Stuart1971

The issue seems to be the same all across the image you posted, also I don’t think you quite nailed the focus, and all the stars look slightly elongated too, sorry I am not tryi to criticise, but BlurX is not a miracle tool, the date has to be pretty good to start with, better data in better data out… I too have been through all this with my FSQ85 and bad stars, and BlurX made them worse..

Then I would look at pinched optics, and or collimation, and or if you are using a flattener, then correct backspace… Do a star test with a low powered eyepiece and see what they look like when slightly defocussed, see what the doughnut shape looks like..

Well, there are many reasons, poorly aligned optics, pinched optics, too much field curvature, incorrect distances if flatteners or reducers used….mis matched correctors…. What scope and camera are you using…?

Here is an example from your first image, see the flat sides to the star shape….I tried to point out the flat sides with the yellow lines…but not very well ☹️

You seem to have some astigmatism in your stars in the first image, so using BluX will just make them worse, as it does not work well with many types of astigmatism…I found this out too with my tak corner stars, which have some astigmatism…

I think that maybe one of the main issues, it’s not…!! 🤔

First of all we could do with more info, like what software you are using to image, whether you are connected to the mount with ST4 cable or just using the camera to pulse guide via USB, your 0.5 seconds guide exposures are way too short, try 2 or 2.5 seconds…get the PA close also

It looks astigmatism caused by field curvature at the edges…but you say it’s all over the image, in which case it’s probably still astigmatism, but due to collimation being out, somehow, so has the cell come loose or something on the scope…or something shifted…?? i have had this issue with my TAK FSQ85, this is what I was dealing with, but only in the outer 25% of my images…

Just to clarify, 56.9mm “physical” spacing…

Correct…I just use the 55mm, as this was the norm for many flatteners, but yes, mine is the Tak with 56.2 needed, so I am at 56.9mm 👍🏻

I am with you though, I want some definitive clarification, before tonight if possible as it’s clear tonight…😂👍🏻

Further away from the flattener, hence needing a bigger spacer…so +

If you have a flattener and a sensor with a 55mm gap as recommended by most, you are all set …👍🏻 If you then add a 3mm filter into that 55mm gap, you are pushing the focus point away by 1mm, (1/3 of 3mm) so to get proper spacing again you now need 56mm of spacing to reach proper focus, my way of thinking to add the 1/3 filter thickness to the physical spacer Makes sense to me….🤔🤔

Hmmm, I think that is incorrect…this is what I am trying to clarify…you would be 1/3 of your filter thickness short in your train using that approach…🤔

Sorry am confused, you addd it and then reduced it…🤔🤔

Yes, this is what I always have believed…🤔

Thanks so I have my set up correct then…?

Good Morning All, Ok, I hope someone will clarify this for me as I just read a really confusing thread on CN My flattener requires 56.2 physical backspace, and I use 2mm filters, so I have a physical backspace of 56.9mm as I added an extra spacer to add the 0.7mm as 1/3rd of my filter thickness….is this correct…?? As this guy on CN has said that if the backspace needed is 56.2mm and you use 2mm filters, then you already have 0.7mm backspace (due to the filter in the light path) and so you only need 55.5mm of physical spacing, to reach the correct 56.2mm…🤔🤔

It could also be some sort of flexure in the imaging train or focus tube, as after the flip the weight will be shifted and so would the tilt….

Very true, I have a TakFSQ85 and the astigmatism is not good, it’s a 4 element quadruplet scope with built in flattener and with modern small pixel cameras the astigmatism is awful, to the point that Tak had to bring out another flattener to add to this scope to correct the issue, so yes, it not needs two flatteners, it’s now a sextuplet, and it’s still not perfect…the new flattener is now shipped with the scope as standard….I would not buy another one…☹️

What software do you use, as NINA had region of interest autofocus, so you can choose an doughnut type area…looks like this, area inside the dough it is used for focus, and the inner and outer lines can be altered

You have already stated the model, LX200 8” Made by Meade, that’s it really, unless it’s one of the newer ACF ones, then that’s the LX200 ACF, but that one does not require the flattener, which is for sale with this, so would assume it’s the older non ACF version Hard to put a price on it, without seeing it, or knowing how well it works and the condition, of both tube and optics…

There is also bad astigmatism there too, as you can see by the star shapes, they look like bloated crosses, try focusing about 2/3 from the middle of the image to even out the curvature, it should help, I don’t think that is all tilt at all….👍🏻

I used to use this scope without the new flattener out of the box with an older SXVR M35c APC-S sensor and it was superb, edge to edge, but the camera has 9 micron pixels, with my QHY268m with 3.76 micron pixels, it’s totally different it shows up every little bit of tilt and astigmatism….and the new flattener is needed without doubt, which I was not happy about at all, as I had to buy extra as was not supplied as standard when I bought mine…

Wrong, trust me you will need it with any sensor APC-S size and bigger, and maybe even with your camera too, they are very careful what they say about which sensor sizes suffer, but I have first hand experience of which do and which don’t…