[DW58]

Does this image look out of focus? Used auto focus on greenery at the bottom. This is a vertical rock with nothing sticking out more than 1/4" from rock face. At f/20 I thought everything would fall into DOF. Camera on tripod using remote with 3 sec. delay. Original DNG image looks a little sharper but not crisp.

All critiques, advice, and HELP! will be greatly appreciated. Am new to "digital" photography and still not used to looking at images on computer screen. A bit different to me than using a loupe on a negative or paper.

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Last edited by DW58; 03-06-2016 at 08:06 PM.

[BigMackCam]

At f/20 the image will suffer from the effects of diffraction. When you're working up close like this, the depth of field at any given aperture will be quite shallow, so it's tempting to stop down if you want as much of the subject in focus as possible, but once you get past f/8 on your APS-C camera, diffraction will start to have an impact. By f/20 I would expect it's getting quite noticeable (I never shoot at f/20... f/16 is probably my limit, and I can usually see some loss of sharpness at this aperture).

[DW58]

Thank you BigMackCam. I knew that when working up close DOF becomes quite shallow but did not know about the effects of diffraction at smaller apertures. This is exactly the type of feedback I was hoping for. Thanks again.

[Gregory_51]

Hi
As mentioned above diffraction degrades the overall sharpness. It's explained well here Digital Camera Diffraction – Resolution, Color & Micro-Contrast .If you go online and plug in the numbers you'll find the DOF is quite small. The closer you get the smaller it gets, down to fractions of an inch. In a situation like above focus stacking would work. Set the camera to manual, set the aperature to f8 and take several photos at different focus points an stack them in software. If things are moving it's a different proposition but here it would work as everything is static. Here's a link for a DOF calculator. It's also a really good site for explaining a lot of concepts. A Flexible Depth of Field Calculator
Regards

[BigMackCam]

Thank you BigMackCam. I knew that when working up close DOF becomes quite shallow but did not know about the effects of diffraction at smaller apertures. This is exactly the type of feedback I was hoping for. Thanks again.

You're welcome. Let us know how you get on.

[DW58]

Hi
As mentioned above diffraction degrades the overall sharpness. It's explained well here Digital Camera Diffraction – Resolution, Color & Micro-Contrast .If you go online and plug in the numbers you'll find the DOF is quite small. The closer you get the smaller it gets, down to fractions of an inch. In a situation like above focus stacking would work. Set the camera to manual, set the aperature to f8 and take several photos at different focus points an stack them in software. If things are moving it's a different proposition but here it would work as everything is static. Here's a link for a DOF calculator. It's also a really good site for explaining a lot of concepts. A Flexible Depth of Field Calculator
Regards

Thanks for the links. Have read about stacking images. Still learning just the basics in PP but I'll give it a shot. I'm really liking this digital camera stuff.

[wildman]

Does this image look out of focus?

Yes.

I'm not at all convinced that it's a result of diffraction. While diffraction at small apertures will give relatively poorer performance at smaller apertures than at larger apertures it shouldn't be this bad given you are using a high quality macro.

It seems obvious to me - take a series of controlled close ups to make sure your gear is up to snuff before you go any further.It might be something as simple as camera movement.

Here's a hand held shot at f/22 taken with a lens far inferior for close ups than your LTD macro (a 350 buck Sigma 18-250mm super zoom).

Something went wrong but it's not at all clear it's the result of diffraction.

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Last edited by wildman; 03-13-2016 at 04:24 AM.

[DW58]

Thanks for the feedback Wildman. That's a nice sharp image. What I'm striving for. Couple of questions. How close to the subject were you when the shot was taken? And what camera?


In my shot front element of lens was about 4" from the rock so I knew there would be a very shallow DOF. The reason I stepped down to f/20. Didn't know about diffraction which makes sense to me but may not be the only problem. Camera on tripod using remote on 3 second delay so camera movement probably not the problem.


I've read about the AA filter on my K-50 will render somewhat softer images than a camera without one. Although I have no idea how much. Another part of the problem may come from the loss of IQ from my PP process. Using Silkypix 3.0 software that came with my camera. Too much of a newbie to attempt anything more complicated than that right now. When downsizing and saving image to jpeg it's saved by default to Windows "My Pictures". Then I upload from Pictures to Pentax Forum. Haven't been able to figure out another way. There's an obvious loss of IQ from what the DNG image looks like in Silkypix to what ends up on PF.


I'm pushing 60 yrs old and have been farming for the last 20 years. Till now didn't have much use for computers except for e-mail and the occasional purchase from Amazon. No cell service here on the farm, we get 6-8 TV channels depending on the weather and our internet service is provided via dial-up. When faster service is needed I take the laptop to the school where my wife works five miles away. Not complaining though. We have 100 acres and live within 1/4 mile of two wineries with a third on the way. One hour away from the Oregon coast and one hour to the top of the Cascades. Not a bad place to live.


I will take your advice and do some controlled tests when the weather clears up and I have more time. Busy right now with baby goats, fixing fence, a crack on the deck of my brush hog needs welding, etc. etc. Usual farm stuff.


Thanks again for your input. One day hope to be able to post images like the one you provided.

[BigMackCam]

There are some other things to consider here, particularly when comparing to @wildman's excellent flower shot:

- was this a one-off attempt, or did you take several shots, re-focusing each time to test the focus accuracy?
- what was the distance between the lens and the subject? Minimum focus distance on the DA35 f/2.8 Macro is ~13.9cm / 5.5"
- did you use auto-focus, and was it using live view or the viewfinder? Have you tried both?
- have you tried manually focusing on a subject? Live view with focus peaking would be easiest for this...
- are you using a UV filter (or any other type) on the lens?
- when you processed the DNG file, did you add any sharpening at all? I believe @wildman's picture has some sharpening, and all DNG files typically require it to some degree

EDIT: I just read your reply to @wildman... how sure are you about that 4" distance between rock face and lens? As mentioned above, the minimum focus distance is ~5.5", so you may need to move back from the subject a little...

[DW58]

Hey BigMacCam.


Just guessing about the 4". I got as close as I could. How embarrassing it would be if I was too close. But I thought the 5.5" was from subject to sensor not subject to front element of lens.
Took several shots at different apertures but used auto focus. Had remote set up to change focus. Used Select AF and changed focus points through viewfinder 3 times. Lens moved slightly and I heard the beep before mirror lock-up and exposure each time.


Looking back I should have tried manual focus. Have not tried live view with focus peaking yet. But plan to now. No filter used.
Minor sharpening in Silkypix. Have had my K-50 for two months and started shooting RAW two weeks ago. Haven't quite got a handle on PP yet. Mostly computer illiterate so it's been an adventure. Will just keep plugging away though.


Rain was moving in and didn't have time to try many different set ups.
I have a lot to learn and I think I'm getting a bit impatient. Want everything to come together NOW.
Thanks for all your help Mike. I appreciate it.

[BigMackCam]

Hey BigMacCam.


Just guessing about the 4". I got as close as I could. How embarrassing it would be if I was too close. But I thought the 5.5" was from subject to sensor not subject to front element of lens.
Took several shots at different apertures but used auto focus. Had remote set up to change focus. Used Select AF and changed focus points through viewfinder 3 times. Lens moved slightly and I heard the beep before mirror lock-up and exposure each time.


Looking back I should have tried manual focus. Have not tried live view with focus peaking yet. But plan to now. No filter used.
Minor sharpening in Silkypix. Have had my K-50 for two months and started shooting RAW two weeks ago. Haven't quite got a handle on PP yet. Mostly computer illiterate so it's been an adventure. Will just keep plugging away though.


Rain was moving in and didn't have time to try many different set ups.
I have a lot to learn and I think I'm getting a bit impatient. Want everything to come together NOW.
Thanks for all your help Mike. I appreciate it.

My pleasure, Eugene. I know all about impatience - I've been perfecting it since childhood

Yes, you're correct - minimum focus distance is from subject to sensor... Worth checking next time that you are far enough back. I've had situations where I've tried to focus a lens while too close to the subject, and have still got focus confirmation back, but the focus has been poor.

Live view uses contrast detect auto-focus which is more accurate than the phase detect used in viewfinder mode. Even so, depending on the exact part of the subject you're aiming at, with a complex focus area consisting of leaves / stalks, this can prove a challenge for auto-focus, and live view with focus peaking will be a great additional test to carry out.

Best of luck and let us know how you get on?

[BrianR]

Just one thing to add - if your tripod is not on sturdy ground make sure you stand back from it. On spongy forest ground with long exposures it's very easy for your own movements to send vibrations up the tripod. I possible trigger with your remote from a few feet away and be sure to stay still during the exposure.

If it's really spongy ground, you may even find the 3 second delay isn't enough. It is sometimes worth it to up the iso in favour of a shorter shutter. Ideally we'd have a rock solid tripod and ground all the time, but this isn't always the case.

[BigMackCam]

Just one thing to add - if your tripod is not on sturdy ground make sure you stand back from it. On spongy forest ground with long exposures it's very easy for your own movements to send vibrations up the tripod. I possible trigger with your remote from a few feet away and be sure to stay still during the exposure.

If it's really spongy ground, you may even find the 3 second delay isn't enough. It is sometimes worth it to up the iso in favour of a shorter shutter. Ideally we'd have a rock solid tripod and ground all the time, but this isn't always the case.

Good point. The rigidity of the tripod is also important... The cheapest aluminium tripods with plastic head and plate are fine for small compact cameras (I use one for that purpose too), but they're usually too unstable for heavier cameras.

[DW58]

Using a MeFoto Road Trip tripod. Although a "travel" tripod it's build quality is fairly substantial. Rated to hold 17 lbs.

Shot this last night under tungsten/halide light @ 2.8. Camera about a foot away. Battery low so skipped live view/focus peaking and used AF. Image behind glass. Cropped quite a bit. Not optimum conditions for sharpness test but too much rain right now for outdoors. Although uploaded image a bit softer than DNG, seems to be sharper than moss pic.
Please disregard fly specks near tail.

[BigMackCam]

Using a MeFoto Road Trip tripod. Although a "travel" tripod it's build quality is fairly substantial. Rated to hold 17 lbs.

Shot this last night under tungsten/halide light @ 2.8. Camera about a foot away. Battery low so skipped live view/focus peaking and used AF. Image behind glass. Cropped quite a bit. Not optimum conditions for sharpness test but too much rain right now for outdoors. Although uploaded image a bit softer than DNG, seems to be sharper than moss pic.
Please disregard fly specks near tail.

Sounds like you're tripod is fine

That pic looks much better to me... particularly as it was shot wide open, and is softened by the upload to the forum. The DA35 f/2.8 Macro sharpens up in the centre to excellent levels around f/4, reaches peak centre sharpness at f/5.6, and the borders peak around f/8. Plus, shooting a subject behind close-up glass can be tricky in that surface reflections, however slight, can fool the AF. So, I would say this is looking much better. Looking forward to seeing how you get on outdoors when the opportunity presents itself