Teleconverters with IS \ VR

[alfa147x]

I was wondering having a TC with IS \ VR would nice because you would be able to have IS on any of your lens's what is holding manufacturers back from doing this?

 

[soydios]

A telecoverter's VR/IS unit would have to be reprogrammed for each lens it was used with. Different focal lengths and all that.

 

[troytime]

i don't know much about IS/VR...but i would imagine that having it between the lens and the sensor is significantly more complicated than having it on the lens OR the sensor

i've been wrong a lot though

 

[corkyg]

This is a pretty good tutorial on IS and VR. Teleconverters are usually very small and not all of them are even capable of AF communication between lens and camera.

IS/VR

 

[alfa147x]

I understand how it works but i was thinking of putting the IS element that moves into the TC
http://www.the-digital-picture...-Converter-Review.aspx

May be make it a bit bigger or all together remove the TC part and make it a IS add on...
Is just something i was pondering about

 

[alfa147x]

oh also is it possible to 'stack' TCs?

 

[corkyg]

Originally posted by: alfa147x
oh also is it possible to 'stack' TCs?

Interesting question.

STack

I only have one TC, the Canon 1.4X. But on examination, it cannon be stacked. The front end of the TC projects into the Canon EF 70-200mm lens. There is no such recessed space in the rear of the TC to allow connection of another TC. Also, it will not work with any of my Canon black lenses.

Generic 3rd party extenders might work OK, but then you may lose the AF functions.

Each TC degrades the image slightly, and that gets worse with additional TCs.

But, as the man says, you can tolerate a lot of degredation to save $7000.

 

[alfa147x]

oh i wasnt aware that canons tc are only compatible with L series lens's
not that i need a TC though...

 

[alfa147x]

is it possible to put a extension tube in between

 

[jamesbond007]

Originally posted by: alfa147x
oh also is it possible to 'stack' TCs?

Yes you can. At least I know it's possible with the Canon system, not sure about others.

 

[fuzzybabybunny]

Originally posted by: corkyg

Originally posted by: alfa147x
oh also is it possible to 'stack' TCs?

Interesting question.

STack

I only have one TC, the Canon 1.4X. But on examination, it cannon be stacked. The front end of the TC projects into the Canon EF 70-200mm lens. There is no such recessed space in the rear of the TC to allow connection of another TC. Also, it will not work with any of my Canon black lenses.

Generic 3rd party extenders might work OK, but then you may lose the AF functions.

Each TC degrades the image slightly, and that gets worse with additional TCs.

But, as the man says, you can tolerate a lot of degredation to save $7000.

Yes, you can definitely stack TCs. However, not all TCs stack well. As corkyg said, the Canon TC has a front element that projects outward. Sigma and Canon are the only ones that make TCs with protruding front elements. This IMO immediately disqualifies them from serious consideration if you're thinking about buying them, as they won't work for many lenses, such as the Tamron 17-50mm, Sigma 30mm, Canon 50mm, because the TC's front element will actually smash or grind up against the rear element of the lens you're trying to put it on.

Sigma TC Front Element Protrusion

Tamron and Kenko TCs are just as sharp as Canon and Sigma TCs, and since they do NOT have protruding rear elements, they can be used on any lenses.

Tamron/Kenko Front Element not Protruding

A Canon or Sigma TC cannot stack with another TC if it is being coupled at the front element end. However, they CAN be stacked onto Tamron or Kenko TCs from the rear element end.

The most I've stacked personally is three TCs (1.4x * 1.4x * 2x = 4x).

Stack

Note how the Sigma TC (APO TELE CONVERTER 1.4x EX) was stacked in front of the other two TCs. There was no other position to stack the TC in without having the front element hitting other TC's rear elements.

The picture quality was horrible, and there's no point in doing this unless you have an absolutely exceptional lens to start out with. Stacking two 1.4x TCs for a total magnification of 2x is ok, and in my tests stacking two 1.4x TCs actually produced BETTER image quality than a single 2x TC.

Losing the ability to autofocus has everything to do with the smallest aperture that your camera can autofocus at. The Canon Rebels and 30D/20D can autofocus down to f/5.6, and *sometimes* f/6.3. The 1D/1Ds series of cameras, on the other hand, can autofocus down to f/8.

So if you start with an f/4 lens and put a 1.4x TC on it, you've made it into a f/5.6 lens. Autofocus still works. If you then stack another 1.4x TC onto it, you've made it into an f/8 lens. Now autofocus won't work on any camera except the 1D/1Ds series. In addition, the viewfinder image gets darker as you put on TCs, and at f/8, can become very difficult to gauge if an object is truly in focus when you're manually focusing.

 

[fuzzybabybunny]

Originally posted by: alfa147x
I was wondering having a TC with IS \ VR would nice because you would be able to have IS on any of your lens's what is holding manufacturers back from doing this?

Not truly sure, but I imagine it's because of the lack of space for the mechanics of an IS motor in the size of a TC. A TC is *pretty* small.

Nikon, however, does make a TC that can actually turn manual focus lenses into autofocus lenses. The TC itself autofocuses, and while it can't focus down the entire focusing range (say, from 4ft to infinity), it's still better than nothing.

 

[Heidfirst]

Originally posted by: alfa147x
I was wondering having a TC with IS \ VR would nice because you would be able to have IS on any of your lens's what is holding manufacturers back from doing this?

Mmm, if you have a KM/Sony DSLR or a Panasonic, Pentax, Olympus, Samsung DSLR with in-body IS you already get IS with any lens fitted to the body incl. with TCs ...

 

[soydios]

optically speaking, it's possible to stack TCs, though optical quality and aperture fall quickly.
for Nikon, I know that it is not possible to stack TCs. they will not mount to each other, as the elements get in the way.

 

[corkyg]

I just put together this quick illustration showing the Canon 1.4X Telextender lens with the 1/4 in protrusion on the lens side, that is also 1.25 in in diameter. The receiving lens would have to be recessed that amount. As far as I know, only the "white" lenses are so recessed.

TC

As Fuzzy pointed out, there is very little space in which IS could be installed. And, if the lens has the IS, then there's really no point to have two. Furthermore, would we want to be required to use a TC in order to have IS? I don't think so.

 

[alfa147x]

How about an add on IS ? it sits like TC but its just IS

 

[TTM77]

Originally posted by: fuzzybabybunny

Originally posted by: alfa147x
I was wondering having a TC with IS \ VR would nice because you would be able to have IS on any of your lens's what is holding manufacturers back from doing this?

Not truly sure, but I imagine it's because of the lack of space for the mechanics of an IS motor in the size of a TC. A TC is *pretty* small.

Nikon, however, does make a TC that can actually turn manual focus lenses into autofocus lenses. The TC itself autofocuses, and while it can't focus down the entire focusing range (say, from 4ft to infinity), it's still better than nothing.

see u have both Sigma and Tamron.. which do U like more?

I'm in need of a lens for my vacation. Right now I have only the kit lens 18-55mm and the 50mm/f1.4. I tried out the Canon 17-85mm f/4-5.6 IS... like it but wow too expensive. Any recommendation? thanks.

 

[corkyg]

I used the Tamron Di XR 28-300mm for over a year with my 20D, and it was a super walk around lens.

XR

 

[fuzzybabybunny]

Originally posted by: TTM77

Originally posted by: fuzzybabybunny

Originally posted by: alfa147x
I was wondering having a TC with IS \ VR would nice because you would be able to have IS on any of your lens's what is holding manufacturers back from doing this?

Not truly sure, but I imagine it's because of the lack of space for the mechanics of an IS motor in the size of a TC. A TC is *pretty* small.

Nikon, however, does make a TC that can actually turn manual focus lenses into autofocus lenses. The TC itself autofocuses, and while it can't focus down the entire focusing range (say, from 4ft to infinity), it's still better than nothing.

see u have both Sigma and Tamron.. which do U like more?

I'm in need of a lens for my vacation. Right now I have only the kit lens 18-55mm and the 50mm/f1.4. I tried out the Canon 17-85mm f/4-5.6 IS... like it but wow too expensive. Any recommendation? thanks.

I like the Tamron/Kenko TCs BY FAR. Like I pointed out earlier, the Sigma's front element protrudes out just like the Canon, which makes it incompatible with a lot of lenses.

For a walkaround lens... sell the 18-55mm and get the Tamron 17-50mm f/2.8?

Or keep the 18-55mm and get a Canon 70-300mm?

 

[fuzzybabybunny]

Originally posted by: alfa147x
How about an add on IS ? it sits like TC but its just IS

It would be tough. There would need to be glass elements in this add-on IS unit, which will result in a drop in light gathering ability as well as optical quality. It would also be a fat little unit, needing to fit things like gyroscopic motors within it.