Four inches of air-spaced ED triplet glass at f/7 — the design that delivers genuinely color-free views of planets, stars, and deep-sky objects that achromats and even ED doublets can't match. The Explore Scientific 102mm f/7 ED Triplet APO (ES-ED10207-02) is an OTA-only premium refractor for observers who've used achromats and want to know what the view looks like without the purple fringe. At 714mm focal length and f/7, it's versatile — usable across the full range of astronomical targets with exceptional contrast and resolution.
Unlike achromats and ED doublets
A standard achromat shows visible chromatic aberration on bright targets. An ED doublet (like the SV503 102mm f/7) reduces it significantly. A true air-spaced ED triplet like the ES-ED10207-02 goes further still — the three-element air-spaced design with ED glass brings color correction to apochromatic standards, where false color is below the threshold of visual perception on all but the brightest targets. At f/7, the correction is optimized without requiring the long tubes of slower designs. The result is higher contrast on planetary surfaces, crisper double star splitting, and imaging performance that doesn't require narrowband filters to control color.
What you'll see
Jupiter appears in natural color — the equatorial belts are warm brown, the zones creamy white, with the Great Red Spot in its true hue. Saturn's rings show the Cassini Division and subtle color gradients across the ring system. The Moon shows fine detail without any color fringing at the limb. Double stars with tight color pairs — Albireo, Gamma Arietis, the double-double Epsilon Lyrae — resolve cleanly with accurate color rendering. Deep-sky objects benefit from higher contrast: the Orion Nebula shows internal structure, and globular clusters resolve clearly. For imaging, tight round stars without false color halos appear across the frame (with a quality field flattener for edge correction).
What's in the box
- 102mm f/7 air-spaced ED triplet APO refractor OTA
- 2-inch dual-speed Crayford focuser with 1.25-inch adapter
- Vixen-style dovetail bar
- Tube rings
- Dust caps
| Spec |
Value |
| SKU |
ES-ED10207-02 |
| Optical Design |
Air-Spaced ED Triplet Apochromat Refractor |
| Aperture |
102mm (4 inches) |
| Focal Length |
714mm |
| Focal Ratio |
f/7 |
| Focuser |
2-inch dual-speed Crayford with 1.25-inch adapter |
| Included |
OTA only — mount not included |
Price Match, Shipping & Questions
We price-match any authorized Canadian or US retailer. Ships free to the contiguous US. Questions? Email us at support@telescopewolves.com or visit our contact page.
Frequently Asked Questions
How does this compare to the SVBONY SV503 102mm f/7 ED doublet?
Both are 102mm at f/7 with similar focal lengths. The SV503 is an ED doublet — excellent color correction, significantly below achromats. The ES-ED10207-02 is an air-spaced ED triplet — the additional element and air-spaced design bring color correction to a higher standard, closer to fluorite-class APOs. The Explore Scientific triplet will show better contrast and color accuracy on the most demanding targets, at a higher price point.
What mount do I need?
At 102mm, the tube is light enough for a capable alt-az (iOptron AZ Mount Pro, Sky-Watcher AZ-EQ5) for visual use. For astrophotography with tracking, an EQ5-class equatorial (Sky-Watcher HEQ5, iOptron CEM26) gives excellent results. The Vixen-style dovetail is compatible with standard saddles on all major mount brands.
Is this good for astrophotography?
Yes. With a quality field flattener (matched to the 714mm focal length), it delivers sharp stars across APS-C and smaller sensors. The triplet APO correction means broadband color imaging is clean without the star halos that achromats produce. At f/7, exposure times are manageable on most modern astronomy cameras. Add a 0.7× reducer/flattener for a faster f/4.9 ratio with a broader field.
Is this better than the 80mm FCD100 APO triplet bundle?
Different tools. The 80mm FCD100 uses fluorite-grade glass for the absolute highest level of color correction and comes with a field flattener — it's optimized for wide-field imaging in a compact package. The 102mm ED triplet gives 60% more aperture and is the better choice for visual planetary work and resolving finer detail. For astrophotography, the choice depends on sensor size, target field width, and whether the FCD100's fluorite correction justifies the smaller aperture.
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