What focal length does the 8 inch EdgeHD reach with the 0.7x reducer?

Celestron makes it one full f-stop faster than f/10, a nominal 1,422 mm at f/7. My frames through it plate-solved at 1,467 to 1,501 mm with ZWO ASI2600MC Air and Duo cameras, 0.72x to 0.74x: the reduction depends on the spacing.

What did I capture through it?

On the Celestron Advanced VX with a ToupTek ATR533C: the Whirlpool in 60 x 60 s, M 13 in 44 x 60 s, the Hamburger Galaxy in 60 x 60 s and the Pinwheel in 118 x 60 s. They are in the video from 7:53, and my C5 video puts the Pinwheel and M 13 beside the C5's at 7:47.

Is the reducer worth it on an 8 inch EdgeHD?

For deep-sky imaging I think so: to really take advantage of the EdgeHD you need the focal reducer, though it is expensive. It fits nothing else, so buy it only with the EdgeHD 800.

How much does the EdgeHD 800 0.7x reducer cost?

The prices I recorded: £429 at First Light Optics (UK), awaiting stock; $419 at Agena Astro (US), in stock; $419 at Celestron (Global), out of stock.

What have I not tested on the 8″ EdgeHD 0.7x Reducer?

I have not used it with a full-frame sensor, and the spacing I used is not recorded.

Celestron EdgeHD 800 0.7x Reducer review: f/7 on my 8 inch

Where does it rank on our leaderboard

Nine of the 46 accessories on my board, against price
Rank	Accessory	Stars for Your Buck	Recorded UK price
1	GEMINI EAF	100 out of 100	£42
2	Generic Dew Heater	93 out of 100	£9
5	Generic 0.63x Reducer	88 out of 100	£54
19	Green laser pen	76 out of 100	£10
27	ZWO 5x1.25″ Filter Wheel	65 out of 100	£198
39	Celestron 8″ EdgeHD 0.7x Reducer	44 out of 100	£429
41	Celestron 11″ EdgeHD 0.7x Reducer	42 out of 100	£855
45	SKY ROVER 2x54 Binoculars	28 out of 100	£139
46	365 Solar Telescope Cover	5 out of 100	£73

Contents

01 Where does it rank on our leaderboard
02 Specifications and features
03 What I captured through it on my 8 inch EdgeHD
04 Raw against finished
05 Watch it in my videos
06 Should you buy it?
07 Questions and more about this review

In 30 seconds

Stars for Your Buck 44/100

Reviewed 12 Jul 2025 Updated 26 Sep 2026

Rank: #39 of 46 accessories
Verdict: With reservations

Written by Damon Scotting 3 min read

Buy it if

You image deep-sky targets with a Celestron 8 inch EdgeHD and want f/7 with its flat field kept.
You want room behind the reducer: Celestron gives it 105 mm of back focus for extra accessories and a wide range of cameras.

Skip it if

Your telescope is a standard SCT or another EdgeHD aperture: this reducer fits the EdgeHD 800 only.
You mainly image planets: they want the EdgeHD's native f/10 or longer, not a reducer.

My 8 inch EdgeHD galaxies went through this reducer: it is made to take the EdgeHD 800 from f/10 to f/7, and at my spacing my frames plate-solved at 1,467 to 1,501 mm.

Specifications and features

Celestron 8″ EdgeHD 0.7x Reducer reviewed #39 of 46
Recorded UK price	£429
Type	0.7x reducer for the Celestron EdgeHD 800
Model	94242
Reduction	0.7x: one full f-stop faster than f/10
Reduction I measured	0.72x to 0.74x: 1,467 to 1,501 mm from 2,032 mm, plate-solved
Lens elements	4
Back focus	105 mm (4.13 in)
Sensor size	Optimised for APS-C
Field of view	43% wider than at f/10
Weight	0.36 kg (0.8 lb)
Coatings	Fully multi-coated
Fits	EdgeHD 800 only, with the EdgeHD 800 T-adapter

What I captured through it on my 8 inch EdgeHD

Four targets

M 51, ASI2600MC Duo

Integration: 1 h 27 min (87 x 60 s)
Field: 0.92 x 0.61 degrees
Telescope: Celestron 8" EdgeHD with the 0.7x reducer
Camera: ZWO ASI2600MC Duo
Mount: Celestron Advanced VX
Target: M 51 Whirlpool Galaxy
Type: Spiral galaxy
Location: Bortle 6.8 (in my garden)

M 101, ASI2600MC Duo

Integration: 1 h 30 min (90 x 60 s)
Field: 0.92 x 0.61 degrees
Telescope: Celestron 8" EdgeHD with the 0.7x reducer
Camera: ZWO ASI2600MC Duo
Mount: Celestron Advanced VX
Target: M 101 Pinwheel Galaxy
Type: Spiral galaxy
Location: Bortle 6.8 (in my garden)

NGC 3628, ASI2600MC Duo

Integration: 29 min (29 x 60 s)
Field: 0.92 x 0.61 degrees
Telescope: Celestron 8" EdgeHD with the 0.7x reducer
Camera: ZWO ASI2600MC Duo
Mount: Celestron Advanced VX
Target: NGC 3628 Hamburger Galaxy
Type: Edge-on spiral galaxy
Location: Bortle 6.8 (in my garden)

M 13, ASI2600MC Duo

Integration: 34 min (34 x 60 s)
Field: 0.92 x 0.61 degrees
Telescope: Celestron 8" EdgeHD with the 0.7x reducer
Camera: ZWO ASI2600MC Duo
Mount: Celestron Advanced VX
Target: M 13 Hercules Globular Cluster
Type: Globular star cluster
Location: Bortle 6.8 (in my garden)

Raw against finished

Watch it in my videos

The 4 targets, the raw combined stack against my finished image, each with its integration, the camera and the palette:

M 51 Whirlpool Galaxy: 1 h 27 min (87 x 60 s) of light, ASI2600MC Duo, the raw combined stack with one automatic stretch
M 101 Pinwheel Galaxy: 1 h 30 min (90 x 60 s) of light, ASI2600MC Duo, the raw combined stack with one automatic stretch
NGC 3628 Hamburger Galaxy: 29 min (29 x 60 s) of light, ASI2600MC Duo, the raw combined stack with one automatic stretch
M 13 Hercules Globular Cluster: 34 min (34 x 60 s) of light, ASI2600MC Duo, the raw combined stack with one automatic stretch

What YOU can SEE with a £2000 "USED" Telescope setup?! · published 12 July 2025 · 12:12 · Watch on YouTube · 9,098 views, 506 likes on 2 Oct 2026

Jump to

1:09 Why the EdgeHD needs a focal reducer
2:29 The 0.7x reducer on my wish list
6:16 Adding the 0.7x reducer
7:53 The Whirlpool through it
8:01 M 13, the Hercules cluster
8:09 The Hamburger Galaxy
8:17 The Pinwheel Galaxy

Check out more videos on the Celestron 8″ EdgeHD 0.7x Reducer

I Pointed a £200 TELESCOPE at JUPITER!? (+ Bonus stuff)

9 Jul 2025

Should you buy it?

44/100 Stars for Your Buck

Pros

One full f-stop faster than f/10: Celestron says it doubles the equivalent exposure at f/10.
Keeps the EdgeHD's flat field: Celestron built it for the EdgeHD 800's own optical design.
A 43% wider field of view than at f/10.
My 8 inch EdgeHD galaxies and M 13 were taken through it: the Whirlpool, the Hamburger, the Pinwheel and the Hercules cluster.

Cons

Expensive: £429 at First Light Optics.
Fits the EdgeHD 800 only: standard SCTs and the other EdgeHD apertures each need their own reducer.
The 0.7x needs its spacing: at mine it measured 0.72x to 0.74x (1,467 to 1,501 mm of 2,032 mm).
Optimised for APS-C sensors, not full frame.

To really take advantage of this telescope we need to buy the focal reducer, which is expensive to say the least.

Three alternatives I have reviewed

Questions and more about this review

Reviewed by

Damon Scotting

The Telescope Man Verified

BSc (Hons) Physics with Astrophysics and Cosmology, Loughborough University PGCE / QTS, University of Nottingham

About Damon About Damon Damon Scotting is The Telescope Man. He holds a BSc (Hons) in Physics with Astrophysics and Cosmology from Loughborough University and a PGCE with QTS from the University of Nottingham, and taught physics in secondary schools before becoming an astronomy creator. He is a contributing writer for BBC Sky at Night Magazine and the author of 42 Wonders of Our Night Sky, and his photograph of the galaxy M100 with the dwarf planet Ceres was Highly Commended in the Astronomy Photographer of the Year 2024 competition run by Royal Observatory Greenwich. He has appeared on the BBC's Blue Peter. More than 750,000 people follow his astronomy channels on YouTube, Instagram and TikTok, and he has reviewed more than 140 telescopes, mounts, cameras, filters and accessories hands-on for this site. More about Damon · How I test · Damon's book

I review all kinds of gear: most of it I buy, some is gifted and some is loaned, and all of it is reviewed the same way. How this site is funded

Five questions, answered

Questions about the Celestron 8″ EdgeHD 0.7x Reducer

Reviewed 12 July 2025 ·Updated 26 September 2026

I review all kinds of gear. Most of it I buy, some is gifted and some is loaned, and all of it is reviewed the same way: no company sees or approves a review before it is published. Shop links marked Ad are affiliate links: I earn a commission when you buy through them, at no extra cost to you. How this site is funded

What focal length does the 8 inch EdgeHD reach with the 0.7x reducer? Celestron makes it one full f-stop faster than f/10, a nominal 1,422 mm at f/7. My frames through it plate-solved at 1,467 to 1,501 mm with ZWO ASI2600MC Air and Duo cameras, 0.72x to 0.74x: the reduction depends on the spacing. The specifications ↓
What did I capture through it? On the Celestron Advanced VX with a ToupTek ATR533C: the Whirlpool in 60 x 60 s, M 13 in 44 x 60 s, the Hamburger Galaxy in 60 x 60 s and the Pinwheel in 118 x 60 s. They are in the video from 7:53, and my C5 video puts the Pinwheel and M 13 beside the C5's at 7:47. Watch it in my videos ↓
Is the reducer worth it on an 8 inch EdgeHD? For deep-sky imaging I think so: to really take advantage of the EdgeHD you need the focal reducer, though it is expensive. It fits nothing else, so buy it only with the EdgeHD 800. Watch it in my videos ↓
How much does the EdgeHD 800 0.7x reducer cost? The prices I recorded: £429 at First Light Optics (UK), awaiting stock; $419 at Agena Astro (US), in stock; $419 at Celestron (Global), out of stock. A record, not a live price The verdict, the readers and the sellers ↓
What have I not tested on the 8″ EdgeHD 0.7x Reducer? I have not used it with a full-frame sensor, and the spacing I used is not recorded.