Understanding Teleconvertors

[JasonF]

I've got a couple of questions reguarding teleconvertors.

For instance, my 17-70mm is suppost to be a macro lens. I know its not a "true" macro but has macro capabilities. In order to take macro shots with this lens, I have to position the lens as close to the subject (sometimes almost touching the glass) as I can.
I wasn't sure if a teleconvertor would give me more range for, say, macro shots or should I get a 10x macro filter for that?
A couple other questions:
What exactly are telconvertors used for?
Is a 4x always better than a 2x or do they both serve their purpose in different situations?
Pros and cons?
Which is the best brand to buy?

Thanks in advance!!

 

[DRB1313]

Jason, A TC is just magnifying the focal length of the lens that it is paired with.
Most are designed and used with 200mm and up lenses to get a longer lens without
the expense of a bigger lens.
For example: putting a 2x TC on a 200mm lens would give you a
focal length of 400mm.
Most TC's will degrade the Image quality slightly, but
not too bad with a good one.
I think the item your are looking for is an extension tube.
Well, maybe not. An extension tube actually allows you to get closer to your subject and in turn
gives you an even closer view of it.
As far as the TC's are concerned, I'll let feral One or Rip give you some answers and Pros and cons, since
they both are shooting Nikon.
I don't guess I was much help, but I tried.

 

[JasonF]

Accually that was helpful...thanks!
I just saw a picture where someone took a really close macro shot with their Sigma 17-70mm and I thought, "how in the world were they able to get that close?" Then I saw were they had used a 1.4x telecovertor. Thought maybe that was what allowed for such a picture with that lens?

 

[Smokey]

Man-O-Man can you believe the nerve of some folks asking all these picture taking questions

 

[JasonF]

Man-O-Man can you believe the nerve of some folks asking all these picture taking questions

You know you like it.
Besides, why not dig into the minds of all these photography gurus here on this wonderful forum.

 

[Smokey]

You know you like it.
Besides, why not dig into the minds of all these photography gurus here on this wonderful forum.

I tried my best to wear'em out but their knowledge is vast and never ending!!

 

[rip18]

We've talked about teleconverters & extension tubes somewhere before, but I couldn't find it, so I'll try again.

I have both & use both - sometimes at the same time...

Teleconverters do exactly what DRB1313 said - they are basically an extra set of lenses that increase the "power" of the lens they are attached to by a certain amount - 1.4x, 1.7x, 2.0x, etc. Unfortunately, they also DECREASE the amount of light coming through to the sensor, so you have to open the aperature or decrease the shutter speed when you use one - which can be a REAL pain when shooting macros because you often want faster shutter speeds (wind on flowers or bugs moving) and more depth of field (the closer the subject is to the lens, the relatively shallower the depth of field for a given set of settings). (You may want to go back and re-read that last sentence again because it is chock FULL of theory & information). There are some folks who use teleconverters to take quasi-macro pictures and do well with them.

Extension tubes come in different lengths and a complete "set" of extension tubes provides a range of lengths (that can in turn be combined...). Extension tubes put extra distance between the lens and the sensor allowing the lenses to focus on things that are closer than they normally would (basically it decreases the minimum focus distance). But the equal & opposite reaction is that it also decreases the maximum focus distance - you can no longer focus to infinity and for each lens/body combo there is a distance beyond which it won't focus. Extension tubes are frequently used with moderate length lenses (100-200 mm) and even long lenses (300 mm to 600 mm) to allow macro or quasi-macro images to be taken.

Screw on magnification filters are not something that I have used on a DSLR - though I did use a couple on a Nikon CoolPix. They seem to affect quality the most of the options for making a "normal" lens focus closer.

Summary: Extension tubes probably won't work for you with that lens because you are already almost touching the subject with the relatively low magnification. Teleconverters will get you a higher magnification, but at the cost of light (may HAVE to use a tripod to get non-blurry shots - and get one with a BALL head, not the 3-way head...). Magnification filters may be a temporary solution.

I'd stay away from a 4x teleconverter & stick with the 1.4x to 2.0x. For what it is worth, I use my 2.0x more than the others...

The best brand to buy in most cases is the one that is sold by the company that made your camera. I have used Sigma and Nikkor teleconverters and been happy with the quality of images taken with both. I've also used Quantaray teleconverters, and they worked, but I think that I did lose a little quality. Kenko teleconverters are supposed to be good, but I have never used them.

Extension tubes are one place where "off brands" may outperform camera brands. I've used Nikkor & Kenko. More of the camera electronics worked with the Kenko extension tubes than they did with the "brand" tubes.

Hope that helped?

 

[JasonF]

That sure did help Rip...thank you!
I was hopping for a "quick fix" to improve my macro shots until I purchase a dedicated macro lens (which is the last on my list).
With that said, I may purchase a 1.4x teleconvertor and a tri-pod and give it a whirl.

 

[Hoss]

Good info there, this one needs to go in our photo info sticky.