Celestron AVX Product Review
Accurate Tracking with your 500mm
By K David in Hands-On Tests on May 4, 2018
B&H Photo Video loaned us a Celestron AVX tracking mount specifically to test with a 500mm f/4.5 Takumar telephoto lens. We wanted to get some close-up, tracked galaxy images for the Astrophotography Series, and this mount seemed like the best option for delivering those images. The mount test afforded us an opportunity to provide in-depth information about an uncommon, niche piece of photography equipment largely unknown outside of telescope photography circles. We elected to use a fast 500mm telephoto lens in lieu of a telescope because the process would be more recognizable to photographers not familiar with the specialized language used for describing telescopes. This article discusses the AVX mount with a telephoto lens and some of the incredible advantages it provides, some limitations, and some drawbacks.
Celestron AVX, Takumar 500mm f/4.5, and Pentax K-3
In the Box
The AVX comes in a box larger and heavier than a half-height mini-fridge (38X26X12 inches). The tripod (assembled) weighs 46 pounds with the German equatorial mount weighting 18 pounds (with counterweight). The shipping weight is 60.1 pounds.
The box's height is governed by the tripod leg height and the width by the tripod's width and German equatorial mount. That leads to the balance of the box using space inefficiently with at least one empty box used for spacing. That box, in the tripod we received, was crushed in transit by the counterweight, which had come loose and moved freely through the box during shipment. Fortunately, the rest of the packaging was secure and the loose counter weight didn't damage other components, which indicates the balance of the packing material's quality.
The box arrives sealed with shipping straps inside a larger shipping box. After unpacking, the AVX can stow in a closet. For travel, it packs well into relatively little space and would fit inside a trunk. Here are the items that Celestron includes in the mount-only box:
- Tripod and leg-bracing plate
- German equatorial mount
- Eleven-pound counterweight and mounting bar
- Remote control and holder
- Connector cables
- Automobile power connector
- Various threaded angle adjusters
- Printed manual
- Compact disc manual and additional software
The loaner AVX arrived and, much to our UPS driver's glee, we were home. The shipping box weighed in at a bit more than 55 pounds and was half the size of a typical refrigerator. Unpacking the mount, it's not meaningfully smaller. As both the photos in this article so far show, the very large 500mm Takumar looks like a silly little stick mounted on the front of a nearly-invisible-it-so-tiny camera. The tripod weighs in at 52 pounds, 11 of which are attributable to the counterweight. The mount itself, a German mount, carries a good deal of weight even without the tripod due to construction quality.
Celestron AVX Counterweight
The mount's legs are two-section, all-metal legs with very strong friction locks for the extension placement. Fully extended and assembled, our tester, who is a bit over 6'2" (190 centimeters) could stand comfortably behind the mount and use the camera without crouching. Had we been using a side-view telescope, we could not have used the mount at full height and seen the camera's screen at an optimal angle. The mount's tripod portion is very tall. The construction makes it stable despite the height.
Typical AVX Friction Lock
The tripod's feet have a bit of a point, in metal, making them well suited for planting firmly in the ground. This affords a good deal of stability. Even on concrete, the mount's stability was impressive. The mount's listed carry weight of 30 pounds (13.6 kilograms) provides the mount more than enough capacity for the relatively light Takumar 500mm f/4.5 and a DSLR.
Celestron AVX Tracking M82
Overall, we felt that the mount's construction was exceptional. It has to be to support a 30-pound telescope during slewing and tracking, but the overall quality still impressed us greatly.
Latitude Range: 7 to 77 degrees (north or south)
Payload: 30 pounds (telescope weight)
Go-to: Yes, automatic after calibration
Control Motor: DC servo
Slew Speed: Four degrees per second
Tracking Speeds: Sidereal, lunar, and solar tracking
Power Needs: 12 volt, 3.5 ampere
Assembled Height: 44 to 64 inches
- Periodic error correction
- Multi-star polar alignment
- Pre-loaded 40,000-object database
- Object data base containing multiple common nomenclatures
The Celestron AVX is packed with some incredible features but also has some shortcomings. Overall, the features outweigh the absent items.
Celestron AVX Detail Photo
This guide assumes that the mount's user knows how to assemble the tripod in the field. Details for assembly are provided in the instruction manual and are of suitable quality and clarity that reproducing them here serves no benefit. This guide discusses some tips, best practices, and methods for aligning using a telephoto lens. The instruction manual's use section assumes the AVX will have a telescope mounted on it, and some fine details about camera placement and other details are slightly different with a telescope.
The best thing you can do for yourself is load the Google Sky View app on your phone before going into the field. You can use this to verify star location when using guide stars to align the mount. Begin alignment at home by setting the mount's tilt to your latitude. With that set, you can save yourself a lot of hassle in the field.
Neutral Mount Alignment
In the field, begin your alignment with the mount in the neutral position. This position is required for precision tracking to commence. Neutral alignment occurs when both pairs of indicator lines are aligned.
Mount Rotational Adjustment (Opposing Handles)
In the field, position the tripod so that the front points roughly to the north. With the position approximate, use the opposing handles pictured above for precision alignment. The object here is to have Polaris somewhere in the vertical center line on your live view screen (this is easiest with live view). After getting Polaris on the center line, fine-tune the tilt to bring Polaris into the screen's center.
Tilt Fine-tuning Controls
The tilt controls allow the mount to move up and down. When using these, make incremental adjustments to prevent the mount from slipping suddenly. With your alignment fine-tuned, you can now go about aligning the mount precisely using stars. The mount, we found, assumes that Polaris will be properly aligned in the viewfinder when performing subsequent alignment.
Because Polaris is not precisely in the planet's northern rotational axis, we found slight tracking improvement when putting Polaris about 5% of the live view screen width away from the actual center (with a 500mm lens). We imagined a circle on the screen. That circle represented a clock face and placing Polaris on that circle where the hour hand on a clock would be at the mount's alignment time delivered an additional 15 to 20 seconds of accurate tracking time compared to on-center alignment.
Tip: Use sights or a rough barrel sighting to align Polaris before fine-tuning with Live View.
Alignment in the Southern Hemisphere will be different and slightly more challenging. Because we are in the Northern Hemisphere we were unable to develop a practical method for Southern Hemisphere alignment. The instruction manual provides directions; however, those assume telescope use.
The AVX's Kit Power Cord
After setting up the mount, you can turn it on. We suggest not turning it on too soon as the mount is not kind to batteries. Out of the box, the AVX comes with a car cigarette lighter adapter. The AVX draws 12 volts direct current and we found that alligator clips on a 12 volt lantern battery clipped to the metal ports on the cigarette lighter adapter worked to deliver power, but that the lantern battery did not have enough power to drive the AVX for more than a few hours and that after an hour or so the tracking rate suffered. The AVX mount's greatest weakness is its power inefficiency.
12 Volt DC Input
We used the AVX when connected to a car's cigarette lighter. Initially, we did not run the car during AVX operation. This was a mistake. The AVX requires that the car be running to provide enough power to drive the AVX's tracking motor consistently and eliminate power-draw-related tracking inaccuracies. After about two hours of use, our battery was providing noticeably dimmer interior cabin lighting and quieter stereo output, and starting our car took longer than normal. At the time of the tests, our battery was only five months old. Our battery appears to have been permanently damaged by the AVX's rapid drain and that our car's battery outputs at a lower voltage than it did prior to the testing period. So, putting aside environmental concerns, if you plan to run this from your car, run the engine.
The AVX has a standard electrical socket attachment available for use at home. The attachment runs $70 from Celestron or B&H. That option is an additional order and is not included with the AVX. We recommend, if you're going to use the AVX in the field, purchasing a portable car charger with a cigarette lighter plug on it and using that for powering the AVX. The batteries are discussed below in the accessories section.
One complaint about the controller is that it has no capacity to track data while off-line, but it does retain data. The date, time, and location don't reset but instead are listed as the last entered data. So each time you power on the AVX, you will need to enter the current date, time, and time zone. After entering current time and location data, pick a means of alignment. We used, excursively, star-based alignment. We picked stars, typically Alderban, Merak, Dubhe, and Vega as they're easily seen from our testing site.
AVX Slewing the 500mm to Align with Merak
Entering a star, which requires scrolling through a long list, causes the mount to slew to where it believes the star should be. From there, the user uses the directional control buttons to center the star in the live view screen. The AVX requires a minimum of two stars. We found that adding two more improved accuracy for longer tracking. We were able to obtain blur-free images for slightly more than 190 seconds using this method.
Optimum Telephoto and Camera Alignment on the AVX
We tested tracking exclusively with the Takumar 500mm f/4.5. Previous to this test, we had managed a 20-second tracked image with a 400mm lens as our long-exposure telephoto record. (We obtained exposures exceeding 20 minutes with a 135mm lens on a film camera, but the technical performance of film allows for a greater margin of error that with digital.)
Media Alignment Distance from the Rotational Axis Limits Accurate Tracking Times
The AVX is not designed for telephoto use and this shows. As with any tracking mount, the film or digital sensor needs to be as close as possible to the rotational axis to minimize tracking errors. The AVX's design for telescopes allows this with side-mounted telescope viewfinders. The distance from the rotational axis (shown as the red line on the above image) governs how long an image can accurately track the sky. We found a causal relationship with distance from the rotational axis and tracking time. The alignment above shows the alignment we used for tracking in excess of two minutes.
Early Tests with Incorrect Alignment Limited Accurate Tracking to Thirty Seconds
Our first tests did not account for sensor placement on the rotational axis and the setting above delivered no usable results beyond 30 seconds and few longer than 25 seconds. The greater the distance from the mount's rotational axis to the film plane along an orthogonal trajectory, the greater the tangent error introduced by the camera's own movement around a central pivot point. We found that, with a 500mm lens, the tracking is so accurate that the possibilities for shorter lenses like 135mm, 77mm, and 15mm would indicate tracking accuracy measurable in hours, not minutes, with on-axis sensor alignment.
The Controller Illuminates the Screen and Buttons at Night
The menu system on the controller feels antiquated but is logical and easy to use once the selection buttons are figured out. The buttons used for selecting menu items are somewhat counter-intuitive and we found that using the 6 and 9 keys to select menu items was less logical than using the central directional buttons.
Celestron AVX Control Detail
The menus are deep and have a LOT of options. We could write an entire article about the menu system. Fortunately, the user manual covers them quite well.
AVX Power Switch and Input Ports
For all that the AVX offers, is has some notable weaknesses. These weaknesses do, to an extent, limit the usability of the AVX and make it feel like it relies on obsolete technology compared to competing products.
The AVX Controller's PC Interface Relies on an Obsolete Input Device Port
An easy improvement, and notable absence in the AVX, is a GPS connection. The competing iOptron product features GPS interface and hands-off operation that allows the user to set it down, turn it on, and after the iOptron unit rotates a full turn it knows where and when it is with far greater accuracy than I was able to provide the AVX through manual alignment. Adding a passive GPS antenna ought to be highly doable and would be a worthwhile, and expected, feature.
A Rechargeable Battery Could Easily Mount Beneath the Leg Stiffener
The AVX, as we noted, did permanent damage to our tester's nearly new car battery through direct current drain. A significant improvement would be an included rechargeable battery. Celestron does sell two versions of its PowerTank, either a seven ampere hour or a 17 ampere hour unit. Both have a lot of thought and good design built into them with flashlights, USB out ports for charging devices, and handles for carrying convenience. The units run $70 and $125, respectively, at B&H. However, a basic battery would be a nice inclusion with the mount, especially if it could affix to the space beneath the tripod leg stiffener.
Celestron 17 Ampere Hour Power Tank
Modern Computer Interface and Downloadable Software
As shown above, the AVX controller's computer interface is a Port Serial 1, an interface popular for computer keyboards in the early 1990s. That port was superseded by the PS2 port in the mid-1990s and subsequently by the universal serial bus (USB) in the mid-late 1990s.
Our reviewer was unable to connect the AVX controller to a computer to run the included software. Doing so required a PS1 to USB adapter and a laptop with CD drive, neither of which our reviewer had. We believe that the software included with the AVX would have improved the user experience but cannot speak to it directly.
Had the AVX controller arrived with a USB connection or had the free software been downloadable from the Celestron website, we could have addressed using the Celestron in concert with a computer. Our reviewer did not have old enough technology to facilitate a computer connection.
Celestron SkyPortal Wi-fi Adapter
The AVX lacks wi-fi connectivity out of the box. Celestron does sell their SkyPortal wi-fi unit for $90 at B&H. We were not provided a SkyPortal to test and so are unable to speak to its functionality.
The AVX arrives as a bare-bones mount. The user can add to it with a battery or two, a wi-fi connection, a wall socket power supply, and other add-ons. However, by the time all the add-ons are purchased the AVX becomes more expensive than the competing iOptron that has all those items included in the box. That the consumer has to piecemeal a system together that functions as well as the competitors does out of the box, and that the piecemealed system costs more than the competitor's complete system unit is the AVX's greatest problem. That said, for users looking to work their way into astrotracking with a telescope and buy an affordable, expandable system, the AVX provides significant cash flow advantages.
The Celestron AVX requires a new type of mounting plate compared to older mounts. The older plates do not fit the mount. The Vixen Optics SX Dovetail Plate, however, works in the AVX. The Vixen plate is made of soft aluminum. This allows the user to mark, when tightening the retaining screws in the AVX mount for the first time, the plates proper position within the mount so that the screws can nest well in the future and help ensure consistent repositioning over multiple nights. The downside to that is that the plate does not look new for long and incorrect positioning can cause multiple pairs of dents with little indication of which dent pair is the correct one.
Vixen Optics SX Dovetail Plate
Set-up and Tear-down Notes
Practice setting up the AVX at home a few times. We found that the first few setups took around 25 to 30 minutes. By our third night out with the AVX, we had the initial setup to around seven minutes with complete setup to alignment taking around 15 minutes. We strongly advise against trying to set the mount up in the field for the first time.
The central reinforcing plate posed a challenge due to awkward retaining nut placement.
Second Engine Verification and Cable Pin Count
Early AVX models included a six-pin cable controller for the declination motor. The unit we used had the eight-pin cable shown below. The first AVX iteration had six-pin declination motor cables. Those early AVX mounts were apparently buggy and were largely replaced by AVX under warranty. And though we are told that (and believe this to be true) the six-pin declination units are no longer in the new-unit supply chain, used models may have the faulty motor or motor control system if the owner failed to have it replaced under warranty. So if you buy or are evaluating an AVX mount, check the pins on the cable and the pins in the declination motor connection and ensure that the unit has an eight-pin connector.
With the testing we did, we have some results we felt warranted sharing. All these images were taken on top of a parking garage in Concord, California. The city lights offered significant pollution issues and the garage roof lights caused glare problems with some lens alignments. Those factors limited the number of successful images we attained.
Whirlpool Galaxy 100% Crop | K David | 118.79-second Exposure
Messier Objects M81 and M82 190.32-second Exposure | K David
Jupiter 30-second Exposure | K David
Jupiter 100% Crop | K David
Mars 30-second Exposure | K David
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