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Celestron – 45-Degree Erect Image Diagonal – 1.25' – Use Your Astronomical Telescope for Daytime Terrestrial Viewing – Right-Side-Up & Correctly Oriented Images in Refractors & Schmidt-Cassegrains

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$35.99

$ 16 .99 $16.99

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About this item

  • A great accessory for daytime terrestrial viewing with your telescope
  • This 1.25” diagonal produces right side up and left-to-right correct images when used with refractors and catadioptric (Schmidt-Cassegrain) telescopes
  • Inserts into 1.25” focusers or visual backs; accepts standard 1.25” eyepieces
  • Package Weight: 136.08 grams



4.2 out of 5 stars Best Sellers Rank
  • #1,030 in Camera & Photo Products (See Top 100 in Camera & Photo Products)
  • #70 in Telescope Refractors
Is Discontinued By Manufacturer No Date First Available April 30, 2002 Manufacturer Celestron Country of Origin China

Did you know that most telescopes work well for daytime viewing as well as for astronomy? If you have a refractor or a catadioptric telescope (the Schmidt-Cassegrain is the most popular example), and you would like to use it for terrestrial observations, the most useful additional accessory you can buy is an erect-image diagonal.
If you look through your telescope with the standard mirror or star diagonal installed, you will notice that objects may be either upside down, flipped so that you see a mirror image, or a combination of the two. This is fine for observations of celestial objects, but it can be a little confusing when you are trying to track a boat as it moves through the water, or an eagle as he flies towards his perch.
Luckily, this is an easy problem to correct. Simply remove the standard diagonal from the telescope’s focuser or visual back, and install the Celestron 45º Erect Image Diagonal. Now, when you insert an eyepiece, objects will be right side up and left-to-right correct. The 45º angle of this Amici prism diagonal is very comfortable for daytime observations, where the telescope is often in a horizontal position.
Please Note: Adding an erect-image diagonal to a Newtonian reflector will not result in images that are right side up and left-to-right correct. The optical design of a Newtonian will always produce images that are rotationally off in orientation. This does not mean that you can’t use a Newtonian reflector during the day, it just means that you have to get used to objects oriented in unrealistic positions.


David Boswell
Reviewed in the United States on March 1, 2025
I wanted to look at terrestrial objects and got tired of inverted and reversed images.The fit an finish are consistent and the optic itself is suitable for looking at distant objects on the ground.The 45 degree angle is a lot more comfortable than the 90 degree for ground objects.I'm currently using it to observe Space X operations in Texas up to a mile away. I can see individual rivets and tiles on the Starship.This has expanded the utility of my Celestron NexStar 127SLT.Well worth the money.
Jean Bernard Minster
Reviewed in the United States on December 10, 2024
Perfect for looking at distant landscapes, or wildlife, across the land or over the ocean.
M.M
Reviewed in France on January 21, 2024
9
Maria
Reviewed in Italy on July 2, 2023
Ottimo prodotto, ho un celestron ed è perfetto!!!
Pierre
Reviewed in the United States on March 3, 2023
Although it is listed as being compatible with the Celestron 114 AZ SR telescope.it is not. It increases the required focal length so much that the telescope cannot be focused.
Jorge Rocha
Reviewed in Mexico on March 30, 2022
Es util
sonny_m
Reviewed in Germany on June 6, 2020
Es handelt sich hier um ein Amici-Prisma. Das Bild eines astronomischen Fernrohrs wird dadurch aufrecht und seitenrichtig. Als Zubehör ist es nicht unbedingt nötig, aber es ist angenehm wegen der einfacheren Orientierung und wegen des besseren Blickwinkels.Eine Qualitätsminderung der optischen Abbildung geht mit so einer Zusatzoptik stets einher, ein erster Test ergab aber keine erkennbaren Mängel.
William D. Thomas
Reviewed in the United States on December 21, 2020
This image prism works with 1.25 eyepieces and provides a erect image (correct side up and correct right/left). Well made by Celestron and very useful when viewing the moon and planets where orientation can be an issue especially with showing views to younger people.
Allen B Sowinski
Reviewed in the United States on January 6, 2020
I use an 80 mm refractor telescope for terrestrial viewing. I enjoy watching wildlife (birds) thru my telescope. I also use my telescope for for checking paper targets at a local shooting range. I use a variable power lens plugged into the 45 degree diagonal. I'm not interested in seeing razor sharp images since my telescope isn't capable of providing the sharp images you'd see with a $5,000 apochromatic telescope. For what I use my scope for, the erect images I see are reasonably sharp and bright enough to satisfy my needs.
CBQ
Reviewed in Canada on December 2, 2018
I was not sure if this would work on a reflector style (Newtonian) Telescope, such as my Celestron AstroMaster 114EQ. Reading a few reviews made it sound like this eyepiece may not work exactly as described. I was worried the image would still be slightly askew, or that my focus adjustment would be out of range.I was thinking at the very least I would need to purchase an additional focal length extender (eyepiece extension tube). As some reviewers had indicated that the focus adjustment would be so far out of range that the telescope would not be able to accommodate. My work-around was going to be using my 2x Barlow lens to extend the focal distance enough to hopefully bring it into focus for me.However it worked exactly as described right out of the box!! No need to even use the Barlow lens, although it works wonderfully with that also! The image was flipped right-side up, and I believe it is correctly oriented left to right as well (tracking of the telescope now follows proper left to right directions when I move it, but I will need to focus on more objects to know for sure... I've only tested it once on a symmetrical object).Very VERY worth it if you want your astrological telescope to serve dual purpose of both star gazing and for some terrestrial scoping.Super easy to use and, so far, a very clear and properly oriented image.
Errol
Reviewed in the United States on May 1, 2016
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Alex the Ghost
Reviewed in the United States on December 14, 2014
I purchased this to expand the capability of my 80mm Orion Short-Tube Refractor. It's currently mounted on top of my Meade 10" LX200R as a guide scope. This diagonal allows me to use it as an intermediary finder scope between my 9x50 and my main OTA.The quality is find for what I use it for, although I wish there was a ring-style clamp inside for holding in the eyepiece. Instead it uses just the tip of the retention screw. It's the same as most inexpensive scopes & diagonals, so if you have nice eyepieces beware: it'll leave marks on them.
S. Pettis
Reviewed in the United States on February 28, 2010
I got this to use with a Astronomy Technology 66mm aperture refractor for terrestrial viewing. The first I sent back as the hole for the tightening screw was too big so it could not be secured in place on my scope. The replacement is fine. There are better optics out there but this item is fine for the price.
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