CG5 mount and polar alignment help!

[Altair]

At last i had a chance to try out this mount with my SCT firmly attached.

3 star alignment successful i went to the utilities menu and tried to do the polar alignment ..

I cant remember now if the scope then slews to where Polaris should be and then asks you to adjust

the front latitude and rear latitude adjustment screws to centralize it but i found that I could not get the ota high enough to focus centrally on Polaris.. is this because my 3 star alignment was not successful?

Adjusting the latitude screws did not bring it into view

i see that there is only movement here of between 30 and 60 deg..and i thought this would be needed to be set at ones own lattitude in my case 51 deg and ofcourse Polaris is higher!

it says you must adjust the mount only, not using the hand controls.so can i higher the ota by releasing the locking clamp to get it in right position?

Sorry for what might seem a stupid question but i have not used a computerised mount before and i really would like to be able to get a good alignment for photography.

One other problem with this old mount is that it doesnt have its lattitude scales printed on the side - guess they must have popped off at some time..So is there an easy way to set it correctly without?

I Would love to see a pic of this so i can see where the scale should be set..if anyone has a close up pic of the latitude scale on the side of their mount i would be most grateful to see it!

if anyone from here give me their twopenneth would be I most grateful

All very frustrating spent 3 hours trying to sort this out!

Oh the joys of Astronomy it made me quite long for my old fork mount again !!

[Alan_B]

There you go

Sent from my Galaxy S3 using Tapatalk 2

[cantharis]

i see that there is only movement here of between 30 and 60 deg..and i thought this would be needed to be set at ones own lattitude in my case 51 deg and ofcourse Polaris is higher!

Not quite sure what you mean there - if you are at latitude 51 deg N, the North Celestial Pole will be at an altitude of 51 deg and Polaris will vary between 50 and 52 deg above the horizon as it circles the NCP.

[allcart]

Are you facing the mount north when you set up. if you are and the latitude is set to 51 deg then polaris should be in the polarscope view.. All you have to do is kick the legs of the mount a little bit and adjust the latitude bolts to put polaris in the circle Then you fine tune it with the 2 plastic knobs at the base of the mount to place polaris at the right position on the circle line, according to the time of day. I use 'Polarfinder exe' to give me a diagram of where to place it.

Then do the 3 star align and choose your target to view.

I have never used the Polar align prog in the utilties menu. Maybe you should do this before the 3 star align.

[Altair]

Thanks Allcart something definitely didnt work right at the beginning and i guess its because the mount wasnt set at 51 deg... i just pointed the scope north on my compass and then sighted polaris in my field of vew which didnt work....I will give it another go whenever we get clear skies again!

[Altair]

HI Cantharis yes i know what you mean if my scope was set correctly at 51 deg it should be in the field of view of the polarscope . Maybe i am reading it all wrong but when i adjust the rear and front latitude screws i couidn t get the mount to move higher than say 45 deg..the front screw was in so tight it wouldnt tighten anymore...

the book says the adjustment of the mount should go from 30 to 60 deg

[Altair]

Not quite sure what you mean there - if you are at latitude 51 deg N, the North Celestial Pole will be at an altitude of 51 deg and Polaris will vary between 50 and 52 deg above the horizon as it circles the NCP.

i meant that my mount wouldnt adj ust to 51 deg Polaris was higher in the sky than i could adjust the mount which has a movement of between 30 and 60 deg so i think i have a problem with the mount adjustment screws

[Alan_B]

Have you slackemed of the bolt /screw on the opposite side enough ?

If so it may be that the weight of the counterweight may be causing the screw to feel stiff and feel as though it may break.

I set mine up without the OTA or counertweight filtted , even without the counterweight on the shaft the screw can be quite difficult to screw in and elevate the head

[allcart]

The screw under the polarscope eyepiece will raise the latitude when you screw it in, but you must slacken off the opposite screw first, or you run the risk of bending the screw. When you have Polaris in the centre of the circle gently tighten the loose screw and keep your eye on Polaris to make sure it doesn't move. you can nudge the legs round to get left right movement, or use the two knobs on the back of the mount. Same deal, slacken one as you turn the other, then tighten both knobs when you are lined up. Fine adjustment to place Polaris at the appropriate place on the circle line is done gently with the lat bolts and the knobs.

I suppose I should mention that the two index marks on the mount should be lined up and locked at the start. Then release the clutch on the RA axis and rotate the scope and counterweight 90 degrees to open the polarscope hole. Then do all the other stuff. When polar aligned, turn the scope back to the index mark and go for the star align.

[Altair]

Thanks Alan_B, yes i think you were right here tonight i tried it without the weight and ota mounted and yes so stiff eventually managed to undo both sides fully the mount head was still very stiff but i managed to move it and yippee its now pointing much higher! IN future i will align it before mounting the OTA and weights! All i need now is some clear sky lol

[Altair]

Thanks Allcart i am sure all the weight on the mount added to the difficulty. When i get the chance i will try your method and hopefully centralize Polaris!

[allcart]

I edited my post as you were typing. there is another snippet of info just in case you need it.

[billhinge]

May be obvious to some but it caught me out the first time

Did you put the little alcove on the bottom of the mount over the top of the pin which is on the tripod top plate, the azimouth bolt uses the pin to push against when the azimouth knob is tightened

(The little alcove has a bolt either side of it when viewed from underneath - pin goes between the bolts)

Also, suggest you replace the bolts that came with the CG5 with some sturdier replacements. I put some lubricant on the threads to make turning easier (I used WS2 but you can try lithium or whatever takes your fancy)