- Capture wall-worthy astrophotographs with any Meade f/8 or f/10 ACF telescope with the aid of this thread-on 0.68x focal reducer
- Reduced focal length cuts exposure times in half, and nearly doubles the field of view for deep-sky astro-imaging
- Ideal for APS-C and smaller camera sensors, providing full illumination of 22mm diagonal sensor and just slight vignetting at 28mm, which is correctable with flats
- Generous 105mm (from flange) back-focus distance to allow ample room for imaging train accessories such as a filter wheel and/or OAG
- Threads directly onto ACF rear cell and comes with T-thread adapter for attachment of DSLR at the standard 55mm back-focus distance
Turn your Meade Advanced Coma Free (ACF) telescope into an astrophotography overachiever with the Meade ACF 0.68x Focal Reducer w/ 50mm T-thread Adapter. By reducing the telescope's effective focal length and "speeding up" the focal ratio, the 0.68x focal reducer significantly shortens the long exposure times typically needed to produce vivid, highly resolved images of faint deep sky objects. In addition, the focal reduction renders a wider field of view, allowing capture of larger objects in a single frame. In short, the 0.68x Focal Reducer increases the versatility and efficiency of your ACF telescope for astro-imaging, giving you more "keeper" astrophotos per imaging session.
Sure, for imaging bright objects like the planets and the Moon, the ACFs at their long native focal lengths and f/8 or f/10 focal ratios will render amazing images. And for that type of imaging you want the strong magnification that long focal lengths provide. Even on fainter deep-sky objects such as galaxies and nebulas, the ACF's exquisite coma-free optics can deliver wall worthy photographic images — with sufficient exposure time. But there's the rub. Longer exposure times require dead-on tracking and guiding, and are more susceptible to image-wrecking factors such as breezes kicking up, pesky clouds moving in, and so often nowadays, satellite trails straight-lining through the frame! Not to mention that having to take enough tediously long exposures to stack for a decent final image can take, well, a tediously long time!
That's all to say that by installing the Meade ACF 0.68x Focal Reducer between your ACF telescope and your DSLR or dedicated astronomical CCD or CMOS camera, you will decrease the capture time and increase your odds of getting the sharp, dramatic, error-free images you want.
The Meade ACF 0.68x Focal Reducer works with all sizes of Meade f/10 and f/8 ACF telescopes. It converts an f/10 telescope into a faster f/6.8 system and an f/8 telescope into a zippy f/5.5 imaging beast! That reduction translates to a nearly 50% wider field of view and exposure times cut by more than half!
The four-element Meade ACF 0.68x Focal Reducer provides full illumination of a 22mm diagonal sensor and nearly full illumination out to 28mm, with just slight vignetting that is corrected with flat field calibration. So it is ideal for use with APS-C and smaller imaging sensors. It boasts a generous 105mm of back-focus distance, measured from the reducer's flange, or 100mm on-axis from the last lens, allowing loads of space for imaging train accessories such as a filter wheel and/or an off axis-guider. The optics are broadband fully multi-coated for maximum light transmission to your camera.
Cutaway drawing showing the design (4 lens elements in two groups) of the Meade ACF .68x Focal Reducer.
The Meade ACF 0.68x Focal Reducer threads directly onto the rear cell of all Meade ACF telescopes for a solid connection. It comes with a 50mm-long universal T-thread adapter with camera-side male M42 x 0.75 threads, which is ideal for DSLR and similar cameras having the standard 55mm flange back-focus distance when used with a T-ring. For imaging trains exceeding 55mm back-focus, the universal T-thread adapter can be removed to access the reducer's standard male SCT 2" x 24 TPI threaded collar. Appropriate spacer rings may be needed to achieve the 105mm back-focus distance for your specific camera and imaging accessories.
The Meade ACF 0.68x Focal Reducer is for photographic use only, and also is not compatible with older non-ACF optical tube designs such as standard Schmidt-Cassegrain telescopes. Weighs 8.5 oz; 5.0 oz without T-thread adapter. Made in the USA.
With the Meade ACF 0.68x Focal Reducer w/ 50mm T-thread Adapter you can turn any Meade f/8 or f/10 ACF telescope into a high-performance astrograph, capable of capturing deep-space images efficiently and with impressive resolution. Order yours today!