Astro-Physics CCDT67 + Skywatcher ED80

Recently I had read about the Astro-Physics CCDT67 telecompressor and how well it works with the 8″ Ritchey-Chretien telescope and also with the ED80 refractor. Hence I took the plunge to get this which was shipped very quickly from Germany. The thought of being able to grab more than an extra stop of light from both scopes, meant it was well suited for my setup.

For an Astro-Physics product, it was actually affordable as compared to their telescopes. It is a two-element telecompressor which will be able to fill a Micro 4/3rds sensor easily without vignetting. With this mounted, my 8″ F8 RC, becomes F5.3, and the F7.5 ED80 becomes F5.0. That will be very helpful for astrophotography, although at the expense of a shorter focal length. But as I will be using them with the ZWO ASI178MMC 1/1.8″ sensor cooled imager (4.5x crop factor) when it becomes available, this focal length reduction will actually be a benefit.

The ideal spacing for the 0.67x telecompression is quoted as 101mm from flange to the sensor. But the optics in the CCDT67 is spaced 16mm from the flange. That means that the ideal distance of the sensor from the flange of the CCDT67 is 85mm, so plenty of space to fit my thin Off-Axis guider, Xagyl 1.25″ filter wheel and Astronomik CLS-CCD filter. And the fact it has a little bit of a flattening effect also helps as there won’t be a need for a field flattener as well.

Astro-Physics CCDT67 telecompressor
Astro-Physics CCDT67 telecompressor
Telecompressor
Telecompressor
AP CCDT67
AP CCDT67

The packaging looks very simple but the telecompressor looks very well constructed and the optics has nice coating. But the question is how well they work with my telescopes. I have had a chance to test this with Orion nebula M42 with and without the CCDT67 telecompressor on my Skywatcher ED80 refractor, but not had a chance to use this on my 8″RC.

Below are the images of comparison taken with the Skywatcher ED80, Olympus E-PL5 full-spectrum camera, Atronomik CLS-CCD filter, all mounted on the iOptron ZEQ25GT mount. I used ISO 1600 60 sec subs unguided.

Skywatcher ED80 @ 600mm of M42
Skywatcher ED80 @ 600mm of M42
100% crop from top left
100% crop from top left
Skywatcher ED80 with CCDT67 telecompressor (400mm)
Skywatcher ED80 with CCDT67 telecompressor (400mm)
100% crop top left
100% crop top left

As you can see from the above single sub images of M42 that the stars in the corner are definitely elongated, whereas the CCDT67 flattens it well so they are rounder with a Micro 4/3rds sensor. It allows me to grab a wider field for larger deep sky objects, as well as grab more than an extra stop of light. When I look at the light flats taken with this telecompressor, I do not see any vignetting in the corners which means it is able to illuminate the entire Micro 4/3rd sensor as claimed.

I have to say that I am well pleased with this telecompressor which seems to work very well with the ED80. And as even Astro-Physics claim that this works very well with the Ritchey-Chretien telescopes, I am sure that it will do just as well with that scope. I would definitely recommend the Astro-Physics CCDT67 telecompressor if you have either (or both) of these scopes that I own.

Boon