Celestron Edge HD 8 – First Impressions from My Backyard

After a lot of research (and a little bit of impulse), I finally picked up the Celestron Edge HD 8 — and I’ve got to say, it’s been quite the experience.

Coming from refractors, the EdgeHD is a completely different beast. Longer focal length, more moving parts, and way more setup time. But it’s also opened the door to deep space targets I just couldn’t get a good field of view for. In this video, I break down my first impressions of the scope, talk about the challenges I ran into with collimation and guiding, and share what I’ve learned so far.

If you’re thinking about adding an SCT to your astrophotography setup—or just curious what the jump from refractors is like—this video is for you. I’ve also written a full post below if you don’t like watching videos.

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SCT vs Refractor – Why I Added an SCT to My Setup

I still use refractors regularly—they’re easy to use, low maintenance, and great for wide-field targets. But when it comes to longer focal lengths, refractors just become too expensive and impractical. I wasn’t replacing refractors; I just needed something with more reach for galaxies and small nebulae.

That’s where the Celestron Edge HD 8” comes in. With a native focal length of 2032mm, it gives me the reach I was missing. Paired with the .7x reducer, I can still bring it down to 1422mm at f/7—a bit more forgiving for guiding and great for many smaller deep sky targets. More importantly, bringing the scope down to f/7 means I can capture those deep sky objects in about half the time it would take at the native f/10, which makes a big difference when you’re working with limited clear skies—especially when working with faint nebula targets.

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The Collimation Learning Curve

I’ll be honest—collimation was the biggest challenge. I installed Bob’s Knobs thinking it’d make things easier (and eventually it did), but what I didn’t realize was that by removing the factory screws, I completely threw off the factory collimation.

The next two nights were spent re-configuring the collimation from the ground up. I spent hours trying to find stars and when I finally did, they looked like blobs. The only reason I knew they were stars was because there were two of them. I then started playing around with Bob’s Knobs and finally got the blobs to resemble stars. Lesson learned – don’t remove the factory screws, as the telescope is collimated at the factory. You want to keep it in collimation or as close to it as possible.

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My Imaging Setup with the EdgeHD 8

I’m using a Celestron Off-Axis Guider with an ASI174MM Mini as the guide camera, and my main imaging camera is the ASI533MM Pro. I also use a .7x focal reducer to help bring the scope down to f/7.

I went with the OAG because a separate 200mm guide scope can possibly introduce flexure at longer focal lengths due to the discrepancy in the focal length of the guide scope and the 1422mm telescope. The .7x reducer is also essential—it shortens the focal length, reduces exposure times, and makes guiding more manageable.

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What I’ve Captured So Far

Since the weather hasn’t been great, I haven’t logged too many clear nights. I did capture 42 minutes of M51 (the Whirlpool Galaxy). I felt like I got nice resolution and a good signal, but I wasn’t entirely confident about my stars or the accuracy of my collimation. Still, it showed me the scope’s potential even in a rough first session.

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Frequently Asked Questions

Is the Celestron Edge HD 8 good for beginners?
Not really. It’s a longer focal length telescope that requires off-axis guiding. That in itself is not for beginners. The best telescope for a beginner is a small refractor like a Redcat 51 since they are forgiving as far as guiding errors. Read my post about my first year of astrophotography and what I purchased to get started.

What’s the native focal length of the EdgeHD 8?
2032mm at f/10, or 1422mm at f/7 with the Celestron .7x reducer which is ideal for deep sky astrophotography.

Can I use a guide scope instead of an Off-axis guider?
Technically yes, but at this focal length, differential flexure can cause problems. An Off-axis guider is more reliable.

What targets are good for this scope?
Larger galaxies, globular clusters, and smaller nebulae are where the EdgeHD 8 really shines due to its long focal length.

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Final Thoughts

This scope isn’t necessarily hard to master—especially if you’re an intermediate astrophotographer. But it does require off-axis guiding, and while collimation isn’t difficult, it’s still another task in a hobby already full of technical steps. That said, once I settle in with this setup, I expect it to be smooth sailing—just like it is with my refractors.

I’ll be sharing more deep sky photos and gear reviews soon, so feel free to subscribe on YouTube or follow along here.

Clear skies,
Kevin

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