27 May 2024 - Gband - w aperture stepdown

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27 May 2024 - Gband - w aperture stepdown

Post by vineyard »

Based on advice from Mark, and seeing there was a short stint of sunshine this morning, I quickly tried 3 different apertures - the native 102mm of the ST102 (so f5), and then 80mm (equiv f6.3), and then 60mm (equiv f8.3). Exact same number of exposures, same % stacked, same ImPPG curve, same GIMP curves. There will be some seeing difference but it wasn't that variable over the 3-4 minutes. The aperture step down makes such a difference - thanks Mark!

I think the 60mm is sharpest at Gband, but the 80mm doesn't seem that far away from it?

102mm

Image

80mm

Image

60mm

Image

ROI at bin1

Image

Same ROI at bin2 w a 2.5x powermate - I actually should have stuck to bin1 as per Marty's spreadsheet

Image

I tried the aperture step down for 540nm continuum as well. Not as much of a difference as in Gband, although the 80mm is still better than the 102mm?

102mm

Image

80mm

Image

60mm

Image


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Re: 27 May 2024 - Gband - w aperture stepdown

Post by marktownley »

Great comparison Vin! Less is more ;)


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Re: 27 May 2024 - Gband - w aperture stepdown

Post by DeepSolar64 »

Vinyard,
I have certainly benefited by stopping my AT72EDII down from 72mm to 40mm while imaging at 430nm and 393.3nm. Mark's advice has proven spot on.

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Re: 27 May 2024 - Gband - w aperture stepdown

Post by ChrisHalpha2017 »

very nice series ^^


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Re: 27 May 2024 - Gband - w aperture stepdown

Post by ffellah »

Great set of images, Vin.

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Re: 27 May 2024 - Gband - w aperture stepdown

Post by rigel123 »

Great comparison Vin!


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Re: 27 May 2024 - Gband - w aperture stepdown

Post by MAURITS »

Nice session Vin.


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Re: 27 May 2024 - Gband - w aperture stepdown

Post by vineyard »

Thanks all, that's v kind.


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Re: 27 May 2024 - Gband - w aperture stepdown

Post by christian viladrich »

Well done !

The 60 mm aperture is clearly the winner in G-band.


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Re: 27 May 2024 - Gband - w aperture stepdown

Post by arnedanielsen »

Very nice, Vin!


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Re: 27 May 2024 - Gband - w aperture stepdown

Post by vineyard »

Thanks both Christian & Arne. Been having a learning curve today in v windy conditions in SW Portugal...ooph.


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