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Sharpness
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Sat Jun 29, 2019 6:36 am    Post subject: Sharpness Reply with quote

I am using a Canon 40D, a Pentax 200mm f/4, and either a Nikon 10x or a Mitatoya 20x, and a Stackshot. I am a beginner with high ideals.

I am disatisfied with the sharpness of my image stacks. I have checked:



#1 The camera and 200mm, I can get sharp images with them.


#2 comparason of images with 10x Nikon and 20x Mitatoya


I'm putting lots of time and effort into this disatisfaction. I have ruined two camera capture bolts for the stackshot because of it. I don't think the indivitual images of the stack contain sharpness anywhere.

I wanted to check the individual objectives but I don't have a microscope upon which they will mount.

I am new to forums so please forgive me for any faux paux.

Regards,
Larry


Last edited by Larry45 on Sat Jun 29, 2019 2:04 pm; edited 1 time in total
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ray_parkhurst



Joined: 20 Nov 2010
Posts: 2560
Location: Santa Clara, CA, USA

PostPosted: Sat Jun 29, 2019 6:57 am    Post subject: Reply with quote

Are you using Live View for your shots?

Oh, and forgot to say...welcome to the forum!
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Sat Jun 29, 2019 10:32 am    Post subject: Reply with quote

Hi Ray,

I'm looking forward to learning from this experience.

Yes, I use Live View when I set the beginning and ending spots of the series. I find it quite helpful for that use. I seem to have the impresson that it is best to turn it off before I run the stack. I've been using Mirror Lock to give the camera and lens time to stop shaking. I havenot looked into it but I get the idea that Live View messes with the number if images I capture.

Regards,
Larry
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rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 20643
Location: Richland, Washington State, USA

PostPosted: Sat Jun 29, 2019 11:31 am    Post subject: Reply with quote

Larry, welcome aboard.

Vibration is by far the most likely source of your problems. At 10X it only takes about 1 micron = 0.001 mm of movement, at the end of the lens, to give you a 2-pixel smear back at the sensor.

The safest approach, especially when you're just getting started, is to illuminate with electronic flash set on low power so as to get especially short light pulses. Most consumer-grade flash units will produce light pulses around 1/5000 second if you set them down to 1/16 power. Such short effective exposure time is a powerful method of freezing out whatever vibration you might have.

If you're using continuous illumination, then you should definitely be shooting in Live View too. The reason is that when you shoot in Live View, there's no mechanical vibration at start of exposure, only at end when it hardly matters. The official phrase is EFSC -- Electronic First Shutter Curtain. See http://www.krebsmicro.com/Canon_EFSC/ for discussion and illustration of why this is important.

One more thing about microscope images: they're never as sharp as a good landscape lens will produce, simply because of diffraction. A 10X NA 0.25 objective has an effective aperture of f/20, and you probably know that setting a landscape lens on f/20 will produce images that are not very sharp. They can be improved a lot by strong sharpening in Photoshop or whatever, but compared to say f/5.6, f/20 will always come out not looking so good. Your 20X Mitutoyo is probably NA 0.42, which means that it will be running at effective f/24. (The formula is Feff = magnification/(2*NA).) This level of unsharpness will be easily visible when viewing actual pixels, but it absolutely should not be visible in images scaled to 640 pixels as you've done here.

And finally, just to cover the base: be sure you have that 200 mm rear lens set on infinity focus. Having it focused anywhere else will introduce some aberrations that will degrade image quality a little bit. Again, this effect is small and would not be seen in the resized images that you're showing here.

Other than vibration and those other minor effects described above, the only thing that can really go wrong is a damaged objective. If you bought new then they're probably OK, but some significant fraction of used objectives have been dropped or banged hard enough to knock lens elements out of alignment. The damage can be completely invisible on the outside, manifesting only in a degraded image. But since you have two lenses, and they're both producing blurred results, lens damage is not likely the source of the problem.

One last thing about Live View: studying a Live View image at maximum magnification can give you some good clues about where things are going wrong. If an in-focus image looks sharp in Live View but a lot less sharp when captured, then the capture is probably degraded by vibration. And of course if the Live View image itself is moving around, that will tell you that your system is picking up vibration from the environment, not just creating its own from moving parts.

--Rik
tag:vibration
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Sun Jun 30, 2019 6:31 am    Post subject: Stack Shot Settings Reply with quote

Hi, Rick

That was a most informative post. I'm still trying to get all that into my mind. Currently I am still working with continuous light. I will move back to flash if I must.

I am having difficulty shooting my stacks, currently. I have mirror lock set to "enable" on the 40D. I was under the impression that I needed to set # pics to 2 in "global Config" so it would trip once to move the mirror up and later, after everything settles from moving trip the shutter. I am getting a behavior not as I described above but the following: After the first series, Live View lifts the mirror, there is a pause and then the shutter trips. The unexpected part is that the shutter trips again without the pause. I expected Figure 3 in the manual but I'm getting Figure 4 with two shots per step. I don't understand why I'm getting that since I set # pics to 2 for the mirrow lock sequence.

I'm sure there is a simple expaination but I'm unable to think of it.

Regards,
Larry


Last edited by Larry45 on Sun Jul 07, 2019 9:49 am; edited 1 time in total
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rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 20643
Location: Richland, Washington State, USA

PostPosted: Sun Jun 30, 2019 10:07 am    Post subject: Reply with quote

I assume that you're using the basic StackShot with physical buttons on the controller, not a StackShot 3x with the color touchscreen.

On the basic StackShot, the red light above the Shutter button is a reliable indicator of what the controller is telling the camera to do: light on is equivalent to a full press on the camera's remote control, light off is equivalent to no press. (There is no equivalent for half-press.)

With #pics = 2, you should see two flashes of the light above the Shutter button, separated by whatever delay you've set in the StackShot controller.

By watching the light, listening for camera actions, and fiddling with the timings (like a really long delay), you should be able to determine what depends on what.

I don't have a 40D or anything in the same family, so I don't have much feel what could be going wrong. From a quick scan of the 40D manual, my best guess is that the camera is set in one of its own delay modes (self timer).

One other check that might be helpful is to disconnect the camera from the StackShot controller, plug in a manual remote control, and see if you can reproduce the odd behavior separate from the StackShot. If you don't have a remote control, then using the camera's own button may work the same way but I can't be sure about that.

--Rik
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Fri Jul 05, 2019 10:32 am    Post subject: Reply with quote

Rik,

I'm in the process implementing suggestions for improvement. I fully expect that my data on the pixel size of images is outdated. It comes from 1999. As you mentioned, it is specially undersized for discussion about sharpness.

I have made a new action in photo shop which produces 1024x683. I hope this works better.

I think I have the equipment issue under control. I reset both StackShot controller and Canon 40D to factory settings and started over.

I have incorporated the use of flash during my captures and I think I'm getting the sharpness I expected with the 20x. I made a series of nearly 500 captures which sharpness I can live with. The only thing I could find was that for some reason one of the series was omitted. Would you look to see if you can see it?

Regards,

Larry


Last edited by Larry45 on Sun Jul 07, 2019 9:48 am; edited 6 times in total
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rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 20643
Location: Richland, Washington State, USA

PostPosted: Fri Jul 05, 2019 11:06 am    Post subject: Reply with quote

I found what appear to be two copies of the same image, uploaded at the same minute and not in use.

Here is one of them:



The other is this:
http://www.photomacrography.net/forum/userpix/7168_pyrite_filiform_phacolite_sugar_grove_pendleton_co_ve_mr_ve3285_2265_2744s1_1.jpg

--Rik
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Fri Jul 05, 2019 12:02 pm    Post subject: two images Reply with quote

Rik,

Sorry about the two images. The site was fighting me in uploading the images. I think you may have to review the images before they are posted. If you wish you may delete one or I will if I can find out how.

Regards,

Larry
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rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 20643
Location: Richland, Washington State, USA

PostPosted: Fri Jul 05, 2019 12:12 pm    Post subject: Reply with quote

See the image hosting instructions at https://www.photomacrography.net/forum/viewtopic.php?t=7 , and note especially Step 5.

We get a lot of duplicate uploads. No worries about this one.

--Rik
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Sun Jul 07, 2019 9:54 am    Post subject: clean up Reply with quote

Rick,

I would very much like to clean up the mess on this forum. I can't seem to discover the cure. Am I missing something?

I have reviewed the hosting instructions, especially Step 5.

How do you resolve these duplications if the author can't make corrections?

Regard,
Larry
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Sun Jul 07, 2019 10:04 am    Post subject: Duplicate images Reply with quote

Hi, Rick

I had planned to say a few words about the duplicate images. Yes, they are the same. I made this stack using Canon 580 EX flashes using 1/16 manual setting. Thing I wanted to point out was the missing image in the stack. I don't know how it happened unless it was caused by an anomaly with the flash function. I'm pretty sure there is only one component of the stack missing. Helicon Focus gets unhappy at my flash stacks and that is why I began using LED lighting. If it were not for the anomaly I would have proudly shown this stack. It was captured using a Mitatoya 20x mounted on a Pentax 200mm and my Canon 40D. Thanks for the suggestion of using flash.

Regards,
Larry
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rjlittlefield
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Joined: 01 Aug 2006
Posts: 20643
Location: Richland, Washington State, USA

PostPosted: Sun Jul 07, 2019 3:13 pm    Post subject: Re: clean up Reply with quote

Larry45 wrote:
I would very much like to clean up the mess on this forum. I can't seem to discover the cure. Am I missing something?

I have reviewed the hosting instructions, especially Step 5.

How do you resolve these duplications if the author can't make corrections?

I've never found the cure either. As far as I can tell, whoever wrote the upload facility never included a "delete" function.

As for resolving the duplications, we don't.

At this moment, duplicate images account for about 15% of the roughly 63,000 images stored at photomacrography.net.

I think it's clear that trying to clean those up one at a time is not worth the trouble.

It would take me a few hours to program a mass removal of all unreferenced images. So far that hasn't been worth the trouble either, since the total space in apparently duplicated images is less than 2 GB.

At this point I think the best approach is to just shake our heads, smile indulgently, and go back to worrying about how to make good pictures.

Thanks for prompting me to check on the numbers.

--Rik
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Thu Aug 22, 2019 10:09 am    Post subject: Sharpness Reply with quote

Hi All,

I wanted to thank you for your help resolving my sharpness issues. Those make me crazy. I am much more sane now.

I wanted you to see my goal for all of that work. I found the pyrite filiform phacolite. I had to reshoot until I got the composition I wanted. It was such a relief to get it. I took myself out to eat that evening as a treat.

The image has not shown up on the preview as yet but I am afraid to try it again. I don't want a duplicate of it here.

Regards,
Larry
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rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 20643
Location: Richland, Washington State, USA

PostPosted: Thu Aug 22, 2019 10:24 am    Post subject: Reply with quote

Larry,

I'm glad to hear that you've made progress worthy of a special dinner.

I believe the image that you uploaded was this one:

http://www.photomacrography.net/forum/userpix/7168_pyrite_filiform_phacolite_sugar_grove_pendleton_co_ve_mr_ve3311_9369_9512s1_1.jpg


When uploading images to this forum, please note Step 5 of the instructions:
Quote:
5) The upload window will now preview the image you have chosen to upload. You will probably have to enlarge this window or use the scroll bars to see the entire image and the important controls, which are at the bottom of the window. To insert the necessary BBCode into your posting, click on the blue part of "insert picture: standard" or "insert picture and upload another one" (red arrows). (Do not click on the black words "insert picture". Nothing will happen if you do that.)


If you just do the upload, the necessary BBCode tags will not get inserted into your post, so your image will not appear. You have to also click the blue part of one of those "insert picture" links. That will insert a line into your posting like this:

Code:
[img]http://www.photomacrography.net/forum/userpix/7168_pyrite_filiform_phacolite_sugar_grove_pendleton_co_ve_mr_ve3311_9369_9512s1_1.jpg[/img]

It is the appearance of the URL inside [img] tags that causes the image to be displayed in the post.

--Rik
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