Accessories for Soviet MTO-500 Mirror Lens Part 2

This is the second part of my accessory set for the classic Soviet mirror lens MTO-500 3M-5A.

These parts are designed for astrophotography and solar observation setups and are fully compatible with the accessories from Part 1.

First part of the accessory set:
https://www.thingiverse.com/thing:7327482

All parts share the same outer diameter as the original MTO-500 hood, so they work together as a modular system.

Included Models

• 150 mm Dew Shield

Extended dew shield for improved contrast and stray light suppression.
Mounts using the M77×0.75 thread
The longer shield helps reduce dew formation and improves contrast when imaging the Moon or bright objects.

• Bahtinov Mask

A focusing mask designed specifically for the MTO-500 front diameter.
Allows precise focus for astrophotography

• Solar Filter Holder

Holder designed for my solar filter frame:
https://www.thingiverse.com/thing:7281720
Secure threaded mounting
Mounts using the M77×0.75 thread
Designed for reliable and stable attachment

Safety Warning – Solar Observation

⚠️ Never observe or photograph the Sun without a proper solar filter.

Looking at the Sun through a telescope or telephoto lens without a certified solar filter can cause permanent eye damage and may destroy your camera sensor instantly.

Always make sure that:

the solar filter is securely installed
the filter material is undamaged
the filter fully covers the front aperture

Use only proper solar filter materials designed for safe solar observation.

Recommended settings:
Layer height: 0.28 mm
Infill: 15–25%
Material: PLA / PETG

PETG is recommended for outdoor use because it handles temperature changes better.

This project is part of a growing collection of accessories for vintage optics and astrophotography gear.
More accessories for the MTO-500 are available in Part 1 of this project.