GSO 1.25" coma corrector for Newtonian telescopes with small focusers for astrophotography

GSO 1.25" coma corrector for astrophotography

Many stargazers would also like to use smaller Newtonian telescopes with 1.25" focusers for astrophotography. GSO has now developed a coma corrector that can also be attached to Newtonians with smaller focusers. The thread on the camera side is M28.5x0.6 - better known as 1.25" filter thread. The corrector has a generous working distance of 72 mm from the stop of thread, whereby the external thread is not included because it disappears in the connection adapter. The corrector is simply clamped to the focuser with the 1.25" receptacle.

What to do if the working distance is less than 72 mm?]
Smaller Newtonians usually have a shorter backfocus, which is the working distance from the receptacle at the inner position of the focuser. The corrector must therefore be lowered further into the focuser. The suitable extension is the TSVF1 - a 25 mm extension with a 1.25" filter thread on both sides. This allows the corrector to be sunk deeper into the focuser and the working distance of the corrector is reduced from 72 mm to only 47 mm.

[*Connection of astro cameras with 17.5 mm flange focal distance and T2 thread:
Many astro cameras have a T2 thread on the telescope side and a flange focal distance of 17.5 mm (distance T2 thread to sensor). We recommend the following adaption to bring the sensor in 72 mm distance to the connection thread of the corrector, the articles are linked in the accessories section:

TSFA1 - the adapter is screwed onto the camera - optically effective length 28.5 mm

T2AbstimmA1 - the tuning ring is placed between TSFA1 and camera - effective length 1 mm

TSVF1 - optically effective length 25 mm

This gives you the perfect working distance. To achieve a reproducible connection to the focuser, we recommend the 1zKonter, a counter ring that is simply pushed over the 1.25" barrel and clamped with small grub screws. This ensures that you always have an exact stop position on the focuser.

Safety informations: PDF Download