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Old 23-06-2019, 05:10 PM
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Peter Ward
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Switching gear2

Funny how during the CCD Jurassic period, exposures that lasted several minutes (vs several seconds) were considered to be epic...as they easily eclipsed the image depth of photographic film taken with much longer exposure times.

Now we are not-infrequently seeing images that have 20-50 hours worth of data. Rather than buck the trend, I've decided to embrace it with a new
SBIG guider that works in front of the CFW and LRGB + 3nm NB AstroDon 50mm filter set (pictured).

Not sure what 50 hours at 3nm will show...(given the current weather very little ) ....but time to switch it up a bit
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Old 23-06-2019, 06:51 PM
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Don't you need 65mm filters for your STX16803? Or are you using something else?

Greg.
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Old 23-06-2019, 06:57 PM
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Slawomir (Suavi)
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Beautiful - there is nothing like a new shiny astro-rig
Now we all look forward to seeing even deeper images from South Sydney
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Old 23-06-2019, 07:04 PM
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Quote:
Originally Posted by gregbradley View Post
Don't you need 65mm filters for your STX16803? Or are you using something else?

Greg.
No, I'm still using the STX16803, but with 50mm square filters you need to go to an external guider (as the internal guide chip can no longer see the sky)

The other issue with the internal guider, is very narrow band filters make finding guide stars very difficult to find.

The STX guider moves the guide chip ahead of the filter train in a similar manner as the STXL integrated guider/CFW's.

Also, while a set of 50mm square 3nm NB AstroDons are not cheap, the price of a 3nm bandpass in a 65mm square filter is eye-watering.
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Old 23-06-2019, 07:24 PM
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Peter Ward
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Quote:
Originally Posted by Slawomir View Post
Beautiful - there is nothing like a new shiny astro-rig
Now we all look forward to seeing even deeper images from South Sydney
Ta. The nice thing about 3nm filters is you could image from Pitt Street
and still have virtually nil effect from light pollution
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Old 28-06-2019, 04:38 PM
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I chatted once with Don Goldman about 3nm filters. He recommended 3nm for O111 and 5nm for Ha was fine as it allowed nitrogen (is it N3??) to go through.

But I think it was assumed we were imaging from dark sites.

O111 seems the real winner though in 3nm from the images I have seen.

With 5nm I don't really like to image with the full moon or with the object too close to a 1/2 or more moon. So there is that. The downside is it will require longer exposure time to compensate.

Greg.
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Old 28-06-2019, 06:08 PM
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Peter Ward
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Quote:
Originally Posted by gregbradley View Post
I chatted once with Don Goldman about 3nm filters. He recommended 3nm for O111 and 5nm for Ha was fine as it allowed nitrogen (is it N3??) to go through.

But I think it was assumed we were imaging from dark sites.

O111 seems the real winner though in 3nm from the images I have seen.

With 5nm I don't really like to image with the full moon or with the object too close to a 1/2 or more moon. So there is that. The downside is it will require longer exposure time to compensate.

Greg.
Indeed. I have the 5nm as well. Small hiccup though....the firmware of my FW-STX needs updating to support both carousels.. Hopefully I'll have the new controller by late next week
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