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07-12-2012, 06:17 AM   #1
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Fine AF adjustment needed for this combo lens - TC?

I have been debating whether to just do away with (sell) my teleconverter - a Pentax-F 1.7x AF adapter - which I have tried countless of times to use with my DA*300/4, or keep it ... I really never get any shots "bang on" with this combo although many forum members here have had success with that same combination.

Granted, when the focus is "bang on", the shots are good, but never great.
I would say that about 1 out of 25-30 shots will be satisfyingly focused.

Now, I am wondering if this would need a fine adjustment because that becomes a 510mm lens and I thought perhaps the reason why the results have always been rather mediocre was because it needs fine tuning?
Is this a possible solution even when while this lens + TC requires input for focal length?

Has anyone have any such "trouble" to make this combo work precisely?

Any feedback will be appreciated.

Thanks!!

JP

07-12-2012, 07:48 AM   #2
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I think you have to fine adjust on "apply all".

I tried the AF 1.7x and AF accuracy depends on the TC only.
No matter what lens you put on it, it will be the same.

However, since the camera cannot recognize it as a lens. So only apply all works.
07-12-2012, 11:32 AM   #3
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QuoteOriginally posted by MegaPower Quote
I think you have to fine adjust on "apply all".

I tried the AF 1.7x and AF accuracy depends on the TC only.
No matter what lens you put on it, it will be the same.

However, since the camera cannot recognize it as a lens. So only apply all works.
Does that mean that all my lenses will be having a correction?
I wouldn't want to have to get OOF with those!

Also, what I am really wondering is: is such an adjustment necessary? Are people using this sort of combo do that?

JP
07-12-2012, 09:45 PM   #4
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QuoteOriginally posted by jpzk Quote
Does that mean that all my lenses will be having a correction?
Yep. Just put a nice bright label on the TC that reminds you to switch apply-all on and off.

I don't have a TC so I don't know if it's necessary.

07-13-2012, 08:58 AM   #5
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QuoteOriginally posted by jpzk Quote
Does that mean that all my lenses will be having a correction?
I wouldn't want to have to get OOF with those!

Also, what I am really wondering is: is such an adjustment necessary? Are people using this sort of combo do that?
Such an adjustment would be neccessary if you don't deliver the TC (along with a long lens and your chosen body) to Pentax Canada for "calibration." They can adjust the internal helicoid on the 1.7x AFA, but it costs money to do so ($75 in my case). After that, no adjustment is needed for any lens, since the AFA is the only bit focusing (but they always require your camera body with any lens calibration - otherwise they won't know if they fixed *your* problem or not)! Sadly, they couldn't fix the CA problems...

Last edited by panoguy; 07-13-2012 at 09:04 AM.
07-13-2012, 10:24 AM   #6
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QuoteOriginally posted by sterretje Quote
Yep. Just put a nice bright label on the TC that reminds you to switch apply-all on and off.

I don't have a TC so I don't know if it's necessary.
So, you mean: install the lens/TC; goto the AF fine adustment option and (after adjustment) goto "apply all"?
Then, if I am to take the TC off, go back to the option and check off the "apply all" ?


QuoteOriginally posted by panoguy Quote
Such an adjustment would be neccessary if you don't deliver the TC (along with a long lens and your chosen body) to Pentax Canada for "calibration." They can adjust the internal helicoid on the 1.7x AFA, but it costs money to do so ($75 in my case). After that, no adjustment is needed for any lens, since the AFA is the only bit focusing (but they always require your camera body with any lens calibration - otherwise they won't know if they fixed *your* problem or not)! Sadly, they couldn't fix the CA problems...

This might be the answer then.

This is too bad that I have just received my K5 back from Pentax Canada (Mississauga) this week after they fixed a "Battery depleted" issue (causing the said K5 to freeze with fully charged batteries).
I would have sent the TC and lens as well !!

In the meantime, I am going to have to test this "apply all" as suggested by sterretje

Thanks guys for the help.

JP
07-13-2012, 10:43 PM   #7
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QuoteOriginally posted by jpzk Quote
So, you mean: install the lens/TC; goto the AF fine adustment option and (after adjustment) goto "apply all"?
Then, if I am to take the TC off, go back to the option and check off the "apply all" ?
More or less, yes. Not quite sure how the apply all works; no camera at hand to quickly check the exact sequence.
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