Differences

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--- en:ost:fokus_new [2020/09/10 20:54] – rhainich
+++ en:ost:fokus_new [2023/12/06 13:30] (current) – [General remarks] rhainich
@@ Line 1: / Line 1: @@
-FIXME **This page is not fully translated, yet. Please help completing the translation.**\\ //(remove this paragraph once the translation is finished)//
 ====== Focusing ======
@@ Line 11: / Line 9: @@
 ++++ Calculation of the ideal adapter |
-The back focus of the telescope is 147 mm (behind the EFA). The eyepiece clamp used has a back focus of 12.5 mm. The length of the ideal adapter ''D'' is therefore calculated as follows:
+The back focus of the telescope is 147 mm (behind the EFA). The Zeiss quick changer used has a back focus of 25 mm. The length of the ideal adapter ''D'' is therefore calculated as follows:
    D = 147 − 12,5 − 33/2 - C,
-where ''C'' is the backfocus of the respective instrument. The STF-8300 together with all attachments has a backfocus of 57.5 mm. Therefore, the ideal adapter for the STF-8300 is 60mm long.
+where ''C'' is the backfocus of the respective instrument. The STF-8300 together with all attachments has a backfocus of 57.5 mm. Therefore, the ideal adapter for the STF-8300 is 50mm long.
 ++++
@@ Line 22: / Line 20: @@
 /*|< 100% 33% 33% - >|*/
 ^ Instrument               ^  Adapter [mm]  ^  Position of the EFA [μm]  ^
-| SFT-8300                 |  40+10  |  9500   |
+| QHY600M                   |  20+10  |  16900  |
-| Canon 700D               |  40+10  |  13000  |
+| SFT-8300                  |  20+10  |  9500   |
-| Baches + ST8             |  40+10  |  20200  |
+| Canon 700D                |  20+10  |  13000  |
-| Hyperionokular: 36mm     |  100    |  14500  |
+| Baches + QHY268M          |  10     |  15000  |
-| Hyperionokular: 22mm     |  100    |         |
+| Baches + QHY268M + Barlow |  20     |  17500  |
-| Hyperionokular: 13mm     |  100    |  25200  |
+| DADOS + QHY268M           |   0     |  17000  |
-| Canon + Superzoom        |  100    |  19550  |
+| Hyperionokular: 36mm      |  80     |  14500  |
+| Hyperionokular: 22mm      |  80     |         |
+| Hyperionokular: 13mm      |  80     |  25200  |
+| Canon + Superzoom         |  80     |  19550  |
 ==== Manually ====
@@ Line 67: / Line 68: @@
 //PWI3// also offers the possibility of automatic focusing. For this purpose, //PWI3// connects to [[en:ost:ccds:maximdl|MaximDL]] to take the necessary pictures. Hence, before starting the automatic focusing, the camera must be connected to //MaximDL//. With a click on ''AF CONFIG'' the settings can be adjusted. One of the most important settings is the ''Step Size (micron)'', which defines the step size in micrometers that the EFA should move at each focusing step. ''Steps (Image Count)'' is the number of focusing steps performed by the EFA and the number of images to be captured. The exposure time in seconds must be specified at ''Exposure length (sec)''. So far the following settings have proven to be useful:
-    Step Size (micron)    = 500
+    Step Size (micron)    = 150
-    Steps (Image Count)   = 5
+    Steps (Image Count)   = 17
     Exposure length (sec) = must be chosen depending on the object
-**ToDo: More to come!**
+{{ ost:software:maximdl:autofocus_good_3.png |}}
+After starting the auto focus, //PWI3// will perform the individual focusing steps, move the EFA by the ''Step Size'' and take one image at a time. Afterwards, //PWI3// will start the program //PlateSolve// (see above), which will analyze each image, search for stars, determine the diameter of these stars and estimate the focus. This is then listed in a table. With a click on ''Show Graph'' you can visualize the result. The determined star diameter is displayed over the position of the eyepiece extension. In the ideal case this representation follows a V-curve, which is also fitted into the data.
+In the following we show an example of a successful and an unsuccessful auto focus run:
+== Successful auto focus: ==
+<WRAP group>
+<WRAP third column>
+[{{ ost:software:maximdl:autofocus_good_6.png | Table with the results }}]
+</WRAP>
+<WRAP third column>
+[{{ ost:software:maximdl:autofocus_good_5.png | Plot visualizing the quality of the focus (V curve plot) }}]
+</WRAP>
+<WRAP third column>
+[{{ ost:software:maximdl:autofocus_good_4.png | Result: well focused star }}]
+</WRAP>
+</WRAP>
+== Unsuccessful auto focus: ==
+<WRAP group>
+<WRAP third column>
+[{{ ost:software:maximdl:autofocus_bad_2.png | Table with the results }}]
+</WRAP>
+<WRAP third column>
+[{{ ost:software:maximdl:autofocus_bad_1.png | Plot visualizing the quality of the focus (V curve plot) }}]
+</WRAP>
+<WRAP third column>
+[{{ ost:software:maximdl:autofocus_bad_3.png | Result: poorly focused star }}]
+</WRAP>
+</WRAP>
+There are several reasons why a autofocus run can fail. One of them is that the ideal focus is not in the area that is covered by the autofocus run. It is therefore recommended to focus the telescope roughly by hand before. Furthermore, it can be that no star is found and therefore the quality of the focus cannot be estimated. A reason for this may in turn be that the option ''Use a Subframe, Central 1/4 pixels'' was selected during setup and that there is no star in the central area of the chip.
 ===== Using MaximDL =====