What order tc with extension tubes

When using extension tubes in combination with a teleconverter, what is the preferred ordering - lens, tc, tubes or lens, tubes, tc? Is there a difference in results - either IQ or image size? I am using a 100-400L with a 20mm tube, 36mm tube, and 1.4 tc for shooting Western Chorus Frogs (about the size of a thumb-nail) and such.

A TC is always used next to the camera body for maximim magnification and then the ext tubes and then the lens.
TCs always reduce the IQ more than ext tubes so for max IQ I would just try the ext tubes with the lens set at 100mm - that should give you just over 0.5:1 magnification.

Brian V.

If it is the Canon or Sigma 1.4x TC, I would put it against the lens and use the tubes between the TC and the camera body. The teleconverter communicates its presence to the lens with the extra three electrical contacts on the lens. This way the lens will know it has the teleconverter and then disable the autofocus for you and the lens will report the actual focal length and aperture to the camera. Canon and Sigma TCs fit up into the back of the lens and are designed to work together this way.

You can try it both ways and see which way looks better to you.

I took some images yesterday to test this query and found something interesting...maybe someone could explain my results.

I used my Ds Mk III, 180mm canon macro, canon 1.4/2.0 TCs, and a full set of Kenko extension tubes. Shots were taken while shooting tethered using canon utilities to assure myself of no camera shake.
While in manual mode at ISO 100 and f/32, exposure was adjusted using SS and following set-up, lens only, lens with 1.4 TC, lens with 2.0 TC, lens with full set of extension tubes.

Results were...IQs were quite similar using TCs or tubes. The problem arose when I combined the TC, either of them, with the extension tubes, order didn't seem to matter.
There was a serious decline in IQ and a serious noise problem, in spite of low ISO. This was evident on the laptop while I was trying to adjust focus, to no avail, and more so on the desktop.

Any explanations out there?

chauncey wrote in post #12068127
I took some images yesterday to test this query and found something interesting...maybe someone could explain my results.

I used my Ds Mk III, 180mm canon macro, canon 1.4/2.0 TCs, and a full set of Kenko extension tubes. Shots were taken while shooting tethered using canon utilities to assure myself of no camera shake.
While in manual mode at ISO 100 and f/32, exposure was adjusted using SS and following set-up, lens only, lens with 1.4 TC, lens with 2.0 TC, lens with full set of extension tubes.

Results were...IQs were quite similar using TCs or tubes. The problem arose when I combined the TC, either of them, with the extension tubes, order didn't seem to matter.
There was a serious decline in IQ and a serious noise problem, in spite of low ISO. This was evident on the laptop while I was trying to adjust focus, to no avail, and more so on the desktop.

Any explanations out there?

Do you really mean F32 ?

You will start to really notice image softening past F11 at 1:1, as soon as you start magnifying the image with anything (TCs or ext tubes) this will get considerably worse.
I'd try again at about F8 and see if you get the same result.

Brian v.

Yes, I did mean f/32...diffraction does begin to set in on that body at about f/10, but that doesn't explain the difference when the f/stop was never changed. Regardless, I will reshoot at f/8.

Thanks all for the responses.
LordV, I agree about using only tubes when possible. When I can get close enough, I use the 150 macro, with or without tubes. However, there are times when I can only get about 6 feet from the subject. Then I use the 100-400. To focus with tubes at that distance I find I need to be at ~400. Then the tc comes in handy to increase the size of the subject in the frame, even at the expense of some IQ.

chauncey wrote in post #12069604
Yes, I did mean f/32...diffraction does begin to set in on that body at about f/10, but that doesn't explain the difference when the f/stop was never changed. Regardless, I will reshoot at f/8.

The diffraction changes with apparent aperture and that changes with magnification even though the set aperture is constant.

Effective aperture = set aperture * (1+M) where M is the magnification so even at 1:1 you are doubling the effective aperture (ie F10 becomes F20). As you add ext tubes or TCs you are increasing the magnification even more.

Brian v.

Uuugh...user error. After taking Brian advice and dropping to f/8 differences in IQ were not discernible until around 250-300%, well more than any sane person would look.

On a side note, I had always gotten soft images when using Canon's 2X TC. Have now come to the belief that the difficulties are as the result of AF errors, as the softness disappears when manually focusing.

chauncey wrote in post #12076787
Uuugh...user error. After taking Brian advice and dropping to f/8 differences in IQ were not discernible until around 250-300%, well more than any sane person would look.

On a side note, I had always gotten soft images when using Canon's 2X TC. Have now come to the belief that the difficulties are as the result of AF errors, as the softness disappears when manually focusing.

Bet you were not shooting at F32 though before ?
Have to admit I always assume people are using MF when taking macro shots at 1:1 or above.

Brian v.

You're indeed correct...had only used it on a 300mm for my BIF (that's birds, not bees) images. Got out and about more then.