Astropedro

On 29/03/2022 at 20:00, Nigella Bryant said:

18 hours ago, Horwig said:

I'm with Nigella on price-point, last year I realised my home made fibreglass on ply dome was shot, and on the same day I decided it was not worth saving, Pulsar had a well used 2.7 m dome advertised for £1500.

Naturally, I was not going to pass on it, so here it is installed. And one year later, not a drop of moisture has entered:

 

Don't lose heart, good used Pulsar domes do come up fairly regularly, why not drop them a mail or phone call to enquire of any possible up-coming domes.

Personally, after ten years of trying to keep my home made dome watertight, I'm asking the inevitable question, why didn't I look for a used dome earlier, in materials alone, my effort was not that short of £1500.

Automation-wise, the older type domes have the motor mounted in the rotating dome, but not a major issue,  I've a LesveDome controlled motor with a 'virtualhere' wifi/usb controlling it from the obsy PC.

 

Huw

Nice looking observatory Horwig.

I did look round for a used one a the time I built mine but there seemed to be nothing, especially locally.  My observatory dome  was built using 3 8x4  sheets of 3mm ply for the outer shell and 3 8x4 25mm ply for the arches to form the dome. This came to £180.  I then spent £170 on a fibreglass kit, including grey topcoat, that I knew was more than enough for the outer skin so I assumed there would be enough to at least fibreglass some of the joints on the inside to give it extra strength.  I assumed correctly.  At any point where 2 pieces of wood meet on the inside, I fibreglassed the area with thin strips and used a good coat of resin.  I figured if it was going to leak, this is where the problem areas would be.  So far it's not showing any sign of leaking and I doubt it will.

I guess another £50 covers the paint brushes, hinges, screws and nails etc that were used.  So apart from my time spent, my 2.2m dome cost me arround £400.  I already had most of the tongue and groove and framing timber left over from my shed and workshop build but I did spend arround another £100 on a bit  more tongue and groove and some 2x2.  Oh and the post brackets were £7 each of which there are 8.

In my case,  £550 covered the basic build.  I've since added a lino floor, painted the interior dome for even more water proofing, I've sealed every point of light i could see on the bottom structure, mainly to keep water and spiders out, and I've added lights and electric to power everything.   When I finally got my first decent image the other night after battling for 6 weeks or so with equipment, software and hardware, I was grinning like a child in that little observatory of mine.  I took a minute to just look arround and enjoy the feeling of pure accomplishment.......then I celebrated with a can of Spanish lager. 🙂 The image wasn't great, it was only arround an hour of data as it was late due to another night of frustration with settings, but it put a massive smile on my face.  I'll post below.

On 29/03/2022 at 20:00, Nigella Bryant said:

I agree with Rusted, you need to up the security, at the moment you're easily broken into with the exposed latch and padlock, even with bolts. I'm speaking from experience several years ago had my 12inch SCT stolen from my RoR. Never recovered, thankfully insured. Anyway I'd fit internal garage door lock's. Two of them one above and below your current padlock. 

I'll look into some better security and insurance. 😊

Well.  I finally got a window of a few hours on Thursday night last week.  I had the reducer on the right way and the stars came into focus across All of the field of view, even if they were a little misshapen  at the edges.  Guessing I'll need to play with the spacing to get it perfect.  I then spent 4 hours battling guiding and plate solving. 

The guiding would not calibrate.  It appeared that it simply would not nudge the mount east.  No matter what I did I couldn't seem to overcome this problem.  Tried clearing the calibration data and flipping and eventually after the 3rd or 4th reboot, it started tracking.

So then i turned my attention to the platesolving problem.  Even though everything was now in focus, the asiair would not platesolve.  I tried slewing to allsorts of targets........."Platesolving Failed".  I eventually looked at the focal length that the asiair plus had assigned to my setup and I realised it had inputed 434mm which is 14mm over the focal length of the telescope.  This must have been done when the reducer was on the wrong way round.  So I erased the value and platesolved again letting asiair recalculate the focal length.  In less than a second........"Plate Solving Succesful "........😊😊🤣🤣🤣😪😪

So at 1.30 in the morning with my EAF achieving good focus and the heq5 tracking reasonably well,  I thought I may as well try and capture something before I call it a night and the clouds roll in.  I slewed to The Pinwheel Galaxy and set the camera to take 5 x 180s exposures in Lrgb and Ha.  The clouds began creating havoc half way through the red filter sub's but I had 5 of everything else except the HA so I called it a night.

I was happy to be finally imaging with a fully working setup and I was loving the Asiair Plus with its simplicity and automation.  It's been a long road to get to this point and I would like to thank anyone and everyone who has advised me in anyway.

So the below image is M101 taken at F5.6 with The Zwo Asi 183mm.   180s exposures x5 in luminance, green and blue, 180s x 2 in red.  Processed in Startools which I had never used before and found to be quite good.  For less than an hours data, I'm a happy chappy......😊😊😊😊

Clouds.............😪😪😪

19 minutes ago, Elp said:

If you want to be more accurate add 0.3-1mm onto the 55mm to account for the filter itself. For simplicity I use +1mm.

Thanks Elp.

So just to clarify,  here's how I have it now.

Reducer orientated the correct  way.  The other end of the reducer also has a removable adaptor that I mistook for being fixed.  Took some separating!  Once off I could remove the knurled adaptor and apply both to opposite ends.  This then threaded onto the rotator the correct way round.

Now I have the spacing as follows as correct if the knurled adaptor is part of the reducer spacing which I'm lead to believe it is.  If it isn't, I will remove the 15.5mm m48 to t2 adaptor and use an adapter I've ordered and some small spacers I already have to make up the 55mm.

1. 15.5mm m48 to t2 adaptor.
2. 11mm t2 spacer
3. 2mm t2 male to male adaptor 
4. 20mm filter wheel.
5. 6.5mm to sensor.

Total..........55mm

if knurled adaptor is part of the 55mm, and I'll know pretty quick when imaging I guess.........then ill space without the 15.5mm m48 to t2 adapter and use the one I've ordered which will look something like this.

1. 15.5mm knurled adaptor. 
2. 2mm m48 to t2 adaptor (arriving tomorrow....I hope 🙂)
3. 11mm t2 spacer.
4. 20mm filter wheel
5. 6.5mm to camera sensor.

Total.............55mm

If either works..................there's a bottle of Cava in the fridge that I'm going to crack open and neck.......😊😄

32 minutes ago, teoria_del_big_bang said:

Well good luck, update the thread with your final version and results, it may help somebody in the future.
I was very frustrated how little info I could find online about this, even Altair's own website.
This lack of info seems to be a repeating issue with a lot of astro gear, well that's what I have noticed anyway often having to find things out on various forums rather than a comprehensive instruction document.
Maybe we all should be geniuses before venturing into Astronomy 🙂 

Steve

Completely agree Steve.  I never like asking for help as I feel that this is stuff I should just know, but after weeks of spending night after night after night trying diferent things and tweaking here and there, I had to reach out as I was getting nowhere.  

I think the core problem here was no instructions or diagram or even an image of the correct orientation of the reducer is provided when supplied with this scope.  But believe me, if I get sharp focus tonight.....all is forgiven and I'm not looking back. 😊😊😊

Hope it works.....fingers crossed.

10 minutes ago, teoria_del_big_bang said:

Oh well good news you at least know the issue even if that gives you other issues 🙂 
How deep is the rotator ? Is that extra width going to be a big problem ?

Steve

It might be.  Going to take it off now and see.  The photo shows the way it should be but that's an altair camera and the spacing will be diferent with  my asi 183.

13 hours ago, Clarkey said:

I know you have found a diagram with the flattener on the way you have it, but I would try the other way round. On my Stella Mira FF for the 90mm ED I had the knurled part on the wrong end as the threads were the same at both ends. (My writing is the other way round too). Looking at the star shapes the exaggerated coma suggests it might be the wrong way.

It would appear you may be right mate.  Will know later tonight hopefully.

Thanks.

Pete

14 hours ago, Elp said:

Have you tried it the other way around?

With my Z61 and the two flatteners I've got they're both 55mm (+1mm for filters) backspace, and I only need to rack the focus out around 20-25mm odd to reach focus, I have a 183mm also.

The one flattener I have the larger thread connects to focus tube with the smaller thread on the camera side, the reducer I have slides all the way into the 2 inch focus tube with only an m42 flange sticking out for the extension tubes to connect to.

Altair Astro have got back to me this morning.........its on the wrong way round......🤣🤣

The rotator has to come off and the reducer attached directly to the focus tube.  So the rotator then becomes part of the back focus.  No idea what that means spacing wise with the filterwheel as well.  I'll have a look shortly.

Thanks again for your help guys....getting there....

5 minutes ago, geordie85 said:

You're welcome. Hopefully all will work out well for you.

Just making sure I'm clear, my 50mm is from camera body to flattener, not camera sensor. Don't want you having more troubles because of me being unclear.

No problem.  I've got you.  I will have 48.5mm between camera body and flattener when the adaptor arrives.  I can manage 51mm at present.  So thats close to your spacing.  Just can't test it as its cloudy......🤔

It would seem I had arround 64mm between camera and flattener originally as I wasn't taking the adaptor that came with the reducer into account.

I've just ordered an m48 to t2 adaptor from harisons.   Hopefully get it Thursday.   If I've got clear skies tomorrow I'll try imaging with the 51mm (2 × 15.5mm adaptors and 20mm filterwheel) between camera and flattener and see what happens.

Thanks Elp for your insights and thankyou geordie 85 and Steve too.

I hope this problem goes away soon  after chatting with you guys. 😊

So.....in the pic from the reducer.....

1. Knurled bit reducing 50something mm to 48mm......15.5mm
2. M48 to t2 adaptor.........................................................15.5mm
3. Filter wheel....................................................................20.0mm
4. Camera sensor................................................................6.5mm

Total..........................................................................................57.5mm

I'm 2mm over........😪😪

Also, please tell me that the rotator between the focuser tube and the reducer isn't part of the 55mm?

I've just put the knurled adaptor alongside the 15.5mm m48 to t2 adaptor and they're the same width.  No matter how hard I try, the reducer only threads into the rotator from the one side.  Another adaptor would be needed to reverse it.  So at this stage I'm thinking you're right.  Need to include the knurled part into the equation or swap it out for something else.  It not only provides 15.5mm of spacing but also reduces the thread to m48 from a much larger size and the interior thread is too big for t2.  Time to get the wallet out again......lol

I'll try Steve.  Nipping out to the observatory in a minute. 

Ok ill have to take that piece out and order an adaptor as I'm not sure I can connect it all up without that.  I'll measure it and see if I can use it.  Even if it's without the filterwheel just to see if I can get a star to focus.

Thanks guys I'll report back but no clear skies tonight, tomorrow looks promising though.

Meant to upload this image.  See the stars.......😪😪😪

13 minutes ago, teoria_del_big_bang said:

The 55 mm back focus is required only to get all stars in the entire FOV focussed the same you still have to focus using the focusser by winding it in or out, so are you saying that from fully in to fully out the stars never get into focus ?
If this is true are they closer to focus when fully in or when fully out ?

I have never seen a reducer so long as that when the focusser is fully out as in your images the camera looks a huge distance from the OTA.

Also by the way you need to add 1/3 the thickness of your filters to the BF distance so if your filters are 3 mm thick the actual BF distance will be 56 mm.
BUT, this is not you primary issue so do not worry about that yet, the small error would only make the stars in the corners slightly elongated or teardrop shape.

Steve

 

Yes I'm saying exactly that.  From all the way in to all the way out, I can't get pinpoint stars either manually or with Eaf.  They are closer to focus arround 75% out.

I have some small 1mm and 0.5mm spacers to tweak the backfocus but nothing big if its way out.

Well spotted re the bolt and padlock.  I just used what I had for the lock and the bolt did indeed come with bolts but I just threw it on with screws to save time with the thought of sorting it mañana.......(tomorrow lol).

Definitely needs a bigger padlock and I'll get those bolts in mate. 😊

Evening guys.

I've spent the last 2 to 3 weeks trying to sort out, what I thought,  was a back focus issue.  I have out of focus stars all over the place, including centre view.  Ive used an Altair hypercam 1600 pro tec and now an Asi 183mm as i wanted to switch to asiair Plus.  Results are really no diferent.  I will attach images of the imaging train in the hope its something imediately obvious.

My scope is an Altair Starwave EDTF triplet and I have the dedicated 0.8 reducer attached.  I then have a 15.5mm adapter, an 11mm extension, a 2mm adapter, a 20mm filterwheel and the 6.5mm to the sensor on the camera.  Thats 55mm so I can only think of a few possibilities why I'm not getting sharp focus at least in the middle.  I would settle for that at this point........😪

1. 55mm is wrong but I can't find anything online that says otherwise.
2. The scope is damaged.  Altair say that's unlikely and the test report that came with the scope a few months ago is good.
3. The reducer is the wrong way round but It didn't come with adapters to fit it the other way round and it's dedicated to this scope.
4. Faulty cameras but I've tried 2 and they  both have the same problem.

If there's anything you can suggest I will be eternally grateful as I'm a tad frustrated as you can imagine.  Clear skies here are rare and I've already wasted so many this year.

Pete

I've ordered spacers to get to the 55mm.  So tonight.......my Canon 1100d comes out of retirement for a few days.......

1 hour ago, david_taurus83 said:

Is that with a bahtinov mask? What's it like when you remove it?

Was no better without it dave.  

Have just read that my camera has 17.5mm of backfocus.  The filter wheel is 20mm.  So at 55mm industry standard I would need a 17.5mm spacer with male m42 thread at filter wheel and female 48mm thread at reducer end.  I can only find a 16.5mm from zwo.  Would the 1mm short be that critical?

Well I've tried all the spacers I've got and I tried removing the reducer too......can't achieve good focus.   The attached photo was the best I could get.

To clarify, the rotator I refer to came with the scope and is at the beginning of the train.  I'll attach a photo in another post of my imaging train which I'm guessing needs a spacer or something removing and changing as good focus is impossible.