Skywatcher 250PX first time collimation surprise.

[Dude_with_the_tube]

My collimator turned up today(baader MarkIII) and as I have not done any collimation since i received the scope i thought this would be a good opportunity to do it as the skies are covered by clouds anyway.So here we go.Tube down to vertical,collimator alligned and inserted and bingo,both mirrors are off.Secondary by 1 inch and primary also pointing who knows where.Well lets start with the secondary and here where the surprises start.Tried to gently adjust any of the 3 adjustment screws and guess what,they are properly stuck and screwed in as max as possible.So instead of trying and moving them and lose the thread on them i decided to pull off the secondary mirror from the spider.And here comes second surprise.I managed to loosen up the main bolt after few unsucessfull atempts,but finally managed it, but by unscrewing you can clearly see that the bolt holding the secondary is bent! So the secondary was coming off by doing wave motions.Spring was completely flat.Lucky i am sort of DIY guy and keep loads of screws,bolts and nuts at home so sourcing replacement was not an issue,however,the spring is another story as I dont keep anything like that at home,but i managed to pull it and get it back to working condition.So, new bolt in,spring back on,secondary mirror back on the spider (ohh,forget to tell ,that i managed to get the 3 adjustment screws loose too) and you will not believe it but i collimated the secondary in literally 20 secs dead center! Luckly no any issues with the primary and after another 1 min I was done and dusted!Both mirrors done,scope collimated.And this was my first time ever collimating a scope!thats the story folks.Very surprised why this happened,but i decided to share the story with you folks as there will be many others doing the first time collimation as i did today and I hope you will not end up in the situation i was.All the issue was a bent central bolt holding the secondary mirror and why the hell on earth they had to tighten it as there is a spring?go and guess lol.

[Optical Dob]

Secondary off by I inch

[Dude_with_the_tube]

well i was expecting it to be off,but yes,1 inch for new tube is a bit too much isn't?but i am blaming the factory in this case for the bent central bolt and jammed in adjuster screws.Still its all spot on now and i will report back once i get the chance to use the scope again.Doesnt look promising in the forecast tho.

[crashtestdummy]

i dont think 1" is actually as bad as it sounds as it just takes a slight angle change to move the dot a cm either way.on the quick collimation,i think people exagerate how hard collimation is.my first time was similar to yours,took less than 5 mins and now i do it every time and it takes less than a minute

[Mr Q]

A point to consider - most all collimators have to be calibrated even from the factory but stars are always "calibrated". I would do a star test before messing with any scope, even if the conditions required for one may take some time. Better be safe than sorry

Then, for curiosity, try the collimator and see if anything is off. If so, rely on the star test adjustments and trash the collimator or try to calibrate it.

Remember, stars don't lie but collimators?

[cotterless45]

I had a similar horror story with my Lightbridge. Delivered from new , the spider had been put on backwards and the vanes then bent to get collimation. After you've collimated your laser ;

An easy collimation check at night is to wind the focuser full in and stick the laser in a Barlow. Independent of slop, you'll see a reflection of the primary centre spot. Just twiddle the primary to get the diffuse beam in the middle. You'll find it'll shift with tube flex and temperature. Not critical for deep sky, but you'll notice the difference to belt detail in Jupiter.

Nick.

[Dude_with_the_tube]

collimation is not difficult.anyone can do it.all it is 3 screws on secondary to adjust and 3 on the primary (after you release and re-tighten the holding screws on primary).i forgot about the barlow,will test with it once i get back from work.I am aware that the tube flexes and also the focuser.I re-checked and adjusted the spider yesterday ,before i did the collimation.

[Optical Dob]

Glad you got it sorted. To be honest I probably don't check mine as much as I should it seems to hold very well. As I've never had a big reflector would being one inch out be as bad in a larger scope than a smaller one or would it be the same. If both scopes had the same aperture?

In other words would collimation errors be more or less apparent in different size reflectors with the same aperture?

[LeeB]

Agree collimation is not difficult , as you were using a laser did you make sure first that the secondary appeared central to the focuser tube and appeared round, many people forget to do this and the laser will not help as it can appear correct even when well off. Making a simple colli cap with a small central hole will help. Also when first doing a colli on a new scope I always check for focus tube alignment (not strictly necessary but hey square is square)

[Dude_with_the_tube]

yes Lee,all was done,and i had a quick test run yesterday evening on a few stars(star test),seems good to go.Could not do long runs as the clouds where running all over the place and the wind picked up,but all seems to be in perfect order.

[LeeB]

Well done, now we need some clear night!!

[Dude_with_the_tube]

according to metoffice this will not going to happen for another 5 days as a minimum.

[bish]

Have to say that I'm rubbish at anything practical. Luckily my 6", 8" and 10" all arrived well collimated so I've only had to do minor tweaks now and then.