Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-06-2013, 09:09 AM   #16
Site Supporter
tabl10s's Avatar

Join Date: Jun 2011
Location: Sacramento(formerly from B'Ham, England).
Posts: 1,401
Is there a video tutorial on how to do adjustments?

04-06-2013, 11:56 AM   #17
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
This might help
AF microadjustment for the 1Ds mark III, 1D Mk3, 5D Mk2, 7D, 1D X
04-10-2013, 04:28 PM - 1 Like   #18
Senior Member
zekewhipper's Avatar

Join Date: Dec 2010
Photos: Albums
Posts: 298
QuoteOriginally posted by fccwpe Quote
All my manual lenses require -10. The brand new Sigma 50mm f1.4 also requires -10. Very strange because the Sigma is all over the place... I just don't know.
You don't make adjustments for manual lenses, because the focusing is done manually.
04-10-2013, 04:30 PM   #19
Senior Member
zekewhipper's Avatar

Join Date: Dec 2010
Photos: Albums
Posts: 298
QuoteOriginally posted by Bruce Quote
Agreed, +9 on most of my M42s and anywhere between +6 - +9 for the newer lenses. The firmware upgrade made no difference that I could detect.
You don't make adjustments for manual lenses, because the focusing is done manually.

04-10-2013, 04:31 PM   #20
Senior Member
zekewhipper's Avatar

Join Date: Dec 2010
Photos: Albums
Posts: 298
QuoteOriginally posted by jcasey52 Quote
I own the Super Takumar 28mm (58mm filter version) and Zeiss Flektogon 35mm F2.4. I've played around a bit with the +/- focus adjustments but couldn't see any difference. I have no experience being an engineer for Pentax or any other DSLR maker for that matter (which seems to be required these days). Can anyone help me regarding how I can best determine if corrective settings are required and whether it's +/-, or is it just try both and see which looks better?
You don't make adjustments for manual lenses, because the focusing is done manually.
04-10-2013, 04:32 PM   #21
Senior Member
zekewhipper's Avatar

Join Date: Dec 2010
Photos: Albums
Posts: 298
Folks, the micro-adjustment function is for AF lenses only.
04-23-2013, 05:39 PM   #22
Site Supporter
tabl10s's Avatar

Join Date: Jun 2011
Location: Sacramento(formerly from B'Ham, England).
Posts: 1,401
QuoteOriginally posted by zekewhipper Quote
You don't make adjustments for manual lenses, because the focusing is done manually.
If this is the case, what happens when you use a 1.2 at it's max aperture and the hexagon indicates you're in focus when you actually aren't?
04-24-2013, 02:41 PM   #23
Senior Member
zekewhipper's Avatar

Join Date: Dec 2010
Photos: Albums
Posts: 298
QuoteOriginally posted by tabl10s Quote
...the hexagon indicates you're in focus when you actually aren't?
That only reenforces the fact that you should not always trust the camera. Focus has to be something agreed to between you and the camera, and should trust yourself more. As for "...you use a 1.2...", I assuming you mean a teleconverter. Teleconverters almost always degrade image quality a bit, but whether the degradation is of any significance is a personal thing. When manually focusing lenses, it is best not to focus them wide open. Why, because virtually every lens (with very rare exceptions) gets a tad bit soft wide open, (some obviously more than others). With that being the case, you can be focusing and focusing and focusing and things may never look tack sharp. It is better to close the aperture down a stop or two from wide open to focus. Then if you still want to shoot wide open, then open the aperture back up but only after having nailed the focus first.


Last edited by zekewhipper; 04-24-2013 at 04:09 PM.
04-24-2013, 02:45 PM   #24
Site Supporter
tabl10s's Avatar

Join Date: Jun 2011
Location: Sacramento(formerly from B'Ham, England).
Posts: 1,401
What makes you think I use a TC with a 1.2(I don't)?
04-24-2013, 03:22 PM   #25
Loyal Site Supporter
AdrianM's Avatar

Join Date: Aug 2008
Location: Ipswich, Queensland, Australia
Photos: Gallery | Albums
Posts: 567
QuoteOriginally posted by Bob from Aus Quote
While we are on the subject. If say my 500mm requires an adjustment of + 6 does that mean if my other lenses are also out, they will also be around + 6?
Just noticed your post, Bob. My Sigma 500 f4.5 APO DG EX requires a +5 on my K5, and I am still working on the adjustment for my K5IIS but it is close to +4, but other lenses such as my DA*300 are 0.
04-24-2013, 04:12 PM   #26
Senior Member
zekewhipper's Avatar

Join Date: Dec 2010
Photos: Albums
Posts: 298
QuoteOriginally posted by tabl10s Quote
What makes you think I use a TC with a 1.2(I don't)?
There is where you are losing me. A 1.2...what? The only thing I know that is a "1.2" is a 1.2x teleconverter. Did you mean a "f1.2" lens? At wide open, the DoF for a f1.2 lens will be very shallow. When you are manually focusing, you could hit the sweet spot for the AF sensor, and before it can "beep" you have already blown by the correct focus setting. That of course would give you the impression that the focus is off, which it is, but that is not the camera's fault, nor is it really your's. It is just the way things go. When manually focusing old M42-mount lenses, I turn the red dot off, and don't generally use the AF assist either unless the lighting is really dim. You have to creep the focus ring slowly back and forth to get the focus right in the end.

Last edited by zekewhipper; 04-24-2013 at 04:26 PM.
04-25-2013, 09:39 PM   #27
Site Supporter
tabl10s's Avatar

Join Date: Jun 2011
Location: Sacramento(formerly from B'Ham, England).
Posts: 1,401
QuoteOriginally posted by zekewhipper Quote
There is where you are losing me. A 1.2...what? The only thing I know that is a "1.2" is a 1.2x teleconverter. Did you mean a "f1.2" lens? At wide open, the DoF for a f1.2 lens will be very shallow. When you are manually focusing, you could hit the sweet spot for the AF sensor, and before it can "beep" you have already blown by the correct focus setting. That of course would give you the impression that the focus is off, which it is, but that is not the camera's fault, nor is it really your's. It is just the way things go. When manually focusing old M42-mount lenses, I turn the red dot off, and don't generally use the AF assist either unless the lighting is really dim. You have to creep the focus ring slowly back and forth to get the focus right in the end.
To my knowledge, there's no such thing as a 1.2 TC.
04-25-2013, 10:22 PM - 1 Like   #28
Veteran Member
awaldram's Avatar

Join Date: May 2008
Location: Hampshire
Photos: Gallery
Posts: 720
Wow what a load of misconceptions in one thread !!

The k5 has f5.6 baseline and the k5 ii f2.8

Ergo neither can indicate peak focus for lens faster than f2.8. AF works with these lens by interpolating the variance between two peaks and adjust to the correct ratio point.
To do this accurate calibration must be done correctly and take account of the different front back ratios various focal lengths and distance will have .

If you have calibrated to 50/50 then you have screwed you camera good and proper and it cannot possibly focus accurately with fast glass, The most obvious symptom of this if the lens will stop at different micro point each attempt giving the impression of inconsistency.

As for manual focus of an f1.2 lens using the camera AF sensor to define 'in focus' then read the above and understand its not possible you've exceeded the limit of the sensor.
No adjustment will make it work.

You could adjust from left note point adjust from right note point use DoF calc to asses ratio required and place lens at that point, It would then be focues, But much easier use you eyes as they were designed. ensuring that the vewifinder adjustment is corrected for your eyesight.
Of cause you also need to understand the limit of the factory fitted focus screen (about f2.8) so unless you have fitted a proper split prism you have no chance focusing an f1.2 lens on a modern Dslr or even a 1.4 , The camera will make a good job for AF for f1.4 though.
Guess that's why you need 'skills' to use these type of lens manually where you can adjust for peak focus with nothing visually to aid you.

I am bewildered that anyone would attempt AF calibration without the faintest concept of what is 'correct'
As an example
an f.12 50mm lens focused on a target 100ft away should have 36% of the image in front in focus and 64% behind again if you adjust for 50/50 you've shafted your camera.
02-27-2014, 04:19 PM   #29
Senior Member
zekewhipper's Avatar

Join Date: Dec 2010
Photos: Albums
Posts: 298
QuoteOriginally posted by tabl10s Quote
If this is the case, what happens when you use a 1.2 at it's max aperture and the hexagon indicates you're in focus when you actually aren't?
First of all, you should not completely trust the focus indicator. Why? Because...

1) ...at f1.2 your DoF (depth of field) can be so shallow that as you focus not everything you want to be in focus will be.
2) ...when you shoot wide open like that you will probably not get everything tack sharp anyways. All lenses get a tad soft wide open, so it is a good idea just to never (unless you have a pressing need to) shoot wide open.

With that said, it is a good idea to open the lens wide open and then purposely stop it down one stop of so to do your actual focusing. That aids in the accuracy of your focusing, because the image will naturally come in sharper as you view it.

3) As you manually focus, especially with a lens wide open, you can actually overshoot the mark as it were before the camera has a chance to give you the in focus indication. In other words, you can miss the focus before the camera can tell you to stop because you are moving faster than the camera can react to.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, dslr, k-5, k-5 ii, k-5 iis, k5, ltd, pentax k-5
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Front focus and back focus K-5 allantois Pentax K-5 48 03-31-2012 09:21 PM
Front focus far away, back focus up close hjb981 Pentax K-5 14 05-05-2011 01:28 AM
Can a manual-focus lens have back focus problems? PocketPixels Pentax DSLR Discussion 33 02-13-2011 05:37 AM
Trying to understand front focus/back focus thing 41ants Troubleshooting and Beginner Help 16 08-31-2010 08:42 AM
front focus, back focus or other? imfinetoday Pentax SLR Lens Discussion 23 07-08-2010 11:49 AM



All times are GMT -7. The time now is 07:02 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top