Imaging Lens FAQs
Q: Who makes Navitar lenses? Where?
We design and assemble most Navitar lenses at the Navitar manufacturing facility located at 200 Commerce Drive, Rochester, New York, USA.
Q: Why should I use a lens attachment to increase the magnification if it reduces the working distance? Why not change the lens adapter instead?
Resolution is determined by the numerical aperture (N.A.) at the object side of the lens system. Changing the lens adapter will increase the magnification but have no effect on the resolution. Increasing the resolution can only be accomplished by adding a lens attachment.
Q: How do I choose the correct components to get a specific magnification at a specific working distance?
The best way to choose the correct parts is to use Navitar's online lens calculator, the Optical Wizard.
Q: How do I mount a lens?
We offer mounting brackets that clamp on the adapter barrel. Motorized lenses have optional flat plates for mounting. We can also create custom mounting fixtures as required.
Q: Can you shorten the optics of a lens?
Yes, we offer a variety of adapter tubes of different lengths. These can be used to change the overall object to image distance. Navitar also provides 90 degree bends in the object and image spaces using both mirrors and Non-inverting Right Angle (NIRA) prisms.
Q: Why can’t I get high magnification and good depth of field?
To get adequate resolution, most high magnification systems also have a high numeric aperture (N.A.). Depth of field is inversely proportional to N.A. If the system has an iris, you may increase the depth of field by closing down the iris, but this will result in less resolution.
Q: What is the resolution of your lens system?
Resolution is a function of the lens system’s numerical aperture (N.A.). The formula to calculate resolution in line pairs per mm is 3000 x N.A.
Q: How do I determine the focal length I require?
Object size and camera format determine magnification. Magnification and working distance determine lens type. Please refer to the lens calculators for fixed focal lengths and the respective charts for zoom systems and Precise Eye systems.
Q: What is the difference between depth of field and depth of focus?
Depth of field is the viewable thickness envelope at the object plane. Depth of focus is the image thickness envelope at the image plane.
Q: Are your optics A/R (anti-reflective) coated?
Q: How can I get more depth of field?
Use a slower lens (higher F/#, lower N.A.). Or, if available, stop down the system with an iris, but be aware that resolution will diminish.
Custom Design FAQs:
Q: Can Navitar design custom products?
Yes. Contact Navitar with your specific requirements and our expert engineering team will work with you to develop a custom solution to meet your needs. After discussing your specifications in detail, we will offer a solution that outlines system performance, operating trade-off, NRE charges, and estimate prototype and serial production costs.
Q: I need a solution that is just a little different from what I see in the catalog. What should I do?
Call your regional sales rep to discuss your application or feel free to complete our custom solution application form.
Q: Do you sell cameras?
Yes. Navitar acquired Canadian based camera manufacturer PixeLINK and offers their full line of cameras. You may contact your Navitar Sales Representative for further information or call Pixelink directly at 1-800-521-5454 from within North America and +1-613-247-1211 from any international location. www.pixelink.com
Q: Can I use a C-mount lens on a CS-mount camera?
Yes, with the addition of a 5mm spacer. This compensates for the smaller flange distance designed into a CS-mount camera.
Q: Do you have lenses for line scan cameras?
Our EasyReader imaging system can be used with line scan. Please contact a representative for more information.
CCTV / Low Magnification Video Lens
Q: I'm using a CCTV lens in my machine vision application. How can I improve the image quality without moving up to an expensive lens?
Use a CCTV lens designed for a larger format camera.
Q: Can you recommend a lens if I know my FOV, working distance, and camera?
Yes. Contact your local Navitar sales representative, who will be happy to determine the correct lens for your application. You can also use the following formula to determine the required focal length (FL) for your application: FL= CCD x WD/FOV.
Q: Do your CCTV lenses have set screws?
Most lenses come standard with set screws. Contact your local Navitar sales representative for additional information.
Q: What is “C-Mount” ?
1” – 32T mounting thread with a 0.690” (17.53mm) flange distance.
Q: How do I put a filter on the front of my CCTV lens?
Most CCTV lenses come with female threads that accept standard filters. It may be necessary to purchase a “step-ring” to adapt to available filter sizes.
Zoom 6000 & 12X Zoom High Magnification Zoom / Video Microscope Systems
Q: What is the difference between the Zoom 6000 and 12X Zoom?
The 12X zoom has a higher N.A. and larger zoom range. The Zoom 6000 has a smaller profile. The Zoom 6000 is shorter with a smaller outside diameter.
Q: What are the resolution capabilities of your zoom systems?
The cut-off frequency is generally 3000 x N.A. in line pairs/mm, in visible light.
Q: Why can't you use a 2/3" format camera with your 12X Ultra-zoom lens?
The 12X lens is designed for use with a ½” CCD. Systems used with sensors greater than ½” can show vignetting at lower magnification settings.
Q: Where can you mount clamps to the zoom lens?
Manual zooms have cylindrical flanges. Motorized zooms can be mounted with flat plates. Both manual and motorized zooms can be held using adapter clamps.
Q: How do I get a required magnification on my monitor with a video microscope system?
Total Magnification on Monitor =
(Lens Attach. Mag.) x (Zoom Mag.) x (Adapter Mag.) x (Cam/Monitor Mag.)
Q: How do I set the lens to stay in focus throughout the entire zoom range (setting the parfocality of the lens)?
INSTRUCTIONS FOR SETTING THE PARFOCALITY OF ZOOM LENS
- Zoom to the high magnification position (4.5X on the Zoom 6000, 7X on the 12X Zoom).
- Set the fine focus (if present) to center of the allowable movement.
- Adjust the working distance of the entire lens system to produce the best focus.
- Do NOT change this position of the lens system for steps 4 and 5.
- Zoom to the low magnification position (0.7X on the Zoom 6000, 0.58X on the 12X Zoom)
- Adjust the rear conjugate (the distance from the rear of the lens to the camera’s sensor).
- Some cameras have a focus screw to adjust this distance (see camera documentation).
- Most Navitar adapter tubes have adjustable back ends to allow for this adjustment.
- The adjustable lenses in Navitar’s adapter tubes are locked into place by a thumb screw on the adapter tube. Do NOT attempt to open the adapter tube to gain access to this lens.
- When adjusting the optics, loosen the thumb screw only to the point where the optics move freely. If the screw comes free from the inner cell, it is difficult to get back into place properly.
- Check to see that the system now stays in focus throughout the entire zoom range travel.
Q: Can I attach an M25x0.75t micro objective to an UltraZoom?
All the M25 x 0.75t objectives will thread directly into our UltraZooms with use of the correct coupler. Zoom 6000 and 12X UltraZoom lenses include these couplers when ordered. Precise Eye lenses also require a coupler to attach objectives. Couplers are also included with Ultra PE.
Q: Can you help me calculate the magnification range when using Navitar 12X Ultra Zoom lenses with a Mitutoyo Objective lens of 5x or other infinity corrected objectives and an adapter of 2X?
To understand the magnification characteristics of the 12x UltraZoom, we must start with the magnification characteristics of the standard 12x system.
The magnification range of a 12X system with a 1X adapter and no lens attachment is 0.58X to 7.00X. Logically, one would assume that placing a 2X adapter on this system (above the zoom) would result in a doubling of the magnification yielding a magnification range of 1.16X to 14.00X and this is correct.
However, when a Mitutoyo objective is introduced the equation changes in two ways. The Mitutoyo objective was designed to function with a 200mm tube lens. The Navitar 12X is equivalent to a 178mm tube lens changing the multiplication factor to (178/200) .89. Additionally, to add the microscope objective to the 12X zoom we must remove the existing lens from the bottom of the zoom. The result is, essentially, the reduction of the magnification of the objective by ½. Therefore, if a 12X zoom is used with a 5X Mitutoyo objective and a 2X adapter the magnification range becomes:
(.58X to 7X)(2)(.9)(2.5) = (2.61X to 31.5X) resulting in a magnification range of 2.61X to 31.5X.
It should be noted that the magnification ranges listed on the web and in the catalogue will vary slightly as these values are directly from the design raytrace.
IR / UV
Q: Do your optics work in the Infrared wavelength?
We offer SWIR lenses (short wave infrared) that function in the wavelengths of 500nm - 1700nm.
Q: Do your optics work in the Near UV?
No, not at this time. Nominal operating wavelengths for our standard lenses are 400-1500 nm.
Q: Do your optics work in the Deep UV?
We offer our NanoVue 248nm 4X Deep UV Zoom lens system that works in deep ultraviolet light.
Q: Do you offer Near IR Lenses?
Large Format Lens
Q: Do you carry large format lenses in either C or F mount?
Yes, we offer both C-mount and F-mount large format lenses. Click here to view our selection of large format lenses.
Q: What endurance can be expected from a Navitar motorized system?
The system wear characteristics are a function of operating speed. Navitar recommends that a complete cycle time not be less than 3 seconds.
Q: Does Navitar offer holders or clamps for their motorized systems?
A flat surface-mount option may be purchased for the 12X and Zoom 6000 systems. Alternatively, the user may affix the system by using a clamp placed on the adapter. Clamps shall NOT be applied in any location other than the adapter as this may cause interferences within the zoom system. Click here for mounting options.
Q: Does Navitar supply drivers for their motorized systems?
Yes, Navitar has gone to great lengths to make a complete motorized solution available for your zoom needs. We highly recommend that our motorized zoom systems be used in conjunction with our driver/control options. The options consist of either a board level or an enclosed driver. Both are computer controlled and an additional manual control box can be connected to any driver model. Additionally, Navitar will supply the source code for easy interface with existing equipment.
Q: Since Navitar has three different motor options (2-phase stepper, 5-phase stepper and DC servo with encoder) how do I select the proper system for my application?
It depends on your personal preference and requirements, as well as the following considerations: The 2-phase stepper and the DC servo have a smaller ‘footprint’ than the 5-phase stepper. However, the 5-phase provides the greatest resolution due to the decreased step-angle from the 2-phase system. Additionally, the 2-phase and 5-phase have ‘holding torque’ inherent in the stepper design. The 2-phase will tend to get warm to the touch where the 5-phase will not, so if temperature is an issue consider the 5-phase.
Q: Can you go from one position to the next position on your motorized lens without going to the home position?
Yes, you can turn off the “homing” feature if absolute magnification repeatability is not an issue. If, however, repeatability is an issue, drive the lens towards the home position and always approach your target location from the same direction (home) to omit the backlash in the system.
Q: How long can the cables be for your motorized zoom lens?
PC to Driver Communication
RS-232 Cables = 32 feet / 10 meters
USB Cables = 16.5 feet / 5 meters
Motorized Lens to Driver Communication
DC Encoded = 10 feet / 3 meters
2-Phase Stepper/HE = 10 feet / 3 meters
5-Phase Stepper/HE = 6.5 feet / 2 meters
Q: Which axis controls the zoom on your control box?
The zoom shall always be axis 1 and the fine focus shall always be axis 2.
Q: Are your zoom lenses telecentric?
The 12X Telecentric Zoom system allows users to reach a true telecentric condition to within less than 0.3° while maintaining constant perspective and magnification. This means that even if the object is slightly out of focus, the size of the image will not change. The 12X Telecentric Zoom provides field coverage from 50 mm down to 4 mm and the coaxial illumination allows clear viewing, even when working with mirror-like surfaces. Click here for details about our 12X Telecentric Zoom System.
Q: When would I need a telecentric lens?
If you are concerned about a shift in magnification with object distance. Or, if perspective error is unacceptable over a given field of view.
Q: Will using a telecentric lens improve my depth of field?
No, telecentricity will keep the magnification constant through the depth of field. However the focus will soften as with any lens. The depth of field will still be determined by the system's F/#.
Vision Illumination / Lighting
Q: Do you sell lighting?
Yes, we offer a variety of lighting options for various applications. Click here for details about available lighting options.
Q: How bright is your LED Coaxial Illuminators?
Specific lumen output varies from LED to LED and is dependent on electrical current. For a list of full lumen specifications please refer to Luxeon technical Datasheet DS64 and DS65 http://www.philipslumileds.com/support/documentation/datasheets
Q: Can I use my own driver for the LED illuminators?
Yes, as long as you are aware of the electrical characteristics of the Luxeon REBEL LED. The Navitar Controller is a current-driven, pulse width modulation device, however end users can develop or utilize their own control method. Caution must be used as the LED’s are easily damaged by improper driving. In addition, typical current drive circuits will cause the color of the LED to vary with intensity. This can cause unexpected complications in many applications. Navitar's driver utilizes a circuit architecture that maintains consistent performance when changing intensity.
Q: What is the voltage of your power supply for the Coaxial LED Illuminator and Ring Light?
- Navitar Coaxial LED Illuminator = 12 VDC
- Ring Light = 5 VDC
Q: Do your fiber bundles fit power supplies from different manufacturers?
Navitar fiber bundles typically fit into power supplies with 0.5” or 0.72” diameter fiber receptacles. Custom couplers can be designed to fit other power supplies.
Q: What are the lifetimes for the Navitar LED systems?
Lifetime for solid-state lighting devices (LEDs) is typically defined in terms of lumen maintenance—the percentage of initial light output remaining after a specified period of time.
Philips Lumileds projects that cool-white, neutral-white, warm-white, green, cyan, blue and royal-blue LUXEON Rebel products will deliver, on average, 70% lumen maintenance (B50, L70) at 50,000 hours of operation at a forward current of 700 mA. This projection is based on constant current operation with junction temperature maintained at or below 135°C.
Philips Lumileds projects that red, red-orange and amber LUXEON Rebel products will deliver, on average, 70% lumen maintenance (B50, L70) at 50,000 hours of operation at a forward current of 350 mA. This projection is based on constant current operation with junction temperature maintained at or below 110°C.
Q: What type of lens is used inside of the Navitar's Coaxial Illuminator system?
A 19°, 20mm circular frosted lens is ideally suited for our full line of 20mm Rebel Star LEDs when used with a matching 20mm lens holder. Manufactured from lens quality polycarbonate, this lens has a 83% transmission efficiency, is UL rated and can operate up to 125°C.
The frosted front surface of this lens provides better beam averaging, resulting in a smoother distribution of light.
Q: My question is not listed here. How do I get my question answered?
You can e-mail your question to Navitar at email@example.com, contact your local sales representative, or call Navitar directly at 1-585-359-4000.