Possible to Stack Teleconverters?

[Photoman101]

I have scanned though the TC page, but did not come across any information regarding stacking multiple TCs.

I currently have one 1.4TC, with access to a second. At first glance it does not appear possible to stack these due to an interference fit. Is there a way to stack these using a connection device, or am I just missing something here?

Any insight is greatly appreciated!

[nosquare2003]

Are these TC from Canon or other brands? If they are Canon, are they Mk1 or Mk2? The newer Canon TC can stack together. The older ones need "extension tube".

[defordphoto]

Photo quality will turn to mush.

[robertwgross]

It is certainly possible, depending on which teleconverters we are talking about. It gets a little fuzzy out there, again depending on which lenses you use.

---Bob Gross---

[kb244]

Well sharpness loss is possible, what I'm more concerned about is the loss of light, if you stuck two 2X convertors together, I think thats 4 if not 6 stop of light, pushing it way past the camera's ability to autofocus, and making it very difficult to shoot things not well lit.

[MDJAK]

I know I'm holding myself out to be flamed here, but I'm having a real big problem with my 1.4 canon teleconverter. I misplaced it in my house and can't find it. It's driving me crazy. I mulled buying it for a while and finally plunked down the cashola in B&H during one of my many visits. I used it once at my daughter's soccer game and the weather was so foggy that the results stunk. Now I want to try it again and it's playing hide and seek. I give up. Come out, come out, wherever you are.

[robertwgross]

Karl, I was thinking in terms of the 1.4x teleconverters. One stop each.

I've stacked two 1.4x teleconverters, and it begins to get a little fuzzy on the long end of a 100-400mm L lens. I would think a 2x teleconverter would do about the same. If you think about it, two 1.4x teleconverters is a little more versatile than a single 2x.

I've heard some users here say they used two 2x teleconverters, but that is two stops each, or four stops. Four stops from the long end of the 100-400 is <sheesh> 22? I don't think I want to go there.

---Bob Gross---

[robertwgross]

I know I'm holding myself out to be flamed here, but I'm having a real big problem with my 1.4 canon teleconverter. I misplaced it in my house and can't find it. It's driving me crazy. I mulled buying it for a while and finally plunked down the cashola in B&H during one of my many visits. I used it once at my daughter's soccer game and the weather was so foggy that the results stunk. Now I want to try it again and it's playing hide and seek. I give up. Come out, come out, wherever you are.

I know exactly where you will find it.

It always turns up in the last place that you look for it.

---Bob Gross---

[kb244]

Hrm so basically its get two 1.4x to make 2.8x but risking making it a lil soft due to stacking, at 2 stops of light loss, or a single 2x at 2 stops of light but being sharper. Or 4 Stops of light with two 2X hehe. In my honest opinion those teleconvertors are best meant for the f/2.8 L glass. But i guess two 1.4x wont be too bad provided you dont mind the loss in sharpness.

[kb244]

I know exactly where you will find it.

It always turns up in the last place that you look for it.

---Bob Gross---

Maybe he can get a L-Glass sniffing dog, i mean should work right, I mean people do get addicted to the L stuff dont they?

[robertwgross]

I'll repeat what George Lepp wrote in an article a year ago. He said that with a very sharp lens to begin with, the 1.4x TC gave him a degradation of 10% and the 2x TC gave him a degradation of 20%. However, I admit that I don't know what 10% or 20% mean, exactly.

---Bob Gross---

[kb244]

Probally something like if you had the lens perfectly focused on grains of sand, that without teleconvertor a shot would seem 10%-20% sharper than with it. Like not being able to see as many grains of sand, or in average not as sharp. Though the TC made by canon was made for the best of lens, degragation is probally not nearly as high as say the cheaper ones not made by canon. I guess you could still do it, but I'd still be concerned about available lighting as telephoto range.

[soccerbyron]

Hrm so basically its get two 1.4x to make 2.8x

If you put one 1.4x on a 200mm lens, it becomes a 280mm. If you add a second 1.4x, the lens becomes a 392mm, with two stops of light lost. A 1.4x combined with a 2x would give you the 2.8x, as well as a three stop loss of light.

[robertwgross]

Hrm so basically its get two 1.4x to make 2.8x but risking making it a lil soft due to stacking, at 2 stops of light loss, or a single 2x at 2 stops of light but being sharper. Or 4 Stops of light with two 2X hehe. In my honest opinion those teleconvertors are best meant for the f/2.8 L glass. But i guess two 1.4x wont be too bad provided you dont mind the loss in sharpness.

Check your optical math.

1.4x plus 1.4x = 2x for the effective focal length
1 stop plus 1 stop = 2 stops for light loss

---Bob Gross---

[kb244]

1.4 x 200mm = 280 x 1.4 = 392 , 392 / 200 = 1.96 , hrm well i'll be damned.

[Cadwell]

Yup. Two 1.4x TCs would multiply the lens focal length by 1.4 twice.... so that's an effective multiplier of 1.96x... lets be friendly and call it 2x ;) With two stops lost. Pretty much what a 2x TC does.

Bob, I'm curious why you'd do it that way... do you find the optical quality better with a pair of 1.4xs than a single 2x?

[kb244]

That or he just wants to have the ability to just do 1.4x total sometimes, then step up to 2.0x when needed.

[tommykjensen]

Photo quality will turn to mush.

I have seen awesome photos on DP shot with a Sigma lens with 2 Tamron extenders. If the quality was good enough for print I don't know but for web they were excellent.

[Cadwell]

That or he just wants to have the ability to just do 1.4x total sometimes, then step up to 2.0x when needed.


Mmm... I thought of that, but given that the 1.4x and the 2x are the same price I can't see why you wouldn't buy one of each in those circumstances... unless you had some other reason. Hence the question.

[KennyG]

I have posted this information before. You can not stack two Canon 1.4 TC's due to the lack of recess in the TC. You can stack a 1.4 and a 2.0 or two 2.0 TC's. The camera will electronically only 'see' one TC. So, for example, with 2 x 2.0 on a 2.8 lens the camera will think it has a 5.6 attached. However, the light loss will be the correct number of stops and you will need to compensate.

The Canon 2.0 MK-II is a long way ahead of any other 2.0 TC for quality and degrades the image much less than Tamron, Sigma, etc. Just be clear when making judgements about TC's that you compare apples with apples. I actually gave away my Tamron TC's as they were not acceptable to me.

[Cadwell]

The Canon 2.0 MK-II is a long way ahead of any other 2.0 TC for quality and degrades the image much less than Tamron, Sigma, etc. Just be clear when making judgements about TC's that you compare apples with apples.

Let me qualify that a bit... I suspect the lens being used has an influence. On my Sigma 120-300mm f/2.8 the Sigma EX 2x TC is better than the Canon 2.0 MK-II. I have both and there is no doubt about it. I wouldn't be at all surprised if the Canon one is better on Canon brand lenses though.

[Anders Östberg]

The quality you get with converters is highly dependent on what lens you put it on, the converter magnifies lens imperfections... the consensus seems to be (I'm generalizing here) that most lenses work well with a 1.4x, it doesn't degrade image quality very much. A 2x is mostly useful with really good lenses (read: good primes), and stacking both teleconverters really only produce useful results with Canon's superteles.

Your Mileage Will Vary - it depends on what is "acceptable" quality to you, but I'd recommend only the 1.4x for most applications.

Stacking two 1.4x (Tamron and other that can do this) should be worse than using one comparable 2x, as you have many more glass elements combined.

[robertwgross]

Bob, I'm curious why you'd do it that way... do you find the optical quality better with a pair of 1.4xs than a single 2x?

Karl guessed it right. I had a single Tamron 1.4x that I was not overjoyed with. Then I got a Canon 1.4x to use on an L lens. Just for an experiment, I stacked them, and the combination works. Of course, if this were a perfect world, I would just get a 600mm or 1200mm lens and be done with it. <sigh> But this sure isn't a perfect world.

What would be neat is if they could make a teleconverter that is switchable. Imagine a big lever on the side, and you switch it to 2x, or 1.4x, or Zero. I think that would be extremely difficult to make.

---Bob Gross---

[Cadwell]

What would be neat is if they could make a teleconverter that is switchable. Imagine a big lever on the side, and you switch it to 2x, or 1.4x, or Zero. I think that would be extremely difficult to make.

---Bob Gross---

mmm... why not an infinitely variable one? A TC which is in fact a small zoom lens going from 1x to 2x. Now there’s an engineering challenge for someone.

[robertwgross]

mmm... why not an infinitely variable one? A TC which is in fact a small zoom lens going from 1x to 2x. Now there?s an engineering challenge for someone.

Oh, that wouldn't be hard. Except that it would be bigger and heavier than the L lens hooked onto it, and it would probably cost more as well.

---Bob Gross---

[CyberDyneSystems]

We are re-inventing the zoom lens ;)

[MDJAK]

I found it. It was staring right at me on a shelf in my closet. I thought I had it in its original box, but it was in the soft, dark gray case it comes in and I looked right through it, like xray vision, I guess.

[KennyG]

I wouldn't be at all surprised if the Canon one is better on Canon brand lenses though.

You are probably right. I have a virtually new Sigma 1.4 sitting on the shelf that I'll give away to the first deserving case as I only use TC's with Canon these days and need the MK-II weather sealing.

[Anders Östberg]

You are probably right. I have a virtually new Sigma 1.4 sitting on the shelf that I'll give away to the first deserving case as I only use TC's with Canon these days and need the MK-II weather sealing.
A little OT tip... the Sigma 1.4x APO teleconverter fits Canon's 100/2.8 Macro USM (Canon's tc doesn't), making it a 140/4 macro lens with longer working distance. It's more or less permanent on mine now.

[Cadwell]

Oh, that wouldn't be hard. Except that it would be bigger and heavier than the L lens hooked onto it, and it would probably cost more as well.

---Bob Gross---

I guess what I'd REALLY like is a 0.7x convertor which I can fit to my 120-300mm f/2.8 to give me a 60-150mm f/2 for all those tricky, low light, indoor shoots ;)

[Anders Östberg]

I guess what I'd REALLY like is a 0.7x convertor which I can fit to my 120-300mm f/2.8 to give me a 60-150mm f/2 for all those tricky, low light, indoor shoots ;)
I think you'd become quite wealthy if your converter makes an f/2 out of an f/2.8 lens... :)

[robertwgross]

Don't listen to what Cadwell types. Listen to what he means. <g>

---Bob Gross---

[Tom W]

Here's a moon shot, using a 300 mm f/4 lens, a Canon 2X, and a Canon 1.4X teleconverter. The stacking order is important - you must put the 1.4X between the 2X and the Camera or it won't fit - there is no space behind the last lens element in the 1.4X.

Anyway, here's the shot:

Stacked moon shot (http://www.pbase.com/photosbytom/image/39431143/original)

Take note that the camera only sees the 2X converter in this case - the 1.4X is invisible. So, the EXIF data will show 600 mm, when in fact, you have 840 mm. Also, the camera will not report the correct f/stop. The reported image was stopped down 2 stops to f/16 reported, but in reality, it was f/22. The good news with that combination is that the reported max aperture is f/8 which allows autofocus (on the 1-series) for those of us that have poopy vision.

There's a serious vibration issue when you hang a heavy 1-series camera at the end of two teleconverters on a lens that is mounted on a tripod. The balance is way off, so its "back-heavy". You should use mirror lockup, and you should allow a couple of seconds of time lag after releasing the mirror to let the vibrations dampen out before you release the shutter.

Frankly, the image is a bit soft, but I think this is partly due to the added glass, and partly due to vibration. Also, at 1/25 second, the earth's rotation will give you some movement. I plan on working with this setup some more - I have a new brace on its way from B&H which will hopefully get rid of the vibration issue. For those interested, here is the link (http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=5545&is=REG) .

[robertwgross]

Take note that the camera only sees the 2X converter in this case - the 1.4X is invisible.

Is that the new/current Canon 1.4x TC? Or some old one?

I have one that is visible to the camera.

---Bob Gross---

[Tom W]

Mark II - the newest one. The converter reports properly to the camera when used alone, but for some reason (probably only known to Canon), it does not report when stacked behind a 2X. Perhaps the camera's logic doesn't understand two converters.

[ssim]

Read this thread and interestingly enough I tried this today. The following shot was taken with the 500 f4 and I stacked the 2.0 and the 1.4 for this shot. While there is some loss of quality it is not as much as I had expected.

http://www.pbase.com/ssim/image/39433334.jpg

The Exif:

Shutter speed: 1/500 sec
Aperture: 11
Exposure mode: Av
Exposure compensation: +1/3
Flash: Off
Metering mode: Spot
Drive mode: Continuous (high): frame 1
ISO: 250
Lens: 500mm

[Tom W]

That's not bad at all, Sheldon. In fact, it's pretty good. There may be a hint of fringing, but its better than one might be led to believe, particularly at f/11 (or was it really f/16, reported as f/11?).

Did you use a tripod?

[ssim]

I don't think you could do this without a tripod unless you bumped up your ISO way up to get the right shutter speed.

I'm not sure how the exif is handled when you do this. I had them in order of Camera-1.4-2.0-lens. The exif reported the focal length at 1000mm. It obviously doesn't read the 1.4 into the calculations that get stored into the exif.

I was trying it more for fun than anything else. These birds make a good subject as they pretty stay in one spot for an extended period of time.

[Tom W]

I don't think you could do this without a tripod unless you bumped up your ISO way up to get the right shutter speed.

I agree - I was wondering if you had experienced any vibration problems though. I suspect that with the 500/4, you already have a very substantial tripod rig. Wimberly?

I'm not sure how the exif is handled when you do this. I had them in order of Camera-1.4-2.0-lens. The exif reported the focal length at 1000mm. It obviously doesn't read the 1.4 into the calculations that get stored into the exif.

I had read elsewhere (an astrophotography site that I don't remember) that stacking like this causes the camera to ignore the existance of the 1.4X. Your use and mine seem to confirm this. BTW, you can't physically stack the 2X between the camera and the 1.4X - the 1.4x has a rear element that is almost flush with the mount.

I was trying it more for fun than anything else. These birds make a good subject as they pretty stay in one spot for an extended period of time.

Fun sums up my primary purpose for photography. Nothing wrong with a little experimentation. :)

[tommykjensen]

Yesterday I also for fun tried stacking my 1,4x + 2x extenders with my 70-200 f4. But it was indoors with poor lighting so I had to bump iso to 3200 but I don't think it was quite enough, see here: http://photography-on-the.net/forum/showthread.php?t=56864