SkyWave CT unlimited (UNL) model 450S for refractors

Welcome to optical AI quantitative telescope collimation!

Please read all the information below before purchasing your model.

This is an unlimited (UNL) SKW CT model to be used for analyzing an unlimited number of images. This model is specific for refractor telescopes.

This is a SKW model purchase order. After completing your purchase, please log in to our portal at portal.innovationsforeisght.com to download your model.

The model is also valid for use with SkyGuide and SkyGuard (SKG) licenses that support SKW. Models are both license- and machine-specific, meaning they are only valid for the license under which they were originally purchased and cannot be used with models tied to other licenses. Please note that once the model is downloaded, it cannot be refunded.

Please review carefully the model 450S specifications, data and plots, below. Pay close attention to the required defocus value in microns. The customer is responsible for achieving this defocus, either by using an external focuser or the telescope's mirror focusing system. We recommend selecting extra focal whenever possible, however the model can be used for extra or intra focal.

The model remains valid if the user changes, in SKW, the wavelength, the seeing or specifies a reduction/expansion factor in the related instrument setting to account for a focal reducer or an extender.

Specifications:

Nominal defocus travel required

The plot below shows the focuser travel, intra or extra, as function of the F/# at 550nm. The customer is responsible to achieve such defocus either by using an external focuser or the scope mirror focusing system. Whenever possible, we recommend using the extra focal defocus.

Caution: The travel value is a function of the scope F/# and CO values, as well as the wavelength used during the SKW analysis.
To compute a new focuser travel distance (NewFocuserTraverl@Lambda) when using a wavelength (Lambda), in nm, different than the @ 550nm employed in the plot below (FocuserTravel@550nm), use the following formula:

NewFocuserTraverl@Lambda = FocuserTravel@550nm X Lambda / 550

Example:  Scope f/# = 8, CO = 50%, from the plot below, @ 550nm, FocuserTravel@550nm = 6000 microns.
If lambda = 640nm the NewFocuserTravel@lambda = 6000 X 640 / 550 = 6982 microns, almost one full millimeter longer.

Recommended imaging camera pixel size

The plot below shows the camera pixel size @550nm.

Maximum recommended seeing FWHM value

The plot shows the recommended seeing @ 550nm.

Recommended minimum total exposure time

The plot below shows the exposure time for best image analysis accuracy and acceptable inter image variability under the user selected local seeing at which the scope may operate.

If the exposure is too large relative to the mount tracking performances, there is a risk of elongated stars due to tracking drifts. One can take several exposures for a cumulative total time identical to the value recommended in the plot. Those images can be either stacked, aligned, using image correlation and averaged without any other pre-processing or calibration. Alternatively, all images can be opened and analyzed in SKW, one at the time, while using the SKW collimator tool scatter plot for estimation of the average score cluster (blue dots on the collimator target). See SKW documentation for further information.

SKW CT tool normal score range versus observed score

We assume that the minimum recommended total exposure time, or longer, is used for the selected seeing FWHM value at which the scope operates. When those conditions are met, it is normal, and expected, for the observed SKW collimator tool scores to fluctuate within those ranges while the quality of the alignment remains essentially the same.The score fluctuation is the normal consequence of the seeing and inline with the analysis accuracy required for achieving a good alignment. As a consequence, the final image quality and MTF are effectively seeing limited, any remaining aberration are therefore negligible.

Key and useful documentation and links to visit:

Full SkyGuide, SkyGuard and SkyWave-Collimator version interactive help and documentation
SkyWave collimator tool proper setup for telescope alignment (PDF)
SkyWave: Dealing with seeing (PDF)
Alignment of Cassegrain type of telescopes having at least one spherical mirror (such as SCT, CDK, iDK) with SKW (PDF)
Alignment of Ritchey–Chrétien Telescopes (RCT) with SKW (PDF)