Telecovertors

**in2toy** · 08-05-2010, 10:39 AM

I have a 18mm-250mm Pentax and would like to know what tele would work on this lens.Did Pentax make one to work on this lens?

**Lowell Goudge** · 08-05-2010, 11:05 AM

Originally posted by in2toy

I have a 18mm-250mm Pentax and would like to know what tele would work on this lens.Did Pentax make one to work on this lens?

while optically it may work, the 18-250 mm lens would not auto focus because the resulting Fstop wpi;d beslower than any known AF system can work with.

SOldBear · 08-05-2010, 11:34 AM

This lens will autofocus with a 1.4X converter, albeit a bit slow and with some hunting, provided there is enough light and something contrasty to lock on.

But I wouldn't bother with a teleconverter. The lens, while quite good for its range and price, is only so-so IQ-wise at the long end. It suffers even more with a TC.

imtheguy · 08-05-2010, 02:03 PM

Agree with all the above...and I have tried it. You will get a better pic by just cropping instead of using any TC on the 18-250mm.

icywarm · 08-05-2010, 02:11 PM

Dido... plus it is very difficult to hold even with a mono pod at the 500mm range(thinking x2 which I tried with a x1.4, not together, but to try)

08-05-2010, 10:39 AM	#1
in2toy Site Supporter Join Date: Nov 2009 Location: Weyburn SK Posts: 35	Telecovertors I have a 18mm-250mm Pentax and would like to know what tele would work on this lens.Did Pentax make one to work on this lens?

08-05-2010, 11:05 AM	#2
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	Originally posted by in2toy I have a 18mm-250mm Pentax and would like to know what tele would work on this lens.Did Pentax make one to work on this lens? while optically it may work, the 18-250 mm lens would not auto focus because the resulting Fstop wpi;d beslower than any known AF system can work with.

08-05-2010, 11:34 AM	#3
SOldBear Veteran Member Join Date: Feb 2009 Location: Alameda, CA Posts: 3,206	This lens will autofocus with a 1.4X converter, albeit a bit slow and with some hunting, provided there is enough light and something contrasty to lock on. But I wouldn't bother with a teleconverter. The lens, while quite good for its range and price, is only so-so IQ-wise at the long end. It suffers even more with a TC.

08-05-2010, 02:03 PM	#4
imtheguy Site Supporter Join Date: Mar 2009 Location: Virginia Beach Photos: Gallery \| Albums Posts: 2,950	Agree with all the above...and I have tried it. You will get a better pic by just cropping instead of using any TC on the 18-250mm.

08-05-2010, 02:11 PM	#5
icywarm Veteran Member Join Date: Jan 2010 Location: Saskatchewan Photos: Gallery \| Albums Posts: 1,278	Dido... plus it is very difficult to hold even with a mono pod at the 500mm range(thinking x2 which I tried with a x1.4, not together, but to try)