EF extender stacking

Started 5 months ago | Discussions
J.K.T. Regular Member • Posts: 322
EF extender stacking

As far as I know it is possible to stack version II 2x and 1.4x extenders, but not version III ones. Can anyone tell what has changed? Is it the rear of 1.4x, the front of 2x or both? Is it possible to stack 1.4x III in front of 2x II? Those are roundabout ways of asking the real question: Is it possible to stack EF 1.4x III in front of RF extenders with a modified adapter?

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John Crowe
John Crowe Senior Member • Posts: 1,461
Re: EF extender stacking

It is the Canon EF 2x II which is the only stackable extender.  It can stack with any of the three EF 1.4x extenders.  The EF 1.4x goes on to the camera body and the EF 2x II has a bigger rear opening to fit onto the protruding front element of the 1.4x.

You can even stack the EF 2x II on top of the EF 2x III.  So you should be able to stack the original EF 2x onto the EF 2x II as well.

Not sure how that fits with your RF plans.

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John Crowe
John Crowe Senior Member • Posts: 1,461
Re: EF extender stacking

I see the RF extenders have a very long protruding element and I see the EF to RF adapter has a baffle in the back. That baffle would very likely have to be cut back, if possible. It should only be plastic. Then it could take the RF 1.4x or RF 2x and then either EF 1.4x or EF 2x of any version onto the front of the adapter.

So the real question is, can the EF to RF be mounted on either of the RF extenders.

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GraphAD Forum Member • Posts: 96
Re: EF extender stacking

Hi,

you put the 2X on the lens, then the 12mm extension tube, then the 1.4X closer to the camera and you can focus on almost any camera in live view.

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John Crowe
John Crowe Senior Member • Posts: 1,461
Re: EF extender stacking

You do lose focus to infinity.  Probably okay to a few hundred feet.

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GraphAD Forum Member • Posts: 96
Re: EF extender stacking

John Crowe wrote:

You do lose focus to infinity. Probably okay to a few hundred feet.

Yes, with a good amount of atmospheric distortion.

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OP J.K.T. Regular Member • Posts: 322
Re: EF extender stacking

John Crowe wrote:

So the real question is, can the EF to RF be mounted on either of the RF extenders.

So far not on an off-the-shelf one, but several can be modified for the job. I have Comlite, which turned out to be a bad choice as the pins on the front are not individually spring loaded. That is a sure recipe for communication errors. The mounting works fine, though. I have not heard of anyone modding an original Canon, though.

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OP J.K.T. Regular Member • Posts: 322
Re: EF extender stacking

John Crowe wrote:

It is the Canon EF 2x II which is the only stackable extender. It can stack with any of the three EF 1.4x extenders. The EF 1.4x goes on to the camera body and the EF 2x II has a bigger rear opening to fit onto the protruding front element of the 1.4x.

You know what they say about assumptions... I had not seen the Canon EF 2x ones, but the 2x ones I have seen did not have such opening, so I assumed it wouldn't have one and that mandated the stacking order assumption.

You can even stack the EF 2x II on top of the EF 2x III. So you should be able to stack the original EF 2x onto the EF 2x II as well.

Not sure how that fits with your RF plans.

It leaves the situation open. Both the RX ones have the same forward protrusion and I know the EF 1.4x II can be mounted in front of it. There is, however, pretty much zero extra space between them. So if any of the other EF ones have glass more rearwards compared to EF 1.4x II it can't be mounted. If not, it can.

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OP J.K.T. Regular Member • Posts: 322
Re: EF extender stacking

Not quite. Mounting FDn 500mm f/4.5 L on 8mm thick FD->EF adapter and then on RF->EF and RF 1.4x, the maximum focus distance is about 35m. That is a bit too close for larger targets. That 8mm adapter acts as 10mm extension considering the flange distances.

I initially got an EF modified FD 1.4x, but the image quality of that is pretty abysmal compared to the RF 1.4x ... or even the EF 1.4x II. Unfortunately RF->FD adapter can't be used in front of RF extenders. The aperture lever does not clear the extender protrusion.

Admittedly this got a bit off-topic.

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John Crowe
John Crowe Senior Member • Posts: 1,461
Re: EF extender stacking

So, you mean you are mounting the RF 1.4x onto the camera, the RF/EF adapter onto RF 1.4x, and then the EF 1.4x II onto the RF/EF adapter?

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John Crowe
John Crowe Senior Member • Posts: 1,461
Re: EF extender stacking

This all getting a bit confusing and I have asked you another question above too. You were talking about stacking 2x adapters but here you seem to be stacking two 1.4x extenders using the RF - EF between them, for an FD 500/4.5 L. Providing you a 1000mm f9 lens.

So, if you can put the EF 1.4x II onto the adapter onto the RF 1.4x then you can put any Canon EF 1.4x or 2x onto the adapter and RF 1.4x II as well.

I find it hard to believe that the Canon FD 1.4x-A converted to EF is that bad, but lets explore other possibilities.

I use a Canon FD 800mm f5.6 L on Canon EF several ways. The first is an ultrathin adapter, they are rare, but they get you focus to about 400 feet.

Second is a Kenko FD -EOS 2x converter/adapter. They too are rare, but I managed to get mine for $30. I don't think the seller realized what it was. It is not as good as the Canon EF 2x but it is still extremely useful.

Third is the Canon FD-EF 1.26x Converter. Again, extremely rare, but less sought after since mirrorless came along. Some are still trying to get over $1000 for it, but I got mine for $300.  I think I saw one recently for $400.  Extremely sharp and makes your lens about 625mm f6.3. The 1.26x has no space at rear since it has glass and it has protruding front element that is fairly long.

Next year, hopefully, when I can go to my local racetrack again, I will be putting the 1.26x onto the 800mm, and then directly onto a Kenko EF 1.4x extender (with no front protrusion), giving me about 1400mm f10.

I have to go back to my tests but it seems to me that the Kenko 1.4x is almost as good as the EF 1.4x in image quality. I did decide that it was a very useful option as I described above.

The easiest way for you to get to 1000mm, if that is your plan, is the Kenko FD-EF 2x mounted to the lens and then mounted to EF-RF then mounted to camera. It should beat stacking 1.4x extenders. I can actually test this if you like, at least with Kenko 1.4x and Canon EF 1.4x.

P.S.  What about simply getting the FD 2x-A and mounting it to the lens and onto an FD - RF adapter?

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OP J.K.T. Regular Member • Posts: 322
Re: EF extender stacking

John Crowe wrote:

So, you mean you are mounting the RF 1.4x onto the camera, the RF/EF adapter onto RF 1.4x, and then the EF 1.4x II onto the RF/EF adapter?

That is a possibility ... for EF lenses, but not the FDn discussed below. Currently that might apply to EF 300mm f/4 L IS USM. With low resolution body it might work even though RF 2x might be better.

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OP J.K.T. Regular Member • Posts: 322
Re: EF extender stacking

John Crowe wrote:

This all getting a bit confusing and I have asked you another question above too. You were talking about stacking 2x adapters but here you seem to be stacking two 1.4x extenders using the RF - EF between them, for an FD 500/4.5 L. Providing you a 1000mm f9 lens.

So, if you can put the EF 1.4x II onto the adapter onto the RF 1.4x then you can put any Canon EF 1.4x or 2x onto the adapter and RF 1.4x II as well.

That was my conclusion as well after the stacking order confusion was cleared.

I find it hard to believe that the Canon FD 1.4x-A converted to EF is that bad, but lets explore other possibilities.

It is. Either it always was or something went wrong with the conversion to EF, which took place was before I got it. After I tried to stack another 1.4x behind the FD 1.4x, it became clear that this was NOT the way to go.

On absolute scale it is not that bad when used alone, but comparing with EF 1.4x II it is. The RF 1.4 is even better, though by a MUCH smaller margin. With these two the sharpness difference is visible near the corners. A high resolution body might show more. There is also more barrel distortion (about 4x more) and magnification difference as well (1.37 vs. 1.41), but that has no practical meaning. I'd love to try EF 1.4x III just to see whether it is closer to EF II or RF. I suspect the latter.

I use a Canon FD 800mm f5.6 L on Canon EF several ways. The first is an ultrathin adapter, they are rare, but they get you focus to about 400 feet.

How thin is that? I have 8mm thick. I won't go into build quality more than this: the pin that was supposed to activate iris lever didn't reach quite that far in.

Second is a Kenko FD -EOS 2x converter/adapter. They too are rare, but I managed to get mine for $30. I don't think the seller realized what it was. It is not as good as the Canon EF 2x but it is still extremely useful.

I'm somewhat picky about the extenders as I have plenty of old ones, which are not very good. With 2x I likely would accept EF III and RF.

Third is the Canon FD-EF 1.26x Converter. Again, extremely rare, but less sought after since mirrorless came along. Some are still trying to get over $1000 for it, but I got mine for $300. I think I saw one recently for $400. Extremely sharp and makes your lens about 625mm f6.3. The 1.26x has no space at rear since it has glass and it has protruding front element that is fairly long.

That is definitely an option ... hoping it is better than the 1.4x. I may have seen the same eBay offer, but missed it. That would likely work with RF extenders, because EF 1.4x does too.

I have to go back to my tests but it seems to me that the Kenko 1.4x is almost as good as the EF 1.4x in image quality. I did decide that it was a very useful option as I described above.

I was not too happy with mine. There are probably 10 versions of it, so some could be better ... or sample variation could be an issue as well.

The easiest way for you to get to 1000mm, if that is your plan, is the Kenko FD-EF 2x mounted to the lens and then mounted to EF-RF then mounted to camera. It should beat stacking 1.4x extenders. I can actually test this if you like, at least with Kenko 1.4x and Canon EF 1.4x.

P.S. What about simply getting the FD 2x-A and mounting it to the lens and onto an FD - RF adapter?

The reputation of the older Canon 2x extenders is not as good as the 1.4x, so I'll pass that. For fun I tested the FD 2x-B with pretty much expected results. I know - it is not meant for the long teles.

The really easy solution is RF 2x with modified RF to FD adapter and a bit of dremeling on the FDn. That WOULD work and would give the best quality. The required modification on the adapter is removal of the pin and on the FDn cutting the iris lever very close to the back plate and putting rubber pushing behind it in order to activate it. I'm just loath to damage the otherwise "pristine" FDn.

The RF 2x I'll likely get anyway as I have some microscope objectives with way more resolution than my camera has.

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John Sheehy Forum Pro • Posts: 25,032
Re: EF extender stacking

J.K.T. wrote:

As far as I know it is possible to stack version II 2x and 1.4x extenders, but not version III ones. Can anyone tell what has changed? Is it the rear of 1.4x, the front of 2x or both? Is it possible to stack 1.4x III in front of 2x II? Those are roundabout ways of asking the real question: Is it possible to stack EF 1.4x III in front of RF extenders with a modified adapter?

As others have already mentioned, the EF 2xII will fit between an EF body mount and any other Canon EF TC.  Keep in mind, however, that as you stack converters, electrical compatibility issues may appear, with some of the newer Canon bodies (mainly mirror-less bodies and with Live View on later DSLRs), causing IS to fail, manual focus only, or communication errors.  Some have reported success, however, with the 2xII + 2xIII with at least some lenses.  When you include 3rd-party TCs, things are more hit-and-miss, which is a shame, because something like the Kenko Pro 300 DG (an older model) is very good, optically, but fails behind my Canon EF 2xIII, and only works reliably when it is the only TC.

OP J.K.T. Regular Member • Posts: 322
Re: EF extender stacking

Improving the odds is indeed another good reason to stay with Canon ... though with FDn the electrical compatibility is less of an issue. 

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John Sheehy Forum Pro • Posts: 25,032
Re: EF extender stacking

J.K.T. wrote:

Improving the odds is indeed another good reason to stay with Canon ... though with FDn the electrical compatibility is less of an issue.

Kenko had something better in some ways, electrically, than Canon for a while. They introduced the DGX series of TC several years back, and it worked well with existing DSLRs like the 7D and 6D that I had at the time, not only being electrically compatible, but if placed between a reporting TC and the body, it gave correct EXIF for both TCs combined! It also allowed for use of all AF points with f/8 total optics, on cameras with f/5.6 AF limits. Sadly, when I got my 7D2, it crashed the camera, and did not work either with the 90D or the R5. That TC was magic back in the day, and still is with most or all the older f/5.6-AF-only DSLR bodies.

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