Same setup + different scope = major problems Help!

[Quetzalcoatl72]

When i use my askar 180 or my ed80 the set up runs fairly smoothly but when i use my rc8" it all goes to hell, first off the finderscope is never in the same calibration as when i perfectly matched it up with the main scope(seriously why don't finderscopes just come permanently attached to the mainscope and corrected flawlessly?) seems that just me picking it up ruins it even though the screws are firmly tight. So i waste over an hour trying to find a bright star to get it all matched up perfectly, EVERY TIME I GO OUT. And Secondly the PHD2 software doesn't seem to work with this scope, when i do exposures, the stars are always zigzagged across the screen. I'm using nina and i refuse to try anything else, time is short and learning a new program is a night wasted, i only had 4 sessions in 2021 due to bad weather. FYI the finderscope im using is a Astro Essentials 50mm f/4 which is supposed to have a 240FL

Edited January 7, 2022 by Quetzalcoatl72

[michael8554]

Your finderscope problems are probably due to the soft-tipped screws that hold it in the rings.

Remove the tips and live with screw marks on the tube.

Are you using this same finder on both  scopes ?

Bound to be a difference in the centre of the FOV.

15 hours ago, Quetzalcoatl72 said:

the PHD2 software doesn't seem to work with this scope,

Plenty of people successfully guiding a NEQ6 Pro, it isn't the scope that's being guided, it's the mount. 

Post a PHD2 GuideLog that includes a Calibration.

You'll find them in the PHD2 folder, make sure the date in the filename is relevant.

Michael

Edited January 8, 2022 by michael8554

[Jiggy 67]

I don’t think it’s sensible to permanently fit a finderscope to an OTA, for all sorts of reasons, damage, storage, transport. And there is no way you can expect it to be aligned across multiple scopes or even the same one after removing it, the very act of removing it from the shoe will send it out of alignment the next time you put it in the shoe as the locking screws will move it. I always align my finderscope on the first alignment Star, takes about 30 seconds 

[pete_l]

16 hours ago, Quetzalcoatl72 said:

my rc8"  ... the stars are always zigzagged across the screen.

Presuming you have got the scope+mount balanced in all three axes, then something is loose.

All you can do is go over everything, even those things that are impossible, and give them a good rattle. Then tighten it all and remember that when out in the cold, stuff gets loose again.

[newbie alert]

Are you trying to use the same calibration regardless of what scope you have on the mount.. balance is key on guiding

On a RC most use a oag to guide

[Quetzalcoatl72]

4 hours ago, pete_l said:

Presuming you have got the scope+mount balanced in all three axes, then something is loose.

All you can do is go over everything, even those things that are impossible, and give them a good rattle. Then tighten it all and remember that when out in the cold, stuff gets loose again.

I'm confident in my balancing. I did fix the zigzag after re-calibrating in phd2, and picked the correct focal length for the finder. Sometimes a star would be lost which caused it or the program just freaked and i had to relaunch but it could not do 4 minutes exposure, it was a little bit windy but nothing too bad, there is something wrong with the gears in RA i'm sure. I spent 3 hours trying to fix the binding

[Quetzalcoatl72]

2 hours ago, newbie alert said:

Are you trying to use the same calibration regardless of what scope you have on the mount.. balance is key on guiding

On a RC most use a oag to guide

I just assume you recalibrated if you mess around with adjusting the gears etc. When do you do it?

[Quetzalcoatl72]

5 hours ago, michael8554 said:

Are you using this same finder on both  scopes ?

Bound to be a difference in the centre of the FOV.

Plenty of people successfully guiding a NEQ6 Pro, it isn't the scope that's being guided, it's the mount. 

Post a PHD2 GuideLog that includes a Calibration.

You'll find them in the PHD2 folder, make sure the date in the filename is relevant.

Michael

I use the standard skywatcher one for my other setup that works, I realized i always had 200fl set on phd2 for that finder when actually i found out last night people say its 180. The astro essentials one i use with my rc is apparently 240. I'm not sure how much difference this makes in phd2. I was guiding 5 minute exposure the night before with my other setup, in the end last night i did end up just imaging bodes because that was the only one i could find, could only do 3 minutes though, could be the wind but it wasn't really that strong at all. So i failed to mention that when i set it to go to the home position the gears would bind and make a sickening noise, I tested this last night when the clouds rolled in and it's pretty bad.

I spend 2 hours trying to adjust the gear mesh ect but still no luck, It seems to bind more rotating from one side. This noise did happen on my other setup but i ignored it because it was still guiding perfectly, auto meridian flip always fails and it could the gears, sometimes it does it when i'm inside so i don't get to see what happened, but one time i sat with it and it didn't even attempt to move, just says meridian flip failed on nina. I seem to have more problems imaging with the scope pointing to the south in general which would explain why the crab and bubble nebulas did not appear on screen even after plate solving and entering the co-ordinate's manually in stellarium. Bodes and pinwheel however did appear after doing that and they're faced on the opposite side. I will post screenshots i took last night and phd2 notes

[newbie alert]

18 hours ago, Quetzalcoatl72 said:

I just assume you recalibrated if you mess around with adjusting the gears etc. When do you do it?

Even if you're using the same camera/ guidescope if you swap things around you won't have the camera in the same axis position, even if you took the camera off and put it back on again it won't be in exactly the same position as previously.. 

If you put the guider on another setup the balance is totally different   ,so id run the calibration and the guiding assistant and apply the settings

Reading above sounds like you have mechanical issues on your mount 

What mount is it?

[michael8554]

On 07/01/2022 at 19:46, Quetzalcoatl72 said:

Astro Essentials 50mm f/4

50 x 4 = 200mm Focal Length.

So if it's actually 180mm then AE are misinforming.

Entering 240mm in the Equipment Profile would make a difference if it's really 180mm, but Calibration would compensate to a degree.

But PHD2 wouldn't compensate for those who enter 50mm Aperture as the Focal Length.......... :-<

Post a PHD2 GuideLog that includes a Calibration.

Michael

[Quetzalcoatl72]

On 09/01/2022 at 10:51, newbie alert said:

Even if you're using the same camera/ guidescope if you swap things around you won't have the camera in the same axis position, even if you took the camera off and put it back on again it won't be in exactly the same position as previously.. 

If you put the guider on another setup the balance is totally different   ,so id run the calibration and the guiding assistant and apply the settings

Reading above sounds like you have mechanical issues on your mount 

What mount is it?

neq6 with belt mod. i recently took it apart, found shredded metal in the roller bearing, idk where it came from but the only real damage i found was on the small bearing, theres 2 dints that cause it to rotate badly, just like the mount binding one way but not the other, the same thing happens rotating the bearing one way. I ordered a replacement, i think that may be the issue, not sure though till i replace it, regrease and re assemble

Edit: The shredded metal could be from the thread around the 4 screws that hold the worm plate in place when tuning which i've done countless times to fix binding and backlash

Edited January 10, 2022 by Quetzalcoatl72

[Quetzalcoatl72]

On 09/01/2022 at 14:00, michael8554 said:

Post a PHD2 GuideLog that includes a Calibration.

Here's the most recent log, i have no idea how to read these so it could be a mess, if there's any settings i should change that show on there please let me know for next session thanks

PHD2_GuideLog_2022-01-07_180540.txt

[michael8554]

From your GuideLog:

As already mentioned, you have the FL entered as 240mm.

The bunched-up steps in the Calibration indicate some Stiction on RA and Dec.

 

PA is very good, so Dec chugs along with almost no correction.

Until you Dither :-<

Then at times Dec never recovers between Dithers, because of the Stiction.

Guidecam focus isn't good,  HFD = 5.23 px

Ideally you should Calibrate near Dec =0, and close to south.

Pulse the mount north until you see the star move, to clear Dec Backlash, THEN Calibrate.

And run the Guiding Assistant to get settings.

So get your new bearings in and the worms adjusted, and post the new logs.

Michael

Edited January 11, 2022 by michael8554

[Quetzalcoatl72]

20 hours ago, michael8554 said:

So get your new bearings in and the worms adjusted, and post the new logs.

Michael

Nice, thanks, interesting info! So i replaced both the small bearings in the RA, ideally I should have did it for DEC too but I didn't want to take it apart as in my eyes I had no problems with that, backlash etc. just a bit stiff! I found other problems that must have been the cause for RA such as loose grub screws on the motors spindle(no idea how that happened) The worm shaft was also loose and the bearing wasn't even in all the way which is why i couldn't get the end cap on fully, the DEC also has that problem but doesn't bother me and it seems fine. I did 2 full rotations on both, no grinding, no chainsaw noise, it worked! I plan to go out thursday so I need to figure out what i'm doing in PHD, but before that my polar scope probably needs adjusting, i've never did it before. Sharpcap gives me decent polar alignment anyway. 

I don't really focus the guide cam, i just make sure the stars are big enough for sharpcaps polar alignment, what HFD value should it be?
What do you mean by calibrate near dec=0? and how do i pulse the mount?

[michael8554]

4 hours ago, Quetzalcoatl72 said:

the DEC also has that problem but doesn't bother me and it seems fine.

Really ! Seems fine ?

4 hours ago, Quetzalcoatl72 said:

What do you mean by calibrate near dec=0?

Sounds like you haven't read the PHD2 instructions if you don't understand that.

4 hours ago, Quetzalcoatl72 said:

and how do i pulse the mount?

Use the handset buttons at lowest slew speed, or the PHD2 Manual Guide with 5000mS Pulse setting, to move the mount north until the guide star actually moves on the screen.

Then the Dec Backlash has been taken up.

Then you can get a realistic Calibration.

Again, it's all in the PHD2 instructiions, you just need to read them.

Michael

[newbie alert]

42 minutes ago, michael8554 said:

Really ! Seems fine ?

Sounds like you haven't read the PHD2 instructions if you don't understand that.

Use the handset buttons at lowest slew speed, or the PHD2 Manual Guide with 5000mS Pulse setting, to move the mount north until the guide star actually moves on the screen.

Then the Dec Backlash has been taken up.

Then you can get a realistic Calibration.

Again, it's all in the PHD2 instructiions, you just need to read them.

Michael

That's abit harsh Michael 

If you're pulse guiding ( ie not using the st4 cable) then you need to calibrate on the merdian/ equator intersection, basically point it south and about 30-40 degrees.. if you then bring up the drift tool and it will bring up the box and tell you where the scope is pointing.. if you get the declination on 0 and depending on what side of the pier the scope is on depends on what side of the meridian  you want.. either + or -

If you then click on the up key until you physically see the the star move this ensures that the backlash has been taken up of the DEC motor.. then press calibrate..

If you're  using st4 method then you need to calibrate on every target and after every flip

[michael8554]

I get tired of seeing the same old problems with so many OPs PHD2 guiding.

Because they are ignoring, or hadn't bothered to read, the PHD2 Instructions.

Instead of fine-tuning OPs PHD2 guiding we're sorting out their basic settings for them.

So yes I'm getting harsh.

Michael

[newbie alert]

4 hours ago, michael8554 said:

I get tired of seeing the same old problems with so many OPs PHD2 guiding.

Because they are ignoring, or hadn't bothered to read, the PHD2 Instructions.

Instead of fine-tuning OPs PHD2 guiding we're sorting out their basic settings for them.

So yes I'm getting harsh.

Michael

It's only on par with assembling some flat pack furniture ( no one reads the instructions until something goes wrong)

[Quetzalcoatl72]

16 hours ago, michael8554 said:

Really ! Seems fine ?

Sounds like you haven't read the PHD2 instructions if you don't understand that.

Use the handset buttons at lowest slew speed, or the PHD2 Manual Guide with 5000mS Pulse setting, to move the mount north until the guide star actually moves on the screen.

Then the Dec Backlash has been taken up.

Then you can get a realistic Calibration.

Again, it's all in the PHD2 instructiions, you just need to read them.

Michael

Sorry I'm a bit slow when it comes to techy stuff and I struggle with retaining information. I tried to follow your advice as best as i can and came up with a new guide log, this time I know it's worse, I first looked at an object to the south about -1 degree, cleared the cali data and manually pulsed north at 5000 until the star moved as you said, then i started calibrating. I also tried at +30ish degrees south, sadly these methods didn't give me 4 minute guided exposures the stars trailed off a bit to the right of the image. The other method at 30-40degree was less dramatic, and i did a third calibration where i just went to Procyon and that yielded better results but still wasn't perfect. There's another in the logs that should be ignored as the clouds rolled past and lost the star.

Before I packed up I tried no guiding, sadly i couldn't get 3 minutes, it trailed off slightly but ended up better than after trying the first 2 calibrations. This may be due to balancing issue because I try to make it east heavy but when it flips the other way I forget to make it weight heavy instead, not sure though.

PHD2_GuideLog_2022-01-12_233242.txt

Edited January 13, 2022 by Quetzalcoatl72

[michael8554]

From your lastest GuideLog.

All your Calibrations had about 15 to 20 steps of Dec Backlash clearing before the Dec part of Cal commenced.

Here's one of your Dec Cals:

 

 

Resulting in very different RA and Dec guiderates, as reported after each Cal:

Cal Dec = 43.2, Last Cal Issue = Rates

Norm rates RA = 11.5"/s @ dec 0, Dec = 3.6"/s;

Your mount was set to 7.5arcsecs/sec on RA and Dec.

For your very last of many Cals you moved down to close to Dec =0 and then guided for about 5 minutes with okay results:

RA = 0.62  Dec = 0.72  arcsec.

You had Dec guiding switched to   DEC guide mode = South.

Which was true at midnight when you did your only Guide Assistant run, but by 02;00 that was no longer true, as by then Dec was drifting south, so needed guiding north !!

So for most of the night Dec was unguided, resulting in huge uncorrected Dec excursions at times.

Luckily your PA was good enough that no corrections were required on that last run, hence the good Dec figure.

The procedure is to move to your target, switch off guiding and see what way Dec is drifting over several minutes, set Dec guiding to correct that drift.

So bottom line, you need to pulse north a lot more before Cal, until you see equal star movements for several pulses.

An even better solution, adjust your Dec worm and bearings !

And guidescope focus is still poor.

[Quetzalcoatl72]

5 hours ago, michael8554 said:

From your lastest GuideLog.

All your Calibrations had about 15 to 20 steps of Dec Backlash clearing before the Dec part of Cal commenced.

Here's one of your Dec Cals:

 

 

Resulting in very different RA and Dec guiderates, as reported after each Cal:

Cal Dec = 43.2, Last Cal Issue = Rates

Norm rates RA = 11.5"/s @ dec 0, Dec = 3.6"/s;

Your mount was set to 7.5arcsecs/sec on RA and Dec.

For your very last of many Cals you moved down to close to Dec =0 and then guided for about 5 minutes with okay results:

RA = 0.62  Dec = 0.72  arcsec.

You had Dec guiding switched to   DEC guide mode = South.

Which was true at midnight when you did your only Guide Assistant run, but by 02;00 that was no longer true, as by then Dec was drifting south, so needed guiding north !!

So for most of the night Dec was unguided, resulting in huge uncorrected Dec excursions at times.

Luckily your PA was good enough that no corrections were required on that last run, hence the good Dec figure.

The procedure is to move to your target, switch off guiding and see what way Dec is drifting over several minutes, set Dec guiding to correct that drift.

So bottom line, you need to pulse north a lot more before Cal, until you see equal star movements for several pulses.

An even better solution, adjust your Dec worm and bearings !

And guidescope focus is still poor.

Ok, I understand that much appreciated! Yeah I think I'll get a matching pair of new bearings for dec as well as making sure the worm shaft is the same at the other. Think the guidescope is a bit grubby, I also struggle with focus without a mask so i'll need to get one of those in the future. How much more accuracy will I get with calibration if i have pure focus? Also from what I see in the stats the RA is fine? in regards to performance, both sound fine as in no grinding or play when they're locked up, as I say before the DEC is stiff, which could also be the problem with backlash?