Off-Brand "Normal-Range" Zoom crop lens (or longer) and non-canon 1.4X TC

I was wondering something!

Since the Kenko/Tamron/(?Sigma? – Sigma protrudes a little?) 1.4X TC will allow my Sigma 10-20mm to be used on a FF with little to no vignetting and AF intact, would the addition of a 1.4X TC work on other Off-Brand (Sigma, Tamron, Tokina) crop lenses to allow them to be used on a full frame camera? This can’t be done with a non-modified Canon EF-S lens as they have a protruding rear end – off-brands don’t.

Yes - I understand that there are better lens options out there for full frame! This though would allow someone to move to a full frame camera and use a non-Canon lens that they already own until a more appropriate lens could be purchased. For instance a Sigma/Tamron 17-50mm f/2.8 OS/VC becomes a still reasonable 24-70mm f/4.0 with OS/VC.

As I said, the combination of my Sigma 10-20mm f/4-5.6 and my Kenko (and Tamron) 1.4X TC works with my 5DII. The combination still has very good IQ, still has AF, and only has a tiny amount of vignetting at the widest end. The problem my only other crop lenses are non-modified EF-S, which will not work.

Does anyone have an off brand 1.4X TC, a crop lens like mentioned above, plus a full frame camera that they are willing to try this with? There is no danger, as the TC keeps the lens away from the mirror. Plus non-Canon crop lenses don’t stick out in the rear, so they couldn’t be hit by the mirror anyway.

These are the questions:
Does it work?
Does it AF?
Does it vignette? (If so how much?)
How good is the IQ? (1.4X usually don’t cause much degrading of IQ on telephotos of good quality)

I just want to know the answer, but it may also help someone thinking on moving to a FF camera.

Anybody?

it seems like if someone had a 17-50mm f2.8, and moved to a FF camera, it'd be just as easy/cheap to get a tamron 28-75mm f2.8...

i mean who wants a 24-70f4 lens...oh wait...canon thinks everyone does...

I found this:

https://photography-on-the.net/forum/showthre​ad.php?t=909337

DreDaze wrote in post #15387376
it seems like if someone had a 17-50mm f2.8, and moved to a FF camera, it'd be just as easy/cheap to get a tamron 28-75mm f2.8...

i mean who wants a 24-70f4 lens...oh wait...canon thinks everyone does...

See, I'm not totally crazy. Though the macro (basically a real macro) feature looks nice on the new zoom.

FEChariot wrote in post #15387380
I found this:

https://photography-on-the.net/forum/showthre​ad.php?t=909337

Thanks, but I already know about this.

And I already know it works on the Sigma 10-20mm - that is the example I used above.

I want to know if it works similarly with a different crop lens.

Ok I misread then. I don't know why it would be any different with a 17-50 OS though.

FEChariot wrote in post #15387638
Ok I misread then. I don't know why it would be any different with a 17-50 OS though.

I agree, I don't know why it wouldn't work either. I think it should and probably will, but sometimes things just don't work like it seems they should. Hence the reason for my question. I guess that I just am wondering for verification.

Yes it works, but the results are not always worthwhile. The Sigma 30 works with a 1.4x on a 5D but it's a 42mm F/2 basically - only a touch wider FoV and shallower DoF than the native lens would be on an APS-C.

Worth mentioning, my Tamron 11-18 on the 5D (no TC) covers the frame from approx 14mm, which is a wider FoV than the lens is on APS-C.

No doubt quite a few APS-C lenses work quite well on APS-H as-is.

I have a Tokina 11-16 for my crop DSLR, and it works without vignetting on my Film SLR as long as I stay at 15 or 16mm. Below that it vignettes, though the image may still be useful for many situations. However, 15mm is REALLY wide on FF, and I doubt I'll ever need wider than that other than just playing around.

My Tamron 18-270 vignettes at all focal lengths on the Film body.

I haven't tried either one with a TC, though.

Anyone with an off brand 1.4X TC, a off brand crop lens (ie crop but not Canon EF-S), and a FF camera to try this?

Again it works with the Sigma 10-20mm, so another lens.

Tried my Kenko 1.4x TC with my Tamron 18-270 on my film body, and there is only the slightest amount of vignetting at the widest setting, and none as I zoom in. Without the TC, I get a LOT of vignetting, so it's a big improvement.

I used to have a Kenko 1.5 extender wich worked well on my 5D Mk1 and 50D with Canon 17-40, 24-105, 100 F2.8 Macro, 100-400, 300 F4 L IS. It also worked fine on a friend's 1D3 and later on my !d4.
The AF was fairly hit and miss on the 100-400 but on the F4 lenses it was OK.
Hope this answers your query.

archer1960 wrote in post #15394872
Tried my Kenko 1.4x TC with my Tamron 18-270 on my film body, and there is only the slightest amount of vignetting at the widest setting, and none as I zoom in. Without the TC, I get a LOT of vignetting, so it's a big improvement.

Thank you! It seems like the 1.4X will allow the porting of a crop lens to a FF. How was the IQ? Did it AF?

johnf3f wrote in post #15394895
I used to have a Kenko 1.5 extender wich worked well on my 5D Mk1 and 50D with Canon 17-40, 24-105, 100 F2.8 Macro, 100-400, 300 F4 L IS. It also worked fine on a friend's 1D3 and later on my !d4.
The AF was fairly hit and miss on the 100-400 but on the F4 lenses it was OK.
Hope this answers your query.

Somehow you missed the main idea. The use of a 1.4X combined with lenses designed for a crop camera, in order to see if they would work with minimal vignetting on a full frame camera.

Every lens you gave was a lens designed for a full frame sensor camera. I know lenses designed for FF cameras work on FF cameras - with or without a TC.

But thanks for trying to help!

I've tried a Kenko 2x with a 35L before and the results were pretty terrible. Results seem to vary lens by lens.

Cesium wrote in post #15395301
I've tried a Kenko 2x with a 35L before and the results were pretty terrible. Results seem to vary lens by lens.

Welcome to the club of people who misread the OP.