Star shapes and guiding

[powerlord]

thanks, but yes that's my point - if you do lock it, then it ain't moving. and different springs are not going to change that it seems to me. I get that with more powerful springs you could not use the locking screws though. But if it can't be the issue seems a waste to change em.

I'm thinking now it's more likely the focuser and weight of asi1600, filterwheel, etc.

I'm gonna put it back together, collimate it and try it with a basic asi224 direct.

stu

[alacant]

1 hour ago, powerlord said:

3 push

Put springs over those as well and leave the screws loose so as to retain the springs; 6 springs in total. At this game, every little counts.

The main source of mirror movement is however lateral movement within the cell, hence the silicone.

55 minutes ago, Robculm said:

they are not really necessary IMHO

And in our opinion too. They are just another source of mis-collimation. As soon as you've used them, you'll see the issue immediately;)

Edited January 20, 2022 by alacant

[alacant]

50 minutes ago, powerlord said:

I'm thinking now it's more likely the focuser and weight of asi1600, filterwheel, etc.

Yes, of course.  But everything else has to be as perfect as you can get it too. No single modification is going to get you over the line. 

Tube reinforcement consists of a sleeve which is riveted/bolted to the existing tube. @laser_jock99 has a post on this. Here's his reinforcement insert:

Edited January 20, 2022 by alacant

[alacant]

JTOL: it's threads such as these which make small, high-end refractors seem like an awfully good proposition!

Edited January 20, 2022 by alacant

[powerlord]

Just dropped secondary on primary.

Doing well do remain calm here...

And yes that is a massive chunk cracked off.. And I imagine primary is damaged too. ###__£/-/?! //

[powerlord]

so.. maybe... just maybe I'm ok. as I'm using an asi1600/533.

the primary jas been 'scuffed' but otherwise ok.

It's now waay out of collimation after spider back on, etc - but it looks like if I get it collimated, the cracked off bit will be outside fov of the sensor.

Edited January 21, 2022 by powerlord

[powerlord]

so.. maybe... just maybe I'm ok. as I'm using an asi1600/533.

the primary jas been 'scuffed' but otherwise ok.

all collimated now and it looks like the cracked but is pretty much completely out of fov of asi1600.

So.. it's shot using full frame cameras with it for sure, but I think ok otherwise.

sheesh... and wednesday I bought at used mobile phone from a bloke on gumtree that turned out to have a touchscreen that didn't work ("oh I've just applied a software update -see - it's now rebooting and all yours"... on getting home and charging I find out its duff and he won't give me my 155 quid back). then this. arg

 

[vlaiv]

36 minutes ago, powerlord said:

It's now waay out of collimation after spider back on, etc - but it looks like if I get it collimated, the cracked off bit will be outside fov of the sensor.

It does not really work like that.

Every point on sensor is illuminated by whole primary mirror - so that mark will impact whole image.

It might not show at all on your images, or it could cause mild diffraction effects.

If that happens - not all is lost, you can simply "patch" it with small black circular patch. Small circular masks don't impact image at all (to very small degree - like very tiny secondary obstruction) and people often use such masks to mask off problematic part of the mirror - either mechanical damage or place on the mirror where surface figure is not good (turned down edge or zone or similar).

I wanted to give you an example in form of picture - but it looks like google search is down at the moment (at least for me).

 

[alacant]

1 hour ago, powerlord said:

dropped secondary on primary

Flat glass glass is cheap to replace:

https://a.aliexpress.com/_uyFNrV

We too have damaged primary mirrors but don't notice any image deterioration. If you do, @vlaiv's idea of the pirate patch to the rescue.

Good luck anyway.

[powerlord]

12 minutes ago, vlaiv said:

It does not really work like that.

Every point on sensor is illuminated by whole primary mirror - so that mark will impact whole image.

It might not show at all on your images, or it could cause mild diffraction effects.

If that happens - not all is lost, you can simply "patch" it with small black circular patch. Small circular masks don't impact image at all (to very small degree - like very tiny secondary obstruction) and people often use such masks to mask off problematic part of the mirror - either mechanical damage or place on the mirror where surface figure is not good (turned down edge or zone or similar).

I wanted to give you an example in form of picture - but it looks like google search is down at the moment (at least for me).

 

i was talking about the cracked secondary Vlaiv. Yes, the mark on the primary is gonna effect things, but it's no worse that dust/dirt on there. I hear you about diffraction - we'll see what it's like - but it's a cheap scope - I'm not burning loads of my time on it frankly.

[powerlord]

All because last time I took a spider off my 200p, i found the arms were  bigger than the scope. so in order to get it out, you had to bend (not bend bend, just springy bend) the spider arms to get it out - so I though this was the same - undid first 2 at same time, undid second 2 at same time - and blam!

sigh.

I am glad it is friday.

[alacant]

6 minutes ago, powerlord said:

the mark on the primary is gonna effect things

Not nearly as much as the mirror clips.

[vlaiv]

8 minutes ago, powerlord said:

i was talking about the cracked secondary Vlaiv.

Oh, I see.

You were thinking of still using that?

I would advise against it - even if your sensor is not illuminated by that portion - part where mirror is chipped will still get some light and will scatter that light all over the place.

You'll get bunch of diffraction effects / spikes and lighter background. Best thing to do is simply to replace that secondary flat - it should not be expensive.

[powerlord]

Will see. at this point it is all I can do to avoid smashing it all to bits with a hammer.

Maybe after a few days with some perspective I'll talk to FLO about a replacement secondary.

stu

[vlaiv]

57 minutes ago, powerlord said:

Will see. at this point it is all I can do to avoid smashing it all to bits with a hammer.

Maybe after a few days with some perspective I'll talk to FLO about a replacement secondary.

stu

Sure, take some time to cool off. Things like that are quite stressful and hobbies are supposed to be enjoyable.

Before you look into getting another secondary - you can try masking trick on secondary as well. It will block funny light scatter, but if it is close to sensor it won't be "invisible" like on primary - it will present itself like vignetting of sorts on that side. Luckily, flats should take care of that.

[powerlord]

i was thinking that myself - a bit of black paint on over the cracked off bit. though that would mean taking it apart again - one for another day.

[powerlord]

Well, stuck some matt black paint over broken bit of secondary. Will see..

Someone mentioned replacement secondaries cheap? But looking here it's 110 with vat.

https://www.orionoptics.co.uk/product-category/optics/elliptical-flats/

89x63 is closest.

I mean,  cheaper from aliexpress but then you don't know what yer getting.

So I feel if paint doesn't work, best binning it all and getting a new one, or the sw 150p-ds.

Edited January 25, 2022 by powerlord

[Starflyer]

40 minutes ago, powerlord said:

Well, stuck some matt black paint over broken bit of secondary. Will see..

Someone mentioned replacement secondaries cheap? But looking here it's 110 with vat.

https://www.orionoptics.co.uk/product-category/optics/elliptical-flats/

89x63 is closest.

I mean,  cheaper from aliexpress but then you don't know what yer getting.

So I feel if paint doesn't work, best binning it all and getting a new one, or the sw 150p-ds.

This is a heartbreaking read 🙁

I have a secondary in my parts box, it's from an OO VX10 that I swapped for a bigger one, it's been a while but I think it's a similar size and was in decent condition.  I'll dig it out tomorrow and measure it for you, if you want it it's yours.

Ian

[vlaiv]

1 hour ago, powerlord said:

Well, stuck some matt black paint over broken bit of secondary. Will see..

What is your minor axis size? I'm guessing about 50-60?

https://www.teleskop-express.de/shop/product_info.php/info/p1669_TS-Optics-Newtonian-Secondary-Mirror-elliptical---D-50-mm-minor-axis.html

[powerlord]

10 hours ago, vlaiv said:

What is your minor axis size? I'm guessing about 50-60?

https://www.teleskop-express.de/shop/product_info.php/info/p1669_TS-Optics-Newtonian-Secondary-Mirror-elliptical---D-50-mm-minor-axis.html

Thanks Vlaiv, but no it's this one:

https://www.teleskop-express.de/shop/product_info.php/info/p1667_TS-Optics-Newtonian-Secondary-Mirror-elliptical---D-63-mm-minor-axis.html

With vat, shipping and import fees it'd be 1/2 the price of a new scope, and I've got that mark on the primary still. I think A new OTA makes more sense frankly.

@Starflyer - a very generous offer if you have something, but honestly don't put yourself out - it's my own stupid fault, and I'm not short of a few bob - it's more the hassle and feeling like an idiot for it happening, than the money to put it right.  As I say above, I feel IF I bought a new secondary, there's the cost, the hassle of shipping, the fitting it to the support, etc.. and then after all that I still have a primary that is damaged, AND an OTA that had a weird problem in the first place again.. seems to me, maybe just getting a SW 150-DS is a better plan. If that all works, I'll probably let someone on here have the old damaged, but sort of working one for the price of postage for someone who wants it.

 

[Starflyer]

2 hours ago, powerlord said:

@Starflyer - a very generous offer if you have something, but honestly don't put yourself out - it's my own stupid fault, and I'm not short of a few bob - it's more the hassle and feeling like an idiot for it happening, than the money to put it right.  As I say above, I feel IF I bought a new secondary, there's the cost, the hassle of shipping, the fitting it to the support, etc.. and then after all that I still have a primary that is damaged, AND an OTA that had a weird problem in the first place again.. seems to me, maybe just getting a SW 150-DS is a better plan. If that all works, I'll probably let someone on here have the old damaged, but sort of working one for the price of postage for someone who wants it.

 

Okay I found it, it's 62 x 88, probably the 63 x 89mm on OO's site.  It's in not as good condition as I remember, or perhaps the coating has degraded somewhat while in a drawer.  The coating isn't terrible but I can see quite a few small patches of light through it from the back when I hold it up to a window.  Not as good as I made out but you're welcome to it if it'll help.

Do you have accidental damage cover on your house insurance?  Maybe better to claim to replace the whole scope?

[powerlord]

thanks, appreciated. It does sound like it might be about same as one I have though, but for different reasons. It's not something I can swap back and forward really either as I understand it - one needs somehow removing from mount, and the other glued on ? I think I'll leave it, but thanks for the offer. I'll see what the current OTA works like next clear night, then go from their.

I'm not wonderful at collimation - every tutorial is massively longer than it needs to be imho (yes.. including astrobaby's) and one contradicts the next one.. But will give that another go and get it close as I can before hand and see what I get.

again, much appreciate the offer.

stu

[powerlord]

just an update, that it's now back together and collimated. looking at terestrial stuff, it looks good. no darker bits. pointing at sky it looks flat.

So.. just have to wait and try when clear I reckon.. there's hope yet.

stu

[powerlord]

hi chaps, contrary to forecast, it's clear at least for the moment. so live now, I'm capturing some subs from IC1805.

here's one stetched in siril.

the good news is stars seem circular in the middle.

and bottom left and right look ok too.

top not so good. bottom left.. weird. top right.. weirder.

but could be unrelated to damage? could this just be tilt ?

it's up just now, so any ideas folk have, I'll try them if I can.

scope will still be cooling down, as this was an unexpected session, so only been out about 30 mins at this point.

stu

Edited January 27, 2022 by powerlord

[vlaiv]

20 minutes ago, powerlord said:

the good news is stars seem circular in the middle.

and bottom left and right look ok too.

top not so good. bottom left.. weird. top right.. weirder.

You need to learn how to pixel peep

None of these stars are ok really. They all show some sort of deformation.

Central stars look the most ok, and they look like they have some issues with seeing or poor guiding or something - until you see corners and start identifying aberrations and then you see that those aberrations are present in center stars as well but to lesser degree.

Astigmatism and field curvature. There is possibly some tilt as well.

I can't really say if any of it is due to damage.