Picking the Perfect Reticle for You

Let&#;s be clear, what we really mean is picking the perfect reticle for your needs. There is no single option that is going to work for every application. Sometimes you will need a specific reticle to get the job done. Sometimes it&#;s just that one reticle is more efficient or easier to use for a given application. Don&#;t set yourself on one. Instead, be willing to invest in optics for different situations. And no matter what anyone says, there is no universally &#;best&#; reticle.

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Though there are dozens of reticle options available, they all fall within just a few categories. This is ignoring some historic examples and a few that are on the fringes. Often these are considered special purpose reticles and are a little beyond the scope of this article. We don&#;t want to go down that road. Instead, let&#;s limit it to the 5 most common categories you are likely to run into.

Crosshair

This is the most commonly thought of reticle made famous by Bugs Bunny cartoons and Westerns. This was the first reticle type, made by crossing wires inside a tube though they are sometimes now etched into the glass of the scope. It really doesn&#;t get any simpler than this standard cross shape making it a good bet for simple applications.

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Burris makes both a Plex and Heavy Plex reticle, used on Scout and Handgun scopes.

The crosshair is generally not going to be the best reticle for any specific task. Instead, it is just very easy to use. There is nothing to it. Line up where the thin lines cross and pull the trigger. This makes it a great option for young shooters or applications where you don&#;t need anything extra. I keep one of these on my around-home varmint gun. Shots are generally short at small targets. It&#;s a good place for this type of reticle.

 

Duplex

If we step a small step up from the crosshair, we get the duplex reticle. These can be known as simply plex, ballistic plex, heavy plex, and many other variations. The premise is the same though there are some slight differences that can be helpful to some shooters. In short, this is a crosshair where the majority of the lines forming the cross are thickened only to thin out near the point where they actually cross.

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The Burris Ballistic Plex is a long-time favorite for hunters, and features in many Burris scopes

The primary advantage of these reticles is the ability to quickly find the crosshair even when vision is limited. This makes them a popular choice for shooters with poor eyesight or those that take their shots in situations where visibility is imperfect. This could be low-light situations or places that have very busy backgrounds like woodlands. The thicker lines add speed and sometimes that speed matters. Especially to hunters.

Choosing The Correct Reticle Glass Size For Your Eyepiece

In order for the eyepiece to properly use a reticle it will need two things. You can check for these by removing the eyepiece from the eyetube, turning it over and looking down inside the bottom of the eyepiece. 1) There must be a "shelf" (a.k.a. field stop) of some kind down inside the eyepiece for the reticle to rest on, and 2) there must be a retaining mechanism of some kind to hold the reticle in place. This shelf is very important as it positions the reticle at the focal plane of the eyepiece lens. This means the reticle is spaced correctly to be in focus when you view it through the top of the eyepiece. The retaining mechanism is typically a threaded ring that you unscrew from the inside of the eyepiece. You then set the reticle down inside on the shelf, and screw the retaining ring back in to hold the reticle in place. You will probably need a spanner wrench or very small flat screwdriver to remove and re-install this threaded ring.  If there is no retaining device but there is a shelf for the reticle, then you can buy a properly sized

If you have determined your eyepiece has the necessary shelf for the reticle you would then measure the inside diameter of the bottom of the eyepiece. Be sure you are measuring against the inside wall of the eyepiece and not the inside of any retaining ring that may be in there. This measurement must be reasonably accurate. It will typically be a fraction of a millimeter over a whole, integer number. For example it may measure 19.3 mm. You would then round down to the nearest millimeter, in this case 19mm, and that would be the proper diameter for the reticle.  Another example is you measured 23.1 mm. You would then select a 23 mm reticle diameter. The tolerance on the reticle's diameter is +0.000" / -0.005" so as long as the inside diameter of the eyepiece is slightly larger than the reticle diameter it should fit.

There are a few exceptions to this integer method of selecting a diameter. For example, Olympus has a few eyepieces designed for 20.4mm diameter reticles, Leica has some for a 24.5mm diameter, and Accu-Scope has some for a 26.5mm diameter, so we offer those, plus 1 in. (25.4mm), as standard products. But the majority of eyepieces are designed to accept an integer number diameter. Of course we can make custom diameters upon request.

Please note that a typical eyepiece will have numbers written on the outside such as WF10X/20MM. These numbers are not specifying the diameter of a reticle for that eyepiece. They are specifying the magnification of the eyepiece and its aperture (optical field diameter). Unless you have the reticle diameter as specified by the owner's manual or other manufacturer's specification, you must measure per the instructions above.

GLASS THICKNESS: Our standard reticle glass thickness is 1.5mm. This is appropriate for over 95% of our Customer's eyepieces. However occasionally we find a need for thinner glass. For example, a Customer has reported the Olympus IX71 requires a 1mm thickness or the retaining ring will be spaced too far to engage the threads of the eyepiece. So we offer 1mm thickness as a no-cost option upon request. Please keep in mind these will be more fragile than the standard thickness.

Most microscope eyepieces (oculars) are designed to accept a reticle on the inside of the bottom of the eyepiece. This is the end of the eyepiece that is positioned inside the microscope's eyetube, which is the tube that is attached to the microscope.In order for the eyepiece to properly use a reticle it will need two things. You can check for these by removing the eyepiece from the eyetube, turning it over and looking down inside the bottom of the eyepiece. 1) There must be a "shelf" (a.k.a. field stop) of some kind down inside the eyepiece for the reticle to rest on, and 2) there must be a retaining mechanism of some kind to hold the reticle in place. This shelf is very important as it positions the reticle at the focal plane of the eyepiece lens. This means the reticle is spaced correctly to be in focus when you view it through the top of the eyepiece. The retaining mechanism is typically a threaded ring that you unscrew from the inside of the eyepiece. You then set the reticle down inside on the shelf, and screw the retaining ring back in to hold the reticle in place. You will probably need a spanner wrench or very small flat screwdriver to remove and re-install this threaded ring. If there is no retaining device but therea shelf for the reticle, then you can buy a properly sized C-Ring Retainer to hold the reticle in place. Choose the C-Ring size that matches the reticle diameter (as determined in the next paragraph). If there is no shelf for the reticle to rest on in the bottom of the eyepiece, then either your eyepiece uses a different method of holding its reticle, or it is not able to accept one. Some eyepieces are designed so the reticle is installed in-between two lenses instead of at the bottom, or possibly by some other method. In this case you would need to refer to the owner's manual or contact the manufacturer/dealer. Ask them if the eyepiece can accept a reticle and how to determine the proper glass diameter.If you have determined your eyepiece has the necessary shelf for the reticle you would then measure thediameter of the bottom of the eyepiece. Be sure you are measuring against the inside wall of the eyepiece and not the inside of any retaining ring that may be in there. This measurement must be reasonably accurate. It will typically be a fraction of a millimeter over a whole, integer number. For example it may measure 19.3 mm. You would then round down to the nearest millimeter, in this case 19mm, and that would be the proper diameter for the reticle. Another example is you measured 23.1 mm. You would then select a 23 mm reticle diameter. The tolerance on the reticle's diameter is +0.000" / -0.005" so as long as the inside diameter of the eyepiece is slightly larger than the reticle diameter it should fit.There are a few exceptions to this integer method of selecting a diameter. For example, Olympus has a few eyepieces designed for 20.4mm diameter reticles, Leica has some for a 24.5mm diameter, and Accu-Scope has some for a 26.5mm diameter, so we offer those, plus 1 in. (25.4mm), as standard products. But the majority of eyepieces are designed to accept an integer number diameter. Of course we can make custom diameters upon request.Please note that a typical eyepiece will have numbers written on the outside such as WF10X/20MM. These numbers arespecifying the diameter of a reticle for that eyepiece. They are specifying the magnification of the eyepiece and its aperture (optical field diameter). Unless you have the reticle diameter as specified by the owner's manual or other manufacturer's specification, you must measure per the instructions above.GLASS THICKNESS: Our standard reticle glass thickness is 1.5mm. This is appropriate for over 95% of our Customer's eyepieces. However occasionally we find a need for thinner glass. For example, a Customer has reported the Olympus IX71 requires a 1mm thickness or the retaining ring will be spaced too far to engage the threads of the eyepiece. So we offer 1mm thickness as a no-cost option upon request. Please keep in mind these will be more fragile than the standard thickness.

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Choosing The Correct Reticle Scale Value For Your Objective

If you need to order a reticle for your application, use the following to determine the correct scale value.

When ordering reticles, take into consideration only your total objective magnification (don't add in the eyepiece). On a typical zoom stereo microscope it would be between 1X and 5X. If you installed a 1.5X auxiliary objective lens on that same stereo microscope, it would then be between 1.5X and 7.5X. On a compound microscope it would typically be between 4X and 100X.

Example 1: Using the 3X objective lens on your stereo microscope, you want to be able to measure .001" of your target specimen for each division of your reticle. Therefore, use the following formula:

Formula: Desired value of Target x Objective = Value of Reticle

.001" x 3X = .003" per division

You can see you need a reticle that has .003" per division.

Therefore:
If you want 100 divisions: .003" x 100 divisions = .300"/100 div. (Part #
If you want 200 divisions: .003" x 200 divisions = .600"/200 div. (Part #

Below are examples of the different values attained from this reticle when used with various objective settings:
Part #
.003" @ 1x objective setting = .003" at target specimen.
.003" @ 2x objecting setting = ." at target specimen.
.003" @ 3x objective setting = .001 " at target specimen.

If you already have a reticle, use the following to determine its measurement resolution.
Example 2: You have a
Formula: Reticle Value / Objective = Value at Target Specimen.
0.1mm / 40 = 0.mm (2.5 micron or 2.5µ)

Below are examples of different values attained from this reticle used with various objective settings.

Part #
0.10mm / 4x obj. = 0.025 (25µ) at target specimen.
0.10mm / 10x obj. = 0.010 (10µ) at target specimen.
0.10mm / 40x obj. = 0. (2.5µ) at target specimen.
0.10mm / 100x obj. = 0.001 (1µ) at target specimen.

When ordering reticles, take into consideration only your total objective magnification (don't add in the eyepiece). On a typical zoom stereo microscope it would be between 1X and 5X. If you installed a 1.5X auxiliary objective lens on that same stereo microscope, it would then be between 1.5X and 7.5X. On a compound microscope it would typically be between 4X and 100X.Using the 3X objective lens on your stereo microscope, you want to be able to measure .001" of your target specimen for each division of your reticle. Therefore, use the following formula:You can see you need a reticle that has .003" per division.Therefore:If you want 100 divisions: .003" x 100 divisions = .300"/100 div. (Part # S- If you want 200 divisions: .003" x 200 divisions = .600"/200 div. (Part # S- Below are examples of the different values attained from this reticle when used with various objective settings:Part # S- : .300"/100 divisions, each division equals .003" actual value..003" @ 1x objective setting = .003" at target specimen..003" @ 2x objecting setting = ." at target specimen..003" @ 3x objective setting = .001 " at target specimen.You have a S- reticle which has a 10mm scale divided into 100 divisions. Therefore each division is 0.100 mm (100 micron). If you use the 40X objective lens on your compound microscope, you want to know the corresponding dimension of your target specimen.Below are examples of different values attained from this reticle used with various objective settings.Part # S- : 10mm scale with 100 divisions, each division equals 0.10mm actual value0.10mm / 4x obj. = 0.025 (25µ) at target specimen.0.10mm / 10x obj. = 0.010 (10µ) at target specimen.0.10mm / 40x obj. = 0. (2.5µ) at target specimen.0.10mm / 100x obj. = 0.001 (1µ) at target specimen.

Calibrating Your Reticle With a Stage Micrometer

For precise measurements, each reticle must be calibrated to each objective using a Stage Micrometer.

Procedure for Calibrating Each Objective:

Accurate measurement of microscopic objects requires the use of an eyepiece reticle (a.k.a. eyepiece micrometer) and a stage micrometer. The eyepiece reticle is a round glass disk with a precision scale on its surface. The eyepiece reticle is inserted into one eyepiece and must be in focus. The eyepiece and eyepiece reticle can be rotated 360 degrees in the eyetube so the measuring scale can be aligned with or superimposed over the image of your specimen. A typical eyepiece reticle would be a 5mm or 10mm linear scale featuring 50 or 100 divisions. Before using the eyepiece reticle for accurate measurements it is necessary to calibrate the eyepiece reticle using a stage micrometer. A stage micrometer is typically a 1" x 3" slide with a pattern of known dimensions on its surface. The stage micrometer is placed directly on the stage of the microscope and brought into focus. By rotating the eyepiece both scales can be positioned parallel to each other. To calibrate the eyepiece reticle you must first find out how many intervals of the eyepiece reticle correspond to a certain distance on the stage micrometer. You can then calculate the value of one interval of the eyepiece reticle. Each microscope objective must be calibrated independently.

Example: Let's say each division of the metric stage micrometer above is 0.01mm or 10µ (10 micron). First determine how many divisions of the eyepiece reticle correspond to a certain distance on the stage micrometer and calculate the length of one division of the eyepiece reticle. In this example 90 divisions of the eyepiece reticle corresponds to 60 divisions of the stage micrometer. (Note: Even though it appears that more than one set of lines are aligned, i.e. 30/20, 60/40 and 90/60, it is typically most accurate to use the largest dimension pair for your calculation.) Each division of the stage micrometer equals 10µ, so 60 divisions of the stage micrometer would equal 600u. To calculate the value of one division of the eyepiece reticle we would divide 600µ by 90 resulting in 6.67µ per reticle division. The reticle value, in this case 6.67µ, would apply only to the objective for which the calibration was made. Each microscope objective must be calibrated independently.

Important Note on Reticle Diameters & Patterns

All geometric patterns available will not fit on all available reticle diameters! Please keep this in mind when choosing a reticle/geometry combination.

For example: The S- Scale Reticle is a 20mm scale. If you order it on a 19mm diameter reticle you can see it will not completely fit.  We will assume this is done intentionally because you want the pattern to go right to the edge. So, if you order this, we will make it! Please be sure you completely understand since these reticles are non-returnable! If you have any doubt or questions at all, please contact us before ordering.

Custom Reticle and Stage Micrometer Designs

We are experts in making custom reticles and stage micrometers (or other similar products). If you need a reticle or stage micrometer with an artwork design, physical dimension or substrate material we don't normally consider standard we can usually still help.  If you have your specifications ready just send them to us for a quotation, or just give us a call and we can assist you in developing the specifications that will satisfy your application.

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Choosing an IMU: FOG vs MEMS IMUs RETICLES: Reticles with custom artwork will have a one-time setup cost, typically around $, and usually run around $249.95/ea in small quantities. Future orders of the same design will not require the setup charge again.  These costs cover most designs but may differ depending on the complexity and size of the artwork, product dimensions and requested substrate material.  An exception is if we can use a standard artwork pattern but simply remove some of the design. This can typically be done less expensively.  Also, reticles using one of our standard artwork patterns, but with a non-standard physical dimension or substrate type, can usually be made less expensively as well since they would not require new artwork. Please contact us for a firm quote.

STAGE MICROMETERS:  Prices for custom stage micrometers vary significantly depending on your requirements so you will need to contact us with your details for a quote. Like the reticles above, any new artwork requirement will have a one-time setup charge plus the price per piece. Please note: it is less expensive to put one of our standard reticle patterns on a stage micrometer than to create new artwork.

Picking the Perfect Reticle for You

How to Select and Use Reticles and Stage Micrometers.

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