2* telephoto lens attachment

[k5MOW]

Good morning all

Just wanted to ask all of your opinions if there is a 2* telephoto lens attachment that works OK. I have a Nikon D 5300. The kit came with 2* telephoto attachment but The quality is terrible. Is there one out there that works at least decently. I have the 55 200 mm Lens and would like to get 300 or 400mm.

Thanks Roger

 

[Braineack]

no.

 

[TCampbell]

Three things happen when you use a focal length multiplier (e.g. 1.4x or 2x "teleconverter" or "tele-extender").

1) You get to multiply the focal length of the lens by the multiplier factor (that's the good news)
2) You ALSO have to multiply the focal ratio of the lens by the multiplier factor (that's the first part of the bad news)
3) Image quality will probably be reduced (that's the second part of the bad news)

Suppose you are using this on a zoom lens with a variable focal ratio of f/4-5.6 ... a 2x adapter changes the focal ratio range to f/8-11 and the problem is that very few cameras can have a working phase-detect focus system at f/8 and none have working phase-detect AF at f/11 (live-view focus might work and of course you can still focus manually -- but that limits you to types of photography where it's ok if it takes a bit longer to lock focus.)

If you have an f/2.8 lens then the 2x adapter turns it into an f/5.6 lens and every camera I know of can still focus at f/5.6. (If you have an f/4 lens then a 1.4x adapter turns it into an f/5.6 lens)

But this still leaves you with the optical quality. Canon makes a 200-400mm f/4 zoom that has a built-in 1.4x extender. The optical quality is amazing. But the *reason* the optical quality is amazing isn't because tele-extenders are that good... the reason is because the tele-extender is built-in so it's been optimized for that one lens (also the lens costs more than $10k) rather than having to be generically designed to work with just about any lens.

I've never seen a tele-converter that didn't reduce the optical quality and soften the focus. Depending on your needs, you might be able to apply a bit of sharpening in software.

 

[k5MOW]

This is kind of what I thought thank you very much for the information.

 

[wfooshee]

Two things being discussed here, I think.

I'm pretty sure the OP is asking about the adapter that attaches to the front of the lens. Those are trash. Have some fun and see how close to dust you can get it with a hammer.

I think TCampbell is describing actual teleconverters, which attach between the lens and the camera body. Those have issues of their own but they are vastly superior to the front-of-the-lens adapters. They do cost you a stop (for 1.4x converters) or two (for 2x converters) of exposure, but depending on the lens they are attached to, and the build and design quality, you can get very nice images from them. The lens being used with the teleconverter must be a superior piece of kit, because all the teleconverter does basically is magnify the center of the image the main lens produces, and any flaws such as softness or chromatic aberrations will be magnified with it. The effect is the same as cropping the frame produced by the lens alone, with any defect from the teleconverter added into the mix.

Good teleconverters are out there, but you have to have good lenses to make them useful, and the kit lens most likely doesn't qualify in that regard.

As a build and design quality example, back in the Canon pre-autofocus FD-mount days you could get 2x converters in two basic designs, a 4-element and a 7-element. The 7-element converter was orders of magnitude better, but significantly more expensive.

 

[petrochemist]

wfooshee beat me to it, I'll just add:
I used tele-converters that go between the lens & camera quite a bit in film days getting reasonable results. Some of the better ones are still worth using on digital, though I don't think any of the 2x or 3x converters are in that class (1.4x & 1.7x can be).

When I first got an AF system (only ~5 years ago!) I tried an adapter that screws in the front of the lens as my old ones all would have lost AF. The quality was cr** so even with only 6MP available cropping gave a better image!

Note; some of the wide angle adapters that screw on the lens front work quite well & even the poor ones can give a slight advantage if your lens selection is limited.

 

[Mr.Photo]

TCampbell and wfooshee have given you some great information.

As wfooshee mentions you need a decent lens and quality teleconverter to get acceptable images. Zoom lenses (with exception of a select few) don't typically work well with Teleconverters. Telephoto prime lenses are typically the lens of choice when using a Teleconverter to gain some extra reach.

My setup is an old Tokina 300mm f/4 prime lens combined with a Kenko Pro 300 DGX 1.4x teleconverter. This gives me a combined focal length of 420mm at f/5.6. This setup depending on conditions can produce some pretty respectable images. The only time I really notice the degradation is if I try and crop the images too much.

Here's a couple of shots I've taken using this combo to show what it is capable of.

Today there are a number of quality super zoom lenses coming out on the market. Tamron, Sigma, and Nikon offer super zoom lenses that will get you out to 500-600mm and produce some stunning images. I will eventually be getting one of these lenses in the not too distant future to replace my current setup.