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Embarrassing question.....

squizza

Established Member
Hi guys

I've been doing photography for a few years now, but have a question - one that I should know the answer to but don't:cool::suicide:

I have a Sigma 105mm macro f2.8. This gets in very close but I've seen photographs recently where said lens has had extension tubes attached (Kenko ones)

So..... the embarrassing question(s)

1) is there a difference between a 1.4 converter/extender and extension tubes - do they do different things?

2) If there is a difference - what would I attatch to my macro lens to get even closer?

Hope this all makes sense.
Many thanks in advance
Kind regards

Sarah
 

Alistair

Established Member
Hi Sarah,

Nope, not a dumb question. :)

Basically an extender (say 1.4x TC) multiplies the focal length of your lens. For macro this can have an advantage as you can work further away from your subject, particularly useful for butterflies, bugs etc.,

An extension tube is useful, say a 12mm or 25mm, as these reduce the minimum focus distance of the lens enabling you to get even closer to your subject.
 
Last edited:

jomike

Prominent Member
Short answer - both.

To get more magnification you use the extension tubes. The problem then is that you start getting so close to the subject that you shade it with the lens if it does not move, or flies or runs off if it does. To get back some working distance you use a TC.

So to sum up, tubes get you closer to give more magnification. TeleConverters get the same magnification but from further away.

TCs also cut down light getting to the sensor, tubes, being empty air, do not.
 

Alistair

Established Member
[snip]
TCs also cut down light getting to the sensor, tubes, being empty air, do not.

Both TCs and Tubes reduce the light hitting the sensor because you are moving the lens further away from the sensor. If you are TTL metering then the camera will compensate but if you will manually meter then you will need to compensate.
 

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