Hello, I recently bought a Tamron 28-300mm Model 185D lens for my Nikon D40. I can't get the Auto Zoom to work. I was wondering what I am doing wrong. is ther any setting I have to put my camera in? Anything I have to do on the lens it self? Help!!! Thank you Higor

If you got a lens with a Nikon mount then you don't need anything else to fit it to a Nikon camera.

The Nikon D40 does not have an autofocus motor, relying on the lens having one. This Sigma lens does not have such a motor, relying on the camera having one. Nikon designates lenses with an autofocus motor AF-S, Sigma calls theirs HSM.

The Nikon D3000 does not have a focusing motor built-in, relying on the lens to have a motor. The Tamron AF 55-200mm does not have the necessary motor; it only auto-focuses with Nikon cameras that have the motor in the camera body.

For Nikon lenses, you need lenses designated AF-S. For Tamron, you need lenses designated USD and/or BIM.

That probably wasn't the answer you wanted to see, but there it is.

The D40 does not have a focus motor, instead relying on a motor in the lens. This lens does not have such a focus motor, and thus will not autofocus with the D40.

That 2x is not AF-s compatible. It is the older Af style which the d40 does not support. Your camera store should have known this when they sold it to you, unless you bought it mailorder. Then see if they will let you return or exchange it.

hi ! iam too a D40 holder,u can opt for AF-s versions or HSM sigma,both of them autofocus on d40,can go for 18-200 AFs VR or if u need still longer end go for 70-300 but it is costly than the sigms 70-300APO DG HSM MACRO..,its a much better reviewed lens and dont forget the cost..anyway do some research before considering..good luck

When using a TC, as the perceived focal length increases and the aperture falls off, AF struggles to work except in very bright light.

Your 28-90 AF-D lens can't autofocus with the D40, which requires AF-S lenses with a focus motor in the lens. Sigma lenses with "HSM" (HyperSonic Motor) in the name also have the focus motor.

The Lens focusing motor is broken and it is replaceable

Autofocus function on the D40 only supports lenses with the
AF-S feature, which have an autofocus motor built into the lens,
instead of using an autofocus motor drive built into the camera.

The Tamron lens you have, does not have a built in motor and
the autofocus function relies on the motor drive in the camera.

It will not work with the D40 or D60, but it will work with other
Nikon digital SLRs, such as the D80. Need to get an AF-S
type lens or upgrade to different Nikon digital SLR. Unless
you do this, you will have to manually focus the Tamron lens.

All of the Nikon DX (for digital) series lenses are also AF-S
type, so they will work with the D40, which is designed as
an entry level digital SLR, therefore it is intended primarily
for use with DX lenses, which are typically sold in a kit with
the D40. Most common one is Nikkor 18-55mm DX AF-S.

Other Nikon AF-S lenses made for film cameras (FX type)
will also work with the D40, but these tend to be expensive
professional models. DX series lenses tend to be more
affordable. You might consider the 18-200mm DX AF-S
as an alternative to the Tamron, but these are not cheap.