Quick Answer
Bortle 4-6: Optolong L-eNhance ($169)
Bortle 7-8: Optolong L-eXtreme ($239)
Budget: Astronomik CLS ($139)
Do You Actually Need a Filter?
Short answer: Only if you live in Bortle 5+ (suburban/urban).
How to Check Your Bortle Class
Use our interactive map →If you're in Bortle 1-3 (dark skies), skip the filter. You don't need it, and it'll just reduce light.
Broadband vs Narrowband: What's the Difference?
| Type | Blocks | Best For |
|---|---|---|
| Broadband | Sodium/mercury vapor lamps | Bortle 4-6, galaxies, stars |
| Narrowband | Everything except H-alpha/OIII | Bortle 7-9, nebulae only |
Top 5 Filters (2025)
1. Optolong L-eNhance - Best All-Rounder
The Optolong L-eNhance is the sweet spot for suburban astrophotography.
- Type: Dual-narrowband (H-alpha + OIII)
- Transmission: 90% at key wavelengths
- Price: $169 (2-inch), $99 (1.25-inch)
✅ Why it wins: Works in Bortle 5-7. Natural colors (ish). Compatible with OSC cameras.
⚠️ Downside: Won't save you in Bortle 9. Stars look dimmer.
2. Optolong L-eXtreme - Urban Nuclear Option
Live in Manhattan? The L-eXtreme is your only hope.
- Type: Ultra-narrowband (7nm)
- Transmission: Blocks 99% of light pollution
- Price: $239
✅ Why it wins: Shoot nebulae from downtown. Unbelievable contrast.
⚠️ Downside: Stars invisible. Nebulae only. Weird colors (purple/green).
3. Astronomik CLS - Best Budget
The classic CLS filter (City Light Suppression).
- Type: Broadband
- Transmission: Blocks sodium/mercury lines
- Price: $139
✅ Why it wins: Gentle. Works on galaxies AND nebulae. Natural colors.
4. Hoya Starscape - For Visual Observers
The Hoya Starscape is designed for camera lenses, not telescopes.
- Size: 77mm, 82mm screw-on
- Price: $99
5. Baader Neodymium - Moon Filter Bonus
The Baader Neodymium enhances contrast on the Moon and planets (not for deep sky).
Which Filter for Which Bortle Class?
Bortle 1-3: No Filter
You're in dark sky territory. Filters will just reduce light and hurt your images.
Bortle 6-7: L-eNhance
This is where narrowband starts to shine. Stick to emission nebulae.
Bortle 8-9: L-eXtreme or Give Up
The L-eXtreme can pull miracles. Or just drive to Bortle 4.
Common Mistakes
- ❌ Using narrowband on galaxies (they disappear)
- ❌ Using filters in dark skies (waste of money)
- ❌ Expecting filters to work like Photoshop (they help, not magic)
- ❌ Forgetting to adjust white balance (colors will be off)
💡 Pro Tip
Stack 100 filtered frames vs. 10 unfiltered frames. More integration time beats any filter.
Installation Tips
- Clean the filter: Use lens cleaning fluid and a microfiber cloth
- Screw in carefully: Cross-threading = expensive mistake
- Focus with filter ON: Filters shift focal plane slightly
Check Your Local Light Pollution
See your Bortle class in real-time before buying a filter.
Open Map →