New Pentax K-x user looking for 2x Teleconversion Suggestions -

mackloon · 06-29-2010, 02:21 PM

As the title suggests. I am a new Pentax K-x user, upgrading from my previous Canon G9, I have entered into a brand new ballgame.

At this point in time I am not 100% sure what type of shooting I want to do, so I am looking to get some less-expensive add-ons to my kit lenses.

I got the Pentax 18-55 DAL/55-300 DAL.

I think I will be snatching up the Raynox 150/250 macro addon, and I was thinking of getting a teleconverter to add on to the 55-300 lens. I would like the zoom to be as long as possible while preserving the AF. Since I will be using the kit lenses that do not have a manual aperture setting I would need one with contacts, and one that support AF.

What have users here had luck with, and what will work on the K-x kit lenses that I have.

I figure after 6 - 12 months with the addons, I should know where my preference is, and opt to make a bigger/better purchase as far as lenses go.

Thanks, in advance for any added information.

Glad to be a member here.

-mackloon

szurinaga · 06-29-2010, 03:12 PM

I too would be interested in which teleconverters are the best for pentax. I might be shooting a wedding in two weeks and would like to have my 55mm prime to be longer. Anyone know if the Bower converters are any good? There are quite a few on ebay

**JohnI** · 06-29-2010, 04:12 PM

AF generally doesn't work if the f/number going into the camera body is > 5.6. Sometimes f/6.3 will work. Since a rear-mount 2X teleconverter (which goes between the lens and the camera body) doubles the f/number, a lens such as the 18-55mm that's f/5.6 at 55mm will become f/11 when a 2X teleconverter is attached, and won't autofocus at all. I have a Tamron 70-200mm f/2.8, and when I put a 2X teleconverter on it, it will autofocus ... sometimes ... on my K-x. The few times I have used it, the results have been acceptable. Mine is one of the cheaper 4-element AF ones, and I bought it on Ebay for a song.

You might consider a front-mount 2X attachment that screws on the front filter threads of the lens. These don't affect the f/number. I've never actually used one of these, but other readers may be able to comment. It's essentially a 2X Galilean telescope.

mackloon · 06-29-2010, 04:51 PM

Hmmmm...

Had not thought about the front theaded ones.

I would not have to worry about the contacts either that way. To be honest, I am just trying to get some addons to see what I like before I spend 500 on a lens.

I would be interested in a front mounted teleconverter. Can anyone comment on the quality of these in use with the kx? I can handle some slight iq reduction, but nothing too bad.

Let me know if anyone has a read on these.

Thanks

mackloon

imtheguy · 06-29-2010, 06:02 PM

Although the DA55-300 is a fine lens, you will not be happy using it with a TC even if you are the best manual focuser in the world. The lens is too slow and lacks critical sharpness for use with a TC. Yes, I have tried mine with 1.4x, 1.7x and 2x TC just to verify that a cropped shot w/o TC looks BETTER than one with the the TC sized the same. Save your money.

mackloon · 06-29-2010, 06:23 PM

Thanks for the 1st hand experience.

Just for the record... Were those rear or front mounted?

imtheguy · 06-29-2010, 06:25 PM

All rear TCs. I sometimes use the Raynox 150 on the front and love that lightweight combo for macro.

mackloon · 06-29-2010, 06:54 PM

Do you think or know if the af improves when front mounted?

Marc Sabatella · 06-29-2010, 07:15 PM

Originally posted by mackloon

Had not thought about the front theaded ones.

There's a reason you almost never hear about these - because quality is generally even worse than with a rear threaded one. With basic consumer zooms like the 18-55 or 55-300, forget about TC's front or rear. You are virtually always better off simply cropping when you want to get a more magnified image.

06-29-2010, 02:21 PM	#1
mackloon Veteran Member Join Date: Jun 2010 Location: Pittsburgh, PA Posts: 415	New Pentax K-x user looking for 2x Teleconversion Suggestions - As the title suggests. I am a new Pentax K-x user, upgrading from my previous Canon G9, I have entered into a brand new ballgame. At this point in time I am not 100% sure what type of shooting I want to do, so I am looking to get some less-expensive add-ons to my kit lenses. I got the Pentax 18-55 DAL/55-300 DAL. I think I will be snatching up the Raynox 150/250 macro addon, and I was thinking of getting a teleconverter to add on to the 55-300 lens. I would like the zoom to be as long as possible while preserving the AF. Since I will be using the kit lenses that do not have a manual aperture setting I would need one with contacts, and one that support AF. What have users here had luck with, and what will work on the K-x kit lenses that I have. I figure after 6 - 12 months with the addons, I should know where my preference is, and opt to make a bigger/better purchase as far as lenses go. Thanks, in advance for any added information. Glad to be a member here. -mackloon

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06-29-2010, 03:12 PM	#2
szurinaga Senior Member Join Date: May 2010 Location: San Juan Photos: Albums Posts: 145	I too would be interested in which teleconverters are the best for pentax. I might be shooting a wedding in two weeks and would like to have my 55mm prime to be longer. Anyone know if the Bower converters are any good? There are quite a few on ebay

06-29-2010, 04:12 PM	#3
JohnI Site Supporter Join Date: Mar 2008 Location: Pasadena, CA USA Posts: 35	AF generally doesn't work if the f/number going into the camera body is > 5.6. Sometimes f/6.3 will work. Since a rear-mount 2X teleconverter (which goes between the lens and the camera body) doubles the f/number, a lens such as the 18-55mm that's f/5.6 at 55mm will become f/11 when a 2X teleconverter is attached, and won't autofocus at all. I have a Tamron 70-200mm f/2.8, and when I put a 2X teleconverter on it, it will autofocus ... sometimes ... on my K-x. The few times I have used it, the results have been acceptable. Mine is one of the cheaper 4-element AF ones, and I bought it on Ebay for a song. You might consider a front-mount 2X attachment that screws on the front filter threads of the lens. These don't affect the f/number. I've never actually used one of these, but other readers may be able to comment. It's essentially a 2X Galilean telescope.

06-29-2010, 04:51 PM	#4
mackloon Veteran Member Join Date: Jun 2010 Location: Pittsburgh, PA Posts: 415 Original Poster	Hmmmm... Had not thought about the front theaded ones. I would not have to worry about the contacts either that way. To be honest, I am just trying to get some addons to see what I like before I spend 500 on a lens. I would be interested in a front mounted teleconverter. Can anyone comment on the quality of these in use with the kx? I can handle some slight iq reduction, but nothing too bad. Let me know if anyone has a read on these. Thanks mackloon

06-29-2010, 06:02 PM	#5
imtheguy Site Supporter Join Date: Mar 2009 Location: Virginia Beach Photos: Gallery \| Albums Posts: 2,950	Although the DA55-300 is a fine lens, you will not be happy using it with a TC even if you are the best manual focuser in the world. The lens is too slow and lacks critical sharpness for use with a TC. Yes, I have tried mine with 1.4x, 1.7x and 2x TC just to verify that a cropped shot w/o TC looks BETTER than one with the the TC sized the same. Save your money.

06-29-2010, 06:23 PM	#6
mackloon Veteran Member Join Date: Jun 2010 Location: Pittsburgh, PA Posts: 415 Original Poster	Thanks for the 1st hand experience. Just for the record... Were those rear or front mounted?

06-29-2010, 06:25 PM	#7
imtheguy Site Supporter Join Date: Mar 2009 Location: Virginia Beach Photos: Gallery \| Albums Posts: 2,950	All rear TCs. I sometimes use the Raynox 150 on the front and love that lightweight combo for macro.

06-29-2010, 06:54 PM	#8
mackloon Veteran Member Join Date: Jun 2010 Location: Pittsburgh, PA Posts: 415 Original Poster	Do you think or know if the af improves when front mounted?

06-29-2010, 07:15 PM	#9
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	Originally posted by mackloon Had not thought about the front theaded ones. There's a reason you almost never hear about these - because quality is generally even worse than with a rear threaded one. With basic consumer zooms like the 18-55 or 55-300, forget about TC's front or rear. You are virtually always better off simply cropping when you want to get a more magnified image.