Backfocus

Backfocus configurator

Build your imaging train as it exists in practice and see your target distance, mechanical length, glass correction, and exact deviation instantly.

StatusNot yet complete
Effective distance0.00 mm
Difference—
Components0
01

Optical foundation

Choose your telescope, camera, corrector, and filter. This foundation determines how the target distance is built.

Telescope

Choose a catalog model or enter one manually.

No telescope selected. The calculation remains usable, but no model-specific context is available. Without an active reducer or flattener, the target distance must be determined by the telescope configuration or entered manually.

Camera

Sensor distance is always included in the total distance.

Known camera detailsNo thread informationNo mount information

Corrector

Only use a reducer or flattener if your setup actually uses one.

Source: manual
No active corrector is selected. Enter the target distance manually for your telescope or optical configuration.

Filter and glass correction

Only add a filter if there is actual glass in the optical path.

No filter is active, so the calculation does not apply glass correction.

Target distance

This field, together with your imaging train and sensor distance, determines the final calculation.

Source: manual
Target distance sourceManual entryNot entered yet
No active corrector is selected. Enter the target distance here manually for your telescope or optical configuration.
02

Imaging train builder

Build your mechanical train from corrector to camera. Add components, change the order, and immediately verify the total length.

Starting pointStarting point: telescope output
Total mechanical length0.00 mm
Train summaryNo components yet
Corrector / telescope side
No components have been added yet. Add spacers, adapters, filter wheels, or other components to build out your imaging train.
Camera / sensor side
Instant analysis

Not yet complete

The target distance is missing. The camera sensor distance is missing.

Complete inputFill in the missing values first

Once all values are complete, you will get precise spacing guidance.

Target distance—
Sensor distance—
Components0.00 mm
Glass correction- 0.00 mm
Effective distance0.00 mm
Difference—

Configuration

TelescopeNot selected
CameraNot selected
CorrectorNo corrector
FilterNo filter

Checks

Telescope context
No telescope selected. The calculation remains usable, but no model-specific context is available. Without an active reducer or flattener, the target distance must be determined by the telescope configuration or entered manually.
Target distance source
No active corrector is selected. Enter the target distance manually for your telescope or optical configuration.
Mechanical
No direct thread conflicts were found based on the values entered.
Optical
No active corrector is selected. The optical context therefore comes from the telescope and your manual configuration.
Missing input
The target distance is missing. The camera sensor distance is missing.