DA*200 and AF 1.7X TC

[SylBer]

Hi,

I recently bought a DA*200 that I just love. However, I sometimes whish I had a little more reach. The Pentax AF 1.7X TC seems really good, but does it work with the DA*200? Would the lens still use SDM with this teleconverter or the screwdrive?

Thanks!

Sylvain

[thomascdk]

I used a Kenko Pz-AF 1.5 with my 50-135 and SDM worked - sort of. AF was worse than without the TC.

[G_Money]

It will use the screwdrive, but focus via the converter, not the lens. You'll have to MF it to get it in the ballpark then the converter will focus. I have used this converter with my DA*300 and it works pretty well. I still wish Pentax would make an SDM compliant TC though. Maybe now that the K7 is on the shelves they can free up some designers to come up with something.

[SylBer]

Hi G Money,

Thanks for your reply. I saw a few pictures on the "other" forum of DA*200 and DA*300 coupled with the AF 1.7X adapter and they look very good. I also hope that Pentax comes up with the 1.4 SDM TC in a near future. In the meantime, would you say that the 1.7X is the best available TC for the DA*200? Would the SDM compatible vesios of the Kenko 1.5 or Tamron 1.4 would offer better optical quality?

Thanks again for your help.

Sylvain

[G_Money]

This is a subject I waffle back and forth with. I have the Pentax AF 1.7X Converter, as well as a Tamron 1.4X TC and a Promaster 1.7X TC. I use these primarily with my DA*300mm. One advantage of the Pentax Converter is that the focal length isn't transmitted to the camera, so the camera asks for a manual FL input when it is turned on. Whenever I use the Tamron or the Promaster, the camera only thinks it has a 300mm mounted, making the shake reduction less effective. I have the greatest success focusing with the Pentax, albeit I have to first get the focus close manually. The Tamron will use the SDM motor. although it is not as precise. I often have to half-press the shutter a couple of times, and use my Katz-eye to ensure that it is accurately focussed. Also the camera sees the lens as a 300mm rather than a 420mm. The Promaster uses the SDM motor as well, but is the least successful at achieving focus. It needs a lot of light and contrast to get any kind of results. The funny thing is that it will hit focus every time with my DA 55-300mm, even though that lens is more than a full stop slower than the DA*300. Perhaps because it uses the screw-drive rather than an SDM.

Here's a sample from the DA*300 and the Pentax AF 1.7X. It's been sharpened and resized, so don't read too much into it, but I'm satisfied with the results. That's not to say that I don't wish it was easier to use. This is the longest focal length I've ever used, and I find it a struggle.

[SylBer]

Thanks for sharing this very good picture with me. I would be curious to see the original picture straight out of your camera. It semms to me like the 1.7 is your favorite TC. I can definetly see why.

Now, if I understand you correctly, when you took this picture with the DA*300, you had to indicate that the focal lenght is 510mm so that the SR works properly. Now considering the crop factor of the K10D and K20D, that means the lens frames like a 770mm f/6.8? Using the same logic, it means if I use this TC with my DA*200, I will get the equivalent of a 340mm f/4.7.

I can't wait to give it a try.

Cheers!

[SylBer]

Hi G Money,

If you don't mind, I have one more question for you. I read that the 1.7X adapter works better on f4 or less lens. Does that mean I would have to use my DA*200 with aperture f4 or less for the TC to focus properly or that I can use it at any aperture with any lens that has constant aperture of less than f4?

Thanks again for your help.

[zorobabel]

Lenses with the A contacts will focus wide open, no matter what aperture you set on the camera.

Originally Posted by SylBer

Hi G Money,

If you don't mind, I have one more question for you. I read that the 1.7X adapter works better on f4 or less lens. Does that mean I would have to use my DA*200 with aperture f4 or less for the TC to focus properly or that I can use it at any aperture with any lens that has constant aperture of less than f4?

Thanks again for your help.

[xxxxx]

Is this Pentax AF 1.7X TC still in production? Can't seem to find a place offering it online.

[SylBer]

Just bought one on Ebay from a seller in Japan who had two new (in box never opened) for sale and paid 348 $.

[SylBer]

Hi G Money,

I am not sure I understand. You mean I will only be able to use my DA*200 at f2.8?

[G_Money]

No, you'll be fine. The problem with TCs in general is that they decrease the light that reaches the sensor. So instead of f/2.8 your sensor will only be getting the equivalent of about f/4.8. This means that the autofocus has a harder time, which is why they recommend these for apertures of f/4 or wider. You can use it at whatever f-stop you like as long as there's enough light to accommodate it. Their recommendation is only for the sake of the autofocus.

[SylBer]

Thanks for your answer, G money. I should receive my TC next monday. I'll post a review once I am used to it.

[SylBer]

WOW. I just received my 1.7X adapter, brand new from Japan. I tried it with my DA*200 on tripod this afternon. I am amazed by the quality of the photos I took. The AF works really well if you prefocus manually. I can't wait to use it in real life situations.

Thanks everyone for you advices.

[sentro]

Ebay has the Pentax 1.7x from jjfinance for $348. Got one myself the other day. A bit more than I wanted to pay but these are brand new. They seem to have plenty of them. Apparently Pentax still manufactures them for customers who order in large quantities. here is the link....

SMC PENTAX F AF 1.7X ADAPTER K20D K200D K100D K10D K110 - eBay (item 200284488123 end time Jul-03-09 02:15:07 PDT)