Let’s Dive into Explore Scientific 2in EDT APO Replacement Focuser
The Explore Scientific 2in EDT APO Replacement Focuser promises enhanced focusing precision for astronomy enthusiasts. Designed as an upgrade for Explore Scientific’s own APO EDT series telescopes, it boasts a rack and pinion system and a 10:1 micro-focusing knob. The advertised goal is sharper, clearer views of celestial objects.
What prompted me to look at this focuser was a persistent issue with image shift on my existing telescope. I needed a robust and precise focuser that could handle the weight of my imaging equipment without introducing any unwanted movement. I was seeking a focuser that would hold focus through long exposures and temperature changes.
Upon unboxing, the Explore Scientific 2in EDT APO Replacement Focuser certainly feels substantial. Its weight, at 2.0 lbs, suggests a robust build, and the machining appears clean. I was initially impressed by the heft and the smooth action of the focusing knobs.
Compared to the stock Crayford focuser on my Celestron, and a William Optics upgrade I tested briefly, the Explore Scientific initially seemed more promising in terms of rigidity. The Crayford slipped under heavy loads, while the William Optics, while smooth, didn’t feel as solid. I chose to try the Explore Scientific 2in EDT APO Replacement Focuser hoping for a rock-solid platform for astrophotography.
My initial impression was cautiously optimistic. The focuser looked well-built, and the micro-focuser knob felt precise. I hoped it would resolve the image shift issues I was experiencing, providing stable, accurate focusing for deep-sky imaging.
Real-World Testing: Putting Explore Scientific 2in EDT APO Replacement Focuser to the Test
First Use Experience
I tested the Explore Scientific 2in EDT APO Replacement Focuser at my usual dark-sky site, about an hour outside the city. The temperature was a cool 45°F with moderate humidity. My primary goal was to image the Orion Nebula using my Explore Scientific ED127 APO telescope and a ZWO ASI294MC Pro camera.
Under these conditions, the focuser immediately exhibited some concerning behaviors. Even with the locking screws tightened, my camera seemed to have a slight wobble. As I racked the focuser in and out, I noticed the image shifting noticeably on the camera’s live view.
The coarse focus knob worked smoothly enough, but the 10:1 micro-focuser showed a disconcerting jumpiness. I had hoped for smooth, incremental adjustments, but instead, I felt a distinct “stick-slip” action. This made achieving pinpoint focus incredibly challenging.
Extended Use & Reliability
After several weeks of using the Explore Scientific 2in EDT APO Replacement Focuser during various imaging sessions, my initial concerns were unfortunately validated. The focuser’s performance didn’t improve with time; the issues remained consistent.
The focuser’s durability, while seemingly robust on the surface, revealed some underlying flaws. The internal Teflon pads supporting the drawtube seemed to contribute to the image shift, as they didn’t provide a stable, consistent surface. I noticed very slight scratching on the drawtube after only a few sessions.
Maintaining the focuser was straightforward in terms of cleaning the exterior, but I didn’t attempt to disassemble it for fear of voiding any potential warranty. The internal mechanics, however, clearly needed some adjustment or redesign to address the slop and image shift issues. Compared to my previous stock focuser, and even the Crayford I briefly used, the Explore Scientific 2in EDT APO Replacement Focuser was a disappointment. The advertised precision and stability were simply not there in real-world use.
Breaking Down the Features of Explore Scientific 2in EDT APO Replacement Focuser
Specifications
Weight: 2.0 lbs (0.91 kg). This substantial weight contributes to the perceived robustness of the focuser.
Diameter: 2″. This standard diameter allows compatibility with a wide range of eyepieces and accessories.
Length: 120.7mm. This length dictates the amount of in-focus travel available.
1.25″ compression ring eyepiece adapter. This adapter expands the focuser’s versatility by accommodating smaller 1.25″ eyepieces.
10:1 micro-focusing knobs. These knobs are intended for precise, fine-tuned focusing adjustments.
Three set screws. The set screws firmly secure eyepieces or cameras in the focuser drawtube. These are designed to prevent slippage and maintain alignment.
These specifications matter because they dictate the focuser’s compatibility, stability, and precision. The weight and build quality suggest durability, while the micro-focusing knob promises fine-tuned control. However, in practice, the implementation of these features falls short.
Performance & Functionality
The Explore Scientific 2in EDT APO Replacement Focuser struggles to perform its primary job: providing stable and accurate focusing. The image shift issue is a significant problem, particularly for astrophotography. The sloppy rack and pinion mechanism and the inadequate drawtube support hinder its effectiveness.
The focuser’s strengths are its initial impression of solid construction and the inclusion of a micro-focuser. Its weaknesses include image shift, a jumpy micro-focuser, and a lack of overall precision. The focuser does not meet expectations for a product in its price range.
Design & Ergonomics
The Explore Scientific 2in EDT APO Replacement Focuser presents a decent initial appearance. The materials seem robust, and the weight suggests quality construction. However, the design suffers from poor execution of critical mechanical components.
The focuser is relatively user-friendly in terms of basic operation, but the jumpy micro-focuser introduces a steep learning curve. Achieving truly precise focus is difficult and frustrating.
Durability & Maintenance
The focuser’s long-term durability is questionable based on my short-term experiences. The internal Teflon pads seem prone to wear, and the rack and pinion mechanism exhibits slop that is likely to worsen over time. Maintenance is limited to external cleaning, as disassembling the focuser is not recommended.
Accessories and Customization Options
The Explore Scientific 2in EDT APO Replacement Focuser comes with a 1.25″ adapter. There are no stated customization options from Explore Scientific, but the standard 2″ barrel allows for the use of aftermarket accessories like extension tubes and coma correctors. However, the image shift issue significantly impacts the usability of heavy accessories like coma correctors.
Pros and Cons of Explore Scientific 2in EDT APO Replacement Focuser
Pros
- Initial impression of solid build quality.
- Includes a 10:1 micro-focuser knob (in theory for precise adjustments).
- Comes with a 1.25″ adapter for added eyepiece versatility.
Cons
- Significant image shift during focusing.
- Jumpy and imprecise micro-focuser.
- Poor drawtube support leading to instability.
Who Should Buy Explore Scientific 2in EDT APO Replacement Focuser?
The Explore Scientific 2in EDT APO Replacement Focuser might be suitable for visual observers who are not particularly demanding of focusing precision and who use lightweight eyepieces. Casual observers who prioritize ease of use over absolute accuracy might find it acceptable.
This product should be avoided by astrophotographers, especially those using heavy cameras or accessories. Anyone who requires precise, stable focusing for high-resolution imaging will be disappointed. A must-have modification would be a complete overhaul of the internal mechanics, but this would likely cost more than the focuser itself.
Conclusion on Explore Scientific 2in EDT APO Replacement Focuser
The Explore Scientific 2in EDT APO Replacement Focuser promises a lot but ultimately fails to deliver on its core function: providing stable, precise focusing. The image shift issue is a critical flaw that makes it unsuitable for serious astrophotography.
The price of $229.99 is not justified given the focuser’s performance. While it may appear well-built on the surface, the internal mechanics are clearly lacking.
I would not personally recommend this focuser. The image shift and jumpy micro-focuser make it a frustrating and unreliable tool. Save your money and invest in a higher-quality focuser from a reputable manufacturer known for precision engineering.