Teleconverters

[My2Girls66]

What can you tell me about teleconverters? If possible, I'd like to get closer to my backyard birds without spending a lot. I have a Nikon D50- a
70-300mm Nikkor and a 70-210mm Nikkor and still can't seem to get close enough shots. Would a 1.5x Kenko work for me with those lenses? I know I'd be losing a stop. If using it on sunny days, would it be ok?
This is one of the ones offered for not much $$. They have a 2x for a little more $$ but would losing 2 stops be too much with my lenses?
Thanks for any info.

http://www.bhphotovideo.com/c/product/389042-REG/Kenko_K15AFDGN_1_5x_DG_AF_Tele_Converter.html

 

[mabas9395]

I'm in the market myself for a Canon one. The thing I keep hearing is that you not only lose two stops with the 2x, but the image quality suffers quite a bit compared to the 1.4 or 1.5 versions.

You also have to do your homework because they are only compatible with certain lenses. So even if you get a Nikon compatible converter, it may not work with all your Nikon mount lenses.

 

[Furgus]

What can you tell me about teleconverters? If possible, I'd like to get closer to my backyard birds without spending a lot. I have a Nikon D50- a
70-300mm Nikkor and a 70-210mm Nikkor and still can't seem to get close enough shots. Would a 1.5x Kenko work for me with those lenses? I know I'd be losing a stop. If using it on sunny days, would it be ok?
This is one of the ones offered for not much $$. They have a 2x for a little more $$ but would losing 2 stops be too much with my lenses?
Thanks for any info.

http://www.bhphotovideo.com/c/product/389042-REG/Kenko_K15AFDGN_1_5x_DG_AF_Tele_Converter.html

Does this help?

Nikonions Teleconverter Compatibility Chart

 

[jann1033]

i just bought a kenko 1.4 pro for my canon and it seems really nice, nice build, matches my cream lens...only problem i have is since it makes my 200 lens almost 300 my shakes show up big time, but that is me not the lens...you can find used 2x all over the place. kenko actually recommended you use the 1.4 teleconverter on 100mm and over lenses and have to be f4 or under. sigma's was f2.8 ( or maybe it was tamron, can't remember the other 3rd party i looked at) and most places i read didn't really recommend the 2 or 3

not the greatest photo that i ever took but it was from at least 50-75 ft away of some of those trains that are big enough for people to ride on( not in)
i got the kenko as it is compatible with any 100mm f4 lens( or less f), canon is only compatible with a few. not sure how the nikon would work but you can always email kenko and ask them( i did)

 

[MarkBarbieri]

Here is a good post showing info about Canon's TC and lens compatibility.

Just in case you were wondering why you lose one stop with the 1.4x and two with the 2x, here is a quick explanation. The stop is lost because the f-stop increases. The f-stop is the ratio between the size of the entrance of your lens compared to it's focal length. When you put on the extender, you increase the focal length without changing the size of the entrance of your lens. The net effect is that the f-stop number increases.

For example, a 200mm f/2.8 lens has a focal length of 200mm. The size of the entrance pupil is about 71mm across. The f/2.8 comes from 71/200 = 1/2.8. If you put on a 1.4x teleconverter, the entrance pupil is still 71mm but the focal length is now 280mm. Now you can see that 71/280 is roughly 1/4.0 of f/4. With a 2x teleconverter, it would be 71mm/400mm or roughly f/5.6.

So the effect a teleconverter has on your aperture is based on simple changes in dimensions and not the quality or design of the teleconverter. You won't find some super-duper high end 1.4x teleconverter that doesn't lose one stop.

You also have to be careful about what that loss of a stop does to your autofocusing. All autofocus systems are optimized to autofocus best at certain apertures. With the Canon 1 series, they are optimized around f/2.8 and f/5.6 but can work effectively up to f/8. The non-1 series cameras only AF up to f/5.6. So if you stick a Canon teleconverter on an f/5.6 lens, it will not AF on a non-1 series body.

You can get around this a bit. With a non-Canon TC, the TC lies to the camera and tricks it into autofocusing being f/5.6. It doesn't work very well, but it tries. You can do the same with the Canon TC by taping over one of the contacts, preventing the TC from telling the camera what is going on.

 

[boBQuincy]

I have a Canon 1.4x teleconverter, it works well and there is little image degradation, none that I can tell. A 1.4x is all I can use with this lens as a 2x would prevent it from auto focusing.
Here is an image taken with the teleconverter and Canon 70-200 f/4:

Date/Time: 2006:12:06 10:53:04
Shutter speed: 1/100 sec
Aperture: 5.6
Exposure mode: Program
Exposure compensation: -1/3
Flash: Off
Metering mode: Evaluative
Drive mode: Continuous (low): frame 1
ISO: 400
Lens: 98 to 280mm
Focal length: 280mm

 

[My2Girls66]

Those pictures look fine to me.
My Nikon lenses are an AF 70-210mm f4 and an AF 75-300 f4.5-5.6(both are older- from the late 80's). Since the 70-210 is an f4 that would be a better lens to use one on? Even tho I'd get closer with the 75-300? The particular teleconverter I linked to says it works with AF-D and AF-S lenses- mine only say AF on them. Also- adding in the crop factor of the camera- a 200mm lens is like 300mm then add the 1.4x for the teleconverter? It would be like 400mm or so? It looks like they won't autofocus at anything more than f4.

 

[jann1033]

oh booy...i am just correcting myself since i actually took my teleconverter out and it's a tamron, not a kenko sorry! now i remember they said in a few reviews the kenko and tamron are the same and the tamron was cheaper so......but yeah it would be like "sort of "400ish, not detail wise but like it's cropped so less of the subject would fill the frame but not be any more detailed than a 280 lens would take.....which is why it's better to have a really sharp lens to start with. i took some with my converter/70-200f4 and tripod today so i'll post some on the san diego zoo thead