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Re: PEC vs Guiding


Apr 9, 2009

 


----------------------------

#42437 Apr 9, 2009

Is there a gain in using PEC and guiding at the same time? With the Ovision worm, my peak to peak PE looks to be approx 7 arcsec. I can get it way down with PEC. I'm wondering if I am better off just leaving the PEC off and using PhD Guiding only--or should I use both?



Mark J



----------------------------

#42438 Apr 9, 2009

Mark, please see -

f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkminJ\

No0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shahe\

en/Post%20McLennan%20results/000155.jpg

f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkmin\

JNo0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shah\

een/Post%20McLennan%20results/000155.jpg>



Notice the sine wave in the PEC off version vs. the more stable pattern

with PEC on.



Now, understand there are separate issues with respect to PEC, such as

drift compensation and such. But, all other factors being equal, if you

can get PEC to work properly you are better off with it.



Regards,



Bill





--- In Losmandy_users@yahoogroups.com, "Mark Jones" yahoogroups01@...>

wrote: >

> Is there a gain in using PEC and guiding at the same time? With the

Ovision worm, my peak to peak PE looks to be approx 7 arcsec. I can get

it way down with PEC. I'm wondering if I am better off just leaving the

PEC off and using PhD Guiding only--or should I use both? >

> Mark J

>









[Non-text portions of this message have been removed]



----------------------------

#42439 Apr 9, 2009

Hi Bill,

Do you get any additional drift as reported by others when PEC is on vs. off?

Floyd --- In Losmandy_users@yahoogroups.com, "William J. Shaheen" wjshaheen@...> wrote:

>

>

> Mark, please see -

> f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkminJ\

> No0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shahe\

> en/Post%20McLennan%20results/000155.jpg

> f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkmin\

> JNo0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shah\

> een/Post%20McLennan%20results/000155.jpg>

>

> Notice the sine wave in the PEC off version vs. the more stable pattern

> with PEC on.

>

> Now, understand there are separate issues with respect to PEC, such as

> drift compensation and such. But, all other factors being equal, if you

> can get PEC to work properly you are better off with it.

>

> Regards,

>

> Bill

>

>

> --- In Losmandy_users@yahoogroups.com, "Mark Jones" yahoogroups01@>

> wrote:

> >

> > Is there a gain in using PEC and guiding at the same time? With the

> Ovision worm, my peak to peak PE looks to be approx 7 arcsec. I can get

> it way down with PEC. I'm wondering if I am better off just leaving the

> PEC off and using PhD Guiding only--or should I use both?

> >

> > Mark J

> >

>

>

>

>

> [Non-text portions of this message have been removed]

>



----------------------------

#42441 Apr 9, 2009

I just asked a similar question in the Gemini group. I was told to retard drift compenstation by .006. I don't have the mount set up and it's going to rain for another day and a half. But Saturday night I'm going to try it out and perhaps get some good data off the Ovision worm.



An interesting question arises. Is there drift even with PE off?



Tom P.



--- In Losmandy_users@yahoogroups.com, "Floyd Blue" fblue@...> wrote:

>

> Hi Bill,

> Do you get any additional drift as reported by others when PEC is on vs. off?

> Floyd

> --- In Losmandy_users@yahoogroups.com, "William J. Shaheen" wjshaheen@> wrote:

> >

> >

> > Mark, please see -

> > f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkminJ\

> > No0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shahe\

> > en/Post%20McLennan%20results/000155.jpg

> > f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkmin\

> > JNo0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shah\

> > een/Post%20McLennan%20results/000155.jpg>

> >

> > Notice the sine wave in the PEC off version vs. the more stable pattern

> > with PEC on.

> >

> > Now, understand there are separate issues with respect to PEC, such as

> > drift compensation and such. But, all other factors being equal, if you

> > can get PEC to work properly you are better off with it.

> >

> > Regards,

> >

> > Bill

> >

> >

> > --- In Losmandy_users@yahoogroups.com, "Mark Jones" yahoogroups01@>

> > wrote:

> > >

> > > Is there a gain in using PEC and guiding at the same time? With the

> > Ovision worm, my peak to peak PE looks to be approx 7 arcsec. I can get

> > it way down with PEC. I'm wondering if I am better off just leaving the

> > PEC off and using PhD Guiding only--or should I use both?

> > >

> > > Mark J

> > >

> >

> >

> >

> >

> > [Non-text portions of this message have been removed]

> >

>







----------------------------

#42442 Apr 9, 2009

I've had all kinds of experiences. In an earlier test, it appeared I got more drift with PEC. But then, the other night, I noticed huge drifting with PEC off.



Bill

--- In Losmandy_users@yahoogroups.com, "Floyd Blue" fblue@...> wrote:

>

> Hi Bill,

> Do you get any additional drift as reported by others when PEC is on vs. off?

> Floyd

> --- In Losmandy_users@yahoogroups.com, "William J. Shaheen" wjshaheen@> wrote:

> >

> >

> > Mark, please see -

> > f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkminJ\

> > No0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shahe\

> > en/Post%20McLennan%20results/000155.jpg

> > f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkmin\

> > JNo0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shah\

> > een/Post%20McLennan%20results/000155.jpg>

> >

> > Notice the sine wave in the PEC off version vs. the more stable pattern

> > with PEC on.

> >

> > Now, understand there are separate issues with respect to PEC, such as

> > drift compensation and such. But, all other factors being equal, if you

> > can get PEC to work properly you are better off with it.

> >

> > Regards,

> >

> > Bill

> >

> >

> > --- In Losmandy_users@yahoogroups.com, "Mark Jones" yahoogroups01@>

> > wrote:

> > >

> > > Is there a gain in using PEC and guiding at the same time? With the

> > Ovision worm, my peak to peak PE looks to be approx 7 arcsec. I can get

> > it way down with PEC. I'm wondering if I am better off just leaving the

> > PEC off and using PhD Guiding only--or should I use both?

> > >

> > > Mark J

> > >

> >

> >

> >

> >

> > [Non-text portions of this message have been removed]

> >

>



----------------------------

#42443 Apr 9, 2009

Thanks, Bill for the info. I'll use both, then.



Mark J

--- In Losmandy_users@yahoogroups.com, "William J. Shaheen" wjshaheen@...> wrote:

>

>

> Mark, please see -

> f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkminJ\

> No0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shahe\

> en/Post%20McLennan%20results/000155.jpg

> f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkmin\

> JNo0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shah\

> een/Post%20McLennan%20results/000155.jpg>

>

> Notice the sine wave in the PEC off version vs. the more stable pattern

> with PEC on.

>

> Now, understand there are separate issues with respect to PEC, such as

> drift compensation and such. But, all other factors being equal, if you

> can get PEC to work properly you are better off with it.

>

> Regards,

>

> Bill

>

>

> --- In Losmandy_users@yahoogroups.com, "Mark Jones" yahoogroups01@>

> wrote:

> >

> > Is there a gain in using PEC and guiding at the same time? With the

> Ovision worm, my peak to peak PE looks to be approx 7 arcsec. I can get

> it way down with PEC. I'm wondering if I am better off just leaving the

> PEC off and using PhD Guiding only--or should I use both?

> >

> > Mark J

> >

>

>

>

>

> [Non-text portions of this message have been removed]

>



----------------------------

#42450 Apr 10, 2009

I usually get very little drift as long as the Polar Alignment is good. The more it is off the more drift I see.

But, when I was trying PEC with guiding, I just did not see an improvement in my images. Perhaps I could try it again?

Really though, with the low PE I have now I am not sure that I need PEC, but maybe that is even a better reason to use it? Not really sure what the real answer is to this question.

Floyd --- In Losmandy_users@yahoogroups.com, "William J. Shaheen" wjshaheen@...> wrote:

>

> I've had all kinds of experiences. In an earlier test, it appeared I got more drift with PEC. But then, the other night, I noticed huge drifting with PEC off.

>

> Bill

>

> --- In Losmandy_users@yahoogroups.com, "Floyd Blue" fblue@> wrote:

> >

> > Hi Bill,

> > Do you get any additional drift as reported by others when PEC is on vs. off?

> > Floyd

> > --- In Losmandy_users@yahoogroups.com, "William J. Shaheen" wjshaheen@> wrote:

> > >

> > >

> > > Mark, please see -

> > > f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkminJ\

> > > No0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shahe\

> > > en/Post%20McLennan%20results/000155.jpg

> > > f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkmin\

> > > JNo0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shah\

> > > een/Post%20McLennan%20results/000155.jpg>

> > >

> > > Notice the sine wave in the PEC off version vs. the more stable pattern

> > > with PEC on.

> > >

> > > Now, understand there are separate issues with respect to PEC, such as

> > > drift compensation and such. But, all other factors being equal, if you

> > > can get PEC to work properly you are better off with it.

> > >

> > > Regards,

> > >

> > > Bill

> > >

> > >

> > > --- In Losmandy_users@yahoogroups.com, "Mark Jones" yahoogroups01@>

> > > wrote:

> > > >

> > > > Is there a gain in using PEC and guiding at the same time? With the

> > > Ovision worm, my peak to peak PE looks to be approx 7 arcsec. I can get

> > > it way down with PEC. I'm wondering if I am better off just leaving the

> > > PEC off and using PhD Guiding only--or should I use both?

> > > >

> > > > Mark J

> > > >

> > >

> > >

> > >

> > >

> > > [Non-text portions of this message have been removed]

> > >

> >

>







----------------------------

#42452 Apr 10, 2009

Floyd,



If you want to test the effectiveness of PEC on your images, I'd recommend th following:



Get the demo of CCDInspector and take a series of images of the milky way with PEC off. Take at least a 5 minute exposure.



then do the same with a set with PEC on.



Analyse the images with CCDI and compare FWHM average values.



BTW, I purchased CCDI because I have an SCT and like to have my collimation tight.



Tom P.









--- In Losmandy_users@yahoogroups.com, "Floyd Blue" fblue@...> wrote:

>

> I usually get very little drift as long as the Polar Alignment is good. The more it is off the more drift I see.

> But, when I was trying PEC with guiding, I just did not see an improvement in my images. Perhaps I could try it again?

> Really though, with the low PE I have now I am not sure that I need PEC, but maybe that is even a better reason to use it? Not really sure what the real answer is to this question.

> Floyd

> --- In Losmandy_users@yahoogroups.com, "William J. Shaheen" wjshaheen@> wrote:

> >

> > I've had all kinds of experiences. In an earlier test, it appeared I got more drift with PEC. But then, the other night, I noticed huge drifting with PEC off.

> >

> > Bill

> >

> > --- In Losmandy_users@yahoogroups.com, "Floyd Blue" fblue@> wrote:

> > >

> > > Hi Bill,

> > > Do you get any additional drift as reported by others when PEC is on vs. off?

> > > Floyd

> > > --- In Losmandy_users@yahoogroups.com, "William J. Shaheen" wjshaheen@> wrote:

> > > >

> > > >

> > > > Mark, please see -

> > > > f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkminJ\

> > > > No0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shahe\

> > > > en/Post%20McLennan%20results/000155.jpg

> > > > f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkmin\

> > > > JNo0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shah\

> > > > een/Post%20McLennan%20results/000155.jpg>

> > > >

> > > > Notice the sine wave in the PEC off version vs. the more stable pattern

> > > > with PEC on.

> > > >

> > > > Now, understand there are separate issues with respect to PEC, such as

> > > > drift compensation and such. But, all other factors being equal, if you

> > > > can get PEC to work properly you are better off with it.

> > > >

> > > > Regards,

> > > >

> > > > Bill

> > > >

> > > >

> > > > --- In Losmandy_users@yahoogroups.com, "Mark Jones" yahoogroups01@>

> > > > wrote:

> > > > >

> > > > > Is there a gain in using PEC and guiding at the same time? With the

> > > > Ovision worm, my peak to peak PE looks to be approx 7 arcsec. I can get

> > > > it way down with PEC. I'm wondering if I am better off just leaving the

> > > > PEC off and using PhD Guiding only--or should I use both?

> > > > >

> > > > > Mark J

> > > > >

> > > >

> > > >

> > > >

> > > >

> > > > [Non-text portions of this message have been removed]

> > > >

> > >

> >

>



----------------------------

#42453 Apr 10, 2009

Hi Tom,

Good idea!

Floyd --- In Losmandy_users@yahoogroups.com, "Tom Picciani" tpicciani@...> wrote:

>

> Floyd,

>

> If you want to test the effectiveness of PEC on your images, I'd recommend th following:

>

> Get the demo of CCDInspector and take a series of images of the milky way with PEC off. Take at least a 5 minute exposure.

>

> then do the same with a set with PEC on.

>

> Analyse the images with CCDI and compare FWHM average values.

>

> BTW, I purchased CCDI because I have an SCT and like to have my collimation tight.

>

> Tom P.

>

>

>

>

>

> --- In Losmandy_users@yahoogroups.com, "Floyd Blue" fblue@> wrote:

> >

> > I usually get very little drift as long as the Polar Alignment is good. The more it is off the more drift I see.

> > But, when I was trying PEC with guiding, I just did not see an improvement in my images. Perhaps I could try it again?

> > Really though, with the low PE I have now I am not sure that I need PEC, but maybe that is even a better reason to use it? Not really sure what the real answer is to this question.

> > Floyd

> > --- In Losmandy_users@yahoogroups.com, "William J. Shaheen" wjshaheen@> wrote:

> > >

> > > I've had all kinds of experiences. In an earlier test, it appeared I got more drift with PEC. But then, the other night, I noticed huge drifting with PEC off.

> > >

> > > Bill

> > >

> > > --- In Losmandy_users@yahoogroups.com, "Floyd Blue" fblue@> wrote:

> > > >

> > > > Hi Bill,

> > > > Do you get any additional drift as reported by others when PEC is on vs. off?

> > > > Floyd

> > > > --- In Losmandy_users@yahoogroups.com, "William J. Shaheen" wjshaheen@> wrote:

> > > > >

> > > > >

> > > > > Mark, please see -

> > > > > f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkminJ\

> > > > > No0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shahe\

> > > > > en/Post%20McLennan%20results/000155.jpg

> > > > > f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkmin\

> > > > > JNo0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shah\

> > > > > een/Post%20McLennan%20results/000155.jpg>

> > > > >

> > > > > Notice the sine wave in the PEC off version vs. the more stable pattern

> > > > > with PEC on.

> > > > >

> > > > > Now, understand there are separate issues with respect to PEC, such as

> > > > > drift compensation and such. But, all other factors being equal, if you

> > > > > can get PEC to work properly you are better off with it.

> > > > >

> > > > > Regards,

> > > > >

> > > > > Bill

> > > > >

> > > > >

> > > > > --- In Losmandy_users@yahoogroups.com, "Mark Jones" yahoogroups01@>

> > > > > wrote:

> > > > > >

> > > > > > Is there a gain in using PEC and guiding at the same time? With the

> > > > > Ovision worm, my peak to peak PE looks to be approx 7 arcsec. I can get

> > > > > it way down with PEC. I'm wondering if I am better off just leaving the

> > > > > PEC off and using PhD Guiding only--or should I use both?

> > > > > >

> > > > > > Mark J

> > > > > >

> > > > >

> > > > >

> > > > >

> > > > >

> > > > > [Non-text portions of this message have been removed]

> > > > >

> > > >

> > >

> >

>







----------------------------

#42454 Apr 10, 2009

If PE is low or very slow-changing, the guiding will take care of the occasional corrections needed. But, with certain types of imaging PEC will still be of value:



1. When imaging at longer focal lengths

2. When imaging and guiding through filters, especially narrow band

3. When guiding through a long focal length scope



PEC has the advantage of correcting the error at or before the time that it is occurring. Guiding will always lag behind the error, usually by at least a second or two, and as the result it will always be somewhat inferior to guiding with good PEC programming.



Regards,



-Paul

--- In Losmandy_users@yahoogroups.com, "Floyd Blue" fblue@...> wrote:

>

> I usually get very little drift as long as the Polar Alignment is good. The more it is off the more drift I see.

> But, when I was trying PEC with guiding, I just did not see an improvement in my images. Perhaps I could try it again?

> Really though, with the low PE I have now I am not sure that I need PEC, but maybe that is even a better reason to use it? Not really sure what the real answer is to this question.

> Floyd

> --- In Losmandy_users@yahoogroups.com, "William J. Shaheen" wjshaheen@> wrote:

> >

> > I've had all kinds of experiences. In an earlier test, it appeared I got more drift with PEC. But then, the other night, I noticed huge drifting with PEC off.

> >

> > Bill

> >

> > --- In Losmandy_users@yahoogroups.com, "Floyd Blue" fblue@> wrote:

> > >

> > > Hi Bill,

> > > Do you get any additional drift as reported by others when PEC is on vs. off?

> > > Floyd

> > > --- In Losmandy_users@yahoogroups.com, "William J. Shaheen" wjshaheen@> wrote:

> > > >

> > > >

> > > > Mark, please see -

> > > > f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkminJ\

> > > > No0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shahe\

> > > > en/Post%20McLennan%20results/000155.jpg

> > > > f1.grp.yahoofs.com/v1/4G_eSZKAidogdxx2F5OK1whWKEyPNDuu3Z4eJKkmin\

> > > > JNo0TAZVb2vW6Ro4Ku2JOuGhK3q_79GWdWXLTHddclmdAYesfiGoGuKoSkuA/Bill%20Shah\

> > > > een/Post%20McLennan%20results/000155.jpg>

> > > >

> > > > Notice the sine wave in the PEC off version vs. the more stable pattern

> > > > with PEC on.

> > > >

> > > > Now, understand there are separate issues with respect to PEC, such as

> > > > drift compensation and such. But, all other factors being equal, if you

> > > > can get PEC to work properly you are better off with it.

> > > >

> > > > Regards,

> > > >

> > > > Bill

> > > >

> > > >

> > > > --- In Losmandy_users@yahoogroups.com, "Mark Jones" yahoogroups01@>

> > > > wrote:

> > > > >

> > > > > Is there a gain in using PEC and guiding at the same time? With the

> > > > Ovision worm, my peak to peak PE looks to be approx 7 arcsec. I can get

> > > > it way down with PEC. I'm wondering if I am better off just leaving the

> > > > PEC off and using PhD Guiding only--or should I use both?

> > > > >

> > > > > Mark J

> > > > >

> > > >

> > > >

> > > >

> > > >

> > > > [Non-text portions of this message have been removed]

> > > >

> > >

> >

>



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