Customer comments/photos.
Updated 6/1/24

ATM Altitude and Azimuth
Bearing Parts

Laminate rings and strips.
Teflon pads.
Azimuth bolt assembly kits

Sharper Image Masks

Primary:Fix Turned Down Edge.    

Primary: Remove mirror clip flare.
Spider: Remove diffraction spikes.

Premium Mirror Cells
for 6" to 13.1" mirrors.

Each cell design calculated to optimize your mirror's performance. Eliminates mirror-clip aberrations for true circular aperture.

Clamshell & Rotating Rings

For Dobsonian mounts
For Equatorial mounts

Premium Mirror Cells

For 6 " to 13.1" primary mirrors.
Designed custom to specifically match your mirror specifications for optimal performance.

6", 8" and 10" examples with acrylic retaining ring eliminating mirror clip intrusion in light path.

Front: adjustable flat black acrylic retaining ring.

Rear: collimation knobs and lock screws.

Fan insert cutouts also available.
Cells are
manufactured individually, designed to mirror diameter, thickness, focal length, and secondary size dimensions. This allows calculating precise support points for optimal performance.

This cell design requires a tube inside diameter at minimum 1" larger than the primary mirror.

Retaining ring eliminates intrusive mirror clips without gluing which can stress the mirror. A 1/8" thick black acrylic ring extends 1/8" over the mirror front, retaining the mirror. The ring is supported by three bolts with inner side 1/16th inch from the mirror edges 120 degree apart. Add a layer of adhesive cause around the bolt to softly prevent lateral movement. Result is a perfect circular aperture for sharper imaging by (reducing star flaring) and/or curing turned down edge that results in image softness. The tiny magnitude loss at the mirror's edge is imperceptible.

We are also now asking for testers of our new spider masks for eliminating bright star diffraction spikes to get glare free star images.

Type Description
6" Cells
SMC6K Standard Mirror Cell Kit.
SMC6F Standard Mirror Cell Finished
8" to 13.1" Cells
PMCK Premium Mirror Cell Kit
PMCKF Premium Mirror Cell Kit with fan inset
PMCF Premium Mirror Cell Finished
PMCFF Premium Mirror Cell Finished with fan inset

Kits arrive assembled. Simple disassembly for fine sand and paint or finish, then reassemble. The mirror cell at left is shown assembled for fit, prior to sanding.


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Your name.
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Zip/postal code.
Cell choice.
Mirror Dimensions
Mirror diameter.
Mirror thickness.
Focal length or ratio.
Secondary mirror diameter.
Tube inside diameter.

  Materials and manufacture:
  • CNC design and cutting assures precision results.
  • Constructed of rigid, thermally stable light weight 3/4" birch plywood.
  • New front ring (described below) replaces wood ring shown in image.
  • Cell design allows maximum openness for quick cool down.
  • Six-point support positions calculated for optimal performance.
  Dimensions and weight:
  • Fully compressed front plate face to tube mounting holes: 1.25".
  • Fully compressed between front and back plate: 0.125".
  • Fully compressed collimation bolts extend 1" from rear of cell.
  • Back plate O.D. Designed 0.125" (0.25" total) less than tube I.D.
  • 13.1" cell shown weighs approximately 3.6 lbs.
  Retaining ring NEW!:
  • Now made from laser cut 1/8" black acrylic. (Replaces wood ring shown).
  • Eliminates mirror clips for a perfectly round mirror face, no intrusions.
  • Overhangs mirror edge by 0.125". Magnitude reduction is trivial.
  • Mirror cannot fall out through opening.
  • 3 black 1/4-20 nylon post pass though acrylic seated into cell.
  • Nylon screws are safe, designed to touch outside edge of primary.
  • Mirror prevented from lateral movement during vertical to horizontal.
  • Eliminates any visible mirror clip flare.
  Front plate:
  • Completely open design. No obstructions behind mirror (8"-13.1").
  • Support arms hold mirror 0.125" above front plate.
  Rear plate:
  • Collimating knobs backed with metal washers; smooth easy turning.
  • Cell position can be locked with three nylon screws (8"-13.1").
  • Options: unobstructed or with drilled inset/screw holes for fan (8"-13.1").
  What you receive and need:
  • Kits arrive assembled, unpainted, sanded with 80 grit.
  • All parts included except 0.25" tube mounting bolts and nuts.
  • Requires: finishing or painting and reassembly for kits.