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05-09-2008, 06:57 PM   #1
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Will K20D's BF/FF adjustment work for Tamron/Sigma lenses?

Hi

I was told that k20D can adjust the BF/FF settings for up to 20 lenses. some say this is only applicable for pentax lenses only and might not work for third party lenses.

May I seek the help of k20D owners to clarify this point?

I am not gonna upgrade my k100D now but if k20D has the built-in capabilities to tune any lenses into its database, I would say I will upgrade when I get my big break.

thanks.

05-09-2008, 08:50 PM   #2
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did a BF adjustment on my Sigma 28mm EX DG f/1.7
it worked. any other lenses didnt need any.....(tho the other 3 i generally use other than the afformentioned lens are Pentax)

so....yeah...it works......
05-09-2008, 08:56 PM   #3
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Can you elaborate how the k20D BF/FF adjustment work...the steps involve?

I would guess you still need the D70 focus test chart but do you need to take a picture of the chart, view it on PC screen, then adjust the k20D...and repeat until the BF/FF is fixed? or you can do it on the fly using just the k20D and test chart without a need to preview the picture on PC first?
05-09-2008, 11:52 PM   #4
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it wasnt sceintific at all, took a photo of a remote control at an angle. did the adjustment, took the photo again....and it was corrected. did a few more test shots......just to be sure....

i didnt get to crazy on it....it's not like you can micro-adjust it in the first place...


and no, i didnt preveiw it on the pc first, i was just looking where it focused, and the k20's screen is plenty big for that...

as for the steps...

i was kinda bored...so....here's some shots of the menu










and a shot of the k20 w/ a mounted sigma lens..(not the one I adjusted)



05-10-2008, 01:17 AM   #5
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Thanks for the photos!! This is very very helpful.

Where the menu indicate "Apply One", is the "one" referring to lens no. 1? Where do you put in the name of the lens that you are calibrating? i.e. does the k20D know that lens 1 = sigma 30 and lens 2 = FA50, etc?
05-10-2008, 05:11 AM   #6
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I calibrated 4 Sigma lenses and one Pentax Lens. The Apply One means apply this adjustment to this one lens, as compared to Apply All and it applies this adjustment across Any Lens attached to the camera.

The camera reads the chips in the Lenses and records the type of lens it thinks it is in the camera's memory. When you attach a lens it reads the chip and adjusts the camera from memory.

I notice that it thought my Sigma 10-20mm and 17-70mm lens was the same lens, Damn! so any adjustment for one lens is applied to the other lens when it is attached and unfortunatley they require different adjustments. The only downside I have seen for Sigma Lenses so far.

I recommend using a tripod and follow the instructions from the website where you download the focus chart.

I found the whole experience a lot easier when I set the focus chart leaning against a book at a 45 degree angle on a table. Set my tripod to shoot horizontally towards the table with the camera set at the table top height directly at the book, if you get my drift.

/
[ ]= ____/____
/ \ | |
/ \ | |

The reason I chose this method is some of my lenses were wide angle and some were telephoto and I needed to change focussing distances and it is seasier just moving the camera tripod back and forward a few feet without have to adjust everything again.

PK
05-10-2008, 06:19 AM   #7
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Thanks very much for your information.

k20D is very impressive so far. I am happy that pentax finally put in the FF/BF adjustment features into their DSLR.

Last edited by raider; 05-10-2008 at 06:26 AM.
05-10-2008, 07:33 PM   #8
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Currently I have the Tamron 28-75/f2.8.

If I were to buy a k20D (in future) and also get the Tamron 70-200/f2.8 (also in future), would the k20D able to recognize that I am calibrating the BF/FF for 2 very different lens, or it would treat both Tamron as just 1 lens, like what happen to your sigma 10-20 and sigma 17-70?

Thanks again.

05-10-2008, 08:19 PM   #9
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thats hard to say, unless someone has a similar set up. in theory it should. again, you dont need to do it on all the lenses, unless you feel that it should.

that sigma lens i tested it on (as shown in the photos) did NOT recognize it as the Sigma I adjusted.

the 28mm Sigma also had a bit of a BF on the k10.
05-10-2008, 08:26 PM   #10
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I am guessing I don't need the calibration on my current Tamron 28-75 as it is sharp and accurate on my k100D. Previously I thought it has a case of BF but I have concluded that it is due to the thin DOF.

But I am not sure if the next Tamrons I am interested in (such as the Tamron 90/f2.8 and Tamron 70-300/f2.8) will require any calibration or not. And the fear is that if I do need to calibrate any of these lenses in k20D, will k20D automatically apply the settings to all the other tamron lenses, something which is not desirable.

If K20D is not able to distinguish between sigma 10-20 and sigma 17-70, I guess similar will apply to tamron lenses. I am really hoping that I am just wrong.
05-11-2008, 07:29 AM   #11
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QuoteOriginally posted by raider Quote
I am guessing I don't need the calibration on my current Tamron 28-75 as it is sharp and accurate on my k100D. Previously I thought it has a case of BF but I have concluded that it is due to the thin DOF.

But I am not sure if the next Tamrons I am interested in (such as the Tamron 90/f2.8 and Tamron 70-300/f2.8) will require any calibration or not. And the fear is that if I do need to calibrate any of these lenses in k20D, will k20D automatically apply the settings to all the other tamron lenses, something which is not desirable.

If K20D is not able to distinguish between sigma 10-20 and sigma 17-70, I guess similar will apply to tamron lenses. I am really hoping that I am just wrong.
it could just be an isolated incident. i have 2 other sigma lenses, and they dont get seen as the same one as the 28mm.

think of it this way......at least w/ the k20, you have that option....
05-11-2008, 07:45 AM   #12
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QuoteQuote:
it could just be an isolated incident. i have 2 other sigma lenses, and they dont get seen as the same one as the 28mm.
I hope so too

Thanks again for your information.
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