Do teleconverters affect depth of field and minimum focusing distance?

[JustJazzie]

I'm having trouble understanding this exactly. Hopefully my question makes sense.

I know that teleconverters lower the light hitting the camera, but does it actually change DOF? Or do we just need to adjust because light is lost in the elements somewhere? In other words, Would an f8 shot, have the same DOF with or without a teleconverter?

Also, does a teleconverter change the minimum focusing distance on a lens?

 

[Ysarex]

The DOF will change with the converter and you'll get less DOF. The converter will increase magnification which decreases DOF.

Joe

edit: The f/stop is changed by the converter so that f/8 is no longer f/8. If the converter reduces exposure by 1/stop then f/8 would in actuality be f/11. But you're still getting less DOF since the magnification factor is dominant.

 

[Derrel]

MFD stays the same....but the image is larger, so one can get a bigger image of the same subject by adding the converter. The Nikon 300mm f/4 AF-S is a good example of a long lens, with a close MFD, of just over 4 feet, which is VERY close for a 300mm prime lens. I've used the 300/4 with and W/O a 1.4 converter for "macro-type" uses...it's pretty handy to use with the Nikon TC14e 1.4x converter.

 

[JustJazzie]

Thanks @Ysarex and @Derrel!

 

[chuasam]

The DOF will change with the converter and you'll get less DOF. The converter will increase magnification which decreases DOF.

Joe

edit: The f/stop is changed by the converter so that f/8 is no longer f/8. If the converter reduces exposure by 1/stop then f/8 would in actuality be f/11. But you're still getting less DOF since the magnification factor is dominant.

What?
It depends on the Teleconverter used. If it's 2x you lose 2 stops, if it's 1.4x you lose 1 stop.
You lose roughly half your DOF on a 2x converter and 1/1.4 on a 1.4x converter.
You can work out the "math" here Online Depth of Field Calculator

 

[Ysarex]

The DOF will change with the converter and you'll get less DOF. The converter will increase magnification which decreases DOF.

Joe

edit: The f/stop is changed by the converter so that f/8 is no longer f/8. If the converter reduces exposure by 1/stop then f/8 would in actuality be f/11. But you're still getting less DOF since the magnification factor is dominant.

What?
It depends on the Teleconverter used. If it's 2x you lose 2 stops, if it's 1.4x you lose 1 stop.
You lose roughly half your DOF on a 2x converter and 1/1.4 on a 1.4x converter.
You can work out the "math" here Online Depth of Field Calculator

So what's with the What? Please explain what I said that was in error.

Joe

 

[Designer]

I know that teleconverters lower the light hitting the camera, but does it actually change DOF?

Yes.

Or do we just need to adjust because light is lost in the elements somewhere?

Very little light is lost "in the elements", but adding more tube length to the whole thing means an effectively smaller aperture. By plugging in a smaller aperture into the DOF calculator, you see what effect it has.

In other words, Would an f8 shot, have the same DOF with or without a teleconverter?

Using the DOF calculator, you will see that the DOF depends partly on the focal length, so no.

In sum; BOTH the aperture AND the focal length will affect the DOF, and a teleconverter changes BOTH.

 

[KmH]

Do teleconverters affect depth of field and minimum focusing distance?

Yes.

 

[Jasii]

Yes! pics shot with the TC will appear to be shot at a different aperture and focal length, making the shot look different from the one shot without the TC. This will also make the DOF look less shallow.

 

[Solarflare]

Interesting.

I always thought a teleconverter was basically a glorified magnification glas.

And would thus not change depth of field.

But apparently, it does ! Thats kinda weird.


Oh, and minimum focusing distance AFAICS definitely changes, and thats by exactly the size of the teleconverter. Thats because minimum focusing distance is measured from the sensor, and not from the front lens. The distance subject to front lens however doesnt change.

As others have said - the magnification factor of course goes up. A teleconverter is a magnification glas, after all.