The Celestron NexYZ smartphone adapter is probably the best cameraphone accessory available for this price, but it’s not without some minor imperfections.If you’ve ever held a smartphone camera over a telescope or microscope eyepiece, you know that it’s nearly impossible to get a consistently usable image. Furthermore, taking a movie via a handheld hovering technique is completely out of the question. I’ve used a couple different inexpensive smartphone adapters for eyepieces, and they just do not deliver, largely due to the difficulty in lining up the camera’s lens with the sweet spot of the eyepiece. I think the Celestron NexYZ is really the best sub-$100 product to address this issue.The NexYZ is made of a lot of different plastic and metal components. The metal components seem solid, while the plastic components, not including the knobs, feel kind of cheap. I’m guessing this was to make the unit as light as possible, since it will be hanging off of your expensive eyepieces. There are a lot of moving parts in this small package. The main clamp opens by depressing the outside lever, followed by positioning the clamp’s arms around your eyepiece and letting go. Initially it’s a loose hold, but you can quickly tighten the clamp by spinning the orange knob that you see on the right in the pictures. This will lock the NexYZ in place. From there you have to gently open the smartphone holder by pulling the spring-loaded slider on the left of the device. Slide your phone in and slowly allow the slider to grip your phone. The face of the holder that interfaces with the back of your smartphone is rubber, so it shouldn’t scratch anything. Now you’re ready to line things up for image acquisition.At this point you’ll be doing a lot of fine tuning with the x, y, and z positioning knobs, which are all located on the rear of the NexYZ. If you are using a monocular eyepiece telescope or microscope, hopefully you already positioned your subject in the field of view. With a microscope, this isn’t much of an issue for fixed specimens or static cell cultures. With a telescope, however, you probably want an equatorial or motorized mount that is tracking your planet or star of choice because it will take you at least 2 minutes to line things up with your phone on the NexYZ, and the planet or star probably moved out of your field of view by then. Something to consider. With an incredibly aligned finder scope you might be able to manage lining up a subject through the camera phone without finding it with your eyes and tracking with an EQ mount first, but it’s a significant challenge for anything other than the moon. If you have a binocular eyepiece system, you can clamp the NexYZ on first, and still find your subject through the other available eyepiece. With your phone clamped onto your eyepiece, you need to open your camera app and then try your best to line things up with the x, y, and z knobs. The knobs are well-designed, and they will slide your phone smoothly on metal tooth-strips guided by metal gears. The NexYZ makes this alignment task as easy as possible – but be aware that it’s still probably not as simple or as quick as you want it to be. While the clamp is pretty sturdy, I found that hitting the virtual shutter button on my phone’s screen caused enough vibration to result in blurred pictures. I highly recommend setting the camera to a 3-second timer to get clear, vibration-free images.Clearly, there was a lot of thought that went into designing the NexYZ. But there are a couple design quirks that prevent a 5-star rating. First, the inside of the clamp has a thin layer of foam affixed by adhesive. The foam is really, really thin. Like maybe a millimeter or two thick, at most. After two days of use, I already have tiny nicks and impressions in that that foam layer that don’t give me a lot of confidence about its long term durability. I’m already thinking about buying a thicker strip of foam with adhesive backing to solve this problem in the near future. Next, there are two plastic ring adapters that you use to wrap around smaller microscope eyepieces which give the clamp something to really grab onto. The plastic rings are cut on an angle on one side so you can kind of open up the ring a little to fit them onto the eyepiece. Again, I’m not sure about the long-term durability of bending and opening these cut, hard plastic rings. I would think a neoprene type of washer/ring would have done a better job. Finally, the arms that directly hold your smartphone are somewhat limiting. These are hard plastic arms (with an interior matte plastic finish) gripping your phone with a spring-loaded mechanism. The hard plastic arms worked just fine to hold onto my iPhone 7 while it was inside a slim case, but I wouldn’t trust the arms to hold onto a case-less phone over and over again without eventually risking a scuff mark. Thin foam on the inside of the arms seems like an obvious oversight here. These problems can all be solved with $5 in hardware or craft parts, but still, with all the other fantastic design elements in the NexYZ, I’m sad Celestron didn’t go a bit further to perfect this product.Overall, I think the NexYZ is still, by a wide margin, the best smartphone adapter for the price for telescopes and microscopes. I wouldn’t bother with the adapters that cost $25 or less…they will leave you wanting because those cheap adapters hardly allow you to smoothly line up your phone in the x and y directions, let alone provide any hope of finely tuning your z-axis alignment. With a couple extra dollars in foam and neoprene, and some engineering ingenuity, you can modify the NexYZ to be a 5-star accessory for your imaging needs.There are small caveats that I feel I need to mention when it comes to smartphone imaging. You need to have tempered expectations as to what your smartphone’s camera sensor can do, even with a steady camera mount. To give you an idea of what you’ll get with a smartphone camera set to “auto” with the flash off, there are two attached images taken with an iPhone 7 mounted in the NexYZ. One picture is Jupiter with a few moons captured with a Celestron NexStar 5SE and a Celestron 24mm-8mm zoom eyepiece at 12mm (about 100X magnification) with a mildly turbulent sky in a light polluted area. The second picture shows a eukaryotic cell culture with a simple Nikon TS100 phase contrast microscope outfitted with a 20X achromat objective and 10X eyepiece. The final caveat I’ll mention is that I only used an iPhone 7 to test the NexYZ at this point. I have no idea how well it performs with a dual lens cameraphone like the iPhone X or Galaxy S9. It may be a real challenge to align those types of phone cameras with most eyepieces that limit fields of view.UPDATE FALL 2018I used the NexYZ throughout the summer and into the fall and I still think it's 4-5 stars. I did experiment with a few different adhesive foams to put into the clamp, which made some subtle improvements, but I haven't settled on the perfect solution. There are a few things you should think about, though. First, think about spending a few bucks on a good camera app where you can manually control exposure times. Sometimes Jupiter or Mars are so bright that you can't make out details or pick up moons. You can sometimes get better images with shorter exposure times, but then stack ten images together using Photoshop or other image processing programs. Also, it is a challenge to get good pictures with short eyepieces (high mag). Once I start using 9 or 8mm eyepieces, there just isn't a lot of eyepiece for the clamp to grab. What tends to happen with those eyepieces is that your phone will weigh down the clamp and the camera lens won't be "looking" straight down into the eyepiece - it will be looking down into the eyepiece on a slight angle, which causes problems with the field of view and focus.My opinion is that this is still a good smartphone adapter, and I'll stick with my 4-star evaluation. Just don't expect the NexYZ to be simple plug 'n play magic. You will need to spend some time with it making subtle adjustments until you find positioning that works for you, your scope, and your phone.