camera lens, 2 tcs and a ex tube ?

Can someone tell me what focal length this combo makes

camera is a 5DSr and in this order 1.4tc - 12mm extension tube - 2xtc and a 600f4

is it 1680mm ?

Rob.

Heya,

The TC's and physical lens will multiply regardless of order.

The 12mm extension tube will then move the elements forward, reducing their minimum focus distance, and reducing infinity focus.

600mm x 1.4 TC x 2.0 TC (in any order) is 1680mm.

Why are you putting the extension tube between the TC's? That will change things and change how the focal lengths work with TC's.

Very best,

Thanks

Its to get this my tcs wont join together hence the tube .

Rob.
Ediit its the space station .

From what I have read on here by other posters, the 12mm ext tube goes between the the two TC's, and doesn't affect infinity focus. It seems with the design of modern TC's you cannot stack them. Even so the multiplication works the same, so you would get base fl×TCa×TCb=Total fl. So in this case it would be 1.4×2×600=1680mm and it will have an f/number of f/11. I think you might need to tape the pins to stop it trying to report to the body though.

Alan

I stack my 2 Kenkos all the time, so perhaps something has happened with newer TC designs, or is this just a Canon thing?

I suspect it's a Canon (and Sigma) thing - their TCs have protruding front elements.

OP - you'll have, as you described the arrangement, a 1200 mm lens on 12 mm extension tubes (so focusing minimally closer than infinity when at infinity; I think around 120 meters) with a 1.4x TC (which, there, won't affect focus range), so a 1680 mm total as others have said. By swapping the two TCs you could get to about 60 m, with the same final focal length.

I haven't tried it but I have also seen a post stating that you do not lose infinity when stacking converters.
I used to stack my Canon version II extenders but (as you know) the MKIIIs cannot be stacked directly together.

Stacking converters, no. But add an extension tube into the mix and you WILL lose infinity. That's what extension tubes are used for. They're like a permanent extra X mm of twisting of the focus ring.

Thanks for reply's

I am using mkIII tcs and they wont fit together

The shots of ISS are just a bit of fun.

As for infinity loss im not sure how close the combo got to infinity focus I'm sure I was close but I could put the ISS out of focus so I went passed the focus and then back again jus as you manually work with any lens.

Rob.

GyRob wrote in post #17896390
Thanks for reply's

I am using mkIII tcs and they wont fit together

The shots of ISS are just a bit of fun.

As for infinity loss im not sure how close the combo got to infinity focus I'm sure I was close but I could put the ISS out of focus so I went passed the focus and then back again jus as you manually work with any lens.

Rob.

I stack EF 1.4II and Sigma APO 2x with a 12mm extension tube between.
I can focus on the moon. I really don't care if infinity focus is reduced but I suspect it is not.

You can no longer focus on Jupiter now.

TeamSpeed wrote in post #17896484
You can no longer focus on Jupiter now.

Now there's a first world problem.

I was curious regards being able to focus beyond the moon and just confirmed I can.
100-400 II with EF 1.4III and Sigma 2x APO DG EX and 12mm tube:

Viewing the glory of the universe is something for everyone, and always has been. However Jupiter is anywhere from around 2000 to 4000 times away than the moon. That all being said, if your farthest goal is the moon, then you are good! That means you can shoot as far as all the planets put end to end.

Since most AF lenses have a certain amount of movement past the actual infinity position, to allow both for thermal expansion etc and also to stop the AF motor driving the system into the hard stop and damaging the drive system, along with the relatively minor extension in relation to the focal length there is probably still room to get the lens and extenders/tube combination to achieve infinity focus. I don't recall how far past the infinity mark the version one 100-400's that I have rented in the past would go, but there seems to be a significant amount of movement available on my Sigma 150-600. Unfortunately, since I do not have either any teleconverters or extension tubes, it's not something that I can test, even though shooting with 1680mm of reasonable quality lens would be interesting. Back in the early 80's I did try out a 500mm mirror lens with a pair of cheap Vivitar 2× converters for 2000mm, as I recall the results on HP5 were not terrific.

Alan