Sharpness of focus

Shakey · 03-10-2019, 06:33 AM

Can someone please direct me to the instructions for testing and then correcting the focus on a lens please? Did a search and got many threads but am looking for some very direct instructions please. I have the 150-450 and cant get sharp photos.
Thanks

Sagala · 03-10-2019, 07:10 AM

Fixing Front and Back Focus and also Yvon Bourque adjustment chart

**ProfessorBuzz** · 03-10-2019, 07:23 AM

Do you mean Auto-focus, or are you manually focusing?
Suggestions: Tripod. Wireless remote control. Self timer. Mirror Lock Up. Rear AF button and shutter button activated focus off.

Be prepared to spend a couple of hours on this. It will be worth it.

To refine the focus, depends on the camera, for the K1, you can adjust focus front and back across a range of +/- 10 from the defaults.

You'll need a test target. Put it at 25x to 50x the focal length of the lens (eg if you use that lens at 450 most of the time, your target need to be at about 35' to 75' away).

A few options that I've tried that can work:

A bunch of AA batteries with the lettering facing the camera, or a bunch of tall flat-head wood screws all in a column, proceeding away from the camera.

Camera must be dead-on at same height, level, and square to the target. Then go through taking 3-5 shots at each step in the AF Fine Adjustment menu (set to option 3, where it stores the adjustment for each lens). View the shots on a large monitor.

This also works well, with the long ruler, and the software, and is time consuming but nails it. It costs more, but is a fraction of the price of your lens:
LensAlign

I had the competing one, and it did not work as well.

Another option that works for some folks is to print a Bob Atkins photo test chart from his website, and stick on a wall. Then use it as a test target, but I found this did not too well.

Some folks use the Dot Tune method.

You Tube

I haven't tried it, but it looks like it is less time consuming.

Other things

- if you wear glasses/contacts, get your eyes checked, get your prescription up to date, play with the diopter dial on the viewfinder. One click in either direction can make all the difference.
- don't try to check focus on the camera LCD panel. Download to a PC and scrutinize there.

Shakey · 03-10-2019, 07:55 AM

Thank you. I also found instructions in the K-3 ebook in chapter 2.I'm seeing the problem when using auto focus with that particular lens.

derekkite · 03-10-2019, 08:33 AM

What body are you using it on?

I do something really simple. Get a box with a printed label, cereal box or something like that, and a yardstick. Set your camera and lens on a bean bag or sand bag, and the box 15-20 ft away. Lean the yardstick up against it so that the surface of the box is a bit past half way of the yardstick. Set shutter speed to 1/1000 and aperture to f5.6, full zoom. Turn the focus ring one way, 2 second timer, focus take a shot. You should have distinct boundaries of focus on the yardstick numbers. Adjust in the camera body + - so you are in the front half.

There are four sources of softness.

1. Technique. Settings, shutter speed, how the lens is held.
2. Vibration.
3. lens adjustment
4. Just a soft lens.

1. Technique. I shoot on a tripod most of the time. Find a minimum shutter speed that works. Set up your camera body to back button focus. Drape your arm on the lens when you shoot. Use Live View and shutter delay. Techniques target shooters use work as well; breathing, holding properly, etc. Learn to depress the shutter without moving the body. A helpful tool is Photoshop. There is a module that can correct for motion blur. I haven't used it except to see what motion blur there is. I was having difficulty getting sharpness, and found that all my shots had oblong dots. Increasing shutter speed helps.

2. Vibration is the bane of long lens shooters. Tripods and gimbals have harmonic resonances that can translate into soft shots. Shutter shock is the source sometimes. That is why you start with a bean bag or sand bag when you do your testing. From there it is trial and error. I purchased an expensive gimbal, the Katana Jr. from ProMediaGear and noticed right away an improvement. Once source of vibration removed.

3. The cereal box and yardstick.

4. If you can't get a sharp shot when on a sandbag and stationary target and high shutter speed, then maybe you have a lens that isn't spot on. Try at f8. There may be a sweet spot that works, or you might have a dud.

If everything is functional and sound, increasing shutter speed and stopping down to f8 will give you better results.

**Kobie** · 03-11-2019, 05:38 PM

This is straight from Ricoh...
How to optimize focusing accuracy with large-aperture lenses / Beautiful Photo-life | RICOH IMAGING
I hope it helps

**rogerstg** · 03-12-2019, 05:51 AM

Originally posted by ProfessorBuzz

Some folks use the Dot Tune method.
I haven't tried it, but it looks like it is less time consuming.

I've used it and not only can it be less time consuming, but seems more logical/scientific. It accepts the reality that there is an adjustment range at which a camera will interpret something as "in focus" and sets the fine tune adjustment to the center of that range. The more common method (fastidious test setup, test shots, interpretation of each shot, guessed adjustment; repeat test shots, interpretation of each shot, guessed adjustment; repeat . . .) seems to rely on tireless testing with the hope of stumbling on a representative sample of the camera's AF tolerances to find the acceptable range of adjustment.

In summary the dot tune method is:
Set up AF Target and put Camera on tripod
Establish Critical focus in Live view. Exit LV when done
Switch to manual focus and set initial AF tune to 0
Cycle through AF tune values to find the range of AF
Set final AF tune to midpoint of range

Last edited by rogerstg; 03-15-2019 at 07:15 AM.

Shakey · 03-13-2019, 05:46 PM

Thank you all,

sutherland · 03-15-2019, 06:42 AM

Do you have any examples (with EXIF) you can provide that best illustrates the issue?

Lens Calibration is a good way to fix known issues with either front or back focus, but it could also be due to:
- technique
- camera settings
- etc.

Shakey · 03-16-2019, 08:04 AM

Getting eyes checked Monday...may be part of the problem. I've also been shooting through a window recently due to the weather and that's a problem, so I will get outside and take some test shots before doing anything and submit for your review, but it will be a little while.

**Kerrowdown** · 03-16-2019, 08:28 AM

Originally posted by Shakey

've also been shooting through a window recently due to the weather and that's a problem

That's a definite contributor to the issue, try without a windy (window glass) in the way and see the difference.

**Rondec** · 03-16-2019, 09:27 AM

For what it's worth, I generally use live view to calibrate my lenses. (See here: Camera AF Microadjustment - for free Canon, Nikon, Sony - any camera with adjustment)

Shakey · 04-28-2019, 06:06 AM

Originally posted by Shakey

Getting eyes checked Monday...may be part of the problem. I've also been shooting through a window recently due to the weather and that's a problem, so I will get outside and take some test shots before doing anything and submit for your review, but it will be a little while.

I finally got around to taking a few shots for you to review. These were shot in green mode using the Pentax 1.4x tele-converter and a B&W XS pro digital filter. The cranes were about 100 yards away (+ or -).
I consider myself sub-amerature in that I hardly ever get out to use my equiment so each time is like a new begining wich is unfortunate.
These are samples only for your technical review. I did not intend them to be reviewed for artistic value. I need to figure out how to use the equipment I have first.
Given the distance I woud want to crop them if they were to be keepers. Once you crop the image steadily gets worse. Am I expecting too much?
Your advice will be greatly appreciated.

**mikesbike** · 04-28-2019, 07:07 AM

The 3rd shot with the 2 birds is the best one both for composition and sharpness, though there is the appearance of slight front focus. Two things- firstly, I definitely do not recommend shooting in the AUTO green mode. This turns virtually all settings factors over to the camera, removing any control. Use the "P" mode for fully automatic exposure so you can change any factor as you wish. This appears to be a sunny scene, and should not require ISO 400, but it's ok to use that if you need more aperture and shutter speed range.

I presume you are using center-only spot AF? And it is set to AF-S? Also, the shutter speed of 1/640 sec is just adequate for this range of focal length and live subjects. You could do with a larger aperture than f/11 where some degradation due to diffraction will begin to appear. I am also not sure if the reported f/11 is accurate, being that with a TC the actual aperture rating becomes smaller (higher number). With a somewhat larger aperture setting, you can get a higher shutter speed. If your user name is any indication, this might be of significant help.

If you are using the "P" mode, you can override the camera's aperture choice by using your thumb dial to select a somewhat larger one (smaller number), which will simultaneously force the camera to change the shutter speed to a higher value. So you'd have a higher shutter speed to fortify anti-shake and to better freeze movement, and also a mid-point aperture that is taking advantage of the best aperture range to provide optimum resolution performance from your lens.

Then, if possible, it would be better to get these birds against a background that is of contrasting color to their own so they would stand out from it.

By overriding your camera's choice of aperture (thumb dial) or directly dialing a specific shutter speed (front finger dial), you are employing the exclusive Pentax Hyper Program system. You can then return to fully automated exposure with a touch of the green button.

BTW, what kind of filter is an XS filter? I am wondering if it cuts incoming light to any degree. Why shoot with a filter for such a well-lit scene with no particular environmental issues, reflections, or harsh contrast? (especially when testing lens performance!)

pentaxfall · 04-28-2019, 07:11 AM

These pictures do not show lens problem. You may be expecting beak to be in focus but it seems some other body part is in focus. So you have to check where was your focus point. There could be front focus & back focus problem. In order to test that do the scale test. It is difficult diagnose front focus & back focus problem using these pictures.

03-10-2019, 06:33 AM	#1
Shakey Senior Member Join Date: May 2014 Location: Wisconsin, USA Posts: 211	Sharpness of focus Can someone please direct me to the instructions for testing and then correcting the focus on a lens please? Did a search and got many threads but am looking for some very direct instructions please. I have the 150-450 and cant get sharp photos. Thanks

03-16-2019, 08:28 AM	#11
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,819	Originally posted by Shakey 've also been shooting through a window recently due to the weather and that's a problem That's a definite contributor to the issue, try without a windy (window glass) in the way and see the difference. Last edited by Kerrowdown; 03-18-2019 at 01:43 PM.

04-28-2019, 07:07 AM	#14
mikesbike Site Supporter Join Date: Dec 2016 Location: Southeastern Michigan Posts: 4,549	The 3rd shot with the 2 birds is the best one both for composition and sharpness, though there is the appearance of slight front focus. Two things- firstly, I definitely do not recommend shooting in the AUTO green mode. This turns virtually all settings factors over to the camera, removing any control. Use the "P" mode for fully automatic exposure so you can change any factor as you wish. This appears to be a sunny scene, and should not require ISO 400, but it's ok to use that if you need more aperture and shutter speed range. I presume you are using center-only spot AF? And it is set to AF-S? Also, the shutter speed of 1/640 sec is just adequate for this range of focal length and live subjects. You could do with a larger aperture than f/11 where some degradation due to diffraction will begin to appear. I am also not sure if the reported f/11 is accurate, being that with a TC the actual aperture rating becomes smaller (higher number). With a somewhat larger aperture setting, you can get a higher shutter speed. If your user name is any indication, this might be of significant help. If you are using the "P" mode, you can override the camera's aperture choice by using your thumb dial to select a somewhat larger one (smaller number), which will simultaneously force the camera to change the shutter speed to a higher value. So you'd have a higher shutter speed to fortify anti-shake and to better freeze movement, and also a mid-point aperture that is taking advantage of the best aperture range to provide optimum resolution performance from your lens. Then, if possible, it would be better to get these birds against a background that is of contrasting color to their own so they would stand out from it. By overriding your camera's choice of aperture (thumb dial) or directly dialing a specific shutter speed (front finger dial), you are employing the exclusive Pentax Hyper Program system. You can then return to fully automated exposure with a touch of the green button. BTW, what kind of filter is an XS filter? I am wondering if it cuts incoming light to any degree. Why shoot with a filter for such a well-lit scene with no particular environmental issues, reflections, or harsh contrast? (especially when testing lens performance!) Last edited by mikesbike; 04-28-2019 at 07:26 AM.

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03-10-2019, 07:10 AM	#2
Sagala Senior Member Join Date: Sep 2012 Location: Montréal Photos: Gallery Posts: 101	Fixing Front and Back Focus and also Yvon Bourque adjustment chart

03-10-2019, 07:55 AM	#4
Shakey Senior Member Join Date: May 2014 Location: Wisconsin, USA Posts: 211 Original Poster	Thank you. I also found instructions in the K-3 ebook in chapter 2.I'm seeing the problem when using auto focus with that particular lens.

03-10-2019, 08:33 AM	#5
derekkite Pentaxian Join Date: Sep 2011 Location: Nelson B.C. Posts: 3,782	What body are you using it on? I do something really simple. Get a box with a printed label, cereal box or something like that, and a yardstick. Set your camera and lens on a bean bag or sand bag, and the box 15-20 ft away. Lean the yardstick up against it so that the surface of the box is a bit past half way of the yardstick. Set shutter speed to 1/1000 and aperture to f5.6, full zoom. Turn the focus ring one way, 2 second timer, focus take a shot. You should have distinct boundaries of focus on the yardstick numbers. Adjust in the camera body + - so you are in the front half. There are four sources of softness. 1. Technique. Settings, shutter speed, how the lens is held. 2. Vibration. 3. lens adjustment 4. Just a soft lens. 1. Technique. I shoot on a tripod most of the time. Find a minimum shutter speed that works. Set up your camera body to back button focus. Drape your arm on the lens when you shoot. Use Live View and shutter delay. Techniques target shooters use work as well; breathing, holding properly, etc. Learn to depress the shutter without moving the body. A helpful tool is Photoshop. There is a module that can correct for motion blur. I haven't used it except to see what motion blur there is. I was having difficulty getting sharpness, and found that all my shots had oblong dots. Increasing shutter speed helps. 2. Vibration is the bane of long lens shooters. Tripods and gimbals have harmonic resonances that can translate into soft shots. Shutter shock is the source sometimes. That is why you start with a bean bag or sand bag when you do your testing. From there it is trial and error. I purchased an expensive gimbal, the Katana Jr. from ProMediaGear and noticed right away an improvement. Once source of vibration removed. 3. The cereal box and yardstick. 4. If you can't get a sharp shot when on a sandbag and stationary target and high shutter speed, then maybe you have a lens that isn't spot on. Try at f8. There may be a sweet spot that works, or you might have a dud. If everything is functional and sound, increasing shutter speed and stopping down to f8 will give you better results.

03-11-2019, 05:38 PM	#6
Kobie Site Supporter Join Date: Oct 2014 Location: Bowmanville Photos: Albums Posts: 1,211	This is straight from Ricoh... How to optimize focusing accuracy with large-aperture lenses / Beautiful Photo-life \| RICOH IMAGING I hope it helps

03-12-2019, 05:51 AM	#7
rogerstg Loyal Site Supporter Join Date: Oct 2007 Location: Rhode Island Photos: Albums Posts: 1,168	Originally posted by ProfessorBuzz Some folks use the Dot Tune method. I haven't tried it, but it looks like it is less time consuming. I've used it and not only can it be less time consuming, but seems more logical/scientific. It accepts the reality that there is an adjustment range at which a camera will interpret something as "in focus" and sets the fine tune adjustment to the center of that range. The more common method (fastidious test setup, test shots, interpretation of each shot, guessed adjustment; repeat test shots, interpretation of each shot, guessed adjustment; repeat . . .) seems to rely on tireless testing with the hope of stumbling on a representative sample of the camera's AF tolerances to find the acceptable range of adjustment. In summary the dot tune method is: Set up AF Target and put Camera on tripod Establish Critical focus in Live view. Exit LV when done Switch to manual focus and set initial AF tune to 0 Cycle through AF tune values to find the range of AF Set final AF tune to midpoint of range Last edited by rogerstg; 03-15-2019 at 07:15 AM.

03-13-2019, 05:46 PM	#8
Shakey Senior Member Join Date: May 2014 Location: Wisconsin, USA Posts: 211 Original Poster	Thank you all,

03-15-2019, 06:42 AM	#9
sutherland Senior Member Join Date: Jun 2018 Posts: 220	Do you have any examples (with EXIF) you can provide that best illustrates the issue? Lens Calibration is a good way to fix known issues with either front or back focus, but it could also be due to: - technique - camera settings - etc.

03-16-2019, 08:04 AM	#10
Shakey Senior Member Join Date: May 2014 Location: Wisconsin, USA Posts: 211 Original Poster	Getting eyes checked Monday...may be part of the problem. I've also been shooting through a window recently due to the weather and that's a problem, so I will get outside and take some test shots before doing anything and submit for your review, but it will be a little while.

03-16-2019, 09:27 AM	#12
Rondec Loyal Site Supporter Join Date: Mar 2009 Location: Gladys, Virginia Photos: Gallery Posts: 27,653	For what it's worth, I generally use live view to calibrate my lenses. (See here: Camera AF Microadjustment - for free Canon, Nikon, Sony - any camera with adjustment)

04-28-2019, 07:11 AM	#15
pentaxfall Veteran Member Join Date: Sep 2017 Location: Bangalore, India Posts: 581	These pictures do not show lens problem. You may be expecting beak to be in focus but it seems some other body part is in focus. So you have to check where was your focus point. There could be front focus & back focus problem. In order to test that do the scale test. It is difficult diagnose front focus & back focus problem using these pictures.