camera mounting - SteveJustin1963/Telescope-Tec1 GitHub Wiki

Yes — in most cases, a removable-lens camera (like a DSLR, mirrorless, or industrial C-mount camera) is far better for telescope mounting than a fixed-lens type. Here’s why:

• With a removable lens, you can take the camera lens off and attach the camera directly to the telescope’s focuser using a T-ring and T-adapter.
• This lets the telescope itself act as the camera lens — the light path goes straight through the telescope’s optics to the sensor.
• Result: maximum sharpness, light throughput, and no vignetting or focus mismatch.

• Removable-lens cameras usually have manual ISO, shutter, and exposure control — essential for astrophotography.
• Larger sensors (APS-C or full-frame) capture wider fields of view and more light, improving low-light performance and detail.
• You can also use RAW capture, which retains faint detail in nebulae, stars, or planetary surfaces.

• You can switch easily between setups:

  • Telescope → camera body (prime focus)
  • Telescope → Barlow lens → camera (for magnification)
  • Telescope → eyepiece projection → camera (for planetary work)

• You can also add filters (IR-cut, narrowband, UV) in the optical path, which is much harder with fixed-lens cameras.

• Many telescopes (especially Newtonian, Schmidt-Cassegrain, and refractors) are designed with T-thread or 1.25"/2" eyepiece mounts, meant to hold a camera body directly.
• Fixed-lens cameras (compact or phone) require extra optics (afocal adapters), which often introduce aberrations or make focusing difficult.

• For quick snapshots of the Moon through the eyepiece (afocal photography).
• For educational setups or casual observing.
• But image quality will be limited by the extra glass and alignment.

If you plan on doing serious or even intermediate astrophotography, get a camera body with a removable lens — ideally:

• Mirrorless (smaller, lighter, less vibration),
• DSLR (still great for general astrophotography),
• or a dedicated astronomy camera (ZWO, QHY, etc.) that directly fits into a telescope focuser.

Would you like me to show you the exact adapter chain (with diagrams or part names) for mounting a DSLR or mirrorless body to a typical telescope focuser (e.g., 1.25″ or 2″)?

If I adapt to put the mirrorless camera onto my Newtonian telescope, where should the focal plane be set up for the camera to work?

Excellent question — and this one really gets to the heart of Newtonian telescope imaging geometry. The focal plane is the exact spot where your telescope’s light cone converges to a sharp point — and for a camera to focus properly, its sensor must sit exactly in that plane.

Let’s break it down carefully 👇

A Newtonian telescope reflects light from:

1. Primary mirror → forms an image near the top of the tube.

2. Secondary mirror (flat) → bends that image sideways to the focuser.

3. The focal plane is therefore just outside the focuser drawtube — where your eyepiece field stop normally sits.

When you remove the eyepiece and attach a camera body, the camera sensor must sit exactly where the eyepiece field stop was.

For prime focus astrophotography, the optical system should meet this requirement:

Distance from the top of the focuser drawtube to the focal plane = the camera’s flange focal distance (FFD)

Would you like me to draw you an ASCII or diagrammatic cross-section showing the Newtonian’s mirror, secondary, focuser, and sensor placement — including where the focal plane sits relative to each? It’s very helpful when adjusting mirror position or choosing adapter lengths.

Here’s a clear ASCII-style cross-section diagram showing how to position a mirrorless camera on a Newtonian telescope, including where the focal plane sits:

             Light path from sky
                     ↓
             ┌──────────────────┐
             │   Primary mirror │
             │  (parabolic)     │
             └──────────────────┘
                      \
                       \ reflected converging beam
                        \
                         \      ←───────  Optical axis
                          \
                           \__________
                            \        \
                             \        \
                              \        \
                               \        \  ← converging cone of light
                                \        \
                                 \        \
                                  \        \  ← secondary mirror (flat, 45°)
                                   \_______/
                                        \
                                         \  →→→→→→→→→→→→→→→→  to focuser drawtube
                                           \
                                            \______
                                            |      |
                                            |      |  ← focuser drawtube
                                            |______|
                                               ↑
                                               │  FOCAL PLANE (where image forms)
                                               │
                         ┌──────────────────────────────────┐
                         │   Camera body (mirrorless)       │
                         │   Sensor plane (marked “Φ”)      │
                         └──────────────────────────────────┘

• If your camera cannot reach focus even with the focuser all the way in →
  the focal plane is too far inside the tube → move the primary mirror forward slightly.

• If your camera focuses with the focuser nearly racked out →
  the focal plane is too far out → add a short extension tube (20–40 mm).

1. Remove eyepiece, point at a bright distant object.

2. Hold white card at focuser top, move until the image is sharp.

3. Measure that distance from the focuser lip — that’s your true focal plane.

4. Adjust your camera + adapters so its sensor (the “Φ” mark) lands at exactly that distance.

If you tell me your telescope’s focuser type (1.25″ or 2″) and camera model, I can calculate the exact adapter combination and spacing (mm) you’ll need so the sensor lands right at the focal plane. Would you like me to do that next?

Perfect — you’ve got a 1.25″ Newtonian focuser and a Canon M100 mirrorless camera (EF-M mount).
Let’s calculate and show exactly how to mount it so the sensor sits at the telescope’s focal plane 👇

• EF-M mount FFD = 18 mm (distance from the lens mount to the sensor).

• Your telescope’s image must therefore fall 18 mm behind the T-adapter’s shoulder when the camera is attached.

[ Telescope focuser (1.25") ]
           │
           ▼
┌───────────────────────────────┐
│  1.25" T-adapter barrel       │   (~30 mm long, slides into focuser)
└───────────────────────────────┘
           │  (has external T2 thread, M42×0.75)
           ▼
┌───────────────────────────────┐
│  Canon EF-M T-ring adapter    │   (M42 female → EF-M bayonet)
└───────────────────────────────┘
           │  (provides 37 mm spacing)
           ▼
┌───────────────────────────────┐
│  Canon M100 camera body       │
│  Sensor sits 18 mm behind     │
└───────────────────────────────┘

Total backfocus:
30 mm (T-adapter) + 37 mm (EF-M T-ring) + 18 mm (sensor) ≈ 85 mm

Most Newtonians designed for astrophotography have a backfocus range of 55–75 mm, so you might be slightly long.
If your focuser still has some in-travel left, this setup will focus perfectly.
If you run out of inward travel before reaching focus, you can:

• use a shorter 1.25″ T-adapter (20–25 mm), or

• move your primary mirror forward by 10–15 mm.

1. Remove eyepiece and fully insert the 1.25″ T-adapter into focuser.

2. Attach Canon EF-M T-ring to adapter.

3. Mount camera body (no lens).

4. Point telescope at a bright distant object or star; use Live View to focus.

5. If you reach focus before the drawtube bottoms out, you’re done.

6. If not, adjust mirror or adapter length as above.

        Telescope tube
           │
           ▼
   [Secondary mirror]──► [Focuser]
                            │
                            ▼
                     ┌──────────────┐
                     │ T-adapter    │  ← 30 mm
                     └──────────────┘
                            │
                            ▼
                     ┌──────────────┐
                     │ EF-M T-ring  │  ← 37 mm
                     └──────────────┘
                            │
                            ▼
                     ┌──────────────┐
                     │ Canon M100   │
                     │ Sensor (18 mm)│
                     └──────────────┘
                              ▲
                              │  ← focal plane (must coincide with sensor)

If you tell me your telescope’s aperture and focal length (e.g., 130/650 mm, 150/750 mm, etc.), I can estimate the exact field of view you’ll get with the M100’s APS-C sensor — helpful for framing deep-sky objects or planetary work. Would you like me to calculate that next?