Do we still need a TC?

Started Nov 11, 2013 | Discussions thread
awaldram Forum Pro • Posts: 13,246
Re: Do we still need a TC?

Mark Ransom wrote:

That was one thing I never considered - you might need the TC not for absolute reach, but for focusing and framing. As long as we have OVF this will be something to consider.

To me it always the only reason I use a TC.

If the subject is to small for the focal length in use no amount of cropping will recover it.

Take a 50mm lens and go birding doesn't work, repeat with 300mm lens and it just about doable got to 600mm and it becomes a pleasure.

Now to get that 500-600 mm length (in rough order of IQ and ease of use)

Pentax 560mm £5500

Sigma 500 EX £3800

Sigma 300 f2.8 +2X or 1.4X £2500

Sigma 50-500 £1000

Pentax da* 300 +1.4 £1100

Now imagine you need 800-1000mm what do you do .?

The assumption you can stick a converter on a sows ear and somehow get a silk purse is one of the most pervasive wives tales on the web , In most cases cropping is considerably better.

Often sticking a converter on a cheap consumer zoom will introduce so many aberrations you will lose AF a clear indication the IQ has hit the floor .

But converters on glass that will support it (Mike did some tests on this and his table is a good source of reference) can produce very high quality results.

One other thought.

My old Sigma 70-200 EX does not have an anti reflective rear coating (DG) so in back lit situations can suffer contrast loss, Putting my sigma 1.4 DG converter on will resolve this.

So in this case the application of a converter increases the IQ of the native lens.

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