ZWO T2-T2 11mm Extender

You just finished a 2-hour imaging session. You open the image. The center looks great — stars are sharp, pinpoint, clean. But then you look at the corners. Stars are stretched. They look like little comets or ovals. Something is wrong.

You didn't make a mistake. Your telescope is fine. Your camera is fine. Your back focus distance is just slightly off.

The ZWO T2-T2 11mm Extender fixes this. It's a small metal spacer — but it solves one of the most frustrating problems in astrophotography.

What is Back Focus — and Why Does it Wreck Your Images?

Every telescope, field flattener, and focal reducer has a specific number called back focus distance. This is the exact gap that must exist between the last optical element and your camera sensor.

Too short? Stars stretch at the edges. Too long? Stars stretch the other way. Only the exact distance gives you flat, sharp stars across the entire frame.

The problem is — your camera, your flattener, your filter wheel, your OAG — they all take up space. When you stack them together, the total length is almost never perfect. You're always a few millimeters off.

That's where a spacer like the ZWO T2-T2 11mm Extender comes in. You add it to the imaging train and gain exactly 11mm of back focus distance. Problem solved.

What Exactly is This Product?

The ZWO T2-T2 11mm Extender is a precision-machined aluminum spacer. It connects two T2-threaded components together and adds exactly 11mm of spacing between them.

One side has a T2 male thread (M42x0.75). The other side has a T2 female thread (M42x0.75). It screws in between any two T2 components in your imaging train.

No optics inside. No glass. Just a clean metal tube that holds everything at the right distance.

Full Technical Specifications — All Here

CNC-machined means the aluminum is cut by a computer-controlled machine. Every unit comes out at exactly the same length. No variation. No guessing. You get exactly 11mm — every single time.

Where Does This Extender Go in Your Setup?

Think of your imaging train as a chain. It starts at your telescope's focuser and ends at your camera sensor. Every link in that chain takes up a specific amount of space.

A typical astrophotography imaging train looks like this:

Telescope focuser → Field Flattener → Filter → ZWO T2-T2 11mm Extender → Camera

Or sometimes like this:

Telescope focuser → Field Flattener → Filter Wheel → ZWO T2-T2 11mm Extender → Camera

You place the extender wherever you need to close the gap. It fits anywhere between two T2-threaded components.

If you're using a ZWO camera, you can explore the full ZWO camera lineup at Sky Deep to find compatible options. And if you need other spacing adapters, browse the complete camera accessories collection here.

Who Actually Needs This Extender?

Not everyone needs this specific spacer. But if any of these match your situation — you do.

You have a field flattener or focal reducer. These optical correctors have a required back focus distance. Most of the time, your current setup is a few millimeters short. This extender closes that gap.

Your stars look sharp in the center but oval or comet-shaped at the edges. This is the classic sign of incorrect back focus. Add this extender and recalculate your total spacing.

You switched cameras and now your images look worse. Different cameras have different sensor distances. When you change cameras, your back focus distance changes too. This extender helps you recalibrate quickly.

You added a filter wheel or OAG (Off-Axis Guider) to your setup. Both of these add thickness to your imaging train. That changes your back focus. You need a spacer to compensate.

If you're building a complete deep space imaging setup, check out the deep space imaging collection at Sky Deep — it has everything you need in one place.

Why ZWO — and Why Only Sky Deep in Pakistan?

ZWO accessories are not just cheap parts. They are precision components built for real astrophotography. The threads are tight and consistent. The aluminum is rigid — it won't flex or shift during long imaging sessions. And the length is exact — not approximately 11mm, but exactly 11mm.

Sky Deep is Pakistan's ONLY authorized ZWO dealer. This is official. ZWO has directly authorized them to sell in Pakistan.

This matters because:

Buy with confidence from an authorized source. You’ll receive a genuine ZWO product, reliable after-sales support, competitive pricing, and free nationwide delivery across Pakistan—from Islamabad and Lahore to Quetta.

Sky Deep is also the official learning partner of Lahore Astronomical Society — which means they understand astrophotography deeply. They don't just sell accessories — they help you use them correctly.

Have questions about your back focus setup before buying? Visit the contact page or book a free consultation. Their team will calculate the exact spacing you need.

Build Your Imaging Train the Right Way

If you're still building your setup, here are the other components you'll likely need alongside this extender.

A good refractor telescope is the best starting point for deep sky imaging. Browse apochromatic telescopes here — they give the sharpest, flattest images.

You'll also need a ZWO camera to connect at the end of your imaging train. Color cameras are here and monochrome cameras are here.

And if you want to add narrowband filters to your setup, the narrowband filters collection has everything — including the ZWO Duo-Band Filter which works perfectly with this extender in the same imaging train.

For learning how to build and calculate your back focus distance from scratch, the Sky Deep Astro Knowledge Hub has free guides that walk you through everything step by step.

Order Now — 10 Units in Stock

Price: Rs. 5,130 PKR — with free delivery across Pakistan.

Stock is available but limited. Don't wait until you're mid-session and realize you're missing this.

Order the ZWO T2-T2 11mm Extender here

Need help calculating your back focus first? Book a free consultation — Sky Deep's team will do the math with you.

 Questions People Ask About This Extender

Q1. What does "T2" mean — and do my accessories support it?

T2 is a thread standard. Its full name is M42x0.75 — it means 42mm diameter with 0.75mm thread pitch. Almost all ZWO cameras, filter wheels, OAGs, and field flatteners use T2 threads. If your accessories are from ZWO, they almost certainly support T2. You can check compatible items in the ZWO accessories section at Sky Deep.

Q2. How do I know if I need 11mm specifically — or a different length?

You need to calculate your total imaging train length and compare it to your field flattener's required back focus distance. The difference tells you what size spacer you need. If you're not sure, contact Sky Deep — they'll help you calculate the exact spacing for your specific setup.

Q3. Will this extender cause any optical problems in my images?

No. This extender has no glass or optics inside. It's just a metal tube. It doesn't change how light travels. It only adjusts the physical distance between components. Your image quality depends on your telescope and camera — not this spacer.

Q4. Can I stack two of these extenders to get 22mm?

Yes. Because one side is male and the other is female, you can thread two together. This gives you 22mm of back focus. Many astrophotographers keep a few different spacers to mix and match the exact distance they need.

Q5. Is this the right product if I'm a complete beginner?

If you're just starting out with a basic telescope and no field flattener, you probably don't need this yet. But once you add a flattener or focal reducer to your setup, you'll need spacers like this one. Sky Deep has a free consultation service to help beginners figure out exactly what accessories they need before buying.

Sky Deep — Pakistan's largest astronomy store. The only authorized ZWO and Celestron dealer in the country. Trusted by astronomers, built for dreamers.