Newbie question

Teferi

I had a look around the forums/FAQ and googled a bit but I couldn't find anything to explain what a 2x teleconverter and macro rings are (although there were a lot of reviews about them). Would somebody be able to?

I may be buying a d40 off a lad and he mentioned he had these + a sigma 70-300 lens so I am trying to research a little to find out what they are.

Dodgykeeper

A teleconverter is a secondary lens which is mounted between the camera and a photographic lens. Its job is to enlarge the central part of an image obtained by the objective lens. For example a 2× teleconverter enlarges the central 12×18 mm part of an image to the size of 24×36 mm. Teleconverters are typically made in 1.4×, 2× and 3× models.

AnimalRights

They also fractionally lessen the quality of an image of your lense, A good quality lense will lose less quality with a converter than a cheaper lense.
The 1.4x does this to a lesser extent than the 2x

Macro rings are especially used with erm funnily enough Macro lenses and are used by in the norm people photographing insects who need that extra light.

Teferi

What kind of photos would a teleconverter usually be used for?

So macro rings are used to get extra light in a shot?

Paulw

A teleconverter is a magnifier.

A ring is simply a tube (nothing in the middle) to allow your lens get closer to the subject without magnification. It's more commonly used as a poor man's macro.

I use the 1.4x TC quite commonly with my 300mm f/2.8. That then gives me (roughly) 420mm f/4 lens. Great when the light is good. But when light is poor, I don't use the TC.

The TC will multiply your focal length and also your max aperture of the lens.

The ring just gives your lens more distance from the sensor getting it closer to the subject.

helios

Now correct me if I'm wrong, but I think the tubes will infact increase magnification as the lens is further from the sensor. It's like moving a magnifying glass up and down from a fixed point.

Paulw

No, my understanding is that there is no magnification at all with the tubes, because there is nothing there to magnify the image.

All you're doing is moving the lens further away from the sensor. While you move the lens nearer the subject, you are just getting closer to it, rather than magnifying it.

helios

http://www.shutterfreaks.com/Tips/ExtensionTube.htm


"An extension tube is designed to increase image size on the film or sensor so that macro / extreme close up photos can be taken"

ThOnda

Tubes do not magnify the image by bending it through optical material. They only shift backwards the focal plane (film, sensor)- the place where the image of the original is focused. However by moving the focusing elements (lenses) forward, you'll get bigger picture of the reality on the sensor/film.

Teferi

Ah thanks everyone, I understand a bit better now

Probably won't get them, doesn't seem like I will need them. Doesn't seem like the teleconvertor is useful for a newb/what I want to use it for.

challengemaster

teleconverters also increase the f-stop of the lens...however i somehow have one that doesnt. :pac:

Paulw

helios wrote: »

http://www.shutterfreaks.com/Tips/ExtensionTube.htm


"An extension tube is designed to increase image size on the film or sensor so that macro / extreme close up photos can be taken"

That is technically incorrect, but practically seems how it is. It is more the fact that your lens is moved closer to the subject, rather than any magnification.

Think about it. Put your camera on a tripod, in a fixed position. Focus on a fixed object and take a photo. Now add the extension tube. Your lens is now closer to the subject, so of course it looks bigger. Take the same photo.

You have not magnified the subject, you have simply moved closer to it.

However, with a teleconverter, your subject is magnified by the glass in the TC.

I hope this is a little clearer.

rgiller

AnimalRights wrote: »

Macro rings are especially used with erm funnily enough Macro lenses and are used by in the norm people photographing insects who need that extra light.

This gooner must be thinking of ring lights, which are a circular flash that attaches to the lens. A macro ring is as described above, an empty tube whose purpose is to let you focus at a closer distance than the lens allows, with the end result being a larger subject on your detector, and so the appearance of greater magnification.

sineadw

rgiller wrote: »

This gooner must be thinking of ring lights, which are a circular flash that attaches to the lens. A macro ring is as described above, an empty tube whose purpose is to let you focus at a closer distance than the lens allows, with the end result being a larger subject on your detector, and so the appearance of greater magnification.

Yep - I think you're thinking of ring flashes there Animal..

AnimalRights

I was actually.