Best focusing method for DA 15 Limited?

TerryL · 04-08-2019, 06:40 AM

Hello folks,
I have a new DA 15 Limited, and am not happy with the sharpness. I want to try different focusing methods to get the best results, rather than send it back. Could someone who has this lens share their focusing method, and overall opinion on what I can expect?
Thank you,
Terry

aaacb · 04-08-2019, 06:48 AM - **1 Like**

The lens has field curvature, so at f4 corners will be out of focus if you're photographing a flat subject perpendicularly. I dont find this a problem in practice, where there's usually depth in the image. I often use it stopped down to f5.6 or f8, with autofocus. Since it's a ultra wide, manual focus is quite tricky with clear dslr screens. For landscapes I use hyperfocal distance or just guesstimate some point midway in the scene, or focus stack on rare occasions. If it's critical I'll zoom in live view and check various points in the frame, on a tripod of course.

TerryL · 04-08-2019, 07:17 AM

Originally posted by aaacb

The lens has field curvature, so at f4 corners will be out of focus if you're photographing a flat subject perpendicularly. I dont find this a problem in practice, where there's usually depth in the image. I often use it stopped down to f5.6 or f8, with autofocus. Since it's a ultra wide, manual focus is quite tricky with clear dslr screens. For landscapes I use hyperfocal distance or just guesstimate some point midway in the scene, or focus stack on rare occasions. If it's critical I'll zoom in live view and check various points in the frame, on a tripod of course.

Thank you for your reply. I use the hyperlocal scale on my Irix 11mm, and 15mm. I plan to do something similar, today. I thought about focusing on the foreground, and stop down to f/8 just like you suggested. Do you get sharp results with your method?
Terry

**microlight** · 04-08-2019, 08:26 AM - **2 Likes**

Don’t forget to fine-tune the AF for best results.

TerryL · 04-08-2019, 09:26 AM

Originally posted by microlight

Don’t forget to fine-tune the AF for best results.

Well, if I'm happy with results out to the box, I normally leave it. I'll see once I test the next shots. I think part of my problem was that I wasn't shooting it like a 15mm. I wasn't focusing on the foreground and stopping down like I do on my Full Frame UWA lenses. I sure hope that solves the problem. Thank you.
Terry

**pres589** · 04-08-2019, 09:47 AM

Assuming the subject is very far away and you have enough light (or time) for proper exposure, f8 & set the focusing ring just of infinite and see what happens. Sharing example images you aren't happy with here can help drum up better advise or questions.

TerryL · 04-08-2019, 10:13 AM

Originally posted by pres589

Assuming the subject is very far away and you have enough light (or time) for proper exposure, f8 & set the focusing ring just of infinite and see what happens. Sharing example images you aren't happy with here can help drum up better advise or questions.

I'll definitely try that. Thank you.
Terry

TerryL · 04-08-2019, 10:50 AM - **1 Like**

Originally posted by pres589

Assuming the subject is very far away and you have enough light (or time) for proper exposure, f8 & set the focusing ring just of infinite and see what happens. Sharing example images you aren't happy with here can help drum up better advise or questions.

Ok, your method worked better than anything else. This is a straight out of camera jpeg with no processing, from my KP.
Terry

**pres589** · 04-08-2019, 11:22 AM

At a quick glance, that image looks fine as far as sharpness and such is concerned. If it isn't able to deliver the same results when using autofocus then your issue lies in that large area. The lens may need some AF adjustment in-camera to come out right OR the camera might be damaged somehow OR you're using an odd AF detection point scheme for that scene.

That lens is pretty sharp all over at f8 baring field curvature aspects. "f8 and be there" will help you deal with whatever is causing poor AF performance with it until you get that figured out. Others that are better at troubleshooting may have opinions on how to figure out where the fault or faults are.

TerryL · 04-08-2019, 11:56 AM

Originally posted by pres589

At a quick glance, that image looks fine as far as sharpness and such is concerned. If it isn't able to deliver the same results when using autofocus then your issue lies in that large area. The lens may need some AF adjustment in-camera to come out right OR the camera might be damaged somehow OR you're using an odd AF detection point scheme for that scene.

That lens is pretty sharp all over at f8 baring field curvature aspects. "f8 and be there" will help you deal with whatever is causing poor AF performance with it until you get that figured out. Others that are better at troubleshooting may have opinions on how to figure out where the fault or faults are.

Thank you very much for your help.
Terry

Marcel K · 04-08-2019, 11:59 AM

Check out this thread with some good tips:
‘What K3 settings for landscape?‘

TerryL · 04-08-2019, 01:06 PM

Originally posted by pres589

At a quick glance, that image looks fine as far as sharpness and such is concerned. If it isn't able to deliver the same results when using autofocus then your issue lies in that large area. The lens may need some AF adjustment in-camera to come out right OR the camera might be damaged somehow OR you're using an odd AF detection point scheme for that scene.

That lens is pretty sharp all over at f8 baring field curvature aspects. "f8 and be there" will help you deal with whatever is causing poor AF performance with it until you get that figured out. Others that are better at troubleshooting may have opinions on how to figure out where the fault or faults are.

Can you recommend a good AF mode to use for my HD DA 15mm f/4? I definitely want to use it around my house when company is over, and holidays.

**pres589** · 04-08-2019, 01:14 PM - **1 Like**

Originally posted by TerryL

Can you recommend a good AF mode to use for my HD DA 15mm f/4? I definitely want to use it around my house when company is over, and holidays.

Use the previous post's advice and read this thread; What K3 settings for landscape? - PentaxForums.com

Something else to look at is this; http://www.dofmaster.com/dofjs.html

All Pentax crop bodies have the same size sensor so you can pick K-7 and it'll work the same as your actual camera. I punch 20 feet away and wide open at f4 to try and get a "worst case" going. Hyperfocal focusing distance is calcuated at just over 9 feet away. That's effectively where you set the focusing ring per my earlier instruction.

To put it another way, with the relative speed of this lens, the focal length of the lens, and the effect of a crop sensor on depth of field, you will probably fine just leaving the focusing ring where it is for a lot of the shots you might take with this lens.

TerryL · 04-08-2019, 01:34 PM

Originally posted by Marcel K

Check out this thread with some good tips:
‘What K3 settings for landscape?‘

I'm not finding that?

Marcel K · 04-08-2019, 01:44 PM

Link in post #13

04-08-2019, 09:26 AM	#5
TerryL Pentaxian Join Date: Jan 2018 Location: Virginia, USA Photos: Albums Posts: 850 Original Poster	Originally posted by microlight Don’t forget to fine-tune the AF for best results. Well, if I'm happy with results out to the box, I normally leave it. I'll see once I test the next shots. I think part of my problem was that I wasn't shooting it like a 15mm. I wasn't focusing on the foreground and stopping down like I do on my Full Frame UWA lenses. I sure hope that solves the problem. Thank you. Terry Last edited by TerryL; 04-08-2019 at 09:30 AM. Reason: apelling

04-08-2019, 01:14 PM - 1 Like	#13
pres589 Site Supporter Join Date: Jan 2014 Location: Wichita, KS Photos: Albums Posts: 4,529	Originally posted by TerryL Can you recommend a good AF mode to use for my HD DA 15mm f/4? I definitely want to use it around my house when company is over, and holidays. Use the previous post's advice and read this thread; What K3 settings for landscape? - PentaxForums.com Something else to look at is this; http://www.dofmaster.com/dofjs.html All Pentax crop bodies have the same size sensor so you can pick K-7 and it'll work the same as your actual camera. I punch 20 feet away and wide open at f4 to try and get a "worst case" going. Hyperfocal focusing distance is calcuated at just over 9 feet away. That's effectively where you set the focusing ring per my earlier instruction. To put it another way, with the relative speed of this lens, the focal length of the lens, and the effect of a crop sensor on depth of field, you will probably fine just leaving the focusing ring where it is for a lot of the shots you might take with this lens. Last edited by pres589; 04-08-2019 at 01:23 PM.

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04-08-2019, 06:40 AM	#1
TerryL Pentaxian Join Date: Jan 2018 Location: Virginia, USA Photos: Albums Posts: 850	Best focusing method for DA 15 Limited? Hello folks, I have a new DA 15 Limited, and am not happy with the sharpness. I want to try different focusing methods to get the best results, rather than send it back. Could someone who has this lens share their focusing method, and overall opinion on what I can expect? Thank you, Terry

04-08-2019, 06:48 AM - 1 Like	#2
aaacb Pentaxian Join Date: May 2016 Photos: Gallery Posts: 3,724	The lens has field curvature, so at f4 corners will be out of focus if you're photographing a flat subject perpendicularly. I dont find this a problem in practice, where there's usually depth in the image. I often use it stopped down to f5.6 or f8, with autofocus. Since it's a ultra wide, manual focus is quite tricky with clear dslr screens. For landscapes I use hyperfocal distance or just guesstimate some point midway in the scene, or focus stack on rare occasions. If it's critical I'll zoom in live view and check various points in the frame, on a tripod of course.

04-08-2019, 07:17 AM	#3
TerryL Pentaxian Join Date: Jan 2018 Location: Virginia, USA Photos: Albums Posts: 850 Original Poster	Originally posted by aaacb The lens has field curvature, so at f4 corners will be out of focus if you're photographing a flat subject perpendicularly. I dont find this a problem in practice, where there's usually depth in the image. I often use it stopped down to f5.6 or f8, with autofocus. Since it's a ultra wide, manual focus is quite tricky with clear dslr screens. For landscapes I use hyperfocal distance or just guesstimate some point midway in the scene, or focus stack on rare occasions. If it's critical I'll zoom in live view and check various points in the frame, on a tripod of course. Thank you for your reply. I use the hyperlocal scale on my Irix 11mm, and 15mm. I plan to do something similar, today. I thought about focusing on the foreground, and stop down to f/8 just like you suggested. Do you get sharp results with your method? Terry

04-08-2019, 08:26 AM - 2 Likes	#4
microlight Site Supporter Join Date: Sep 2011 Location: Hampshire, UK Posts: 2,129	Don’t forget to fine-tune the AF for best results.

04-08-2019, 09:47 AM	#6
pres589 Site Supporter Join Date: Jan 2014 Location: Wichita, KS Photos: Albums Posts: 4,529	Assuming the subject is very far away and you have enough light (or time) for proper exposure, f8 & set the focusing ring just of infinite and see what happens. Sharing example images you aren't happy with here can help drum up better advise or questions.

04-08-2019, 10:13 AM	#7
TerryL Pentaxian Join Date: Jan 2018 Location: Virginia, USA Photos: Albums Posts: 850 Original Poster	Originally posted by pres589 Assuming the subject is very far away and you have enough light (or time) for proper exposure, f8 & set the focusing ring just of infinite and see what happens. Sharing example images you aren't happy with here can help drum up better advise or questions. I'll definitely try that. Thank you. Terry

04-08-2019, 11:22 AM	#9
pres589 Site Supporter Join Date: Jan 2014 Location: Wichita, KS Photos: Albums Posts: 4,529	At a quick glance, that image looks fine as far as sharpness and such is concerned. If it isn't able to deliver the same results when using autofocus then your issue lies in that large area. The lens may need some AF adjustment in-camera to come out right OR the camera might be damaged somehow OR you're using an odd AF detection point scheme for that scene. That lens is pretty sharp all over at f8 baring field curvature aspects. "f8 and be there" will help you deal with whatever is causing poor AF performance with it until you get that figured out. Others that are better at troubleshooting may have opinions on how to figure out where the fault or faults are.

04-08-2019, 11:56 AM	#10
TerryL Pentaxian Join Date: Jan 2018 Location: Virginia, USA Photos: Albums Posts: 850 Original Poster	Originally posted by pres589 At a quick glance, that image looks fine as far as sharpness and such is concerned. If it isn't able to deliver the same results when using autofocus then your issue lies in that large area. The lens may need some AF adjustment in-camera to come out right OR the camera might be damaged somehow OR you're using an odd AF detection point scheme for that scene. That lens is pretty sharp all over at f8 baring field curvature aspects. "f8 and be there" will help you deal with whatever is causing poor AF performance with it until you get that figured out. Others that are better at troubleshooting may have opinions on how to figure out where the fault or faults are. Thank you very much for your help. Terry

04-08-2019, 11:59 AM	#11
Marcel K Forum Member Join Date: Aug 2012 Photos: Albums Posts: 82	Check out this thread with some good tips: ‘What K3 settings for landscape?‘

04-08-2019, 01:06 PM	#12
TerryL Pentaxian Join Date: Jan 2018 Location: Virginia, USA Photos: Albums Posts: 850 Original Poster	Originally posted by pres589 At a quick glance, that image looks fine as far as sharpness and such is concerned. If it isn't able to deliver the same results when using autofocus then your issue lies in that large area. The lens may need some AF adjustment in-camera to come out right OR the camera might be damaged somehow OR you're using an odd AF detection point scheme for that scene. That lens is pretty sharp all over at f8 baring field curvature aspects. "f8 and be there" will help you deal with whatever is causing poor AF performance with it until you get that figured out. Others that are better at troubleshooting may have opinions on how to figure out where the fault or faults are. Can you recommend a good AF mode to use for my HD DA 15mm f/4? I definitely want to use it around my house when company is over, and holidays.

04-08-2019, 01:34 PM	#14
TerryL Pentaxian Join Date: Jan 2018 Location: Virginia, USA Photos: Albums Posts: 850 Original Poster	Originally posted by Marcel K Check out this thread with some good tips: ‘What K3 settings for landscape?‘ I'm not finding that?

04-08-2019, 01:44 PM	#15
Marcel K Forum Member Join Date: Aug 2012 Photos: Albums Posts: 82	Link in post #13