Author Topic: STAR ALIGNMENT DIFFICULTY  (Read 534 times)

Offline dpaul

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STAR ALIGNMENT DIFFICULTY
« on: 2018 June 27 14:21:08 »
Hi,

I've been taking narrowband frames of M57 and also using a 2x Powermate to increase the image size. The frames are good but there are not that many stars in the field but still enough (I hoped) for star alignment. However, no matter what settings I use, I can't get star alignment to work, or at best I got about 20% of the frame sto align.


What is best settings for the most difficult cases - the other probelm is that HA and OIII by their nature also reduce the number of visible stars.


It all works without the powermate but not with it.


Is there a way to manually selct the reference stars?

David

Offline John_Gill

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Re: STAR ALIGNMENT DIFFICULTY
« Reply #1 on: 2018 June 27 23:18:06 »
Hi,

For difficult star alignment I use the following settings for DSLR.  This may work for NB images as well.

Star Alignment
 - Star Detection 3
 - Noise Scales 0
 - Hot Pixel Removal 1
 - Noise Reduction 5
 - Log Sensitivity -1.0
 - Peak Response 1.0
 - Maximum Distortion 0.500
 - Upper Limit 1.00

Start Matching
 - RANSAC Tolerance 7.00

Look up
John
APM 107/700 apo on CGX mount
ZWO Optics - Autoguiding
ZWO1600mm and filters
... when there are no clouds ...

Offline dpaul

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Re: STAR ALIGNMENT DIFFICULTY
« Reply #2 on: 2018 July 20 17:41:51 »
Hi John

Apologies for the slow reply - Unusually for me I haven't logged in for a while (too many clear nights in last 4 weeks).

thanks for the advice

David