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Old Jan 6, 2007, 3:47 AM   #1
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Okay, I seem to recall a Tele-converter being discussed here some months back that does Auto Focus.

Now I already have a TC with AF contacts on to allow the AF lens to MAINTAIN its AF functions with the camera, no big deal.

However, this specific TC that was discussed allowed a certain amount of AF in Manual lenses!!!!!!

Well at first I coudn't see how a manual lens without any contacts or focusing drive could be made AF, but then I read that the TC had it's OWN AF built in which provided SOME AF for the Manual lens.

So my friends, the question is....Does anyone know which TC this is, that can do AF for attached Manual Lenses???

Regards and the LBA is kicking in again.... :G

Crash
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Old Jan 6, 2007, 6:29 AM   #2
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From Bojidar Dimitrov's pagehttp://www.bdimitrov.de/kmp/ :



F 1.7X AF

[align=center][/align]
General Description

Provides AF functionality with manual focus lenses.




Product Information

Exact Name
SMC PENTAX-F 1.7X AF ADAPTER

Color
dark grey

Years of Production
1987 ~ 1997

Availability
roughly once a month, used

Sales Variations

Catalog Number
30924
30925

Sold with Case
soft case: S70-70

Technical Specifications




Optics

Optical Formula
6 elements in 4 groups

Mechanics

Maximum Diameter
64 mm

Length
26 mm

Weight
135 g

Accessories

Fitting Case(s)
soft case: S70-70


Kjell
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Old Jan 6, 2007, 9:26 AM   #3
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That about covers it all! They are getting hard to find and are getting spendy on ebay. The AF is done in the TC, which is why it doesn't cover the full focus range of the lens so you have to pick, long focus or short focus on the MF lens.

I have one and it works just fine, but it works better the faster the lens you are using is. Some people have found it to work on lenses up to 5.6 but that has not been how I found the AF/TC to be. Mine only works reliably up to f/4 and then only in very good light.

Tom
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Old Jan 6, 2007, 11:23 AM   #4
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Hi Crash,

I have two of these and use them all the time with my faster teles. My favorite combo is with the FA*300/4.5. I think that the only reason that it works well with this lens is the fact that it's so sharp and contrasty wide open. The AF works well (probably even faster than the lens alone because of its limited focus range -- no hunting full stop to stop) even in light overcast conditions.

The reason I got the second was that I used mine so often that I knew my original couldn't last forever, and I wanted a backup.

BTW, it's the only TC that I've encountered that actually calculates the effective aperture with the TC and sends it to the exif as such. -- f4.5 on the lens shows up as f8 (actually it's f7.65, so it apparently rounds up) in the exif. Unfortunately, focal length is not converted and sent, so, for example, the FA*300 sends 0mm as FL, and for SR purposes, you have to manually enter 500mm (there's no 510mm) to calibrate the SR system. When you manually enter a focal length to the SR, that's what's reflected in the exif for shots with that lens.

Scott
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Old Jan 7, 2007, 4:55 AM   #5
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The fount of knowledge here is still flowing strong, thank guys, I am thinking about one for a couple of my best MF lenses, getting ticked off with missing the shot on some.

I actually started a bit of LBA yesterday and spent hours researchng some seriously expensive lenses, like a nice 80-200 f/2.8 from Pentax :-)

Then today I went out and shot some really average pics with my current lenses , bland no contrast, soft and so forth. Then I switched over to my old MF 50mm f/1.7 and just dropped my jaw at how great the old lens is, maybe I just need to play with my old lenses some more.

I will start hunting for that TC though, thanks again.

Crash

This was taken today in Honiara, Solomon Islands dealing with some found live unexploded ordinance from WWII, as I said the difference between these lenses is self evident for contrast, sharpness and vibrancy, shots taken 3 mins apart no PP except cut and paste
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