postcount=2

Is this a reference to second-hand, as every site I have found lists a set of Kenko tubes for well over 100 euro.

Can they be used with a 50mm prime on a crop body?

Anouilh, as Nforce has said you can get very cheap ones from ebay but they have no electrical contacts. This means that on a modern lens you cannot set the aperture without going through quite a hassle or use autofocus. I use mine with an old 50mm lens with aperture ring which makes it a bit easier.