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Old May 16, 2008, 2:42 AM   #12
Old Engineer
Senior Member
Join Date: Jun 2007
Posts: 179

Hey Dawg, really nice bird photos. I have a sears 2X tele conveter PK. It shows a K1 on inside front face. There is plenty of room for any of my Pentax/Sears'Rikoh lenses bases. It seems to produce good images using my long lenses (Sears 60-300mm f/4-5.6, Tamrom Adaptall II SP 60-300mm f/3.8-5.4, Pentax 70-210mm.) I am going to run some tests to see which of those lenses give me the sharpest pix at various focal lengths and f stops, at three distances from camera, probably at 12 feet, 24 feet and 50 feet, all of the same photographed object. I have done this on other lenses, but never with the TC. The testa will be made with seven color cards attached to a printed page having half-inch high letters graduated downward to teeny-weeny. It is surprising to me how much difference there can be in the color rendition from one lens to another. I use a K10D, and have experimented with color tests to see whether the camera settings seem to correspond properly between the camera setting (i.e. sun, cloudy shade, etc.) and the actual conditions at the time of shooting. I have gotten some erratic results doing this, and have concluded that if the result looks good, to just leave the picture without fussing around with trying to get accurate tonal images. So far, I think that has worked pretty well. The place I think that method falls down is when shooting well-known human subjects. For example, I have some beautiful teen-age granddaughters. My pictures of them sometimes end up with too much red in their hair, even though the face is correctly colored. Or, I may get good hair but wrong skin.

I would liketo receive your comments, if you will, please,on the whole colorization subject.

I would also like to know how the 2XTC affexts the lens F stop setting,and what difference the TC makes in the F stop results. In other words, with a camera setting of f/8, and a 2X TC, what is the real-time F stop? And will the camera's EXIF reading actually show the modified F stop?

It seems that a 1.5X or 1.7X TC is preferred by most users. Why is that? Using a zoom lens, adjusting the zoom factor should allow you to have exactly the same result with either TC power. Can you throw any light on that subject.

Sorry to lean on you forso much information, but you appear to have been around these situations quite a bit, so I suspect you have most of the answers to these sorts of questions.

Please help me if you can.

To me, having the questions, then finding the answers (and reasons), is almost as interesting as the actual photographic results. I know that if you know the reason why something happens, you can make adjustments in the mix ofcomponent patsto reach the result you want. The trick is to get the right mix, and most of this can be intuitive or from experience. You seem to excell at both.

Old Engineer
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