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Suggestions on getting better at imaging Jupiter

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#1 HarveyDeckAstro

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Posted 26 August 2021 - 12:37 PM

Here is Jupiter imaged with Meade 8" AFC last night at 11 pm. ASI462MC, GSO 2X Barlow screwed on the noise piece, 1.25" IR/UV cut, AS3, RS6, PS. 2 min videos with ASICAP, exposure 20 ms. 10% stacked. Focused on Altair with BN mask. Tried WinJupos to combine 5 processed images but did not seem to help much.

 

I know that 8" is limited, but sometimes I do see excellent images from 8", with details far better than what I got here. I would like to hear what I should do to get better at imaging Jupiter.

 

Several questions to start with.

1) Is 2 min right video length for Jupiter?

2) Is 20 ms exposure too long or too short? If I use shorter exposure, I get more noisy image.

3) Would a PowerMate 2.5X make a difference?

 

Thanks for your suggestions!

 

Harvey

 

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#2 matt_astro_tx

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Posted 26 August 2021 - 12:43 PM

You can go up to 3 min on Jupiter before you have to start derotating images.

 

I think your focusing could use improvement.  A BN mask won't cut it.  Some will argue, but I've seen the difference first hand.  Once you're aligned on Jupiter you need to focus, and focus again, and lastly refocus to get the equatorial bands as sharp as possible.  It's tedious but that is what will ultimately yield the sharpest images.

 

In FireCapture use the target tracking feature to keep jupiter stabilized in the center of the frame when you're focusing.  It's a game changer.

 

For your sensor pixel size of 2.9um, you want to be shooting at between F/15 and F/20.  Since your Meade 8" is already an F/10 instrument, the 2x barlow gets you to F/20, that's as high as you'll likely want to go.  A 1.5x barlow would get you to F/15.

 

In the end however, you're at the mercy of the seeing conditions.

 

Overall you're off to a good start!

 

I too shoot with an 8" (a newtonian) and I'm still working to improve my game.  You can see some of my efforts in my image galleries.


Edited by matt_astro_tx, 26 August 2021 - 12:47 PM.

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#3 John Miele

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Posted 26 August 2021 - 12:50 PM

What Matt said!


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#4 HarveyDeckAstro

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Posted 26 August 2021 - 12:52 PM

Thanks Matt for the suggestion! I will try focusing on the band next time. FireCapture did not do well with Mac last time I tried. However with the EQ6R I can get Jupiter centered for quite some time with a good polar alignment.

#5 Tim J Fowler

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Posted 26 August 2021 - 01:09 PM

Yes, as Matt said, focus is key, but ultimately the best focus or scope or camera won't mean squat when the planets look like they're under about 4 inches of rippling water due to seeing conditions, and that, I'm afraid, is out of our control. I focus on Jupiter's moons. If they're in focus, so is Jupiter. Also, as Matt said, 3 minute videos for Jupiter will be okay. Any longer and Jupiter's rotation will come into play. Being in NJ, using an ADC may help you. I've never used one, but have seen the benefits.

My best image of Jupiter with my 8" LX90 using a 2X barlow and a Canon T3i.

Good luck and clear skies!

TJF

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Edited by Tim J Fowler, 26 August 2021 - 01:17 PM.

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#6 JMP

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Posted 26 August 2021 - 01:14 PM

Adding to Matt, it's worth fine tuning the collimation as much as you can, allow the scope plenty of time to cool, and increase the frame rate. I agree that the shorter exposures have more noise, but it can sometimes "freeze" the seeing. 10ms exposures might be the next step, twice as many frames per second and go with 3 minute avi's

Patience and practice will pay off!

Jeff
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#7 Lopper

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Posted 26 August 2021 - 01:22 PM

It looks like you've got a good start, Harvey, and I agree with all the suggestions above. Looks like Jeff beat me to the collimation question. Do you feel pretty good about your scope's collimation? If not, investing some time in obtaining excellent collimation before you make your captures can contribute greatly to the quality of the resulting images. Metaguide, a red filter, and practice can be very helpful in getting your collimation spot on. Start out by making sure the shadow of the secondary is centered in an out-of-focus star image (that's rough collimation), then fine tune it using an in-focus star image and make sure the first diffraction ring is as round and uniformly-illuminated as you can get it. If it's flaring to one side or brighter in one place than another then the optical system could benefit from an adjustment. If you've got a well-collimated system and a steady sky to peer through then your 8" should give you some nicely detailed images.


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#8 dcaponeii

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Posted 26 August 2021 - 01:35 PM

You can go up to 3 min on Jupiter before you have to start derotating images.

 

I think your focusing could use improvement.  A BN mask won't cut it.  Some will argue, but I've seen the difference first hand.  Once you're aligned on Jupiter you need to focus, and focus again, and lastly refocus to get the equatorial bands as sharp as possible.  It's tedious but that is what will ultimately yield the sharpest images.

 

In FireCapture use the target tracking feature to keep jupiter stabilized in the center of the frame when you're focusing.  It's a game changer.

 

For your sensor pixel size of 2.9um, you want to be shooting at between F/15 and F/20.  Since your Meade 8" is already an F/10 instrument, the 2x barlow gets you to F/20, that's as high as you'll likely want to go.  A 1.5x barlow would get you to F/15.

 

In the end however, you're at the mercy of the seeing conditions.

 

Overall you're off to a good start!

 

I too shoot with an 8" (a newtonian) and I'm still working to improve my game.  You can see some of my efforts in my image galleries.

In addition to what Matt said, you also need to get shorter exposures than 20ms.  Use the ROI feature and the Cutbox to capture video only around the planet.  GAIN = whatever it takes (within reason) to get your exposure times at least under 10ms.  I couldn't achieve that with ASICAP and long ago switched to Firecapture which I highly recommend (hopefully it will run on your Mac (although you could maybe run an windows emulator and get it to work that way).  You'll see most folks imaging Jupiter at these shorter exposures.  In terms of frames per second a good target is 150 fps and certainly faster than 100 fps.  You're only at about 50 fps assuming no delay is happening as you transfer data to the computer via the USB.  How many frames did you capture and what percentage of the captured frames are in your stack? Ditto on the ADC as well.


Edited by dcaponeii, 26 August 2021 - 01:36 PM.


#9 Gary Z

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Posted 26 August 2021 - 01:43 PM

This is a timely learning process.  But, with what you have shown us both in your image and in the software you are using, I think it is clear you are most certainly on your way to obtaining the imaging and processing you are seeking.

 

Many nights, conditions won't be great.  Either the wind at the surface, or the conditions in the atmosphere just is working against you.  But when that time comes when conditions are a definite improvement, you'll know it.  So for all those other bad conditions, consider that training.  Additionally, for all those nights you can't setup, use some of those to reprocess your data and improve on those skills as well.  

 

If you haven't done so already, seek out the planetary imaging, processing groups on FB.  The one's to reach out to will certainly stand out.  

 

Back in 2018, couple of us from our astronomy club went to image at a dark site.  The conditions were really favorable and when I started to observe, I had to ask the others to come look at what the camera was picking up.  The detail and the slow movement of the planets were amazing.  This is what I'm talking about.  When you have these conditions, you can select SER 16 bit format and get higher resolution images.  However, during those nights where the planet looks like its going to boil off your screen, move to maybe 8 bit and 2 binning in order to get a much higher frame rate to help reduce the noise.  Additionally, capture darks.  I use SC Pro for imaging.  However, I think I also need to learn Firecapture, as I've seen really amazing results.  

 

Another device that might help you, is the ZWO ADC and yes, I can affirm that the 2.5x powermate is a huge benefit.  I don't leave home without it...lol.  

 

Gary


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#10 dcaponeii

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Posted 26 August 2021 - 02:01 PM

This is a timely learning process.  But, with what you have shown us both in your image and in the software you are using, I think it is clear you are most certainly on your way to obtaining the imaging and processing you are seeking.

 

Many nights, conditions won't be great.  Either the wind at the surface, or the conditions in the atmosphere just is working against you.  But when that time comes when conditions are a definite improvement, you'll know it.  So for all those other bad conditions, consider that training.  Additionally, for all those nights you can't setup, use some of those to reprocess your data and improve on those skills as well.  

 

If you haven't done so already, seek out the planetary imaging, processing groups on FB.  The one's to reach out to will certainly stand out.  

 

Back in 2018, couple of us from our astronomy club went to image at a dark site.  The conditions were really favorable and when I started to observe, I had to ask the others to come look at what the camera was picking up.  The detail and the slow movement of the planets were amazing.  This is what I'm talking about.  When you have these conditions, you can select SER 16 bit format and get higher resolution images.  However, during those nights where the planet looks like its going to boil off your screen, move to maybe 8 bit and 2 binning in order to get a much higher frame rate to help reduce the noise.  Additionally, capture darks.  I use SC Pro for imaging.  However, I think I also need to learn Firecapture, as I've seen really amazing results.  

 

Another device that might help you, is the ZWO ADC and yes, I can affirm that the 2.5x powermate is a huge benefit.  I don't leave home without it...lol.  

 

Gary

8-bit is more than adequate for planetary imaging.  By the time you complete the stacking, etc. you're at 12-bit anyway if memory serves from reading other posts on this forum.


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#11 MarMax

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Posted 26 August 2021 - 02:04 PM

Great question and a nice set of responses which are very helpful to me as well.

 

Regarding focus, which is my most complicated task, I'll 2nd the comment on using the moons to achieve focus. IMO using the moons as a focus aid is the best tool with the C11. I also have a 2.9 sensor (IMX464).

 

And when in doubt I'll find best focus and then shoot three AVIs. One at what I think is best focus, one with a 1/32 turn inside and one with 1/32 turn outside. Many times I can not tell the difference between the three looking at the laptop screen.

 

I've not tried FireCapture yet but I may give it a try tonight. And the less than 10ms exposure is a great tip.


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#12 dcaponeii

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Posted 26 August 2021 - 02:53 PM

Great question and a nice set of responses which are very helpful to me as well.

 

Regarding focus, which is my most complicated task, I'll 2nd the comment on using the moons to achieve focus. IMO using the moons as a focus aid is the best tool with the C11. I also have a 2.9 sensor (IMX464).

 

And when in doubt I'll find best focus and then shoot three AVIs. One at what I think is best focus, one with a 1/32 turn inside and one with 1/32 turn outside. Many times I can not tell the difference between the three looking at the laptop screen.

 

I've not tried FireCapture yet but I may give it a try tonight. And the less than 10ms exposure is a great tip.

Firecapture review screen has a feature that allows you to increase the brightness and the gamma of just the image in the preview window without actually changing the settings for your capture.  This helps me with focusing.  In addition you can use the feature that keeps the image centered and combine that with post-processing average feature to yield a stable image on the screen which really helps you nail the focus.


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#13 HarveyDeckAstro

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Posted 26 August 2021 - 03:26 PM

Wow, these are amazing suggestions! Thanks to you all!

The kind of details Tim got is what I am looking for.

Last night I did see Jupiter being like a ripples from time to time. Bad seeing I suppose? But my focus was definitely off. I will try the equatorial band and the moon techniques for focusing. Also will try 10 ms exposures and 3 minutes videos.

Upgrading to PowerMate, ADC and to FireCapture will be done.

Jupiter is such a beautiful planet! It is worthwhile to go distances to do it right.

Edited by HarveyDeckAstro, 26 August 2021 - 03:33 PM.

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#14 RedLionNJ

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Posted 26 August 2021 - 04:16 PM

You can go up to 3 min on Jupiter before you have to start derotating images.

 

A BN mask won't cut it.  

 

A 1.5x barlow would get you to F/15.

 

In the end however, you're at the mercy of the seeing conditions.

 

 

Abbreviated Matt's post just to show the highlights.

 

And you should check collimation EVERY SESSION, too.  And add an ADC.


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#15 MarMax

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Posted 26 August 2021 - 04:18 PM

Firecapture review screen has a feature that allows you to increase the brightness and the gamma of just the image in the preview window without actually changing the settings for your capture.  This helps me with focusing.  In addition you can use the feature that keeps the image centered and combine that with post-processing average feature to yield a stable image on the screen which really helps you nail the focus.

I really do need to try FireCapture and also AstroSurface for that matter. I have both installed on the laptop but have not tried either yet. I'm just now getting used to SharpCap and there are (to me anyway) a lot of things to remember to get the most out of a Jupiter session.

 

If I'm going with f/20 using either the BARADV or 2" Powermate, should I also be 2x2 binning? This is something I've not really messed with yet. Or is my logic backwards and I should stick with 1x1 at f/20 and then go 2x2 at f/10? Yes f/15 would be ideal but I don't have a 1.5x presently.



#16 HarveyDeckAstro

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Posted 26 August 2021 - 04:23 PM

Abbreviated Matt's post just to show the highlights.

And you should check collimation EVERY SESSION, too. And add an ADC.


Definitely yes!

#17 Borodog

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Posted 26 August 2021 - 06:57 PM

I really do need to try FireCapture and also AstroSurface for that matter. I have both installed on the laptop but have not tried either yet. I'm just now getting used to SharpCap and there are (to me anyway) a lot of things to remember to get the most out of a Jupiter session.

 

If I'm going with f/20 using either the BARADV or 2" Powermate, should I also be 2x2 binning? This is something I've not really messed with yet. Or is my logic backwards and I should stick with 1x1 at f/20 and then go 2x2 at f/10? Yes f/15 would be ideal but I don't have a 1.5x presently.

Binning reduces your resolution by effectively increasing your pixel size. It is the same as using a reducer. It reduces noise at the cost of image scale. 
 

If you are screwing the lens element from your 2X Barlow directly onto your camera nosepiece, you are likely already nearer f/15 than f/20. The magnification depends on the distance between the sensor and the lens, so if you remove the barrel from the Barlow the magnification goes down. You should take a frame at capture resolution and calculate your actual focal length from the formula:

 

206.3 x pixel size in microns / focal length in mm = Jupiter’s diameter in arcseconds / Jupiter’s diameter in pixels

 

Solve for focal length, divide by your aperture of 200mm and you will know the actual focal ratio you imaged at. Jupiter is currently 49” in diameter. 


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#18 CrazyPanda

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Posted 26 August 2021 - 10:34 PM

Here is Jupiter imaged with Meade 8" AFC last night at 11 pm. ASI462MC, GSO 2X Barlow screwed on the noise piece, 1.25" IR/UV cut, AS3, RS6, PS. 2 min videos with ASICAP, exposure 20 ms. 10% stacked. Focused on Altair with BN mask. Tried WinJupos to combine 5 processed images but did not seem to help much.

 

I know that 8" is limited, but sometimes I do see excellent images from 8", with details far better than what I got here. I would like to hear what I should do to get better at imaging Jupiter.

 

Several questions to start with.

1) Is 2 min right video length for Jupiter?

2) Is 20 ms exposure too long or too short? If I use shorter exposure, I get more noisy image.

3) Would a PowerMate 2.5X make a difference?

 

Thanks for your suggestions!

 

Harvey

 

attachicon.gif2021-08-26-0316_8-Jupiter_lapl5_ap733-RS6-2-DeNoiseAI-low-light-PS.jpg

Based on my experience with an 8" SCT (LX90), I can take a stab at answering your questions:

 

1. Capture *length* is not as relevant as number of frames. The only time capture length becomes a thing to consider is when you're worried about rotation, but there is WinJupos to help derotate stacks of images, or single videos. How many frames you need to capture in a given scope depends entirely on your atmospheric conditions. Turbulent air means you want shorter exposures. But shorter exposures means you need more gain to keep your histogram around 40-60%. More gain means more noise. More noise means you need more frames to average out that noise. Turbulent air means fewer usable frames, so more frames are needed since you need to be more selective. Turbulent air also means you'll be pushing sharpening harder, which also sharpens noise, which means you need to stack more frames to keep noise under control. So the moral of the story is if seeing is bad, shorten exposure and capture more frames.

 

2. 20ms is too long IMO. You need EXCEPTIONALLY stable skies and a mount that has no micro vibrations when tracking in order to not have any blurring in 20ms. While lucky imaging cannot combat the geometric distortions of atmospheric turbulence, shorter exposures can at least eliminate motion blur from changes in those distortions. I almost always image between 4ms and 6ms on Jupiter, and I use a gain level that gets me to about a 60% histogram. For my 224mc imaging at F/20, that's typically between 320 and 375 gain. Yes, each frame is incredibly noisy, but minimizing motion blur is more important, and if you capture a minimum of 40,000 frames or so, you have a lot of data available to average out that noise when stacking.

 

3. Going with a 2.5x PowerMate is not a good idea. That would bring the system to F/25 rather than the roughly ~F/20 it is now (I did the math based on the image you supplied, and assuming you've not modified the scale of the image, you imaged this at a focal length of 3,988mm, which is F/19.6). So if anything you're already oversampled for that camera. Adding a 2.5x PowerMate would make things worse.


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#19 HarveyDeckAstro

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Posted 27 August 2021 - 07:48 AM

Thanks CrazyPanda for these detailed suggestions! Makes a lot of sense! Even calculating the focal length for me, that is just extra helpful! I have a flip mirror to help me find the planets, so that adds to focal length. I did screw directly the lens to the nose piece so it is effectively 1.5X.

Your analysis of how to beat bad seeing is spot on. I see some imagers suggesting 20 ms, but that could be only when the seeing is exceptional and the image is steady. Will experiment with 5 ms exposure.

Your comment about the mount is very interesting. I have a very steady mount in EQ6R, but I put it on the deck, which could have been a major problem with vibrations. I was try to be steady but inevitably I might have constantly created small smearing motions. The day before I put the mount on the grass and worked on Saturn, and the result was much better. Of course Saturn is far less challenging and the seeing could have been different. But indeed this vibration on my deck could have been of my major issues. Plus the focus was off.

A lot to do next clear sky!

#20 dcaponeii

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Posted 27 August 2021 - 08:19 AM

Thanks CrazyPanda for these detailed suggestions! Makes a lot of sense! Even calculating the focal length for me, that is just extra helpful! I have a flip mirror to help me find the planets, so that adds to focal length. I did screw directly the lens to the nose piece so it is effectively 1.5X.

Your analysis of how to beat bad seeing is spot on. I see some imagers suggesting 20 ms, but that could be only when the seeing is exceptional and the image is steady. Will experiment with 5 ms exposure.

Your comment about the mount is very interesting. I have a very steady mount in EQ6R, but I put it on the deck, which could have been a major problem with vibrations. I was try to be steady but inevitably I might have constantly created small smearing motions. The day before I put the mount on the grass and worked on Saturn, and the result was much better. Of course Saturn is far less challenging and the seeing could have been different. But indeed this vibration on my deck could have been of my major issues. Plus the focus was off.

A lot to do next clear sky!

Careful.  The focal length of the scope is not affected by the presence or absence of the flip mirror except for the minor effect of changing the position of the main mirror relative to the secondary mirror in an SCT.  You have more back focus which means you need to move the mirror forward to focus but the focal length of the scope isn't changing because you have a flip mirror.  The Cut Box in Firecapture can help with moderate vibrations as well.  I have some issues if surface winds get too much above 10 mph because the sides of my ROR Observatory are fairly low when the roof is open but the cut box seems to keep up ok.  Use vibration pads under your tripod legs to change the high-freq. vibrations from the deck into low-freq. that won't affect your image quality as much.  Firecapture log will report out the f/number you imaged with but doing the calculation described by Borodog for you.



#21 Luca_

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Posted 27 August 2021 - 09:25 AM

Hi everyone, as someone who is brand new into planetary imaging this thread has been really helpful. I'm starting to understand the importance of exposure times depending on conditions but I'm still not quite understanding the importance of the focal ratio with regards to the pixel size. For reference I have a Nexstar Evolution 9.25 on an Alt/Az mount. I believe it has a focal ratio of F/10? Paired with this I'm using an ASI178MC which has a pixel size of 2.4μm. So from my understanding my optimal focal ratio is going to be between F/10 - F/15 meaning at the most I would want a 1.5x barlow correct?

 

Additionally, what is everyone's opinion on the telescope/camera combination? After reading through the forums I'm seeing a lot of people with the ASI224MC and I'm starting to worry I should have gone with that instead.



#22 CrazyPanda

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Posted 27 August 2021 - 09:27 AM

I did screw directly the lens to the nose piece so it is effectively 1.5X.

Going by the math from your image, it’s behaving more like a 2x barlow (slightly less). But that’s assuming native focal length in your SCT is 2032mm (it could be more depending on the mirror’s position since the secondary mirror is like a 5x multiplier).

So even though you screwed the barlow into the nosepiece, it’s not a guarantee that it’s actually operating at 1.5x. The math indicates your picture had to have been captured by an optical train with a focal length of 3,988mm. If native focal length is 2032mm, then the effect of the barlow is 1.96x. For the barlow to actually be 1.5x, native focal length would have to be 2,658mm - which is more like a 9.25” SCT’s focal length.

Edited by CrazyPanda, 27 August 2021 - 09:28 AM.


#23 Borodog

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Posted 27 August 2021 - 09:35 AM

Luca,

 

Your native focal length is well matched to your camera for most seeing conditions. I would stick with your native focal length while you are learning to capture and process. It will be much more forgiving. If you have a night of exceptional seeing and wish you had a Barlow, that is the data to experiment with 1.5X drizzle.

 

To elaborate, The rule of thumb is that for critical sampling you want a focal length that is about 5 times the pixel size in microns. Some would argue that for exceptional seeing you can push that up to 7X. But even the 5X rule in my experience demands at least good seeing (4/5), which is rare. At f/10 you are at 4.2X, and some very, very good posters have claimed to take their best images at 4.2X. Also remember that even with perfect seeing, a larger image from the same scope will not look sharper. It may be better for detecting the finest possible details, but the cost will necessarily be a softer image.

 

Good luck.



#24 matt_astro_tx

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Posted 27 August 2021 - 10:32 AM

Hi everyone, as someone who is brand new into planetary imaging this thread has been really helpful. I'm starting to understand the importance of exposure times depending on conditions but I'm still not quite understanding the importance of the focal ratio with regards to the pixel size. For reference I have a Nexstar Evolution 9.25 on an Alt/Az mount. I believe it has a focal ratio of F/10? Paired with this I'm using an ASI178MC which has a pixel size of 2.4μm. So from my understanding my optimal focal ratio is going to be between F/10 - F/15 meaning at the most I would want a 1.5x barlow correct?

 

Additionally, what is everyone's opinion on the telescope/camera combination? After reading through the forums I'm seeing a lot of people with the ASI224MC and I'm starting to worry I should have gone with that instead.

You'll accomplish quite a lot with your 178, don't worry.  Yes the 224 is very popular and the 462 is the newer version of that camera.  They support higher frame rates but your 178 is no slouch either, and I think it has a larger FOV so that will be more forgiving with finding and framing your target.

 

The general rule of thumb for optimum focal ratio is 5x to 7x your pixel size.  So, 5 x 2.4um = F/12 and 7 x 2.4um = F/16.8.  That being said I would just shoot for F/15 and call it a day.  The NE9.25 is indeed a F/10 scope, so that means you need a 1.5x barlow.

 

From what I've gathered from the community oversampling is not really a thing in planetary.  The bigger concern is undersampling and losing detail.

 

Many folks also recommend using an atmospheric dispersion corrector (ADC) but I would say you don't need that yet.  Grab an affordable apochromatic barlow and see what you get!

 

Just throwing this all out there - I'm sure others will correct my mistakes.

 

-- Apologies for stepping on Borodog's response; didn't see he had already answered much of this.


Edited by matt_astro_tx, 27 August 2021 - 10:39 AM.


#25 HarveyDeckAstro

HarveyDeckAstro

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Posted 27 August 2021 - 10:57 AM

Going by the math from your image, it’s behaving more like a 2x barlow (slightly less). But that’s assuming native focal length in your SCT is 2032mm (it could be more depending on the mirror’s position since the secondary mirror is like a 5x multiplier).

So even though you screwed the barlow into the nosepiece, it’s not a guarantee that it’s actually operating at 1.5x. The math indicates your picture had to have been captured by an optical train with a focal length of 3,988mm. If native focal length is 2032mm, then the effect of the barlow is 1.96x. For the barlow to actually be 1.5x, native focal length would have to be 2,658mm - which is more like a 9.25” SCT’s focal length.


Thanks for the calculation! I do suspect that the flip mirror added to focal length. I would respectfully disagree with @ dcaponeii; the length of the image train does in fact change focal length with SCT. I know this because when I do DSO imaging, plate solving reports different focal length depending on whether I use a short T adapter or a long T adapter. I will tinker the image train to reduce that focal length.


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