Best Apochromatic Refractor Telescopes for Astrophotography

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.

Using this data, our pick as the best apochromatic refractor to buy in 2023 is the Askar FRA 600.

This is a petzval quintuplet apochromatic refractor with a 108mm aperture, 600mm focal length, and f/5.6 focal ratio.

Our data shows that the most successful apochromatic refractors for astrophotography are petzvals with key specifications in this range.

Our upgrade pick is the Sky-Watcher Esprit 120ED.

Sky-Watcher is one of the most successful apochromatic refractor brands with numerous models in the most-used list.

This is a triplet apochromatic refractor with a 120mm aperture, 840mm focal length, and f/7 focal ratio.

This is in a higher price bracket to the Askar model above, but it has a bigger aperture as well as the reliability and customer support that comes with models under the Sky-Watcher brand:

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:

Finally, our budget pick is the Sky-Watcher Evostar 72ED.

This is a great low-cost option for those with smaller budgets, or just someone looking for a small and compact model that’s easy to travel with.

It’s a doublet and has a very fast f/5.8 focal ratio and relatively short focal length which works well for wide-field imaging:

Read to see the full results of our data analysis and for more details on each of our key recommendations above.

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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:

1. Doublets
2. Triplets
3. Quadruplets
4. Quintuplets
5. 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 Takhashi FSQ-102ED.

This is a quadruplet petzval apochromatic refractor with an aperture of 102mm, a focal length of 530mm, and a focal ratio of f/5.

The problem with this is that this particular telescope is fairly old and rarely available to buy in 2023.

It is also very expensive. This is why in this article we are recommending a model that is a close match in the Askar FRA600.

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. It is also fairly hard to buy in 2023 though.

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.

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Askar FRA600

Best Apochromatic Refractor Telescope

The Askar FRA 600 is our pick as the best apochromatic refractor to buy in 2023.

This is a quintuplet petzval apochromatic refractor with a 108mm aperture and 600mm focal length. This gives it an extremely fast f/5.6 focal ratio.

The petzval optical design means that there is no need to add an additional flattener as you need to with some apos.

In addition, the focal ratio can be increased to f/3.9 with the addition of the focal reducer made specifically for this telescope.

As you can see in our findings above, the most successful apochromatic refractor is the Takhashi FSQ-102ED but this is almost never available to buy in 2023. So we are recommending this Askar model as it is a very close alternative in terms of the key specifications, plus it has a lot of good feedback from deep sky imagers, as well as being substantially cheaper.

Here is an example image of the M42 Orion Nebula taken with the Askar FRA600:

A video here from Sharpstar also gives a quick overview of this telescope:

Pros

• Great deep sky imaging capacity
• High-quality mechanical build
• All in one package including case and everything you need
• No need to add a field flattened like with other apos

Cons

• Fairly heavy for a small telescope
• Not ideal for visual astronomy use
• May need to buy the additional focal reducer to get full value from its capabilities

Askar is a sub-brand under Sharpstar Optics and this is a relatively new model on the market but is gaining a lot of fans in the astrophotography world.

There are also smaller aperture versions of this telescope from Askar that are also cheaper:

• Askar FRA300
• Askar FRA400
• Askar FRA500

Overall, the FRA600 is a great value apochromatic refractor for astrophotography. It compares well to the Takahashi FSQ-106ED which was so popular but is now very hard to find and also substantially more expensive.

Key specifications

• Type: Petzval Quintuplet Apochromatic Refractor
• Aperture: 4.3 inch (108 mm)
• Focal Length: 23.6 inch (600 mm)
• Focal Ratio: f/5.6
• Glass Type: ED
• Weight: 14.3 lbs (6.5 kg)
• OTA Length: 19.4 inch (493 mm)
• Image Circle: 66 mm
• Back Focus: 160 mm

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):

• Sky-Watcher Esprit 80ED
• Sky-Watcher Esprit 100ED
• Sky-Watcher Esprit 150ED

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:

• Sky-Watcher Evostar 80
• Sky-Watcher Evostar 100
• Sky-Watcher Evostar 120
• Sky-Watcher Evostar 150

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

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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:

1. Doublet – two lenses
2. Triplet – three lenses
3. Quadruplet – four lenses
4. Quintuplet – five lenses
5. 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:

1. Evostar – These are doublets and are the cheapest range
2. Esprit – These are triplets and are the more premium option
3. 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.

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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.

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Conclusion: What are the best apochromatic refractor telescopes?

In summary, we recommend the:

1. Askar FRA 600 – As the best apochromatic refractor to buy in 2023
2. Sky-Watcher Esprit 120ED – As the upgrade option for higher aperture
3. Explore Scientific 127mm – As a lower cost, but high aperture, alternative
4. 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.