Stacked teleconverters?

I have seen some remarkably crisp images in the last few weeks on other forums taken with stacked teleconverters, primarily with the Canon 300/f2.8, but before I go out and buy another one, I have some questions.

The results I saw were taken with 2 1.4x converters, one a Canon and the other a Kenko or Tamron

It's said that the addition of a 1.4x reduces AF acquisition by roughly 30%; a 2x by 60-70%. Is this accurate?

If you extrapolate that out, would the use of 2 1.4x converters also reduce AF by 60%?

Does the camera "see" the second converter or does it only see one?

Does anyone have good experience stacking TCs with a 500/f4? And, by stacking them, does that eliminate the use of AF with an xxD series camera?

Lastly, has anyone had good to excellent results using this technique for BIF.... besides Artie...;)?

I look forward to hearing your responses.

I think you will be very hard pressed to get decent BIF pics with stacked TC's unless its a very slow bird, especially on a xxD body, on a 1D or maybe 7D you might have better luck.

From the tests I did with the 1.4 Canon and the 1.4 Tamron stacked the AF was no faster than using the canon 2x, and the IQ was slightly worse, that was with the 500 and 1d MKII. If I recall I put the Tamron on the body, and then the canon tc between the tamron / lens... and if I recall it only saw one of them.... it was months ago so I dont recall for sure. But because of the weather sealing on the canon you cant put the tamron after the canon so that part I am sure of.

I saw somewhere before that said its better to use 2 x 1.4's instead of a 2x, thats not possible with the canon ones because of the weathersealing which is probably why they did the tamron / canon route.

I have 2 x 1.4 Tamrons, 1 x 2x Tamron, 1 x 1.4 Canon and 1 x 2 Canon, since I got the canons I dont use the tamrons anymore maybe its just me but it seems to autofocus better with the canons, and the IQ of the canon 1.4 is slightly better, the 2x canon is noticeably better. Of course someone else may run the same tests and fine the tamrons to be better, I only had one to try it on :)

Something I noticed last weekend which I found odd was with the 500L IS + 7D, 1.4 & 2x canon TC's stacked I was able to autofocus using liveview ! it was darn slow but seemed to pretty accurate when it worked... but it did not work all the time. If I tried it without liveview it did nothing at all. I saw some buffleheads on the other side of the pond so I was using the 7D liveview screen as a TV to watch them lol

you will not be able to use AF on a xxD if you stack TC's (with the F4 I mean) .... unless you use the tape trick which I did with 2 x 1.4 tamrons and one with the tape trick... it was not great for sure but it did work with the 40D

Lastly using the 500 with a single 1.4 for BIF you should be able to get good results, even with a 1D body and a 2x you should be ok depending on the birds speed, I was able to get some herons without issue. Same for the 300 2.8 I would imagine it would work but I have never used it.

if you have a friend or someone around you could always try it out

Many people use a 2x TC on the 300/2.8 and it works on the 500/4 if you have a 1D camera body. On the 500 there is some loss of quality, I prefer using a 1.4x TC on it.

The camera body only recognizes the one TC, hence the slow down will only be about 30%. But the slow down is there for a reason. Slowing down the AF makes it more accurate.

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unless you use the tape trick

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I'm sorry but I have to ask... tape trick?

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Originally Posted by Bob Decker

I'm sorry but I have to ask... tape trick?

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if you put a small piece of tape in front of 3 of the pins on the tc it will not report it to the camera, only works on some of them from what I know

it seemed to work decently on the 400 5.6 on a crop body with the tamron TC

I just picked one of the first links from google http://atinyblip.com/photography-stu...teleconverter/

Thank you all for your thoughts and suggestions!

Prior to the 500/4 I currently have, my "long lens" was a 300/2.8 + 1.4x and +2x, and other than the AF acquisition loss with the 2x, my images were sharp and crisp. Images that I've made with the 1.4 on the 500 have been excellent, albeit a little slower focusing.

Based on the comments so far, it seems pointless for me to try this unless on perched birds. I'll see if I can't borrow a TC from a friend...

Hi Chris I rely on converters a lot for my 500 Canon both the 1.4X and 2.0 They will slow the AF but will get sharp results.

Stacking will also produce surprising results but is not something you want to do all the time, I stack the 1.4X and 2.0X both Canon converters, with Pro body camera the AF works but very sluggish !! Post examples from time to time.

I use a 1.4X TC regularly on a Canon 500 f/4 with a 50D with excellent results. One loses the autofocus with the 2X TC and I didn't have any luck with taped pins; the autofocus just kept seeking even if there was a sharp edge to focus upon.

Initially I found it difficult to manually focus with the 2X TC, but have learned to do it with practice. It is essential that you have the view finder adjusted exactly right for your eyes if you want manual focus to work successfully. Stacking in the order lens:2X:1.4X:camera works well, but the mm doesn't register properly in EXIF. At this point you really need to have closed down the aperture to f/10, f/11 or perhaps a little more to get better focus & depth of field. This means that you will probably be working at a pretty slow shutter speed even in reasonably good light and ISO 800. Thus, I think you are out of luck for birds in flight since you are also stuck with manual focus in addition to slow shutter speed.

The stacked TC approach works reasonably well if you can fill the frame with the subject and have the time to carefully adjust the focus manually.

One other trick for focusing with stacked converters or slower lenses with TC, is to use LiveView, if your camera has it. The AF is slow, but very accurate. It works good on stationary objects like nests and perches.

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Originally Posted by Jeff Donald

The camera body only recognizes the one TC, hence the slow down will only be about 30%. But the slow down is there for a reason. Slowing down the AF makes it more accurate.

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Jeff,

As per Canon the AF acquisition with 2x will slow 60-70%. In theory the slowing down will make it more accurate, reality proves otherwise. FYI- Nikon AF does not slow as much as Canon when using converters.

To all,

STACKING CONVERTERS SHOULD BE A LAST RESORT! It is better to keep up the shutter speed with wider f/stop and introduce less glass and subsequent problems. Moreover, there is a significant loss in resolution when stacking. You can always enlarge/crop a sharp image, a blurry one that is closer goes in the trash. I highly recommend stopping down at least 1 f/stop from wide open when using any converter and 2 f/stops if possible when stacking. I guarantee the images will appear sharper out of the camera when doing so. And, I urge you try this for yourself. Oh, and the light loss when stacking is greater than 3 f/stops ;)

I have stacked on occasion with good results when stopping down 2 f/stops as explained above...but this requires slower shutter speeds, a stationary subject, and/or increase in ISO, and superb stability technique. The odds if you will are "stacked against you"

Best,

Chas

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Originally Posted by Charles Glatzer

Jeff,

As per Canon the AF acquisition with 2x will slow 60-70%. In theory the slowing down will make it more accurate, reality proves otherwise. FYI- Nikon AF does not slow as much as Canon when using converters.

To all,

STACKING CONVERTERS SHOULD BE A LAST RESORT! It is better to keep up the shutter speed with wider f/stop and introduce less glass and subsequent problems. Moreover, there is a significant loss in resolution when stacking. You can always enlarge/crop a sharp image, a blurry one that is closer goes in the trash. I highly recommend stopping down at least 1 f/stop from wide open when using any converter and 2 f/stops if possible when stacking. I guarantee the images will appear sharper out of the camera when doing so. And, I urge you try this for yourself. Oh, and the light loss when stacking is greater than 3 f/stops ;)

I have stacked on occasion with good results when stopping down 2 f/stops as explained above...but this requires slower shutter speeds, a stationary subject, and/or increase in ISO, and superb stability technique. The odds if you will are "stacked against you"

Best,

Chas

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I agree with Chas' comments above with one exception. I have been able to get really sharp images with individual and stacked converters when shooting wide open when the light has been really good. I have been able to get very sharp images with the 500mm + 1.4xTC in just about any light shooting wide open. I have also been able to get sharp images with the 2x when shooting wide open in just about any non low light situation. I've posted some stacked converter BIF shots here, but it really is a last resort, IMO.

Happy New Year All,

Why do you stipulate wide open for sharp images? In my experience stopping down 1 or 2 stops improves performance dramatically when stacking convertors.

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Originally Posted by Jeff Donald

Happy New Year All,

Why do you stipulate wide open for sharp images? In my experience stopping down 1 or 2 stops improves performance dramatically when stacking convertors.

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I shoot a lot of action hand held. I often need to open up all the way to get enough shutter speed and avoid the noise of very high ISO settings. When you add TCs you lose light increasing the need to open up the lens. With stacked TCs on a F4 lens you end up at F11 when you are wide open.