GOTO Best Focus
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davemartin88
- Posts: 46
- Joined: Thu Dec 17, 2020 6:43 pm
GOTO Best Focus
When using the multi-star focus assistant routine, once the scan has completed and I see the graph points, the button for goto Best Focus is greyed out? Should I just be able to use this at that point or is there another step in the process?
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admin
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Re: GOTO Best Focus
Hi,
there are a couple of possibilities here...
First - has SharpCap drawn a best fit curve on top of the graph points? If there is no curve then SharpCap isn't sure enough about the shape of the graph to be able to work out the best focus position. You can see the curve in the documentation here : https://docs.sharpcap.co.uk/4.1/#Point% ... 0Detection . The most likely causes of a curve not being added are either that the random scatter in the focus score is too large compared to the depth of the curve or that there are not enough measurement points on one or both sides of best focus .
The other thing is... do you have a SharpCap pro license? You will need one to use the GOTO best position button (although the button will be enabled without a license if the data is good - it will just pop up a message about needing a license when clicked).
cheers,
Robin
there are a couple of possibilities here...
First - has SharpCap drawn a best fit curve on top of the graph points? If there is no curve then SharpCap isn't sure enough about the shape of the graph to be able to work out the best focus position. You can see the curve in the documentation here : https://docs.sharpcap.co.uk/4.1/#Point% ... 0Detection . The most likely causes of a curve not being added are either that the random scatter in the focus score is too large compared to the depth of the curve or that there are not enough measurement points on one or both sides of best focus .
The other thing is... do you have a SharpCap pro license? You will need one to use the GOTO best position button (although the button will be enabled without a license if the data is good - it will just pop up a message about needing a license when clicked).
cheers,
Robin
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davemartin88
- Posts: 46
- Joined: Thu Dec 17, 2020 6:43 pm
Re: GOTO Best Focus
Thanks. There was no curve so that must be the issue. I do have SharpCap Pro and it’s great! I’ll try again using the contrast edge today to see if I can sort it out. I’ve been starting just a bit positive of focus and then scanning in the negative direction but probably not giving a chance to get a sweep on both sides of the focus point. This is a long focal ratio SCT and very hard to get dialed in for consistent auto focusing. It’s FL is 1700mm at about F11 from a Celestron C6. I’ve decided this isn’t really worth the effort and will go back to using the reducer but do want to get the auto focus working. Thanks again.
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admin
- Site Admin
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- Joined: Sat Feb 11, 2017 3:52 pm
- Location: Vale of the White Horse, UK
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Re: GOTO Best Focus
Hi,
yes, sounds like you may have been starting too close to the best focus position, which may only give 1 or 2 points before best focus is reached. Really you need 3 each side to stand a good chance of it working. You may find that actually allowing the scan to go a fair bit wider helps - it can be hard to spot how the focus is changing when you are close to best focus on an SCT, but further away the pattern usually becomes clearer and SharpCap will happily find the midpoint between bad focus on one side and bad focus on the other.
cheers,
Robin
yes, sounds like you may have been starting too close to the best focus position, which may only give 1 or 2 points before best focus is reached. Really you need 3 each side to stand a good chance of it working. You may find that actually allowing the scan to go a fair bit wider helps - it can be hard to spot how the focus is changing when you are close to best focus on an SCT, but further away the pattern usually becomes clearer and SharpCap will happily find the midpoint between bad focus on one side and bad focus on the other.
cheers,
Robin