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Does it work out with bias and flat frames only?


Guest Tuomo

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1 hour ago, alacant said:

A random dither in both RA and DEC of up to 15px works well on my 700d. I find I need to have 20 or more snaps to get the best noise reduction. HTH

Thanks!  When I had a trial of BYEOS and using PHD1 I got a good dither ok.  Now with APT and PHD2 it doesnt move as much, but this will be due to my settings no doubt!  In APT it only says dither about 1,2,3,4,5 which I assumed to mean pixels.

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1 hour ago, tooth_dr said:

In APT it only says dither about 1,2,3,4,5

This number is then scaled by the PHD2 dither. E.g. with my 60mm f4 guidescope and asi120mm, guiding my imaging telescope with a focal length of 812mm, I set PHD2 dither at 0.9 with APT dither at 5. This gives me around 12px. I wrote a very hard to follow explanation. HTH.

dith.jpg.9b0f851e2bce604a8de5ac86bf1363ca.jpg

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11 minutes ago, alacant said:

This number is then scaled by the PHD2 dither. E.g. with my 60mm f4 guidescope and asi120mm, guiding my imaging telescope with a focal length of 812mm, I set PHD2 dither at 0.9 with APT dither at 5. This gives me around 12px. I wrote a very hard to follow explanation. HTH.

dith.jpg.9b0f851e2bce604a8de5ac86bf1363ca.jpg

You are a legend sir!

400mm guide scope with DMK21, guiding my 600mm scope, canon 1000d (5.7um)-  I'm trying to understand it but it's really above me!  

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35 minutes ago, Peco4321 said:

I'd like to try dithering, can someone explain exactly how you do it. Do I take a few images, then press the buttons on the controller in RA and DEC, just one press each, take more, then press the buttons again. 

Pretty much yes

Dithering is taking a sub then moving the mount say North about 8 -10 pixels roughly then take another sub, dither west, another dither south and so on. I found taking 3 subs then dithering seems to work well too.

 

Nige

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20 minutes ago, alacant said:

This number is then scaled by the PHD2 dither. E.g. with my 60mm f4 guidescope and asi120mm, guiding my imaging telescope with a focal length of 812mm, I set PHD2 dither at 0.9 with APT dither at 5. This gives me around 12px. I wrote a very hard to follow explanation. HTH.

dith.jpg.9b0f851e2bce604a8de5ac86bf1363ca.jpg

I've worked out the following:

600mm 5.7um = 1.96

400m 5.6um = 2.89

(2.89/1.96) x 5 = 7.37

15 / 7.37 = 2.03

x5 APT and then x2.0 with PHD2

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7 hours ago, Stub Mandrel said:

I need to find a way for PHD2 to co-ordinate with my interval timer.

Hi. Lose the interval timer and control the session via APT instead maybe? Between them, they handle the dither and settling times between frames before PHD2 locks the new guide-star position and resumes guiding. HTH.

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2 hours ago, alacant said:

Hi. Lose the interval timer and control the session via APT instead maybe? Between them, they handle the dither and settling times between frames before PHD2 locks the new guide-star position and resumes guiding. HTH.

I have a home made scope controller and at the moment it only works using ST4; not sure I want to dedicate  a month to converting it to work via ASCOM, largely because I hate the awful way the interface is documented.

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