Orion Nebula M42 imaged in 5 different sessions from 2023 to 2025, with a 4 in refractor at 557 mm focal length, an ASI 533MC cooled astronomy camera, dual band H-alpha and O-III filter, with an LXD75 mount and an ASI 174MM guide camera. This image was taken with a DIY focal length reducer.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
Totally-eclipsed moon imaged with an 8 inch Celestron SCT and a Pentax KP DSLR, at ISO 6400, 3 seconds exposure time, on 08 September 2025 at the PAGASA Astronomical Observatory in Quezon City, Philippines. An improvised focal reducer was used to shorten the native focal length from 2000 mm to 1140 mm to fit the full disk of the Moon to an APSC-sized sensor. Focal ratio was also reduced from f/10 to f/5.7, resulting in a brighter image with shorter exposure time. Stars were visible with the fully-eclipsed moon.
Related links:
Time-lapse of the 08 September 2025 Total Lunar Eclipse.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
Lagoon Nebula M8 imaged with a 4 in refractor at 557 mm focal length, an ASI 533MC cooled astronomy camera, dual band H-alpha and O-III filter, with an ASI 174MM guide camera. This is a test image taken with a DIY focal length reducer.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
Eastern Veil Nebula imaged with a Sky-Watcher Equinox 4 in refractor at 557 mm through a DIY focal length reducer, ASI 533MC cooled astronomy camera, dual band H-alpha and O-III filter, and an ASI 174MM guide camera.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
I am now using a Pentax KP as my main astrophotography DSLR. Recently I have been testing this new setup using the Pentax KP and a Celestron 8 inch SCT with DIY reducer. Here are some photos taken at with this setup at 1335 mm focal length at f/6.6. I used an improvised adapter to attach the KP to this telescope.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
Pinwheel Galaxy M101 imaged with an 8 inch SCT at 1140 mm focal length, an ASI 533MC astronomy camera with UV-IR filter, DIY reducer, and tracked with a restored Vixen Great Polaris mount. M101 has a very low surface brightness. Use the stars near Alcor and Mizar of the Big Dipper to find M101.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
Eagle Nebula M16 imaged with an 8 inch SCT, an ASI 533MC cooled astronomy camera, and dual band H-alpha and O-III filter. I used a restored Vixen Great Polaris tracking mount and an off-axis guider with ASI 174MM guide camera. Use the bright stars of Sagittarius as pointers to find this target.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
Sombrero Galaxy M104 imaged with a Celestron 8 inch SCT at 1140 mm, and an ASI 533MC astronomy camera. I used a restored Vixen Great Polaris mount and an off-axis guider with ASI 174MM guide camera. M104 is in the constellation Virgo, near the bright stars of Corvus. This galaxy is relatively bright and easy to find.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
M13 Globular Cluster in Hercules imaged with a Celestron 8 inch SCT at 1140 mm, and an ASI 533MC astronomy camera. I used a restored Vixen Great Polaris mount and an off-axis guider with ASI 174MM guide camera. This target is bright and easy to find with just a finder scope.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
Trifid Nebula M20 imaged with a Celestron 8 inch SCT, an ASI 533MC cooled astronomy camera, dual band H-alpha and O-III filter, with an ASI 174MM on an off-axis guider. The dark dust lanes that divide the nebula into three sections are visible in this photo. This photo was imaged and tracked using a restored Vixen Great Polaris mount.
Related link:
OnStep DIY Go-to Telescope Controller
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
Omega Centauri (NGC 5139) imaged with a Celestron 8 inch SCT at 1140 mm, and an ASI 533MC astronomy camera. I used a restored Vixen Great Polaris mount and an off-axis guider with ASI 174MM guide camera. This target is bright, easy to find, and should be visible even in the finder scope.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
Dumbbell Nebula M27 imaged with a Celestron 8 inch SCT at 1140 mm focal length, OIII and H-alpha dual band filter, and an ASI 533MC astronomy camera. I used a restored Vixen Great Polaris mount and an off-axis guider with ASI 174MM guide camera. To find M27, use the bright stars of Aquila and Cygnus as pointer stars. This target is bright, easy to find, and should be visible even with small telescopes.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
Whirlpool Galaxy M51 imaged with an 8 inch SCT at 1140 mm focal length, an ASI 533MC astronomy camera with UV-IR filter, DIY reducer, and tracked with a restored Meade LXD75 mount. M51 is relatively bright and may be visible through a small telescope. Use the stars of the Big Dipper to find M51.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
To find the Crab Nebula, locate Auriga first and then scan the region south of Auriga, near the bright star in Taurus. A narrowband filter helps in increasing the contrast between the nebula and the sky (such as using a 12 nm OIII for visual use, or 6 nm dual-band OIII and H-alpha for photography). Due to the nebula’s small angular size, a telescope with 4 inch aperture or larger with relatively long focal length is recommended for this target.
Crab Nebula M1, unguided image with an 8 inch SCT at 1140 mm focal length on a DIY reducer, an ASI533MC cooled astronomy camera, dual-band H-alpha and O-III filter, and a Meade LXD75 mount.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
The moon imaged with an 8 in SCT with 0.75x DIY reducer and a Canon 50D camera. Registering and stacking done in SIRIL.
For a complete list of astrophoto images, click here.
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
Focal reducers are optical elements (a convex lens or lens group) that converge light from a telescope’s objective. It shortens the focal length and in effect, produces a faster telescope (lower f/ratio) and widens the field of view (larger portion of the sky is imaged). Any decent quality objective lens from an achromat telescope or a finder scope could work as a focal reducer. DIY focal reducers may introduce aberration (coma) and must be considered when attempting this modification.
Using a Vixen 90 mm Objective Achromatic Lens
I have built a DIY focal length reducer (focal reducer) by inserting an objective lens from a 90 mm Vixen achromat along the optical system of a Sky-Watcher Equinox 100ED . The telescope’s native focal length is 900 mm at f/9. Using the objective lens of a Vixen 90 mm f/14 achromat, the focal length of the Sky-Watcher Equinox 100ED is reduced to 557 mm at f/5.57. To reach focus, I had to shorten the optical tube to about 55 mm. The focuser’s draw tube was also shortened to prevent it from obstructing the light and stopping down the objective lens when the draw tube moves inward. Varying the distance between the main lens and the reducer lens affects the resulting effective focal length. From 2020 to 2024, I have tried placing the DIY reducer at various distances until I finally found one configuration that produces stars with acceptable sharpness. To view a sample photo with a DIY reducer using a Vixen 90 mm achromat objective lens, click here.
Using a Threekor 40 mm or 50 mm Finder Scope Lens
Finder scope lenses can also be used a reducers. I have used the objective lens of a 40 mm Threekor finder scope as DIY reducer for my 8 inch Celestron SCT. I just removed the finder scope’s lens and then placed it at the threaded end of the 8 inch SCT, where you would attach a visual back adapter. I used a spare tube extender (I use M42 spacers) to mount the lens and insert it into the optical path. Upon testing, it reduced the focal length from 2000 mm to 1140 mm. I have also successfully used a 50 mm finder scope achromat lens as a DIY reducer. To view a sample photo with a DIY reducer using a 40 mm finder scope achromat objective lens, click here.
Related link: Images taken with a DIY Focal Reducer
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines
Night Sky in Focus 