0.5X reducer for photography

Excellent for a wide-angle eyepiece, not for a CMOS camera

( 3 / 5 )

Tested with the Skywatcher Maksutov 102/1300 telescope.
This lens is expected to work for most amateur telescopes, screwed into the back of a common 1.25" barrel and of any common eyepiece or CMOS camera.

Unfortunately this is not the case, at least certainly not for the SkyWatcher Maksutov 102/1300.
I have all the alternatives uses of this lens, with the best sky object for a image quality test, the full Moon. My results follow, according to the barrel this lens was screwed into:

1) Diagonal. Certainly this is not what the Product Description advises, but is recommended in some websites. Forget it: for this lens and a small telescope this just does not work, being impossible to focus the image.

2) Skywatcher MA 25mm eyepiece. Excellent result: this lens appears to be geared towards extending the AFOV of a wide-angle eyepiece, and does this very well. It has to be said however that if this is the only way it will be used, a similar result can be achieved with a separate 40mm eyepiece of similar quality.

3) Skywatcher MA 10mm eyepiece. Serious loss of sharpness.

4) Explore Scientific Ar 9mm: very good result, yielding something like a 16mm with a fair quality. However, the much-lower-cost alternative of the Skywatcher MA 25mm eyepiece inserted into an Omegon Barlow 2X yields the equivalent of the similar 12.5mm with better image quality.

5) CMOS Camera: good image quality, but limited to the centre region of the picture (not more than about 700x500 of the total 1280x1024), with significant coma elsewhere blurring everything. I tried different diagonals, screwing the Focal Reducer to different extents, meddling with the focus, to no avail.

My conclusion: at least when in use with this telescope or similar ones, this Focal Reducer appears to deliver poor results with a CMOS camera and short-focal eyepieces. Its only use is to widen the AFOV of a 25mm or similarly-long-focal eyepiece.