ALMOST THERE!. Help us with a final push needed to keep mindat.org running. Click here to help.
Catawiki are hosting a mindat.org benefit auction. All proceeds to mindat.org! BID NOW
Log InRegister
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for EducatorsMindat Articles
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsThe ElementsUsersBooks & MagazinesMineral MuseumsMineral Shows & EventsThe Mindat DirectoryDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery
bannerbannerbannerbannerbannerbanner

Significant difference between Canon and Nikon Live-view

Posted by Henry Barwood  
avatar
Henry Barwood March 30, 2013 02:35AM
I was working with a Canon 40D and a Nikon D90 this evening. I removed the lenses and observed the live-view function.

The D90 drops the mirror, then raises it to take the shot and then returns it to the up position to resume live-view.

The 40D simply starts the image, then moves the shutter curtain to end the exposure and returns to live view. The mirror remains locked up.

The level of vibration generated by the two systems is significantly greater in the D90.

I looked at my Panasonic G3 and it, of course, does not have a mirror, but it does have a double shutter that is quite noisy.

My Samsung NX-10 is quiet, but I can't test it since the body will not fire without a lens in place. I stopped using it for other imaging reasons than the shutter.

Could other photographers out there with different live view cameras take a moment to check their camera/model and let me know if this is common to all Nikon cameras, Other Canon cameras, or other camera systems. Thanks.

Henry Barwood
Troy University
Troy, Alabama USA
avatar
Owen Lewis (2) March 30, 2013 03:00PM
Interesting, Henry. Thanks. The Canon EOS 600D seems to function as you describe for the 40D model. As already discussed, subjectively, I don't find camera-shake at shutter release to be an issue for me using the 600D. My gut feeling is that whatever diminution of sharpness a user experiences is likely to be affected byt the rigidity, vibration damping and harmonic vibrations induced into the whole system (camera/camera adapter and microscope and stand). Without a a shred of empiric evidence, I still fret about the use of pole stands, those with extended arms most particularly.



Edited 1 time(s). Last edit at 03/30/2013 09:35PM by Owen Lewis (2).
avatar
Volker Betz March 30, 2013 05:04PM
Hello Henry,

Recently i assembled a new configuration with bellows Macro Lenses and A Nikon D 400. I use that in live view with Helicon Remote only. I tested with an objectmitrometer and could not detect any shutter influence.

With my new 650 D in Live view mode: (Remote control with Helicon View)
The mirror is always up. If you start a long time exposure the nothing mechanical happens only after exposure time the shutter closes and opens again to continue live view. The mirror does not move until you close live view.

As the movement of the second mecanical curtain (shutter) is only at the end of exposure, it shoud not cause vibration.

I switched from Nikon Bodys many years ago to Canon EOS because the first (cheapers) versions of Nikon did not work with manual Lenses or bellows. This was possible with Canon EOS, and with an adapter I could use all my Nikon bellows and lenses.

Regards

Volker
Volker
avatar
Ronald J. Pellar March 30, 2013 06:43PM
Henry,

I checked my Nikon D300 and it behaves like your D90 in live view. However, I have not had any evidence of mirror shake problems with both micro- and macro- photography.

Ron
avatar
Henry Barwood March 30, 2013 06:59PM
Ron,

Have you tried theD300 with mirror lock-up enabled?

Volker,

As you have pointed out it is the initial vibration that is so damaging. When the shutter curtain closes to stop the exposure there is minimal vibration.

Owen,

Yes, external vibrations can be significant, and like you, I don't like the post mounts!

Henry Barwood
Troy University
Troy, Alabama USA
avatar
Douglas Merson March 31, 2013 02:48AM
The silent mode found in most Canon cameras is why I switched from a Nikon D300 to a Canon T2i. There was a noticeable difference in picture sharpness.

The mirror lockup on the D300 cycles the mirror when the shutter is triggered. I used the shutter delay feature and a 1 to 2 second exposure to reduce vibration.

See the discussions on the following forums. http://www.photomacrography.net/
Doug



Edited 1 time(s). Last edit at 03/31/2013 02:49AM by Douglas Merson.
avatar
Henry Barwood March 31, 2013 02:55AM
Doug,

I've been very frustrated by my Nikon D90. I'm going to try an old 40D Canon for a while and see if things improve any.

Henry Barwood
Troy University
Troy, Alabama USA
avatar
Christian Auer March 31, 2013 07:01AM
I`ve changed first from a Nikon D90 Nikon to a Nikon D200 and am working now with a Nikon D700 - and its excellent. My only limitation is that I want to document masses of specimen so I cannot invest too much time for a single pic.

My shutter delays are 5-6 sec.
What`s also important is that I`m working in the cellar on a concrete floor!
avatar
Henry Barwood April 03, 2013 01:01AM
I have tested my Nikon D90 (live-view with shutter delay), Canon 40D (silent mode live-view), Samsung NX10 (mirrorless live-view) and Panasonic G3 (mirrorless live view) on my Nikon SMZ10 Trinocular microscope. I found no significant differences between images taken with all of the cameras. This is apparently a reflection of the microscope optics, and not the cameras.

I attached the 40D to my bellows stand and imaged a burbankite that has been difficult to get right. This image was taken with a B&L achromat 40mm objective and stacked using CZ software. Other than color correction and size reduction, this is the image as output without additional sharpening. I find it to be a good bit sharper than images produced with the other cameras:



Henry Barwood
Troy University
Troy, Alabama USA
open | download - Burbankite 40mm B&L CZ CC s.jpg (241 KB)
avatar
Mineralogical Research Company April 03, 2013 02:10AM
Hi Henry,

Can you tell me about the B&L achromat 40mm objective? I'm not sure what that is. If it's a microscope objective, it should be specified by its magnification and NA, for example 4X 0.1. Also, what is the FOV for your image?

Gene
avatar
Henry Barwood April 03, 2013 02:36AM
Hi Gene,

The main crystal is about 0.3mm long. The FOV is about 1.5 X 1.5 mm.

60+ years ago B&L made microscope objectives that were long working length. They are fairly simple achromats, but are highly corrected. They have a standard RMS thread and, if you remove the nose shroud, they make really nice objectives for photomicrography. I have examples from 20 to 48mm in my parts box (they were marked with mm rather than power). Some are more highly corrected than others, so you just have to try them out to see what works. An equivalent modern lens would be the 4X objectives you can purchase from China. They are pretty much a copy of these old lenses using modern glass and coatings. I can't afford the high end micro lenses, so I scrounge lenses from eBay and from the piles of old microscope stuff I've accumulated over the years.

Lenses I've found to have good resolution for photomicrography include:

B&L 40 mm
B&L 23 mm
Plan 4/0.10 (160/0.17) from China
Summar 25mm

Except for the Summar, these can be found on eBay for low prices (quality of the lenses varies a good bit, however, depending on how they have been treated).

Henry Barwood
Troy University
Troy, Alabama USA
avatar
Mineralogical Research Company April 03, 2013 04:10PM
Thanks Henry, I vaguely remember those lenses now. I also have a selection of inexpensive, but fairly good, lenses that I have been using while improving the mechanical and electronic aspects of my equipment. My current system is mechanically limited and I am slowly building a more stable one. Once the bugs are all worked out, the only thing left for improvement will be lenses. I was shocked at the prices for Mitutoyo infinite focus objectives and other high end pieces. I’m not sure that the prices are justifiable.

Nice image of the Burbankite!

Gene
avatar
James Pool April 03, 2013 10:22PM
I'm not sure what resolution you are shooting for but it is my understanding that you can get the same effect as shutterless mode by using the video recording mode on various cameras. You would have to deconstruct the video file into linked image files. The disadvantage would be in smaller resolution image files compared with the resolution for the non video recording modes of the camera as well as the extra step of video deconstruction. Also you can't currently shoot video in raw mode for dslrs so files can't be adjusted as much as a normal image raw file for exposure and so on.

A rather big advantage would be in greatly reducing the shutter counts for some of the huge stacks made for some images, as a single video counts as only one or possibly two shutter activations. The high frame rate of video should also give you more "keepers" to help in constructing a stack especially if you get vibrations from stacking or the environment.

Has anyone tried this method or are there other vibrations introduced in the action of shooting video?

For your unrelated information I am using the mirrorless Pentax K-01 camera but haven't gotten the adapter equipment for using a RMS thread objective for direct micro shots yet. It performs very well for my macro shots so far. It does not have an electronic shutter though and can't be tethered to a computer and live view is limited to either the screen on the camera or an external monitor using the low resolution composite cables. The focus peaking is fantastic for manual macro shots though so I think it will work very well for micro shots as you can clearly see when regions come into sharp focus while stacking.

James Pool
avatar
Henry Barwood April 03, 2013 11:02PM
James,

Astrophotographers use video stacks to image planets. Stacks of 2K frames are not uncommon and there are several versions of software to handle this automatically. I have not tried them, but they should work on minerals as well. There is a fairly steep learning curve for this sort of work.

As you said, the main disadvantage is in the lower pixels of the video frames.

I think that (at least until recently) both Kodak and Pentax used the same chips that are used for astrophotography, so the resolution and anti-blooming should be excellent.

Henry Barwood
Troy University
Troy, Alabama USA
avatar
Ronald J. Pellar April 04, 2013 07:26PM
Video clips can have another problem. The cameras may use MPEG3 or the newer MPEG4 for data compression. These are lossy compression techniques that can lower image quality. I personally would not use any video clips. The astronomers may be using uncompressed video frames.

Ron
avatar
Mineralogical Research Company April 08, 2013 01:54AM
Regarding video stacks:

While astronomers use video stacking to great advantage, I cannot find any utility in this method for use in stacking as it applies to microphotography. Astronomers use video stacking to eliminate the statistical effects of atmospheric turbulence on their images. Because Lunar and planetary imaging requires high resolution, the non-laminar flow of the atmosphere that they image through distorts and blurs the images. Video stacking takes advantage of the notion that if you take enough images, over time, you will get a few good ones during fleeting moments of good seeing. It is typical to collect video at a rate of up to 60 frames per second for up to two minutes. Two minutes is the limit due to rotation of the larger gaseous planets. The sensor resolution is usually limited to 640x480 because through the telescope the image scale is very small and even the largest planet, Jupiter, only fills a small part of the FOV. Shooting at higher resolutions does nothing for the quality of the data collected and only increases file size. A two minute MPEG file shot at 640x480 and decompressed to RAW is huge and it’s a lot of data to manipulate. This can result is upwards of 7000 frames, from which only the sharpest few hundred are usually selected and integrated. The integration process also effectively reduces the noise contained in the final image to less than that of any of the individual images.The scheme works for astronomers as stacking does for us, effectively cheating the immutable laws of optical physics. In their case it solves the problem of frames that are not perfect and integrates them to produce a high resolution image that would be impossible otherwise. For us, it solves the problem of lack of depth of field in our microphotographs.

Back to the question of will video stacking work for us? I don’t think so for several reasons, some of which previously touched upon here .

1. Resolution of video cameras is poor, though higher resolution cameras are available at high cost.

2. Shooting at video rates of 30 f/s and higher is fruitless, because file sizes grow very quickly.

3. Synchronizing the frames to physical z-axis steps would be very difficult, if not impossible. A hundred frames could be shot, and wasted, just in the time that it takes to increment a z-axis step. We could discuss continuously moving the subject on the z-axis, but there are problems with that too (guess).

4. We are not trying to beat a statistical fluctuation, as in turbulence. We only need a comparatively few number of images, each of which is already high resolution.

Cheers,
Gene



Edited 1 time(s). Last edit at 04/08/2013 02:10AM by Mineralogical Research Company.
avatar
Henry Barwood April 08, 2013 03:03AM
Hi Gene,

Your commentary is very accurate, and I basically agree. My suggestion was that the video stacking software could be useful in mineral photography for creating the stack from a video file and cleaning up the stack. If memory serves me, there is an automatic function that analyzes the frames and rejects those that are too blurry or misaligned so it can reduce a mega-file down to a reasonable number that can then be fed into the stacking for DOF program. I can envision this as being useful for a vertical scan of 5-10 seconds to capture the mineral. This could then be broken down to say 30 clean, useful frames from a total of 200-300 on the video clip.

Henry Barwood
Troy University
Troy, Alabama USA
avatar
Mineralogical Research Company April 08, 2013 06:12PM
Hi Henry,

I can envision this as being useful for a vertical scan of 5-10 seconds to capture the mineral.


Correct me if I am wrong. I interpret this to mean that you would move the subject continuously along the z-axis while shooting the video. In that case you have a moving subject and unless the individual exposures are very short, there may not be any critically focused parts of the images in the stack.

On the other hand, say that the exposures could be sufficiently short so as to guarantee that every frame did have the motion along the z-axis stopped. You would then have to sort out which images have the proper amount of overlap in DOF, because every frame would have a region of sharp focus. Otherwise, you would have 450 frames to deal with (30 f/s x 15 sec). It appears to me that this scheme actually increases the complexity of stacking for our purposes and it still requires a z-axis stage that can be incremented.

Gene
avatar
Mineralogical Research Company April 08, 2013 06:21PM
Here is another method that is somewhat overlooked that may be of interest. Actually, I will be trying this very soon, first for macros and then for micros. Many of the new DSLR lenses have internal focusing. My new Canon lens that should arrive here today has the ability to be focused remotely through the tethered to the computer utility program. That means that you can focus on a part of the subject, expose and then remotely re-focus on another part of the subject, etc. From what I understand, the minimum focus increment is small enough to use for micros, when the lens is adjuncted with an infinite focus microscope objective. This would releive the user of the need for a z-axis stage. I'll report later as to how it works...or, if it works. :-S

Gene
avatar
Henry Barwood April 08, 2013 06:24PM
Gene,

Yes, the vertical motion would introduce a new problem with the focus. I'm assuming a frame rate that would allow a sharp image, but you may be correct that local motion during the frame would reduce focus to an unusable level. I'm not advocating it over regular imaging and stacking, but I would be curious to see it tried.

I have no idea how you would sort out focus levels so you got a uniform stack. I agree that rather than simplifying matters, it might introduce more difficulty.

Henry Barwood
Troy University
Troy, Alabama USA
avatar
Ronald J. Pellar April 08, 2013 07:15PM
Gene,

All my current macro photos use the remote focus feature of the camera control software on my computer. The smallest focus increment is more than adequate for stacking macros. In fact, I sometimes use one, or two, increments larger in order to reduce the number of images in the stack.

For micros I use the camera mounted with adapters to a photo output tube on my microscope without any intermediate lenses so remote focus is not possible.

Ron
avatar
Volker Betz April 08, 2013 08:12PM
Hi Gene,

since a few weeks I am using a stackshot rail as a specimen support mounted with bellows, fixed to a home made vertical macroscope stand. For that i use a Canon D 450 under Helicon Remote control and Live view. Helicon remote controls also the stackshot rail (better than the box, but via the box).

To my opinion it is better to move the (mostly) small specimen instead of the whole camera and bellows.

I t was a little tricky to mount everything, but finally it works well. Its my now routinely used equipment for larger fields of view (4-20 mm) with either a 63 mm Zeiss luminar or a 35 mm Canon Maco lens. Usually with steps of 100 µm and 50 µm.

For this kind of range the stackshot works fine, for shorter focal lenght (25 mm Zeilss Lumniar and others) you need 25 µm steps so you need to use the microsteps. This is going a little into the design limits of stackshot , so I prefer to use here my Leitz Ortholux Micoscope body with a phototube. But if you take care, stackshot works also in this range.


What I feel what is essential: I have not only the camara mounted on the bellows over the objective mount, but also extra the camera body on the rack. So I can now do large stacks remote with a smile and study the next sample under the microscope while the equipment works. I did some resolution test with a objective micrometer and my observation is that thre is no significant loss of resolution caused by vibration.

As the lenght of the rail, specimen,working distance ,lens bellows and camera add, the stand is 50 cm high, I mounted vertical so the footprint is not so big.

Regards

Volker
avatar
Mineralogical Research Company April 08, 2013 08:13PM
Henry,

Please be assured that I am not trying to be contrary, but playing devil’s advocate. Sometimes stirring the pot can stimulate people to think more about a problem. I know that these exchanges certainly are stimulating and many times instructive for me. In fact, I am now having second thoughts about how video could be used, even though I still don’t believe efficiently. Now we need someone to step up and volunteer to do the experiment. Don’t look at me.

Well, the new lens was just delivered. It’s a Canon f2.8 USM IS macro that is quite different from any of my old Nikon macro lenses. One oddity is that the lens does not extend when focused, as the focusing is done by moving a group of lenses internally by means of an “ultrasonic motor”, whatever that is. It also has image stabilization, which doesn’t do much in the macro mode, but is effective for normal photography. It will do 1:1 directly with a working distance of 15 cm. I’m still just sitting here looking at the thing and wondering if it can do multi-focus without a z-axis stage. We’ll see…

Gene
avatar
Henry Barwood April 08, 2013 08:47PM
Gene,

I didn't think you were being contrary. I've learned a lot from these discussions. I have always been a "Gizmo" person and constantly experiment with new apparatus and techniques. Of course, my budget is somewhat anemic (vast understatement).

My biggest obstacle is just finding the time to experiment.

Henry Barwood
Troy University
Troy, Alabama USA
avatar
Henry Barwood April 08, 2013 08:50PM
Gene,

I had to back up and pick up your comment about the remote focus lenses. I will be very interested to hear how that works out!

Henry Barwood
Troy University
Troy, Alabama USA
avatar
Mineralogical Research Company April 08, 2013 09:14PM
Ron,

Thanks for confirming that the remote focus will work for macros. I was fairly sure that would work but dropping a significant amount of money on the lens, made me a little nervous. I have a special project for macros and realized that stacking would be required, but didn’t want to go the movable stage route.

Micros are another thing. I currently use bellows and microscope objectives, similar to your setup. However, it may be possible to get good results by mounting an infinite focus microscope objective on the front of the macro lens (operating as tube lens) and use the internal focusing to step the focus. It is only a matter of the steps being small enough. I won’t have time to test that aspect soon, but will get to it after the macro project is done.

Gene
avatar
Mineralogical Research Company April 08, 2013 09:51PM
Hi Volker,

It sounds like you have been working hard. How about posting a picture of your new setup? I have been a little doubtful about the performance of the StackShot for steps smaller than say 10 um, but Ric Littlefield (author of Zerene Stacker) has worked with Cognisys to micro step down to the um level. He claims that it works well. It was a surprise to me, as I didn’t think the lead screw could be that accurate.

The homemade system that I have been using is a stepper motor driven precision z-axis stage that gets me down to 1 um/step when using micro stepping. What I like about it is that it is transportable to any microscope or bellows system. However, plagued by vibrations (above 10x), I have recently started building a new system where the camera and bellows will be moved and the subject remains stationary. This new system is built on a 60 cm x 45 cm x 8 cm granite slab. It has a commercial vertical stage that is very solid and capable of <1 um steps. I’m looking forward to commissioning the system in the next week or so. All that is left is to modify my software for controlling the motor from the windows based application.


Current system


Close up of the computer controlled z-axis stage with newly added x, y stages


Regards,
Gene
open | download - DSC07347sm.jpg (543.9 KB)
open | download - DSC07402sm.jpg (534.2 KB)
avatar
Volker Betz April 09, 2013 12:13AM
Hi Gene,

I will make a picture of my setup. I m using automated stacking for macros by remote focus now since a nearly two years using a Canon Macro 60 mm EFS USM. I did it first with a canon 450 and now with 650, which is more comfortable switching from remote live view to camera live view. I made some comparsions between focus stacking and sledge stacking. The re is no quality difference, but pictures are a litte different. also I wrote a paper for LAPIS (5/2012) (in German)
Using a Raynox 250, field of goes down to 11 mm. I always use f= 8 which by experiments, was the best f-stop concerning resolution in the field of view range from 1 to 25 + cm.


I know your article in Axis and one of my projects is to contol the fine focus of my Ortholux by a stepper motor as helicon can control that also. I see you are using an O-ring as belt drive, does this work well ? The fine focus of the ortholux has a distance of 2 mm and a resolution of 1 µm, I like to use it for fields of view from 3 mm down to 0.8 (with 40 mm, 25 mm, 20 mm and 15 mm lenses. Always wth the 22 cm tube with binocular view.

I had also the idea to copy you z-axis solution, but now instead I use the stackhot. Its total travel distance allows to fix the bellow, and all movement is by the stackshot. The type of stand in your picture may be not completely free from vibration.


Regards

Volker
avatar
Volker Betz April 09, 2013 10:04AM
Hi Gene,

this is a fast picture if the design prototype.

Remote automated stacking with Stackshot


Stackshot mounting


Regards

Volker
avatar
Ronald J. Pellar April 09, 2013 06:42PM
Gene, Volker,

The difference between focus stacking and rail stacking is perspective. Rail stacking moves the focus plane through the specimen which removes any parallax. Focus stacking retains the parallax that a person would see viewing the sample from the same aspect as the camera.

For macros, I prefer focus stacking for the natural perspective. This is usually not possible for rail stacking that is required for micros.

Ron
avatar
Mineralogical Research Company April 09, 2013 07:55PM
Hi Volker,

Thanks for showing the photos of your new system. I like your use of the StackShot to move the subject, rather than the camera. It does offer several advantages over the latter. Very nice system….as usual! I’m sure that we all look forward to seeing more of your work.

Without any great preparation, I tried the new Canon macro lens last night with focus stacking. I only shot one set of 7 frames at a magnification of 0.5x and stacked them with Zerene Stacker. Actually, I think 4 frames would have been enough for this specimen. The result was excellent, aside from forgetting to set the color balance. So, it certainly works well for macros. I have to complete a current project that I am working on and then I’ll be testing focus stacking for micros.

Regarding my old system, my use of an O-ring was due to its simplicity and availably. A timing belt would certainly be better. My experience has shown that the O-ring works well down to the 5 um step level and even smaller if you drive in one direction only. So, for smaller steps, <5 um, I drive the stage beyond its starting point and then come back in the other direction to the starting point of the stack. The problem is that the O-ring has hysteresis. That is it stretches in one direction and when reversed, it has a dead spot until it stretches in the other direction, which translates into ~5 um on my stage. I have become used to compensating for it at very small steps, so have kept this design since 2009. If you are thinking of using an O-ring drive on your Otholux, it may work much better than for me as the load would be less, resulting in less stretch. I have found that stretching the O-ring fairly tight reduces the hysteresis.

I have been working on a new system for a couple of months now, but keep getting sidetracked onto other things. I was lucky to find a surplus commercial stand that was used for inspecting semi-conductor chips at very high magnification. I took a chance and bought it and had it shipped half way across the country. Fortunately, it looks like it will function perfectly for multi-focus. It has both coarse and fine focus, the latter having 100um/turn. It also has a stepper motor built into the fine focus that can give 0.25 um/step. It turns out that my controller from the old system will drive it directly and only requires a scale factor in my software to be changed. As soon as I can get back to modifying the program, the system should be operational. Here is a quickly made photo of it, as it currently stands. The x,y stage still has my old z-axis stage bolted to it, but I will probably remove that.



New setup - 55 kg granite base, coarse/fine focus, internal motor w/ 0.25 um/step

Too many projects, too little time!

Best regards,
Gene
open | download - DSC07842s.jpg (93.8 KB)
avatar
Ronnie Van Dommelen April 09, 2013 11:42PM
Gene and Volker,

Thanks for the photos of your setups. They give me something to work towards!

Does moving the specimen instead of the camera cause problems with lighting of the specimen? Or is the amount of movement too small to make much of a difference?

Also a note on the heavy granite slabs. Is the vibration problem due more from the camera/autostages themselves or transmitted vibration from the house? I remember making holograms back in high school. I used a concrete tile set on a partly inflated inner tube one time and a sandbox another time. They both worked well. If transmitted vibration is more of a problem, I would suggest setting the granite slabs in a shallow sandbox to reduce vibration further (or maybe a rubber mat would work fine too). If it's the camera/autostages creating the vibration, that's a harder problem.
avatar
Henry Barwood April 10, 2013 12:12AM
In addition to shutter, etc. vibration, beware of those fiber optic illuminators. The fans create a lot of vibration and, if not isolated from the rest of the set up, it will be transmitted to the whole system.

Henry Barwood
Troy University
Troy, Alabama USA
avatar
Volker Betz April 10, 2013 08:12AM
Hi Gene,
this is a very impressive stand. It does lokk like custom made.

Concerning vibration: I have banned fiberoptics with fan motors and use LED-spots

External vibrations: I am photographing in the basement with garden all around, and do not stack if anyone is walking in the room..
Truck and train trafffic is a good reson th go on a vibration reducing table. One trick from analytical labs in the days of mechanical balances: A heavy plate of stone on a sand-bed.

One carrier for all parts. This is the reason a have mounted the stackshot on the vertical profile, not on the base plate.


Regards

Volker
avatar
Mineralogical Research Company April 10, 2013 03:40PM
Ronnie and all,

I have not experienced any problems with lighting when moving the subject rather than the camera. If point source illuminators were used, there may be a problem, but I use a diffuser between the lights and the subject. For that reason, the light source is essentially non-directional for the small z-axis movements involved.

The Canon camera body that I use has electronic first curtain shutter, so no mechanical events occur before and during the exposure. I have no evidence that any vibration is coming from the camera itself. My auto stage is programed to have settable delays after a move to allow for damping of any vibrations before firing the shutter. However, with my current system, I still see effects of vibration at 10X and above. Just watching the live view on the computer monitor shows continuous movement at the pixel level. The building, which is 3 stories in height, is in continuous low frequency resonance, driven from external sources such as vehicles, wind and human activities. This is what has prompted me to go to a high mass base. In the past isolation between the environment and a heavy base has been implemented with sand beds and other methods such as inner tubes. The latest, and highly effective, technology for absorbing vibration is Sorbothane. This gelatinous mechanical isolator material is designed for specific weights and damping factors and can effectively damp specific resonant frequencies that plague a system. In the worst case, I can still move the whole system to the concrete basement floor, but I am afraid that it would not get much use during the winter.

I agree that fiber optic illuminators with fans are to be avoided. Even with the illuminator sitting on 2” of foam rubber, I could still see continuous movement on the monitor.

Cheers,
Gene
avatar
Volker Betz April 12, 2013 07:36PM
Hi all,

I made a test with an object micrometer. Under my (possible good) conditions I cannot see any vibration with my above mentioned setup.

1. Close up of live view of an transmission object micrometer (The arrow is 100 µm)
This is a sceen shot.

Live view of object micrometer




2. Single shot of object micrometer after the normal Helicon filtering (reduced to 1024 resolution)
The lens is an (old) Ernst Leitz Wetzlar A= 0.18 6:1 at 250 mm tube length on my setup with stack shot.
Focusing works fine with 5 microsteps as long as direction is not changed. I need to adjust the barrel hysteresis. Most likely also a lens with A= 0.25 can be used.

Object micrometer


This also shows that this lens is quite good for photography.

Regards

Volker
avatar
Mineralogical Research Company April 13, 2013 05:20PM
Hi Volker,

By calculation, the resolution for your lens should be ~1.86 um. From the live view screen shot, it certainly looks like it meets or exceeds that number. It appears to be an excellent lens! Let me know when you get tired of it. ;-)

Gene
Sorry, only registered users may post in this forum.

Click here to login



bannerbannerbannerbannerbannerbanner
Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2018, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: December 14, 2018 12:32:48
View slideshow - Go to top of page