Teleconverter stacking?.

[Journeyman]

Good day,

Is it possible to link two teleconverters via an extender?

I have a Canon x1.4 and a Tamron x1.4 with the appropriate lenses for each. The converters don’t offer the possibility of joining them.
My mind is suggesting that it may be possible to hook up an assembly of
400 lens - x1.4 - extender- x1.4 - Canon EOS 90D. It would be manual focus only of course but would offer a possible 1250mm focal length including the crop factor of 1.6.

Thank you, kind regards,
Dennis

[ameerat42]

Good evening, Journeyman.
Would you be able to provide an image of the setup? My first thought was that the
converters should just stack behind the lens, and the result attachable to the camera.

Then there is the "extender" - a term sometimes used in the form "tele-extender" in
place of "teleconverter". All I can imagine is that it's an extension tube, such as used
for moving a lens out from a camera body to allow close-up photography.

To speculate further: do you mean that you would have an arrangement such as:

Lens + teleconverter 1 + "extender" + teleconverter 2 + camera

If so, then I could not say what the optical result would be, except to suggest that the
extender would introduce some noticeable vignetting AND that the resulting focal length
would not be a simple doubling of that of your lens alone. In fact, you'd effectively get a:

Lens with teleconverter + and extension tube to render it a "close-up lens" + a teleconverter
multiplying the image. BUT you would not achieve infinity focus.

As I said, post a pic for fine-tuning.

- - - Updated - - -

Some moments after hitting the "post" button I recalled a memory from my filmic past
where I did indeed carry out such an experiment. I had:

50mm lens + 2X converter + extension tube.

It gave me a 100mm lens + extension tube.

In another version I swapped the converter and extension tube, and if I recall
correctly, that was better for "macro" work. Of course, neither arrangement
allowed for infinity focus.

[paulheath]

The design of Canon's extenders ( including 3rd party for Canon ) means that you can't directly couple two extenders together because the protruding glass element physically doesn't fit. The way to get around this is to use a 12mm extension tube between the two extenders
i shall add, you could couple a 2x with a 1.4x , but not a 1.4 x with a 1.4x , or a 2x with a 2x if that makes sense

[ameerat42]

Ta, that's interesting.

I found this: https://www.canon.com.au/lens-extenders

It looks like you could have a ghost of a chance with the EF versions...
Perhaps make that a wraith of a chance - even slimmer.

So, Paul, can you focus at infinity using the 12mm extension tube like that?

[Journeyman]

Good day & thanks,
The intruding lens mounts definitely cause the problem. I have read articles elsewhere that photographers have used a lightproof non-camera barrel to extend their lenses for macro work.

Nardes used a multi teleconverter setup with great result using extenders however he used all Canon gear, my plan is a hybrid set up.

It is the hollow of the extender and the ability of the mounts to couple that interest me.
The photo shows the fittings and couplers. The better mousetrap (in this case lunar pic) seems to be in reach.

As always, many thanks for your advice, kind regards,
Journeyman



EAF512C8-F9E0-4681-B5E2-C1F6334F8997.jpeg

[nardes]

This worked for me and retained infinity focus.

The camera body is the EOS R6.

Cheers

Dennis

Moon Jupiter Saturn Canon EOS R6 100_400 1x4 2x0 2x0 Crop 1200.jpg

5D Mark IV IMG_3150 Crop 1200.jpg

[ameerat42]

Revising...

- - - Updated - - -

Does that extension tube read 12mm? Did it induce any vignetting in that position?
(I guess not, though.) How did you get by with the protrusion of the teleconverters?

- - - Updated - - -

---Oh, I see, and will answer my own question: They are EF versions, with hardly
any protrusion

[paulheath]

jeeeeeez nardes, if thats on a 600 prime your at 5376mm if applied the 1.6 crop mode

[nardes]

jeeeeeez nardes, if thats on a 600 prime your at 5376mm if applied the 1.6 crop mode

I wish I had the 600mm Prime, this was on the 100-400mm Mk II.

Cheers

Dennis

[ameerat42]

Hi Nardes, I might as well ask you: have you noticed any drawbacks at all, like vignetting,
with the interposed extension?

[nardes]

Hi Nardes, I might as well ask you: have you noticed any drawbacks at all, like vignetting,
with the interposed extension?

I've only used this combo mounted on a tripod when shooting the Moon and then Jupiter and Saturn so I did not check for vignetting.

Also, from memory, I did try something similar on a 300mm F2.8 lens and I think it would not reach infinity focus with the 12mm Ext Tube, so one would need to experiment on a lens by lens basis.

Incidentally, the Canon RF Extenders will not fit into the Canon Model of the RF to EF Lens Mount - you cannot fit the round barrel into the rectangular hole. This means you cannot go EOS R -> RF Extender -> Canon RF to EF Adapter -> EF Lens.

You may be able to do this with a non-Canon RF to EF Adapter if the hole is large enough?

Cheers

Dennis

[ameerat42]

Ta for the info, Dennis.

[Journeyman]

My lens mounts are both circular, EF 400 and EF mount Tamron. It would require a minimum of 16mm to space out the 1.4x mounts.

From a lunar photography perspective one option is a 600 variable lens from Tamron when coupled with a 1.4x, may work although not an inexpensive option. The other is a refracting telescope with a dslr mount.

I have seen astonishing pictures of the moon from good telescopes with stacking of many images, in the 100s. Of course using tracking equipment and specialised cameras. Dennis’s photos show what is possible using DSLR camera and lens combinations with thought and ingenuity.

Remaining budget conscious an extender is inexpensive.

As always many thanks.

[ameerat42]

A slight digression - and a WKE-UP call!

I've just checked on prices for various teleconverters - brands, mounts, powers...
They range from $519 to $600 - GAH!!!

A few years ago, mine cost $250 (a 2X)

Rip-OFF van Winkle

[Journeyman]

My Canon II was 2nd hand, Gumtree $250 works well, the Tamron as per your quote.

[Journeyman]

Another slight diversion. There are inexpensive tubes available for purchase. Genuine Canon tubes are not cheap, where as the non genuine start as low as $20.00.
Any info would be welcome. Regards JM

[ameerat42]

It's just another gouge-point

I think we'd better start saving up hens' teeth.

[Journeyman]

Good day,
I emailed Canon to ask whether two [Canon] teleconverters could be coupled successfully. The reply was prompt, good service indeed.

The upshot was that it could done. Manual focus would be required.

A better way perhaps is that a 2X alone would help, focal length of 800 rather than 560 with the 1.4X.

I am after better quality lunar photos, the other possibility is using an equatorial tracking device. Making stacking a more complete option. A basic one is about the same price as a converter. More of the hens teeth savings required. It would be more useful for astro photography though.

Thanks for your interest,
Journeyman

[ameerat42]

Well, 800mm will give you ~8mm lunar image. If you are talking about tracking (equatorial mount)
and then stacking, perhaps an astro tracker would do. You can get to track at star/solar/lunar
rates. Of course it's BYO (sturdy) Tripod. Featured ones are about the same price as a TC or an
eq mount. Have a look at this page for some Oz prices:

https://www.bhphotovideo.com/c/buy/s...ounts/ci/48647

In the meantime, you could try to improve your PP skills on single image captures. That will
always be necessary, no matter how you capture your image(s).

[Journeyman]

Thanks for the tracker info.

Manual focus technique is something I need to polish up.
PP does offer quite a few opportunities. I don’t always understand what is required particularly related to contrast and brightness. The PP programs need more time from me.

The last full moon shot has developed a green perimeter and latitude lines with saturation increases. No added colours. I will post a photo later this morning.

I will invest more time to follow the PP track. I am reluctant to buy the 2X without good reason. The tracker has a lot of appeal though.

Thanks again.