Originally posted by jatrax Auto focus smokous. Who cares about AF, the fact that you got what I would think are printable images with that rig is amazing. Very good technique I'm sure and good light but still, well done.
I assume the 60-250 was at f/4?
Have you tried the A-400 and the 1.4x? Curious if the IQ was fine though no AF of course.
My ƒ-stop showed the correct ƒ stop wide open a ƒ6.7, I stopped down to the next full ƒ-stop, ƒ8 just to be neat and tidy I guess.
Oops my mistake. The 1.7 on a ƒ5.6 lens is ƒ9.5 so I actually stopped down to ƒ11. Originally posted by photolady95 Whoa! I said and/or, not both. I have no intention of stacking two on a 50-200mm lens at it's f stops. But I have a Vivitar 2x and it will not allow autofocus to happen because the lens at 200mm is f5.6 and it needs to be less than f4 for a 2x TC to work.
Thanks for spelling whoa, I was wondering how to spell it.
My experience says the 1.4 might work on your 200, but probably not well and for the cost of the Pentax TC you could get a 55-300, that would be faster and more convenient.
Originally posted by UncleVanya I'm confused. The 1.4 is always stationary. It only passes AF power or screw drive shaft power. Putting the 1.7 anywhere as long as AF shaft powers it gives focusing options. I always added it to the camera first. But typically my stacks involved non-AF Teleconverters. So an FA* 300 with 2x-s and then the AF 1.7x. My rationale was that the AF 1.7 would have the most focusing impact placed last in the optical path.
That's what happens when you think about things you shouldn't.
You've obviously thought about it a lot more than I have. My thought involved standing in front of the lens and two TC-s lying on the table in my kitchen, wondering which one to put first, staring at the three pieces.
Then when it worked, I saw no point in thinking any further.
You can't get away with nothing around here.
I bought the 1.7 before the 1.4, and it was my first TC. In my mind apparently, all TCs move, whether they claim to be AF adapters or not.
Oh and credit where credit is due, the original idea to try this stuff came from watching my Canon shooting buddies. I know I should probably not say stuff like that but hey.
We were standing around at the place we shoot Gray Jays, me with my old A-400 and one of the guys waved his Canon 70-200 ƒ2.8 with a Canon 2x on it and said, "I've got the same thing with AF and better IQ." The better IQ thing was against forum ideology, but, it's always better to investigate than it is to repeat hearsay. I managed to keep my foot out of my mouth. The thing that took the most time was getting to stacking the 2 TCs. Again, forum wisdom said "don't do that,". I went for quite a while thinking "it's too bad Pentax doesn't make 2x TC, before I even thought of stacking.
I guess the thing I took from the whole experience, is if you pay the price for premium equipment, don't take advice from people who didn't. The 1.7 and 1.4 are both premium pieces of equipment, and work best with premium glass. Any shortcuts are likely to mess up the whole process. Three combined pieces are only as strong as the weakest link.