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 Replies: 20 / Views: 4,634 |
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Valued Member
United States
71 Posts |
What was the working distance of this B&L microscope objective when you took the pictures?
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Pillar of the Community
  United States
4038 Posts |
It is around 8mm.
Contact me for photographic equipment or visit my home page at: http://macrocoins.com |
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Pillar of the Community
United States
949 Posts |
Please forgive the newbie (me) who has not yet figured out how to search the forum very well. How does one make use of an objective lens for coin photography? Are you shooting through the microscope, or does the objective lens mount to your camera somehow? Either way, I assume the field of view is quite small.
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Pillar of the Community
2087 Posts |
I mount microscope objectives on a bellows, other people use extension rings. This requires an adapter; usually RMS to whatever mount the extension rings Or bellows are. I have some generic microscope objectives and they are designed for specific extension distances which are indicated on the objectives. I just set the bellows to that distance. Yes the area you see is very small but I find all the objectives I have will produce an image that will cover the cameras sensor
Edited by austrokiwi
04/12/2016 1:50 pm
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Pillar of the Community
United States
949 Posts |
Thank you austrokiwi, I am looking into this now too. Apparently this is part of the move toward image stacking that got hot with this group starting back in January. Quote:
Even with the B&L you need to have consistent 10um steps to get a full-resolution image, and this is on the edge of the capability of most equipment. You can of course automate and achieve 1-2um consistent steps, but the cost of those setups sort of trumps the need for low cost objectives! All this may be obvious to you guys, but I need help getting into it. Thank you for your patience. @rmpsrpms Is this incremental adjustment something one can do well manually or does it require a special tool? Are you using the Helicon focus system or the Zerene Stacker system (manually)? Do you otherwise recommend/use the Cognisys StackShot? Edited by lrbguy
04/12/2016 5:13 pm
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Pillar of the Community
United States
4038 Posts |
I use a custom-built system similar to the StackShot. I've heard good things about StackShot so would have no issue recommending one. However, you don't absolutely need such an elaborate system unless you're doing a lot of stacking, or if you do "deep" stacks with many images (>10). If you want to stack manually, and will be doing it for coins (which typically require <10 images), then you might just consider getting a manual Z-stage. I use one of these for full-coin photography for fine focusing: http://www.ebay.com/itm/NEW-Z-axis-...AOSwewJTnwnT This stage has a micrometer control that gives 10um increments, which is sufficient for 10x magnification. If you're careful you can even do 5um half-steps. I process the image stacks with Helicon Focus. Contact me for photographic equipment or visit my home page at: http://macrocoins.com |
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Pillar of the Community
2087 Posts |
I use The stack-shot but starting out manual stacking can work, but as already pointed out getting fine consistent movements is an issue. You can buy a Z stage with a micrometer( usually expensive) or look for a parts Microscope that has a fine adjustment nob for the focusing stage. You will need to remove the objective head/turret with an angle grinder or similar tool. An Olympus CH2 or similar will work OK. You will then get the ability to adjust focus by amounts less than 10um Here is an example of the sort of microscope I mean ( note I think its too expensive with looking you should be able to find what you need for less than US$40.00) http://www.ebay.com/itm/Olympus-CH2...AOSwG-1W0mcMEdited by austrokiwi
04/12/2016 11:49 pm
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Valued Member
United States
441 Posts |
Do you have any pics of the stages attached to your rig to show how they would integrate with a bellows setup and rms objective? Need lots of pics.....visual learner is quicker for me.
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Pillar of the Community
2087 Posts |
Quote:
Do you have any pics of the stages attached to your rig to show how they would integrate with a bellows setup and rms objective? Will post pictures of bellows set up later. Here is an old picture that includes the microscope I modified to be a focusing stage. instead of moving the camera the coin is moved for stacking  Edited by austrokiwi
04/13/2016 02:40 am
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Valued Member
United States
441 Posts |
Very intricate setup. I assume the stage is mounted to the baseplate and can move vertically/horizontally in minute amounts, correct? How do you control how much the stage moves..micrometer, computer?
Do you have any coin pics using this system? This process is very cool!
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Pillar of the Community
United States
949 Posts |
Looking at your setup, austrokiwi, I thought this looked like a pretty good item. http://www.ebay.com/itm/371579679057It allows movement in XYZ planes. However, I don't think that there are micrometer rulings. Should I look for some kind of reticule to mount on the X and Y movement rails? Add one of these? http://www.ebay.com/itm/181606261433My big question for both of you (austrokiwi and rmpsrpms) is this, what is the critical direction of movement of the coin with respect to the lens when one is creating the photo stack? (May I assume the direction of shooting is straight down the Z axis)? Ray, is the stack created from shots that vary in depth? Edit: here's another one for about the same price - http://www.ebay.com/itm/322068713895Edited by lrbguy
04/13/2016 6:00 pm
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Pillar of the Community
United States
4038 Posts |
You're correct, the critical direction is vertical, assuming the camera is looking straight down on the coin. The stack is created by varying the distance between camera/lens and coin.
As long as you are not planning to go to higher magnification than 10x, I see no reason to go with a stripped-down microscope stand. The main reason to use one is to get higher vertical resolution, but even at 10x you generally don't need better than 10um resolution, and this can be achieved with the smaller and cheaper Z-stage I linked to. Plus, it requires no modifications be made!
But if you do go the stand route, make sure you get one that has the correct adjustments. You are looking for a stand that has concentric coarse/fine adjustment knobs. These have "infinite" fine step capability, ie you can turn the fine focus knob forever and it will keep moving the stage. Some don't have fine focus at all, while others have limited range to the fine focus. I don't think the Leitz stands you linked to have this infinite capability, but I may be wrong. Not my area of expertise.
Contact me for photographic equipment or visit my home page at: http://macrocoins.com |
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Pillar of the Community
United States
9395 Posts |
Quote:
Should I look for some kind of reticule to mount on the X and Y movement rails? The Zeiss microscope stage I have has measurement reticles in the X and Y directions, but I never really look at them. Of course, the Z-axis markings on the fine focus knob are useful when stacking. |
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Pillar of the Community
United States
4038 Posts |
You usually only use XY adjustments to frame the shot, so precise measurement is not needed. I suppose if you do stitching then it's important to have reasonable XY measurements but even then you can probably do it visually since you will almost certainly ensure some degree of overlap.
Contact me for photographic equipment or visit my home page at: http://macrocoins.com |
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Pillar of the Community
2087 Posts |
RMPSRMPS has answered your question but I would add the following:
When stacking using Microscope objectives I use the Commercially sold Cognisys focusing rail. I purchased the stack-shot system before I learned that a microscope could do the same job. The microscope I use has the fine focusing system that rmpsrmps mentioned its a CH2. I know that some people actually build their own stacking system by motorizing the fine focus using a stepper motor. I use the CH2 as a focus stage for most non stacked coin shots.
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Replies: 20 / Views: 4,634 |
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Posted 04/11/2016 9:59 pm
