Celestron – EclipSmart Safe Solar Eclipse Filter – Meets ISO 12312-2:2015(E) Standards – Works with Your Telescope, Spotting Scope, or DSLR Camera – Observe + Photograph Eclipses or Sunspots Safely

I tested this filter out against a lot of other ones and while this one wasn't the best, it did have the virtue of being the most versatile. The ability to collapse or expand the opening to fit a lot of different telescope and camera lens sizes is very handy! And it has excellent design and construction for what is basically a paper-craft project with a bit of solar filter film super-glued to a bit of cardboard. The directions are a bit hard to follow because of the uneven drawing skills of whomever did the art, but once you have the idea, it's fairly easy to construct and get it into the proper configuration. The solar filter is obviously not H-alpha quality, so you won't see solar prominences, but I was able to make out sunspots without too much difficulty. The color balance of the filter is also fine, tinting the sun to the orange-red side of the spectrum, which reduces eye fatigue when keeping the sun under longer observation. This will work fine for the coming eclipse or for any other solar observation use!

My son is a amateur photographer. He wanted this for the eclipse and for solar pictures. Works great, fit on the camera just fine. Allowed great viewing safely. Read the directions as it does say only use this for 3 minutes at a time to prevent damage. So you have to take breaks while shooting. Great affordable way to capture the eclipse.

First, the filter works. However, the cardboard can accommodate up to 100mm outer-diameter lenses while the filter material itself is 60mm. I believe that while this makes no difference in terms of optical performance, it does present a challenge for those with lenses that are about 60mm or smaller. Bigger lenses will press against the cardboard at the back, but smaller lenses want to pierce the filter material. If you don't add a shim or press the filter against the lens, it will droop. One suggestion to Celestron: a total of 4 straps, one for every 90 degrees, should hug the lens under the rubber band, not just 2 that are 180 degrees apart. With 2, one degree of freedom is removed while the other is not constrained. Here's an analogy: While wearing sunglasses, try moving them side to side while someone presses against the parts that go behind your ears. This will pin them against your head (like the rubber band holding the strap). This movement won't be easy. Next, try raising them up and down while they are still pinned against your head behind your ears. This will be easier because they will pivot at the point at which they are pinned. If the glasses were also pinned to the top of your head and under your chin, then this too would not be as easy. Or, a shim of some kind could be included to center the lens.

Does what it's supposed to do. My images come out clean though this filter.

This is exactly what you would expect. A simple foldable cardboard piece with a round filter in the middle. You must use provided rubberbands to secure the folder structure to a lens or telescope. The filter is effective, but not durable. Overall, it is overpriced for what you get. Good for single use, like an eclipse, but would not stand up to regular use. Should be almost ten dollars less than what I paid.