Starizona EvoFF v3 Field Flattener for SW EvoGuide 50ED

Starizona EvoFF v3 Field Flattener for SW EvoGuide 50ED

The field flattener is optimized for astrophotography with astrocameras and system cameras (both mirrorless and DSLR) through the Evoguide 50ED, other compact refractors and finder scopes also benefit. These compact telescopes have a very curved field of view. As a result, stars off center are distorted into streaks, and the image becomes blurry. The EvoFF corrects this error and allows wide field astrophotography with very good results. With a ZWO-ASI camera with APS-C sensor, the field of view is about 5.5°x3.7°!

[[kein Bild]]Comparison with/without EVOFF (predecessor)

The two test images were taken with a ZWO ASI294 astro camera with 23.2 mm sensor diagonal. Imaging telescope was a Skywatcher EvoGuide 50ED refractor.

On the left you see the result without EvoFF corrector. The stars are distorted to distinct lines.

On the right you see the result with EvoFF. The stars are sharp over the entire image field.

For which cameras is the EvoFF v3 suitable?

The working distance of the field flattener on the Evoguide 50ED is 55 mm from the T2 thread, thus the corrector in this new version is also suitable for DSLR cameras. For use on refractors with longer focal length, the distance would have to be reduced.

For which telescopes is the EvoFF v3 suitable?

The corrector has been developed for the Evoguide 50ED, but it can also be used on other small and fast refractors between 240 mm and 450 mm focal length. The corrector is connected via the 1.25" barrel.

The refractor must have sufficient backfocus, which is given with the Skywatcher EvoGuide 50ED after unscrewing the 40 mm extension tube.

The T2 rings, T2 extension tubes and tuning rings needed for the camera are linked in the accessories section.

Astrophotography through the Skywatcher EvoGuide 50ED:

The Skywatcher EvoGuide 50ED has a doublet ED lens with 50 mm aperture and fast f/4.8. The finder offers a good helical focuser and a 1.25" receptacle. So you can attach the corrector directly to the telescope.

The working distance from the T2 thread of the EvoFF is 55 mm, so you can connect a DSLR or mirrorless system camera directly via a T2 ring and have the correct distance.

For a cooled ZWO camera with 17.5 mm flange focal distance, you will need the 21 mm T2 spacer ring, the T2-M48 adapter and the 16.5 mm M48 T2 adapter ring, which are all included with the camera.