Feature Request - FWHM in ArcSec

[dts350z]

Setting to have FWHM displayed in ArcSec, vs. Pixels. Requires knowing the focal length of your scope.

 

Formula is here: http://stargazerslounge.com/topic/208732-what-are-the-units-for-fwhm/#entry2223687

 

The purpose of this is to evaluate the quality of Autoguiding. Rule of thumb (from here  http://www.innovationsforesight.com/GuidingError.htm) says that your Guiding RMS (in ArcSec) should be less than 1/4 of your seeing FWHM (in ArcSec).

 

FYI I use PHDLab: http://countingoldphotons.com/phdlab-intro/ to analyze logs from PHD2 to get RMS error etc. It's free.

 

 

 

 

[s3igell]

Ah, but that is a simple equation that you can easily do in Calc:

 

[dts350z]

Yeah and it occurred to me that I could also just use the RMS error in pixels from PHDLab for the rule of thumb calc, however it still a "nice to have" and something that other programs do.

 

When people ask what the seeing was you need to speak the same units 

[admin]

Yeah and it occurred to me that I could also just use the RMS error in pixels from PHDLab for the rule of thumb calc, however it still a "nice to have" and something that other programs do.

 

When people ask what the seeing was you need to speak the same units 

 

I agree, this one goes on the to do list.  But no promises for 3.1.

 

Guylain

[jimwc6491]

Ah, but that is a simple equation that you can easily do in Calc:

 

 

S3igel

 

This can't be a one size fits all because of the different camera models i.e. different pixel size.

Guylain would have to get all the different pixel sizes and have it linked to the camera setup.

or there has to be a setup for each of those parameters somewhere (pixel size and Focal Length).     

he is running out of real estate in the setup area. which means another setup page. from what I have read some people don't like to do tweaking and would just like to use a generic setup.   I'm sure this won't be a easy task.   

[s3igell]

This is the correct formula, and it IS a "one size fits all" equation that directly accounts for the Pixel Size of the Camera...

(see the "pixel size [um]" factor in the center of the equation...)

 

And, why are you taking me to task ??  I suggested that the user can surely do this simple math with Calc, as well as anything which Guylain might offer to add to BYE...

[dts350z]

Well as to settings space, maybe this an a feature for only the pro version. It's really not a big deal.

 

[Z goes off on a tangent]A bigger deal would be to include the functionality of this:

 

http://www.newastro.com/book_new/camera_app.php

 

So you can determine the framing of DSOs, given your scopes and cameras, as part of your image planing.

 

Also with the third party image set for the above (or add your own) it makes great add on functionality for BYEOS + AstorTortilla. Like that shot of M81 & M82 (or need to come back to the same image for more integration time)? Have AstorTotilla take you there.

 

And PHD logfile guding analysis

 

And...[/tangent]

 

No worries, I can tell folks here are stressed about what features get priority. I'm just brain storming, not pushing anything.

 

Great software, and great to have a user community forum where we can discuss. 

 

Now if I could just get the summer evening fog to go away so I can use it 

[fred_76]

Hy

 

The above formula is for black and white sensors. The color sensors have a Bayer matrix that makes that formula more tricky.

 

- for the red and blue pixels, the sampling returned by the formula shall be multiplied by 2

- for the green pixels, the multiplication factor is 1.414 (square root of 2).

 

Therefore, the average sampling for the color sensor should be multiplied by (2+2+2x1.414)/4=1.71

 

The formula becomes : e (arcsec) ~ 350 x p (µm) / F (mm) instead of 206 x p (µm) / F (mm)

 

Where :

- e is the sampling in arc seconds

- p is the photosite size, in µm

- F is the telescope or lens focal length, in mm

 

As debayerisation of Canon sensors is now available (at least in France), BYE should propose both calculations in the parameters.

 

In my opinion, this feature shall not be limited to the Premium version only.

 

Fred

[jimwc6491]

This is the correct formula, and it IS a "one size fits all" equation that directly accounts for the Pixel Size of the Camera...

(see the "pixel size [um]" factor in the center of the equation...)

 

And, why are you taking me to task ??  I suggested that the user can surely do this simple math with Calc, as well as anything which Guylain might offer to add to BYE...

 

S3igel

 

Sorry I was not trying to take you to task. I was just trying to use the formula as reference.

and show its not as easy to program something with variable inputs (and this formula has 2) over the large audience that this program has, as some may think.

 

 

 

 

 

[admin]

This is the correct formula, and it IS a "one size fits all" equation that directly accounts for the Pixel Size of the Camera...

(see the "pixel size [um]" factor in the center of the equation...)

 

And, why are you taking me to task ??  I suggested that the user can surely do this simple math with Calc, as well as anything which Guylain might offer to add to BYE...

 

S3igel

 

Sorry I was not trying to take you to task. I was just trying to use the formula as reference.

and show its not as easy to program something with variable inputs (and this formula has 2) over the large audience that this program has, as some may think.

 

 

I already know which camera is connected so I already have the pixel size.  The user would only need to supply focal length of their optical train.

 

Regards,

 

 

[jimwc6491]

Guylain

 

would the scope focal length be something that is needed for auto focus anyway? (not knowing what kind of formulas you are using for this purpose) just asking.

 

 

 

[admin]

Guylain

 

would the scope focal length be something that is needed for auto focus anyway? (not knowing what kind of formulas you are using for this purpose) just asking

 

 

Nope, not needed