We analyzed 685 images shortlisted for the Astronomy Photographer of the Year competition in the past five years to see what telescopes were used.
We found that apochromatic refractors are the most successful telescope type for astrophotography.
Read to see the full results of our data analysis.
Best APOs: Data Analysis
We analyzed all 685 images shortlisted for the Astronomy Photographer of the Year competition for the past five years (2018 to 2022) to see what telescopes and other gear were used.
Of these 685 images, 121 were taken using apochromatic refractor telescopes.
Apochromatic refractors vs other telescope types
Firstly, we can see that apochromatic refractors are by some distance the most successfully used telescope type in the competition:
This is particularly so for deep-sky imaging, where apochromatic refractors have an even greater share.
The second most successful telescope type – Schmidt-Cassegrains – are the most successful for planetary imaging, where the long focal length that is a key characteristic of these telescopes lends itself particularly well to the narrow framing of planetary objects.
Apochromatic refractors can be:
- Doublets
- Triplets
- Quadruplets
- Quintuplets
- Sextuplets
This refers to the number of glass lens elements that are contained within the tube and, in general, the more lenses the sharper the images it is capable of.
The downside of this is that they get more expensive with more glass, so, in general, doublets are the cheapest and sextuplets the most expensive.
Our results show that in the competition, the apochromatic refractors most commonly used are triplets:
This likely reflects the balance of affordability to performance. Where doublets are cheaper and therefore more accessible, but less able to produce images of the level of triplets which cost more.
In turn, the triplet apos are more accessible than the quadruplets, etc.
Apochromatic Refractor Brands
If we look at the manufacturers of apochromatic refractor telescopes, we see that Takahashi are the most successful, followed by Sky-Watcher, Astro-Physics, and William Optics:
If we narrow this down to just the models used in 2022, we see that Takahashi and Sky-Watcher are still the top two but other brands like Sky Rover, Explore Scientific, and Askar are now being more commonly used:
Apochromatic Refractor Models
Looking now at the individual models, there is a clear leader in the Takahashi FSQ-106. This is a quadruplet petzval apochromatic refractor with a focal ratio of f/5.
In second place is the Takahashi FSQ-85EDX. This is also a quadruplet petzval apochromatic refractor. It has an 85mm aperture, 450mm focal length, and a focal ratio of f/5.3.
Looking now at which models were used just in 2022 there is a slightly different mix although the Takahashi FSQ-106 remains number one:
There are a number of models in joint second:
- Explore Scientific 127mm – 127mm aperture, 952mm focal length, f/7.5 focal ratio, triplet apochromatic refractor.
- Sky-Watcher Esprit 120ED – 120mm aperture, 840mm focal length, f/7 focal ratio, triplet apochromatic refractor.
- Sky Rover 102APO – 102mm aperture, 714mm focal length, f/7 focal ratio, petzval quadruplet apochromatic refractor.
- Takahashi TOA-150 – 150mm aperture, 1100mm focal length, f/7.3 focal ratio, triplet apochromatic refractor.
- Takahashi TOA 130 – 130mm aperture, 1000mm focal length, f/7.7 focal ratio, triplet apochromatic refractor.
We will now examine the top apochromatic refractors that we recommend and explore the pros and cons of each.
Sky-Watcher Esprit 120ED
Upgrade Pick – Best Apochromatic Refractor Telescope
Our upgrade pick is the Sky-Watcher Esprit 120ED.
As you can see above, Sky-Watcher is one of the most successful apochromatic refractor brands and has many models in the list of most commonly used by deep sky imagers.
This is a triplet apochromatic refractor with 120mm aperture, 840mm focal length, and f/7 focal ratio.
It is more expensive than the Askar model above, but it has a higher aperture and longer focal length. It also comes with the field flattened included, which is an additional component to buy with some other models.
Here is an image of the Centaurus A galaxy taken with the Sky-Watcher Esprit 120ED:
You can watch this video from Sky-Watcher that gives an overview of this model as well as the others in the range:
Pros
- High aperture apo for great light gathering
- Sky-Watcher are one of the most reliable telescope manufacturers and provide top support for their customers
- Field flattener and other accessories included
Cons
- Fairly big and heavy
- Premium price bracket
Overall, this is an astrophotography telescope that has a lot of fans and has proven imaging performance. It is fairly expensive and so only for the more dedicated hobbyists.
It does also come in a number of other sizes that are either more expensive (for larger aperture) or cheaper (for smaller aperture):
Key specifications
- Type: Triplet Apochromatic Refractor
- Aperture: 4.7 inch (120 mm)
- Focal Length: 33 inch (840 mm)
- Focal Ratio: f/7
- Glass Type: ED
- Weight: 22 lbs (10 kg)
- OTA Length: 27.4 inch (696 mm)
- Image Circle: 43 mm
- Back Focus: 75 mm
Explore Scientific ED127
Mid-Range Pick – Best Apochromatic Refractor Telescope
Our mid-range pick is the Explore Scientific 127mm.
This is cheaper than both the models above but ranks highly in our rankings of the most successful apos in 2023.
It has an even larger 127mm (5-inch) aperture which makes it a great value option with a lot of enthusiastic astrophotographers giving great feedback on its quality and performance.
Here is an image of the Cave Nebula taken with this telescope:
You can watch this video from the great Chuck’s Astrophotography YouTube channel where he uses the Explore Scientific ED127 to see how it compares with the Hubble Space Telescope in photographing the Pillars of Creation:
Pros
- Excellent value in terms of aperture to price
- Capable of producing advanced deep sky images
Cons
- Fairly large and heavy
This telescope is also available in 80mm, 102mm, and 153mm aperture sizes – you can see them here.
Overall, this is a great option if you do not have the budget for either of the models above but want a large apo for advanced imaging.
Key specifications
- Type: Triplet Apochromatic Refractor
- Aperture: 5 inch (127 mm)
- Focal Length: 37 inch (952 mm)
- Focal Ratio: f/7.5
- Glass Type: ED
- Weight: 18 lbs (8 kg)
- OTA Length: 34 inch (863 mm)
- Back Focus: 150 mm
Sky-Watcher Evostar 72ED
Best Budget Apochromatic Telescope
Our budget pick is the Sky-Watcher Evostar 72ED.
This is a great low-cost option and also works for someone looking for a small and compact model that’s easy to travel with.
It’s a doublet but has a very fast f/5.8 focal ratio and a short focal length which works well for wide-field imaging.
To show you what is capable with this small telescope, see this image of the IC434 Horsehead nebula taken with a Sky-Watcher Evostar 72ED:
Here is a good video giving an overview of why this makes a good apochromatic refractor for beginners:
Pros
- Cheap
- Small and light
- Wide focal length
- Great for beginners
Cons
- Low aperture
- Doublet, not triplet or more
The Evostar doublet range also comes in a number of other larger sizes that are more expensive:
Slightly confusingly, Sky-Watcher also sells a cheaper range of Evostar achromats (rather than apochromats) with very similar names – look for “AC” in the model name for “achromat”, rather than “AP” for “apochromat”. These are not as good for astrophotography so avoid them if it is an apo for imaging that you are after.
Overall, this is a great option for those not wanting to spend thousands, a beginner looking for a first apochromatic refractor for astrophotography, or someone just wanting a smaller and lighter model to travel with more easily.
Key specifications
- Type: Doublet Apochromatic Refractor
- Aperture: 2.8 inch (72 mm)
- Focal Length: 16.5 inch (420 mm)
- Focal Ratio: f/5.8
- Glass Type: ED
- Weight: 4.3 lbs (2 kg)
- OTA Length: 16 inch (419 mm)
- Back Focus: 150 mm
FAQs: Apochromatic Refractor Telescopes
What are apochromatic refractor telescopes?
Apochromatic refractors are telescopes that are optimized for astrophotography by correcting the chromatic aberration that occurs with regular refractors.
Chromatic aberration is where a colored fringe appears around bright objects.
They are also known as “Apochromats” or just “APOs”.
What is the difference between achromatic and apochromatic?
Apochromatic refractors correct chromatic aberration by focussing three colors of light together.
They are more expensive and work especially well for astrophotography.
Achromatic refractors suffer from chromatic aberration as they do not focus the different light colors together in the same way.
They are cheaper but not as good for astrophotography.
What is the difference between a doublet and a triplet refractor?
Apochromatic refractors can be:
- Doublet – two lenses
- Triplet – three lenses
- Quadruplet – four lenses
- Quintuplet – five lenses
- Sextuplet – six lenses
Generally, the more lenses, the sharper the image will be, but also the more expensive the telescope will be (although this is not the only factor in determining the price).
What is an ED refractor?
ED refers to “extra-low dispersion” glass which is often used in the lenses of apochromatic refractors.
It is high quality and improves the imaging quality.
What is a petzval refractor?
Petzval refractors are apochromatic refractors that have at least four lens elements (i.e. quadruplets) and are designed to produce fully flat images so that no additional field flattener is needed.
What is the best mount to use with an apochromatic refractor?
Our data shows that Sky-Watcher mounts dominate for imagers with apochromatic refractors.
See the Best Mounts for Astrophotography for more on this.
What camera to use with an apochromatic refractor?
It is best to use a dedicated astronomy camera with an apochromatic refractor.
The ZWO ASI1600MM Pro is our top recommendation for deep sky imaging – see the Best CCD and CMOS Cameras for Astrophotography for more on this.
Sky-Watcher Evostar vs Esprit vs Evolux: What’s the difference?
Sky-Watcher has three main ranges of apochromatic refractors:
- Evostar – These are doublets and are the cheapest range
- Esprit – These are triplets and are the more premium option
- Evolux – These were newly released in 2022 and (in the words of Sky-Watcher) “sit between our popular Esprit triplets and Evostar series”. They are compact doublets with two options – 62mm and 82mm.
Why You Should Trust Us
We are an independent astrophotography-focused publication that conducts objective research to make product recommendations.
For this article, we have conducted unique research to see what apochromatic refractor telescopes were used to take nearly 700 of the best astrophotography images in the world in the past five years.
Conclusion: What are the best apochromatic refractor telescopes?
In summary, we recommend the:
- Takahashi FSQ-106 – As the best apochromatic refractor
- Sky-Watcher Esprit 120ED – As an alternative option
- Explore Scientific 127mm – As a lower cost, but high aperture, alternative
- Sky-Watcher Evostar 72ED – As the budget option that is also great for travel
Please let us know if you have any questions in the comments below.
