Phone Adapters, T-Mounts and Budget Optics: A Beginner’s Guide to Photographing Through Telescopes and Binoculars

This site used to have eleven short listings for phone adapters, camera T-mounts, small monoculars and budget telescopes sold with smartphone holders. They all answered the same question: how do I take a picture through my telescope or binoculars? This guide combines them, keeps the facts we could verify, and drops the marketing claims we could not.

Two ways to take a picture through optics

• Phone held at the eyepiece (afocal imaging): BBC Sky at Night Magazine describes afocal imaging as pointing your smartphone camera through the telescope eyepiece. It calls this one of the simplest ways into smartphone astrophotography, but notes it can be tricky to get right by hand. A phone adapter holds the phone steady and lined up.
• Camera attached in place of the eyepiece: a camera body without its lens connects to the telescope with a T-adapter and a camera-specific T-mount, so the telescope acts as a long telephoto lens.

Smartphone adapters: what the Gosky manual says

The Gosky universal phone adapter was the subject of the main original post. Its manual says:

• Standard version: fits eyepieces 28 to 47 mm in outside diameter
• Big version: fits eyepieces 32 to 62 mm in outside diameter
• Phone width: 54 to 90 mm
• Construction: aluminium body with a plastic clamp
• The manual includes step-by-step tips for centring the phone camera over the eyepiece

Before buying any phone adapter, measure the outside diameter of your eyepiece or binocular eyecup and the width of your phone, and check both fall inside the adapter’s ranges.

T-adapters and T-mounts

Several old posts covered Meade camera adapters. Meade’s ETX-60AT manual gives a clear example of how this works: the optional #64ST T-Adapter lets you close-couple a camera body to the ETX-60 at a focal length of 350 mm and an effective photographic speed of f/5.8. The manual warns that in this format some darkening (vignetting) appears in the corners of a 35 mm frame. In general, the T-adapter fits the telescope, and a T-mount made for your camera brand fits between the adapter and the camera body, so you need the right T-mount for your camera.

Budget telescopes and monoculars sold with phone holders

Many cheap kits bundle a phone holder with a small refractor or a monocular. A few points to check:

• Magnification is focal length divided by eyepiece focal length. Orion’s AstroView manual gives this formula. For example, an 80 mm refractor with a 400 mm focal length gives 400 ÷ 25 = 16x with a 25 mm eyepiece and about 44x with a 9 mm eyepiece, which matches one of the old listings.
• Ignore extreme magnification claims. The same Orion manual says every telescope has a useful limit of about 2x per millimetre of aperture, and calls higher claims a misleading advertising gimmick. An 80 mm telescope tops out around 160x.
• Hand-held monoculars and binoculars have limits too. Astronomy magazine says about 10x is the highest you will want for hand-held binoculars, because above that it is hard to hold them steady. Nikon recommends magnifications up to 12x for comfortable hand-held viewing, warning that higher power brings a narrow field, image shake and a darker image. A “40×60” pocket monocular claim should be treated with suspicion.
• Exit pupil: Astronomy magazine explains you can calculate it by dividing the aperture by the magnification. A 12×50 monocular gives about 4.2 mm.

Getting your first good photo

• Start with the Moon. BBC Sky at Night Magazine notes that shorter exposures work well on bright objects like the Moon and the brighter planets.
• Use manual controls. The same article says many phone camera apps hide manual focus, exposure and ISO settings in a “Pro” mode.
• Use the lowest-power eyepiece first. It is easier to centre the phone and find the target.
• Steady everything. Use a tripod for the binoculars or monocular, and a timer so you do not shake the phone when you tap the screen.
• Let the telescope cool. Orion’s manual suggests at least half an hour outdoors before observing.

Safety

Never point a telescope, monocular or phone-plus-optic at the Sun without a professionally made solar filter covering the front of the instrument. Orion’s manual warns that permanent eye damage can result, and phone cameras can be damaged too.

Quick summary

• Phone adapters hold your phone over the eyepiece for afocal imaging.
• Check the adapter’s eyepiece and phone size ranges before you buy.
• T-adapters plus a brand-specific T-mount attach a camera body directly.
• Treat huge magnification claims on budget kits with suspicion.

Jargon buster

• Afocal imaging: photographing through an eyepiece with a camera or phone.
• T-mount: a ring that adapts a standard T-thread to your camera’s lens mount.
• Vignetting: darkening at the corners of an image.
• Exit pupil: the width of the light beam leaving the eyepiece.