Level of details in prime focus vs eyepiece images

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  • Thread starter PhysicoRaj
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  • #126
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I think tonight went well. I got RGB as well as narrowband Hydrogen, Oxygen and Sulfur data of an emission nebula at 600mm f/9 with 3 cameras running concurrently in a single session. I was on site at about 7:45pm had all 3 narrowband cameras up and running by around 11:30p and let them run until 3am, so that’s over 9 hours of narrowband data in just over 3 hours. I set up one camera with no narrowband filter first to capture rgb, and once this was up and running I got the 2 other cameras capturing narrowband. Once those two were up and running I reconfigured the RGB camera for Hydrogen Alpha and as I mentioned from 11:30p til 3am all 3 cameras were capturing narrowband. I left the cameras running dark frames on the way home and will continue to let the cameras capture more dark frames while I sleep. The settings I chose were pretty extreme on the narrowband… 10 minutes per exposure at 6400iso for the hydrogen and oxygen filters and a full 20 minutes of open shutter per exposure on the sulphur filter. Haven’t had a chance to look at the data but I do know they were in pretty decent focus as I used a bahtinov mask to focus every camera, and again after switching from RGB to Ha. The most troublesome thing that happened was I had very slow internet on my phone for plate solving to confirm aim. Also one of my USB batteries powering the mounts kept shutting off so I ended up running 2 mounts off a single USB battery pack (fortunately it had 2 output ports). Also next time I’ll remember to switch camera batteries when switching from RGB to Ha as I think the Ha session may have ended a little early from the camera battery running out of juice at some point. All in all I deem the mission a success (having not yet seen the actual data). Will begin processing data tomorrow…

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9D3E4734-3D73-4B78-B877-EAB6A7F4E009.jpeg


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  • #127
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…getting dark frames while I catch some zzz’s…

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  • #128
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DSC_8781-Median-2-2_blended.jpg
 
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  • #129
PhysicoRaj
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I took these a couple of nights ago with some handheld 10 second exposures on an iPhone…
You have some serious steady hands... And btw 10s exposure in a little light pollution makes night look like day! I see why NB is the way to pursue this hobby in difficult skies. But there's no solution for clouds :(

They are all stock Sky Watcher Star Adventurer 2i Pro Pack mounts...
Was asking about the DSLRs - two others you bought. Isn't a full spectrum modified camera going to give amazing results for Hubble palette?
 
  • #130
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All 3 DSLR’s are standard unmodified D800’s. I don’t have any experience with the modified cameras except clipping in narrowband filters.

I ended up with about 48x 60s RGB shots (2880s) @ 3200iso 600mm f/9, 19x 600s Ha shots (11400s) @ 6400iso, 28x 600s OIII shots (16800s) @ 6400iso and I think around 10x 1200s SII shots (12000s) @ 6400iso or about 12 hours of data total. I was physically there for about 7 hours and did about 4 hours of work in one chunk at the beginning of the session.
 
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  • #133
PhysicoRaj
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Great Shots. What were the shutter actuation counts on the used Nikons?
 
  • #134
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My original Nikon which I’ve had since it was new has 186259 shutter actuations. The two I bought used have 29895 and 14358 actuations respectively.
 
  • #135
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Here's each of the 4 bands (stacked with some minimal histogram stretching). I subsequently removed the stars from each of the SII, Ha, OIII images after blending with the RGB...

RGB:
DSC_8781-Median.jpg


Ha:
DSC_8836-Median.jpg


OIII:
DSC_4098-Median.jpg


SII:
DSC_4879-Max.jpg


RGB-SII-Ha-OIII Composite:
dsc_8781-median-2-2_blended-jpg-jpg.jpg
 
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  • #136
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A couple quick tips that could save one from a ruined evening of astrophotography...

Some or all of the Star Adventurer 2i mounts have what I would call a slight software bug that could have you tearing your hair out if you don't know about it. Essentially what happens is this...

The Star Adventurer 2i mounts have an "app" mode that lets you connect to your phone through WiFi, which is useful because you can potentially use the tracker as also an intervalometer that controls your camera exposure times, shutter releases, shot counts, etc (and control it all from your phone -- potentially eliminating the standalone intervalometer)...

Where the "bug" comes into play is this. On at least some Star Adventurer 2i mounts (& I have tested this), suppose you set up an exposure campaign in the "app mode" that shoots suppose 10x 60s shots totaling 10 minutes of exposure time and you run this exposure campaign. So far so good. But suppose several weeks later, you get an external intervalometer, and you don't use the mount in "App" mode but rather just "plain old" star tracker mode... You carefully point and aim the camera, set the exposure and program the external intervalometer to run for 2 hours then you go in your car to get warm... You'll find that low and behold, somehow the "App mode" setting for a 10 minute campaign from weeks ago has turned off the tracking function of the mount after 10 minutes in the "regular old" star tracking mode. The solution is, whenever you expect to be running star tracker ("non-app") mode, make sure the last exposure campaign in "app" mode is set to something like 40 hours, that way when you go to regular old star tracker mode, the motor will be "programmed" to run for at least 40 hours. Probably 16 hours would be enough for any given evening but on second thought, maybe not if you're in Alaska.... 6 months??

The other one is quality settings on your camera. Obviously you'll want to be shooting in RAW mode... but if you're doing plate solving through your phone and you have slow internet in the middle of nowhere, you don't want to be fiddling around with RAW files, so at least on my camera I set it up to record both the RAW file and a "small" size jpg (there's also medium and large). So instead of trying to fiddle around with converting and uploading a raw file on your phone, you transfer the small JPG and use that for plate solving ( http://nova.astrometry.net/upload ) while you also retain the RAW file for later processing.
 
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  • #137
PhysicoRaj
Gold Member
528
41
A couple quick tips that could save one from a ruined evening of astrophotography...

Some or all of the Star Adventurer 2i mounts have what I would call a slight software bug that could have you tearing your hair out if you don't know about it. Essentially what happens is this...

The Star Adventurer 2i mounts have an "app" mode that lets you connect to your phone through WiFi, which is useful because you can potentially use the tracker as also an intervalometer that controls your camera exposure times, shutter releases, shot counts, etc (and control it all from your phone -- potentially eliminating the standalone intervalometer)...

Where the "bug" comes into play is this. On at least some Star Adventurer 2i mounts (& I have tested this), suppose you set up an exposure campaign in the "app mode" that shoots suppose 10x 60s shots totaling 10 minutes of exposure time and you run this exposure campaign. So far so good. But suppose several weeks later, you get an external intervalometer, and you don't use the mount in "App" mode but rather just "plain old" star tracker mode... You carefully point and aim the camera, set the exposure and program the external intervalometer to run for 2 hours then you go in your car to get warm... You'll find that low and behold, somehow the "App mode" setting for a 10 minute campaign from weeks ago has turned off the tracking function of the mount after 10 minutes in the "regular old" star tracking mode. The solution is, whenever you expect to be running star tracker ("non-app") mode, make sure the last exposure campaign in "app" mode is set to something like 40 hours, that way when you go to regular old star tracker mode, the motor will be "programmed" to run for at least 40 hours. Probably 16 hours would be enough for any given evening but on second thought, maybe not if you're in Alaska.... 6 months??
Yikes. Will write this down for the future me. I already have an intervalo so probably not gonna mess with any tracker mode other than - just track.

The other one is quality settings on your camera. Obviously you'll want to be shooting in RAW mode... but if you're doing plate solving through your phone and you have slow internet in the middle of nowhere, you don't want to be fiddling around with RAW files, so at least on my camera I set it up to record both the RAW file and a "small" size jpg (there's also medium and large). So instead of trying to fiddle around with converting and uploading a raw file on your phone, you transfer the small JPG and use that for plate solving ( http://nova.astrometry.net/upload ) while you also retain the RAW file for later processing.
Good point.
 
  • #138
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The moon probably won't be down long enough for me to shoot again til around the evening of 10/31-11/1 so here's a few more lens/OTA tests on the local bird population... two Anna's Hummingbirds and a Lesser Goldfinch... An interesting fact about the Anna's Hummingbird is they are the fastest vertebrate on Earth for their length... faster than a fighter jet relative to length and to sustain this flight they flap their wings 50-60 times per second or more... they can also hover, fly backwards & even upside down…

"The cheetah, the fastest land mammal, scores at only 16 body lengths per second,[5] while Anna's hummingbird has the highest known length-specific velocity attained by any vertebrate."

https://en.wikipedia.org/wiki/Fastest_animals

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