Focus Problem with Teleconverter

ryand70s

Hi guys! Just bought a new 2x Teleconverter for my Sigma 135~400 APO Lens. But my problem was, the focus time takes too long, sometimes it's hard to focus. Can't do the manual focus if you have the teleconverter on.
What/Where do you think is the problem ? :dunno

Thanks,

Ryan

PS: I'm using a Nikon D70s body.

ziggy53

ryand70s wrote:

Hi guys! Just bought a new 2x Teleconverter for my Sigma 135~400 APO Lens. But my problem was, the focus time takes too long, sometimes it's hard to focus. Can't do the manual focus if you have the teleconverter on.
What/Where do you think is the problem ?

Thanks,

Ryan

PS: I'm using a Nikon D70s body.

Ryan,

The problem is that the lens is an f4.5-5.6. The 2x tele-extender adds 2 stops so now you are working with an f9-f11 lens, or so. Your camera is not going to focus well at those apertures, either automatically or manually with assist. I believe the D70s is designed to autofocus with lenses of f5.6 or better.

A much better solution, if you really need the reach, is the Sigma 300-800mm, f5.6. You had better have deep pockets as this lens is around $5000-$5500USD.

ziggy53

ryand70s

Ziggy,

Such a great help. Maybe i'll consider selling the teleconverter on ebay.
Investing on a teleconverter was a bad money for me. i should have ask first before i bought it. Anyways, we all learn from mistakes:cry .

Thanks,

Ryan

ziggy53 wrote:

Ryan,

The problem is that the lens is an f4.5-5.6. The 2x tele-extender adds 2 stops so now you are working with an f9-f11 lens, or so. Your camera is not going to focus well at those apertures, either automatically or manually with assist. I believe the D70s is designed to autofocus with lenses of f5.6 or better.

A much better solution, if you really need the reach, is the Sigma 300-800mm, f5.6. You had better have deep pockets as this lens is around $5000-$5500USD.

ziggy53

wxwax

Ziggy shoots and scores again. Man, you're incredibly helpful, thanks for all of your great advice.

Steve Cavigliano

with Waxy. Good work Ziggy

Ryan,
You may want to try the cheap Tamron 1.4X TC. Since it doesn't report a new aperture to the camera, it will usually allow you to retain AF on F5.6 max aperture lenses. I used this guy on my F6.3 max aperture Bigma and it worked well for stationary subjects

Attached to an excellent prime, it will allow you to capture moving subjects.

Steve

ryand70s

Hi Steve! Thanks for you recommendation . I'll check if that one is available here in the Philippines.

Thanks,

Ryan

Steve Cavigliano wrote:

with Waxy. Good work Ziggy

Ryan,
You may want to try the cheap Tamron 1.4X TC. Since it doesn't report a new aperture to the camera, it will usually allow you to retain AF on F5.6 max aperture lenses. I used this guy on my F6.3 max aperture Bigma and it worked well for stationary subjects

Attached to an excellent prime, it will allow you to capture moving subjects.

Steve

gtc

paperweight
i bought an old vivitar 2X TC for use on my 400/5.6 for almost nothing

focussing was very difficult and the image quality was awful..disgraceful...nightmarish even

it did however give me a pentax takumar end cap and spotmatic body cap so all was not lost-its now a paperweight on my desk...

so you are not alone-1.4X would be as high as you would want to go but i found that with manual lenses the sigma sent a message to the camera that there was no lens attached and so no shot-this would of course be fixed by use of the eos emulation chip attached to an adapter..

Bob&Glennie

gtc wrote:

i bought an old vivitar 2X TC for use on my 400/5.6 for almost nothing

focussing was very difficult and the image quality was awful..disgraceful...nightmarish even

it did however give me a pentax takumar end cap and spotmatic body cap so all was not lost-its now a paperweight on my desk...

so you are not alone-1.4X would be as high as you would want to go but i found that with manual lenses the sigma sent a message to the camera that there was no lens attached and so no shot-this would of course be fixed by use of the eos emulation chip attached to an adapter..

Now there's a man after my own heart. Sorry to be off topic but don't you love those old Spotmatics? Real work horses and how about that Takumar 200mm f4? They don't make anything like that anymore. Even with a real nice DSLR and some great glass I still miss my old screw mount.

Cheers
Bob

gtc

takumar 200mm/ f4.0
i like the spotmatic sp-metering is a little primitive but once you get used to it a lovely and easy camera to use-looks great too and a solid gold build.

the pentax smc 20Omm/f4.0 is my favourite all round telephoto-sharp,great colour and contrast, no flare problems and quite compact-and such a nice smooth focussing action.

i use it a lot when i am around the streets and its good for(outdoor) portraits too

you can get these for between $50-80 in pristine condition and with an adapter they work very well on my 20d,especially as it crops out the edges, so its sharp across the frame.

also i find due its weight i can sometimes successfully handhold at less than 1/200 th

go out and get another one

Andy

ziggy53 wrote:

Ryan,

The problem is that the lens is an f4.5-5.6. The 2x tele-extender adds 2 stops so now you are working with an f9-f11 lens, or so. Your camera is not going to focus well at those apertures, either automatically or manually with assist. I believe the D70s is designed to autofocus with lenses of f5.6 or better.

A much better solution, if you really need the reach, is the Sigma 300-800mm, f5.6. You had better have deep pockets as this lens is around $5000-$5500USD.

ziggy53

Yo Zig,

Thanks man, for all you do here on Dgrin - you are an incredible asset to our forum!

howard

Hi Ryan, have you tried taping the pins to see if that will allow maual focus? The ones to tape are on the side of the TC which the lens fits into and they are not the 3 on their own it's the 3 on the other end of the row. The quality is unlikely to be very good but it's worth a try. I think that even with them taped you are unlikely to get autofocus.

Good Luck
Howard

ryand70s wrote:

Hi guys! Just bought a new 2x Teleconverter for my Sigma 135~400 APO Lens. But my problem was, the focus time takes too long, sometimes it's hard to focus. Can't do the manual focus if you have the teleconverter on.
What/Where do you think is the problem ?

Thanks,

Ryan

PS: I'm using a Nikon D70s body.