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Astroarg
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Some may recognise this on the Altair FB group, however reaching out to others here who may be able to help.

 

See image.. I have now suffered this "issue" with 2 cameras and 2 flattener/reducers (altair 0.8x and altair 1x Lightwave)

 

Anyone had anything similar who can point me into the right direction ?  This is probably worse because I dropped spacing down to 50mm, but I've had it up to 57-58.  I'm not entirely convinced it is spacing, but maybe it is.  I now have a way to test 60+ but will likely need to buy some more spacing to get further..

 

 

241196800_10159724637484289_1041417947292124046_n.jpg

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Anyone had anything similar who can point me into the right direction ?  This is probably worse because I dropped spacing down to 50mm, but I've had it up to 57-58.  I'm not entirely convinced it is spacing, but maybe it is.  I now have a way to test 60+ but will likely need to buy some more spacing to get further..

 

This image may help you. I would say the spacing between the sensor and flattener needs increasing, looking at your images.

 

post-51900-0-10016000-1622930440.thumb.jpg.30cfe6188c397f34f44cfc4408d22c4d.jpg

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38 minutes ago, AstronomyUkraine said:

Anyone had anything similar who can point me into the right direction ?  This is probably worse because I dropped spacing down to 50mm, but I've had it up to 57-58.  I'm not entirely convinced it is spacing, but maybe it is.  I now have a way to test 60+ but will likely need to buy some more spacing to get further..

 

This image may help you. I would say the spacing between the sensor and flattener needs increasing, looking at your images.

 

post-51900-0-10016000-1622930440.thumb.jpg.30cfe6188c397f34f44cfc4408d22c4d.jpg

Would spacing cause the comet shapes though? They are what I’m struggling with, their odd shape and focus

 

i dropped to 50 here but have it at 55. I’m sure I’ve been up to 57,58 and even 59.. odd that everything is suggested (all Altair equipment) 55.

 

uk weather is appalling at the moment, I just need a few hours to test:

no filter 55mm 0.8x and 1x flatteners

filter 55mm 0.8x and 1x flatteners to see what they show 

- extend outwards (I think I have enough to get to 61-62mm at the moment) and see what they show

 

 

Someone mentioned poor collimation on the scope, but I can’t see how that’s the case .. unless I’ve had the issue since receiving the scope last August. Not sure if there’s an easy way to test refractor collimation (I have no eyepieces or diagonal for visual)

 

only other thing I can think is somehow tilt in the focus rack 🤷‍♂️

Edited by Astroarg
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25 minutes ago, Astroarg said:

Would spacing cause the comet shapes though? They are what I’m struggling with, their odd shape and focus

 

i dropped to 50 here but have it at 55. I’m sure I’ve been up to 57,58 and even 59.. odd that everything is suggested (all Altair equipment) 55.

 

uk weather is appalling at the moment, I just need a few hours to test:

no filter 55mm 0.8x and 1x flatteners

filter 55mm 0.8x and 1x flatteners to see what they show 

- extend outwards (I think I have enough to get to 61-62mm at the moment) and see what they show

 

 

Someone mentioned poor collimation on the scope, but I can’t see how that’s the case .. unless I’ve had the issue since receiving the scope last August. Not sure if there’s an easy way to test refractor collimation (I have no eyepieces or diagonal for visual)

 

only other thing I can think is somehow tilt in the focus rack 🤷‍♂️

Poor collimation would show all the star shapes pointing in the same direction, and it's rare for a reflector to go out of collimation, but not unheard of. Have you tried shooting a few image without the flattener in, this will show if it's the scope, or the spacing that's the problem?

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32 minutes ago, AstronomyUkraine said:

Poor collimation would show all the star shapes pointing in the same direction, and it's rare for a reflector to go out of collimation, but not unheard of. Have you tried shooting a few image without the flattener in, this will show if it's the scope, or the spacing that's the problem?

Not yet, someone else suggested that so may have to give that a go.

the issue is having the ascom focuser and swapping kit puts everything out!

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I had a similar issue -it was the FFFR

No matter what spacing I used it would not correct. I sent it back to my supplier who sent me a replacement. That had the same issue! Frustrated, I inspected it closely and discovered that the end pieces could be unscrewed and swapped around. A quick star check showed perfect stars. So in my case it was a QA issue.

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44 minutes ago, paul said:

I had a similar issue -it was the FFFR

No matter what spacing I used it would not correct. I sent it back to my supplier who sent me a replacement. That had the same issue! Frustrated, I inspected it closely and discovered that the end pieces could be unscrewed and swapped around. A quick star check showed perfect stars. So in my case it was a QA issue.

You mean they put the optics in the wrong way around?

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At least for my FFFR the construction is a central barrel with the glass, on each end there are screw-on adapters to match the focuser and camera threads. It arrives fully assembled so it left the factory that way (at least twice 😉). 

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On 9/18/2021 at 10:24 AM, MarkAR said:

The direction of the aberration points to the sensor bing too close but the shape is a little alarming. Could be pinched optics or the reducer has been assembled wrong.

if assembled wrong, both 1x and 0.8x Altair Lightwave pieces missed QC!

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IMO this is  comatic aberration - similar to the problem I had but not as strong - perhaps because your FF is a 1x and not 0.8x. 

Can you check if your threaded parts can be reversed?

As happens my scope is sheltering from the rain next to me... This is how my FFFR arrived:

image.png.0626e523de6625616baa758bc847fb09.png

But it needed to be reversed:

image.png.45e8a56c21f8951c3839fb8a654d4cae.png

image.png.a348e0075568c44478fb10eefcc3a0f8.png

Once reversed it looked "right" on the scope and at it was arguable if I needed to adjust the spacing at all. This QA fail suggests that these FFFC cells are made and tested and then go to a final assembly stage to match threads of the scope it will ship with.

 

(To be clear I'm not posting this to be in any way critical, I love my refractor! AA were very helpful. It was easy to resolve once I'd discovered it, if a little frustrating at the time.) if in doubt get advice from your supplier 🙂

Edited by paul
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If you have the same issue with both flatteners and adjusting backfocus doesn't resolve it then it sounds like the primary cell 😕to me. A discussion with your supplier or asking for advice in the equipment forum might get a more knowledgible answer. 

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12 hours ago, paul said:

If you have the same issue with both flatteners and adjusting backfocus doesn't resolve it then it sounds like the primary cell 😕to me. A discussion with your supplier or asking for advice in the equipment forum might get a more knowledgible answer. 

I'm waiting for Altair to respond to emails.. I dont normally have issue with their kit, or them replying.

 

Looks like clear skies tomorrow, I'm going to attempt to go without flattener/reducer and any spacing and see what happens.. I have a 2" nosepiece that should work, I think I still need spacing though as wouldn't have enough focus travel.

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  • 2 weeks later...

turns out it was my "generic" Altair Lightwave 1x and 0.8x flatteners after all... I could have saved on the 26c haha!

 

Speaking with Nick, arranged a test with the new dedicated 72EDF flattener (1x) and corner issues have gone.

I also picked up the Altair Duo Band filter, long story about my Optolong L Extreme not for today haha

 

1hr 45m from a cloudy night last night

RGB_stars.png

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