New Feature : Double click on image to recenter

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New Feature : Double click on image to recenter

#1

Post by admin »

This is a new feature in SharpCap 4.0.7529 (still to be considered a prototype at the moment) to allow you to recenter by double clicking on the part of the image you want to be centered in view. Unfortunately due to lack of clear sky time this week, I haven't been able to test this in anger (except on simulator cameras). I'd be interested in feedback - if something goes wrong then a lot of information gets written to the log, so please post your log.

In order to use this, you need to have an ASCOM GOTO mount (that has been configured in SharpCap) and an installed plate solving application (ie Astap, Astrotortilla, Ansvr, etc).

Make sure the mount is set up and connected in SharpCap, then when you are roughly on target use the 'find location' button in the mount controls to perform a plate solve operation and adjust for any mount alignment error. So far, this is the standard way of using plate solving in SharpCap
p1.JPG
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Now go to the reticule list in the toolbar - you will find a new item at the bottom called 'Pixel Position' (I will move this to the tools menu soon, but it is built using the same technology as the reticules, so is easiest to add to the reticules list for now). Select Pixel Position...
p2.JPG
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Providing everything has gone to plan, you will see a red cross appear on the image and next to it the co-ordinates in the sky of that point in the image - like this:
p3.JPG
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If something didn't work as planned then you should see some information explaining why the position cannot be shown (for instance the mount has been moved too far since the plate solving operation happened).

You can click anywhere on the image to get the co-ordinates of that point in the image. Note that SharpCap is internally correcting for any mount pointing error that remains - these are the true sky co-ordinates, not necessarily the ones that your ASCOM mount would show at that point.

Now it should simply be a case of double clicking somewhere on the image to make the mount perform a GOTO to put that location in the center of the image (you will get a message box to confirm that you want to do this)
p4.JPG
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Once again, SharpCap corrects (if necessary) for any offset between the mount co-ordinates and the true co-ordinates, so the point that you click should really end up in the center of the image.

Robin
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Menno555
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Re: New Feature : Double click on image to recenter

#2

Post by Menno555 »

Robin

Yet another very useful feature! Thanks!! Will test it as soon as the skies here too are open.
But I already maybe have an extension on this feature (at least I think so, I didn't see it in SC): manual coordinates input.
The same as the cross but then after a plate solve, a text field where you can enter the coordinates of that one, illusive, mega faint object that only becomes visible after stacking.
It could be that it's maybe overdone because you can search with the cross for those coordinates, but it could be handy
The Ioptron Commander software has this and works fine but it's always a bit of a guess where it is in your FOV because of the possible mount pointing errors.

Menno
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Re: New Feature : Double click on image to recenter

#3

Post by timh »

Thank you for the new feature and explanation of how to use it Robin. This is definitely something that I will want to start using since it is so often the case that the best position to centre an image is not the dead centre of any particular object. Look forward to trying it once we get some clear sky
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Re: New Feature : Double click on image to recenter

#4

Post by Ddaniel84 »

Excellent Robin,
thanks and bravo for this new functionnality!

If I can give you another idea, I really appreciate if SC would give ADU and "r" (roundness or eccenticity) of a star directly selected on the screen during acquisition. It's usefull when choosing exposition time to priorise a specific object (inside a nebulae ou galaxy ou for exoplanet). Clouzot gave me a turnaround using ASTAP (from SC) but it's not as "fluent" aas if it was native inside SC.
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Re: New Feature : Double click on image to recenter

#5

Post by admin »

Hi,

thanks for the feedback - looking forward to reports from the field :)

Now that I have the facility to map pixels in the image to sky co-ordinates, more interesting things become possible - for instance highlighting a target as Menno suggests or even drawing information about the objects in view over the image. It will be interesting to see what else might be useful.

@Dominique - you can read out the ADU for any pixel already - choose 'Pixel Value Readout' from the tools menu. Does this cover any of what you want to do?

cheers,

Robin
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Re: New Feature : Double click on image to recenter

#6

Post by Ddaniel84 »

Thanks Robin
for the information on "Pixel Value Readout". It gives information about ADU, but what information is given by x and y? Sometimes it seems to be in relation with roundness (x/y), other time definitively no... Roundness is the ultimate value to estimate tracking performance.
I don't find Pixel Value Readout in the documentation...

NB: "Pixel Value Readout" is not translated in the french version I get (V 4.0.7529 64bits). The french words are "Lecture de la valeur de pixel" or more simply "valeur de pixel"

Dominique
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Re: New Feature : Double click on image to recenter

#7

Post by admin »

Hi Dominique,

the x&y are just the (x,y) co-ordinates of the pixel within the image - there is no measurement of star size or roundness in this mode, just brightness.

Thanks for the translation - I know that there are some gaps at the moment for new additions and have to do some work to fix those.

BTW... Having just tested the double-click to recenter, it works correctly in the horizontal but it increases the error in the vertical by mistake - I had the direction of the Y co-ordinate in the plate solve mapping matrix inverted.

cheers,

Robin
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Re: New Feature : Double click on image to recenter

#8

Post by Ddaniel84 »

Thank you Robin for these details ... and for all this work to make SC even more efficient. You have good ideas and know how to code them! We, we just have some good ideas ;-))
Chers. Dominique
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timh
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Re: New Feature : Double click on image to recenter

#9

Post by timh »

Hi Robin,

Had a try at using this feature last night on my set up. Latest update of SC 4, most recent ASCOM version and Windows 10.

Ioptron CEM70 and ioptron commander driver plus Cartes du Ciel running

I slewed to a bright star (Dhube I think?) and then used the SC dot icon to sync and that worked well as usual and the star was centered.

The centre of the field was at RA 11.04.46 and DEC+61.37.

I then used the reticule position menu to double click on a close by star at RA 11.04.11 DEC+61.28 in an attempt to shift centre field to there.

The mount moved but not as expected. Rather than move the star to the centre of the field it moved it to RA 11.05 and DEC 61.33.44.

On repeated tries the mount moved consistently but incorrectly. The RA movement was in the inverse direction I think and the DEC movement 2X what was needed?

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Re: New Feature : Double click on image to recenter

#10

Post by admin »

Hi Tim,

I think you encountered the issue I described above where the correction in the horizontal image axis is right, but in the vertical image axis it was in the wrong direction. I've now corrected this in the code and I had it working correctly for me (admittedly using the excellent sky simulator software rather than on the real sky).

Another thing to note is that it's important that your epoch configuration (JNOW/J2000) is correct for this to work properly.

There are two ways that your epoch configuration can be correct (as far as I can work out)

1) you have an Ascom driver for your mount that accepts J2000 coordinates and then converts them to JNOW when actually moving the hardware. I'm not sure if there are any Ascom drivers that actually work like this, but if one did and also reported correctly that it using the J2000 epoch, then everything should work nicely together providing your planetarium application is sending J2000 coordinates.

2) you have an Ascom driver for your mount that works in JNOW coordinates and also reports correctly that it works in JNOW. Working in JNOW is essentially the default, but some drivers don't report that correctly. In this case you need to make sure that you are planetarium application sends JNOW coordinates to the mount when performing go to operations. Since all the plate solving applications work in J2000, SharpCap will spot that a conversion is to be applied and deal with the coordinate conversion when you do plate solving.

Cheers, Robin
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