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Hi all,

First light with my new Ioptron CEM26 and WO ZS73  with WO 73R x0.8 FF/FR with APC-S Canon 60D.

I levelled the mount, balanced everything up and did a "perfect" pole alignment with Ipolar.

This is a 120sec unguided sub but something is very wrong on the right hand side, any help would be greatly appreciated.

LIGHT_120s_1600iso_+12c_20210130-23h22m57s550ms.png

Edited by MARS1960
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Looks like tilt in the imaging train, being as it gets progressively worse from left to right. However, there is a tracking error in there too.

1) Check for saggy or loose connections.

2) Take shorter subs to get an image free from tracking issues (or get guiding) - that will allow you to correctly judge where the tilt is.

3) Inspect the corners of the test sub, make adjustment as required

4) Rinse and repeat until satisfied

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5 minutes ago, Uranium235 said:

Looks like tilt in the imaging train, being as it gets progressively worse from left to right. However, there is a tracking error in there too.

1) Check for saggy or loose connections.

2) Take shorter subs to get an image free from tracking issues (or get guiding) - that will allow you to correctly judge where the tilt is.

3) Inspect the corners of the test sub, make adjustment as required

4) Rinse and repeat until satifsied

Thanks Rob,

After zooming in and seeing seagulls I was worried it might be the scope.

Everything was very tight as the FF screws directly to the scope and I used a quality WO M48 DSLR adapter which gives a super snug fit.

How would I cure tilt in the imaging train? I don't even know what that means :).

5 sec sub attached.

PREVIEW_20210131-00h24m51s738ms.png

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Ok, looking at that image... it is out of focus, but it does display corner characteristics (the distortion is of equal magnitude in all corners) that tell you either:

1) The FF/FR spacing is too long

or

2) The optics cannot provide a (perfectly) flat field across APS-C or larger.

 

But, get the image in proper focus first - that might correct a lot of the issues.

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1 minute ago, Uranium235 said:

Ok, looking at that image... it is out of focus, but it does display corner characteristics (the distortion is of equal magnitude in all corners) that tell you either:

1) The FF/FR spacing is too long

or

2) The optics cannot provide a (perfectly) flat field across APS-C or larger.

 

But, get the image in proper focus first - that might correct a lot of the issues.

Thanks Rob,

The 73R was apparently built with DSLR's in mind, so according to FLO website no spacing is needed (It gives the 56.8mm needed) BUT, I did just notice that I also need to move the adjuster out by 1.8mm which I have now done, maybe this will fix the issue?

Not sure what happened with focus as I used the built in mask, possibly it shifted when I locked off.

I'm hoping any tracking errors will sort themselves with more use.

I'll be guiding next time too, I didn't do it last night as I didn't need the extra hassle just to check the scope and mount.

I've just read about CCD inspector, I will download that too.

Thanks.

 

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You only need to adiust the flattener if you have introduced a filter into the imaging train or had the camera modified (filter removed).

Making the spacing longer will only make it worse, it needs to be shorter. Or in focus. The spacing as detailed by FLO is 11.4mm, however that is the recommended distance, and not every camera/filter combination is the same, so you may need to tweak that by a mm or 2.

But, only from a properly (centrally) focused image can you make a proper assessment and decide which way to go (longer or shorter).

When focusing, zoom right in to the diffraction pattern... not on the camera screen but using either EOS tools or something like APT. Then, after 45 min or an hour... do it again. (especially during cold weather).

 

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5 minutes ago, Uranium235 said:

You only need to adiust the flattener if you have introduced a filter into the imaging train or had the camera modified (filter removed).

Making the spacing longer will only make it worse, it needs to be shorter. Or in focus. The spacing as detailed by FLO is 11.4mm, however that is the recommended distance, and not every camera/filter combination is the same, so you may need to tweak that by a mm or 2.

But, only from a properly (centrally) focused image can you make a proper assessment and decide which way to go (longer or shorter).

When focusing, zoom right in to the diffraction pattern... not on the camera screen but using either EOS tools or something like APT. Then, after 45 min or an hour... do it again. (especially during cold weather).

 

Thanks Rob,

I think you might be looking at a different FR, I know the one that says 11.4, (73A, mine is 73R) this is mine: https://www.firstlightoptics.com/reducersflatteners/william-optics-x08-adjustable-reducer-flattener-for-zs73.html

I also did CCD inspector, attached image image but not sure how to read it, good, bad?

Thanks.

Screenshot (6).png

Edited by MARS1960
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DIfficult to see since you havent poseted a full screen shot. But from what I can see it is tilted to one side a little.

Even my Star 71 needed its focuser (which was also R&P) tweaking out of the box, there are two bolts on top of the focuser- you may need to nip those up a little (and I mean little).

You can check for focuser movenent by racking it out a bit - then basically give it a tug in all directions. If you detect any movement/wobble (no matter how small), then it needs to be tightened up.

Still needs to be in focus though to make the correct assessment, before you do any adjustments.

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10 minutes ago, Uranium235 said:

DIfficult to see since you havent poseted a full screen shot. But from what I can see it is tilted to one side a little.

Even my Star 71 needed its focuser (which was also R&P) tweaking out of the box, there are two bolts on top of the focuser- you may need to nip those up a little (and I mean little).

You can check for focuser movenent by racking it out a bit - then basically give it a tug in all directions. If you detect any movement/wobble (no matter how small), then it needs to be tightened up.

Still needs to be in focus though to make the correct assessment, before you do any adjustments.

Ok thanks Rob, I'll check that now.  So those numbers look ok?

More images.

Screenshot (8).png

Screenshot (9).png

Edited by MARS1960
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Looks consistent with tilt.

A fully loaded imaging train acts as a lever under gravity. So any movement in the focuser or imaging train would be exposed.

But, I take CCD inspector with a pinch of salt. You would need to take multiple shots of different parts of the sky (but not go past the meridian) to see if the readings are consistent.

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2 minutes ago, Uranium235 said:

Looks consistent with tilt.

A fully loaded imaging train acts as a lever under gravity. So any movement in the focuser or imaging train would be exposed.

But, I take CCD inspector with a pinch of salt. You would need to take multiple shots of different parts of the sky (but not go past the meridian) to see if the readings are consistent.

Drat, I'm not sure what to do then Rob.

I have pushed, pulled, wiggled and wobbled and this gear is so snug all three parts of it act as a single unit without even whisker of movement.

Thanks for your help.

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I have just been checking the image train and decided to focus on a distant branch. 
when I turn (fine or coarse) to focus the branch moves up and down by about 10mm across the LCD screen. 
will this focus shift be causing my issues? See attached video.

TIA. 

IMG_0476.MOV

Edited by MARS1960
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  • 3 weeks later...

Just to conclude this thread.

I explained the above and sent screenshots to the guys at FLO, they were extremely helpful and said it was tilt in the image train.

They immediately arranged for the scope and  FF/FR to be collected and sent to ES Reid next day.

I heard back from them this morning and was told the FF/FR was faulty, they sent another to ES Reid which was checked and found to be perfect.

They have couriered my scope and FF/FR back to me today.

I'm extremely grateful to the guys at FLO for recognizing and dealing with the problem in such a timely and professional manner.

Thank you.

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