teleconverter autofocus workaround

[Mattijs]

Hey guys,
I have bought an old nikkor prime lens: 300mm f2.8 ED, AF. With the DSLR crop factor this gives me some distance. To get some more, I bought the Nikkor teleconverter TC 17E II and found out this won’t fit the AF-mount of the telelens. A little nudge or bajonet if you like prevented the prime from being mounted on the converter.

Not easily discouraged I unscrewed the mounting plate of the TC and carefully grinded down the nudge. I put the thing together again, and the incompatability is fixed. I can now mount and lock the telelens. Aperture, light metering and matrix metering are all comunicated between camera and lens. Fastest aperture is 2.8, so apparantly the camera does not know there is a teleconverter between lens and body.

Now the only thing that does not work is the autofocus. When pressing the shutter half down the AF-motor starts whining but with no visual effect. It seems there is no lens movement. My first thought was that I destroyed the focusmotor in the lens with my fooling around, but that is not the case. If the TC is left out, the autofocus works just fine.

Light conditions were good during the test. And the 2.8 f-stop of the prime, with the extra 1.5 stops of the converter should also be no problem in my opinion.

Does anyone have a clue on how to work around this and get the AF working?

Thanks for any suggestions, cheers!

Mattijs

[Andy Bright]

Just how old is your lens? If it's an AF-I type (after 1992), the tc-17e should work. If it's a really early one, then it was a different focus system.
The fact that you had to remove the lug to get it to fit makes me wonder if this is a pre1992 lens.
cheers,
Andy

[Mattijs]

Hello Andy,
Thanks for your reply. The plate on the prime only says Nikkor AF 300mm ED 1:2.8. I have not been able to track this down to a time frame. I gambled the TC 17E II would be no problem, since a compatability chart showed it would work with the AF 300 f2.8 ED II.

If the lens is too old to work with the converter, would it not also be too old to work with the camera?

Mattijs

[Andy Bright]

Hello Andy,
Thanks for your reply. The plate on the prime only says Nikkor AF 300mm ED 1:2.8. I have not been able to track this down to a time frame. I gambled the TC 17E II would be no problem, since a compatability chart showed it would work with the AF 300 f2.8 ED II.

If the lens is too old to work with the converter, would it not also be too old to work with the camera?

MattijsThe TC-17E, 14E, 20E are only really designed to work with AF-I and the more modern AF-S and AF-S II lenses.... getting rid of the metal lug on these teleconverters will allow them to work with many Sigma HSM lenses as well.

It doesn't always follow that if the lens AF's on the camera, it will do so with a teleconverter in between... the popular (and current) non AF-S, Nikon AF-D lenses will not work with the above teleconverters, simply because these lenses use a mechanical screw-drive AF system that the teleconverters simply do not have provision for. Like-wise, the ancient AF system that your lens may have, may be featured on the camera but not catered for on the teleconverter.

Are you sure the lens has internal focus motors? and is not driven by a mechanical type drive from the camera?

Have you got a photo of the lens?

BTW: You did take care when re-assembling the teleconverter?

cheers,
Andy

[Andy Bright]

A quick way to determine if you have an AF-I /AF-S lens (AF-S should be written on the plate anyway) is that I'm pretty sure both of these have the multiple focus lock buttons towards the end of the lens, pre AF-I won't have these.

cheers,
Andy

[Mattijs]

A quick way to determine if you have an AF-I /AF-S lens (AF-S should be written on the plate anyway) is that I'm pretty sure both of these have the multiple focus lock buttons towards the end of the lens, pre AF-I won't have these.

cheers,
Andy

You must be right. Indeed there is some sort of screwhead in the mounting ring of the lens. The lens itself has no motor. I thought it did because all the noise was coming from the lens, not the camera... and because I am an absolute beginner with DSLR.

So, a lesson learned. I have to manually focus. I tried the combination for the first time today and it works fine. The big focus ring turns very smoothly and is accurate. I do need practice, that is for sure. But I managed to take some shots that were quite pleasing.

If I have submitted this post correctly there should be a picture of my museum worthy lens. Can you give me an estimation of the age?

Thank you for your time so far, you are a great help.

Mattijs

[I4ani]

Hi Mattijs,
The lens you appear to have is the AF Nikkor 300mm f2.8 IF-ED, and is an old lens. I am looking at an OLD Nikon Lens catalogue and it appears to show this lens; the technical info at the back shows that this lens IS usable with the following nikon telecons.
1- tc301.
2 - tc14B.
3 - tc201 and tc14A with some vignetting.
Please note it does not quote that AF is possible!!!
Also there is NO reference against this lens for the use of tc14E/14EII or tc20E/20EII and since you have had to remove the "anti fit lug", this would appear to be true.The tc17EII is only a mid distance tc between the 1.4 and the 2.0 and this maybe why you are having a problem.
If you go to the Nikon web site in your country you will find a section on discontinued lenses/cameras and you should see your lens.There is also a site which gives the age of Nikkor lenses according to their serial nos.I have it written down somewhere amongst many other useful bits of info you can never find when you want it.If I can find it I will come back to you.
regards I4ani.

[I4ani]

Hi Mattijs,
The site is www.nikonlinks.com. On the home page there is a section on lenses, look for the one called "general info", then go to the item called NIKON LENS SERIAL NUMBERS by a guy called Rolank Vink, this should help you identify your lens from the six AF versions of the 300/2.8.
regards I4ani.

[Mattijs]

Great, thanks. The site is in my favorites. The serial number is rubbed of the plate, but it seems my lens was made somewhere between 1988 and 1992.
The manual focus is no problem, I have already taken some good shots, and I am only starting.

Thanks for your info, cheers!
Mattijs