HydrogenBadger

I haven’t got a copy of the error message unfortunately, and the weather has not allowed me to go out again and test since I started this thread. 
 

I will take your advice on board when the sky finally clears. 

It tried to validate and centre 5 times before giving an error message. I then selected Polaris as a target to check polar alignment and the scope shot off and was out by about 45 deg to the west.
 

Went to try the polar alignment again but was thwarted by clouds!

3 hours ago, dannybgoode said:

Goto won’t be accurate first time round regardless of how good your PA as your mount will be a little be out to what the goto commands think it is.

For imaging in particular plate solving is the answer. It sounds daunting at first but once you’ve nailed it you’ll never go back. If you’ve not looked at plate solving before what it does is goes to where it thinks the object should be, takes a shortish exposure, matches the stars to a database and works out exactly where the scope is actually pointing, adjusts the mount, takes another exposure, matches etc until the object is centred. And by centred last night I got targets centred to 2-3 arc seconds. 

As for the park position, I suspect the software may have a different home position stored. I am not familiar with the Air software but there will be a way of telling it the scope’s current position is home. So you’d manually set the mount to where you want home to be and then tell it to use that position going forward.

Thanks Danny, my understanding is the ASI air pro uses platesolving as part of the goto routine. However, mine failed after slewing to the target - please see screen shot of the error. 
 

I will have a look to see how to set the home position. 

Finally managed to get it focussed after around 2 hours of back and forth with the auto focusser. Then tried a polar alignment using he the asi air pro which initially appeared to have worked but then after trying to “goto” an object clearly hadn’t. I then tried to use the “goto home command” which strangely put the scope out by around 45 degrees in declination which I don’t understand. 

Thanks Steve, unfortunately that is not my flattener. This is the one I have. https://www.firstlightoptics.com/reducersflatteners/william-optics-adjustable-flat6a-iii-08x-reducer-flattener.html
 

Managed it put it on, but have removed it again as I am finding it impossible to focus the camera. Just about ready to put the damn scope in the bin. 

Yes it does - thank you!  I thought that the yellow locking ring was supposed to clamp against the adjustable end to keep it in position and prevent the distance changing?
 

All, I have a 2” iptolong l_enhance filter which I am trying to fit to my Williams Optics adjustable field flattener and ZWO ASI 533 pro cam. I cannot see where it fits as the field flattener has a threaded connection and the filter only has threads on one side.
 

many thanks in advance. 
 

2 hours ago, teoria_del_big_bang said:

Then with this flattener, which is adjustable, you should  not need anymore spacers than what came with the camera. 

Whilst the photograph I put on my previous post is not mine I think yours just needs to be exactly like that and the 11mm, 16.5 mm and 21 mm spacers that come with the camera are all that is needed.

 I have a WO scope, but not this one, and unfortunately was bought before the adjustable flattener came out so mine is fixed which means all the adjustment to make the back focus correct has to be done with spacers between the flattener and camera and I had to obtain 0.5 mm spacers to get it just right. With these adjustable ones that is not required as the fine adjustment can be done on the adjustment of the flattener. 

I am not sure where the image in the post from  @inFINNity Deck  came from, maybe that is the fixed flattener that was used before this new adjustable one, but it doesn't seem to tie in with any info I can find for this particular flattener.

EDIT - I am now had I have just seen the reply so that settles that (Thanks @inFINNity Deck 🙂 )

 

Looking at the Info on the WO website and the FLO website I would think it is as follows,

2019-all-new-adjustable-flat6aiii

william-optics-adjustable-flat6a-iii

The back focus for this flattener with the GT71 is 64.1mm is as below:

The distance from the front of the camera body to the image plane, without any attachments or spacers, is 6.5 mm.

The first thick spacer that screws directly to the camera is 11mm, you should also have a 16.5 mm and a 21 mm spacer with the camera. So 6.5 + 11 + 16.5 + 21 = 55 mm.

Back Focus needs to be 64.1 so 64.1-55 = 9.1 mm - So adjust the flattener by 9.1 mm.

The image below shows the distance from the end of the flattener to the image plane to be 55 mm (being made up by 1 or more spacers which you should have). 

Sorry if I have confused you, that was not my intention and hope you have the required information to set it up correctly when you fit the flattener.

Also whilst doing this I see why you need the 1.5 hex key, those grub screws are not present on my older WO scope it all just screws off. I guess yours is much more secure and cannot now come loose.

 

I hope I have helped anwyay rather than confuse you more 🙂 

Steve

Steve, thank you so much for this. Extremely helpful. I really appreciate the time and effort you have put into this response. 
 

Just need to get the hex screw driver to fit the flattener. 

Thanks again. 

11 hours ago, inFINNity Deck said:

Below diagram shows you how much space there should be between the flattener (assuming it is a Flattener 6 for GT71) and the chip. Your camera has 6.5mm from its front surface to the chip. So for the GT71 you need 65.82-6.5 = 59.32mm of spacers between the rear surface of the flattener and the front surface of the camera.

Nicolàs

 

Thanks very much for this. Very helpful. 

12 hours ago, teoria_del_big_bang said:

What flattener is it exactly, is it this one:

2019-all-new-adjustable-flat6aiii

Yes it is this one. 

If it isn’t enough are there generic spacers I can buy? I guess it is worth getting a few spare to deal with when I try to fit the flattener. 

“When it comes to fitting the flattener then it gets a bit more complicated”. 

More complicated! 

I have 15mm of outwards movement left. 
 

All, just managed my first photo with my new rig. It is of a tree. Most importantly however, it is a nearly focussed tree. I am a happy boy.

I need to buy extra spacers (which is annoying). Needed around 70mm from the end of the telescope to the camera body. 
 

Will I need to increase that to focus on stars or will 70mm distance decrease slightly?
 

Looks like 100% cloud cover tonight! I will be happy if I can set up around 7 or 8 pm and see something other than white noise. Fingers crossed!

Thanks all, I will try again this evening. I don’t have any eyepieces with me which is a bit annoying but I am hopeful I can point it at a street lamp. 

47 minutes ago, teoria_del_big_bang said:

Also you should be able to fit the flattener without tools, well on my WO 73 I can.

Steve

Unfortunately not on this model, it requires an extremely small hex drive for 3 screws to be removed. 

1 hour ago, inFINNity Deck said:

Hi HydrogenBadger,

Your scope has a 420mm focal length, so the CMOS surface should be around 420mm behind the centre of the objective, which can easily be measured with a tape measure.

HTH,

Nicolàs

 

Thanks for all the replies. 
 

I have a field flattener - this again arrived without a single instruction. I found some instructions online. As I am on holiday I do not have the tools to fit it. 
 

I really hope that I don’t need any additional spacers. I bought the setup as a ‘job-lot’ from a supplier with the specification being I wouldn’t need to go out to buy a single  extra component, nut or bolt to get started. I have already had to spend £80 on the correct counter weights. I will be pretty disappointed if I also need more spacers. I think I have around 50-60mm of spacers. 
 

All, I have a brand new rig including my first dedicated camera the ZWO 533 mc pro with a Williams Optics GT71. I am using (or trying to) an ASI Air Pro for control. I have spent a week learning how to balance the damn thing as it was not sold with the correct counter weights and last night was the first clear sky to try and polar align. I cannot get an image of anything vaguely resembling a star - out of focus or otherwise. All I have is noise. I have turned the gain down to the minimum settings, up to maximum and everywhere in between and experiment with spacers and focus. Nothing. 
 

Pointing at the same bit of the sky I was able to focus my asi 120 mini guide scope. 
 

Really frustrated by the total lack of instruction available for any of the equipment. 

Help would be very much appreciated. A picture of my rig below. 
 

All, thanks for all your help. I managed to get the scope balanced. I had to buy 2 x 2.5kg counter balance weights As the weight provided was way too heavy.  I also installed a 300mm long losmandy plate which has allowed me to install the asi air pro in front of the scope and adjust is location (left to right) to balance in the 3rd axis  

Trouble is I now can’t see a single star through my camera. I will have to start another thread on that!
 

Thanks again. 

2 hours ago, Richie092 said:

Edited as I can see you have it fixed with the metal bracket, how is it rotating?

The focuser has given me more headaches than the rest of the system combined... including the RPi4 and Stellarmate that was as familiar as alien technology to me.

This was a schoolboy error on my part. I didn’t realise that the whole focussing unit didn’t just rotate freely by that it was just loosely fastened. I just needed to tighten it up on the threads. 

3 hours ago, RayD said:

If you have a look at my video here you will see the issue you are having is common (this in on my CEM120).  I added an ADM weight to the front of my longer dovetail which helped sort out dec (and it will help RA) but also allowed for trimming off centre balance on the third axis.

FLO does variousl types and styles of dovetail weights.

Thanks yes, I have beeen watching all of your videos in the run up to my scope arriving!

4 hours ago, Richie092 said:

I had a similiar issue with my Star 71. Purchased a longer rail and stuck my Pegasus up the front. Works like a dream now 🙂

 

Thanks, yes I have just order a losmandy style plate which I am hoping will do the same thing you are suggesting here.  Should the focuser unit be fixed in position?  Mine is allowed to rotated freely and I can't see how I fix.

3 hours ago, Stuart1971 said:

You need the scope further forward than shown in first image, to balance in Dec, as ATM its all rear heavy, and to get RA balanced move the weight up the counter weight shaft to effectively lighten it...it may all work then... 👍😀

The counter balance is a far up as is possible.

All of the equipment is now upside as otherwise it fails against the mount i.e. the autofocuser, ASI Air Pro and the fine foucuser.  Not sure if this is a problem.  If I move it any further forward the scope will only be connected by one clamp in the dovetail which does not seem like a very good idea.

Thanks all, from what I am hearing I am not doing something fundamentally wrong so my options for the RA problem is either buy a lighter counter weighted or buy additional weight to hand scope side. 
 

How do I solve the declination balance problem? As you can see from my photos I have pushed the tube as far forward as I can including having to rotate the auto focuser and ASI air pro so theY can pass over the mount - doesn’t feel it is supposed to be done like this.