Teleconverter vs. Extension Tube

Heather Koch

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I did google this but not quite sure what I was reading, so I know you guys here are great at explaining things :p

ALSO, since I can't afford a 'real' telephoto zoom lens, I am getting the Tamron 70-300mm. My question after the above is answered, which do I get and what do I get?

I have found several 2x converters but they range from $20-$300. AND are they all universal (Nikon)?
 

tirediron

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Two different animals; extension tubes are simply empty tubes (no optics) designed to allow closer focusing, they're a substitute for a macro lens. Tele-converters on the other hand are designed to "increase magnification", so putting a 2x TC on your 70-300 will give you a 140-600, BUT.... it will also resduce your maximum aperture, so if yours is a f4-5.6 lens, it will become an f8-f11 lens, meaning that at the long end, it will be dark enough AF probably won't work. SInce TCs have optical elements, like any lens, cost (generally) equals quality and a $20 TC is probably not going to be useful even as a paperweight, whereas the latest Nikkor 1.4, 1.7 and 2.0x TCs are very, very good.

Non-Nikon branded TCs in Nikon mount (Tamron, Kenko, etc) will fit any Nikon lens, but Nikon-branded TCs will only fit certain (higher-end) Nikon glass such as the 70-200 f2.8, tele-primes and up basically their 'gold ring' line.
 

480sparky

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Putting even a 1.4x TC on the Tamron will make it an f/5.6-8 lens. F/5.6 is at the edge of the ability of most entry-level Nikon bodies to autofocus, and at the long end of the lens' focal length f/8 will most likely fail to autofocus at all.

Going to a 2x TC you'll have to manually focus at all focal lengths, most likely.
 
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Heather Koch

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Thank you very much! That helps a lot.

I'm merely looking for something decently priced to get nice moon/star shots. That is all I'd use the converter for.
 

tirediron

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Thank you very much! That helps a lot.

I'm merely looking for something decently priced to get nice moon/star shots. That is all I'd use the converter for.
Then spend the money on a good, rock-solid tripod. Unless you're using a top-of-the-range TC on a top-of-the-range lens, you're going to lose enough IQ to make it pointless. If however, you have a tripod that will hold up the proverbial shick brithouse, then you will be able to crop in a bit and still have much sharper images.
 
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Heather Koch

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Thank you very much! That helps a lot.

I'm merely looking for something decently priced to get nice moon/star shots. That is all I'd use the converter for.
Then spend the money on a good, rock-solid tripod. Unless you're using a top-of-the-range TC on a top-of-the-range lens, you're going to lose enough IQ to make it pointless. If however, you have a tripod that will hold up the proverbial shick brithouse, then you will be able to crop in a bit and still have much sharper images.
I have a decent tripod, I mean not the most expensive one out there, but its good.
 

Solarflare

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Haha, the moon is surprisingly small.

I think to actually fill the frame you would need something like an 2k or 3k focal length ?
 
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Heather Koch

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Don't want to fill the frame lol that would take thousands of dollars. Just want something large enough to crop.
 

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