Astronomical Telescope Accessories D114F900mm with Short-axis Secondary Mirror 25mm, Newton Reflector Spherical Mirror

Showed up in great condition and work well! The optics won’t blow you out of the water, but for the price it’s hard to argue!

I received a part with a chipped secondary. I contacted the vendor for a replacement secondary with no reply (edit: As it turns out, they did reply, but I never saw the email), so I sourced another secondary. After getting the new secondary in, primary installed, and collimated, I have struggled for multiple weeks to get a good image. I could not get a good sharp image with higher power lenses (150x, well under the theoretical capability of this primary). Defocused star performance is *abysmal* in spite of the airy disk having nearly perfect concentric rings (indicating good collimation). I repeated collimation quite a few times wondering if I had done anything poorly with that. I guess the old, dirty mirror is going back into the telescope. Maybe I'll give this primary to someone as a vanity mirror.

The first set I got were damaged but the supplier replaced them quickly. They are working great and fit right in as needed. Could have used a slightly bigger secondary mirror, but I got it to fit no problem since it was smaller.

Used this mirror to make a homemade Dobsonian just in time for the 2024 solar eclipse. The top of my images were a little out of focus due to my 3d printed focuser not supporting the camera's weight properly - but this wasn't the mirror's fault. I only paid around $20 for this mirror set, it came well packaged, dust free, and visually flawless - and the images I've seen through mine seemed great for the price.

I was very happy with the quality of the main mirror. For my daughter's middle school science fair project, I made a Schlieren imaging setup using this mirror on a kinematic adjustable mount I made with plywood and some hardware. Paired with a Canon 5D4 and a 100-400 lens, the results were great for seeing heat waves coming off hands, candle flame gases, butane, carbon dioxide, nail polish remover, etc. Yeah, I know it was my daughter's science fair project, but come on, that's just what dads do. Anyways, thumbs up to the quality of the mirror in this type of usage; didn't get to try the secondary lens.

I bought this not expecting a lot, I tried to replace my dobsonian parabola mirror with this non-parabola mirror and it did not work out, the larger mirror was the correct size but the smaller one was too small to fit my Celestron scope, the mirrors were clean and would most likely work pretty good in a non-parabola scope.

I don’t really have an objective way to judge quality of the coating but as far as I can tell it is fine. The mirrors look great and fit perfectly with focal distance in the ballpark.I had a problem with the order and vendor instantly responded and resolved it 100% to my satisfaction. Shipping time from China was at low end of quoted range. I think a nice addition to the product would be short instructions on cleaning and care of first surface mirrors but not a concern for me.

At this aperture and focal length, a spherical mirror shouldn't yield results very different from a parabolic mirror, but this particular spherical mirror is apparently the exception. Even relatively sharp focus is impossible (on an easy target like the moon, to say nothing of more distant targets), leaving images fuzzy and overly soft regardless of focus position, and compared side by side with a parabolic mirror of the same aperture, the difference is stark.Very dissatisfied, but cannot return it as it's been adhered in a primary mount, now soon to be removed and tossed in the trash.A mirror from a different manufacturer was far better for almost the same price, and did not suffer the same terrible views.