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NightCap Long Exposure Mode for iPhone

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#1 GeezerGazer

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Posted 08 February 2020 - 12:53 PM

NightCap Camera App in Long Exposure Mode for Phonetography

Ray Taylor

 

While I’ve used NightCap Camera application over the last 2.5 years with my night vision (NV) device (NVD), Mod 3C as the eyepiece in various telescopes, I have made discoveries and formed some opinions.  I thought I’d share what I’ve learned, to help others who might use NightCap with their iPhone to capture astro images.  Most of this narrative is a tutorial for those who are just starting to use Long Exposure Mode with NV, but all of it applies whether you use glass eyepieces or NV with a telescope, and it might be helpful even to old hands of NightCap Phonetography.  There is an abbreviated checklist at the end which may be helpful, but I encourage you to read this narrative to understand the process.  NightCap is specific to iOS devices; if you use Android devices, this will not apply to your equipment.  

 

Using a phone bracket is essential to simplify this process; making these settings becomes complicated while hand holding a phone over an eyepiece in the dark.  And, moving a phone, no matter how slight, during a long exposure, ruins an image.  I have used a very simple phone bracket for 2.5 years that works fine for my needs, like this one:  

https://www.amazon.c...0?ie=UTF8&psc=1

Any phone bracket will simplify and improve your phone imaging.  

 

NightCap works best in Long Exposure Mode, if it is given the time needed to work its magic.  A tracking mount provided the single biggest improvement to my iPhone/NightCap imaging.  I started using NightCap Long Exposure Mode with my home built, completely manual alt/az mount.  Any manual mount limits magnified astro imaging time to a maximum of about 3 seconds, depending where in the sky you are pointed and how much magnification is applied; at 20-30x I was pretty much limited to 1/2 second exposures.  

 

For non-tracking use of NightCap without a telescope or other supplemental magnification, you can use the Rule of 500 to determine a maximum exposure time to avoid obvious star trails.  Divide 500 by the focal length of your optics.  The f:1.8 lens in my iPhone XR has a 26mm equivalent focal length; 500 divided by 26 =  19 seconds of averaging time (without adding supplemental optical magnification).  Using just the iPhone to take a long exposure, you are permitted more time for a non-tracked image.  For use with a telescope or other optics in front of my iPhone, the Rule of 500 does not apply.  

 

In early 2018, I purchased an iOptron AZ Pro mount… it is an alt/az GOTO- tracking mount.  Normally, these mounts are not used for AP, because tracking accuracy is limited.  Traditional AP requires hours of tracking accuracy.  But NV makes a subject bright enough to require only seconds to photograph… up to about 40 seconds may be needed.  The AZ Pro is accurate to a few minutes, so there is plenty of time to gather the needed photons without showing star trails.  By using a tracking mount, you let NightCap do what it is designed to do… take very low-light photos. 

 

NightCap was designed around the limitations that Apple imposes on software developers.  I learned that the iPhone camera can be controlled manually without NightCap… if you know how to access the controls.  But even accessing those controls does not reach the level of performance that NightCap offers.  I have found it to be a powerful imaging tool, even for low light terrestrial photos.  This is possible because it averages many photos to eliminate noise that shows up as a grainy appearance otherwise.  Averaging is different than stacking.  Stacking photos involves a registration point on several photos to align them before they are stacked and averaged.  Averaging does not register the photos for alignment; it only averages the images to eliminate noise from higher ISO settings, or, as in NVDs, electronic noise, also called scintillation. When noise appears in different places within several images, it can be eliminated by averaging.  

 

Now I’ll walk through the steps I take for Long Exposure Mode in NightCap.  I suggest you open NightCap to follow along.  Before you begin, set the screen brightness on your iPhone to a low setting, about 20% to 25% of total available brightness.  If your phone screen is set to a brighter level, it will not be showing the true brightness of what the camera is seeing and your images will come out darker than you planned, especially noticeable when you transfer them to a computer.  Turning the screen brightness level down alleviates this problem and it is still plenty bright enough in the dark to see what you are doing.  Screen brightness can be accessed in the control center (swipe down from the top) or by selecting iPhone Settings, Display and Brightness. 

 

Also, under Display and Brightness, adjust your screen Auto-Lock to at least a 3 minute delay.  It’s really frustrating to be taking photos, having made all the adjustments and then the screen goes dark and shuts down because you have it set for a very short Auto-Lock activation.  I usually set mine to 3-4 minutes which is a LOT more time than I need to move from subject to subject, taking multiple photos.

 

Obtaining perfect focus is a little difficult when using supplemental optics like a telescope because both the optical system and the phone camera must be focused together.  When attaching your phone to the eyepiece of a telescope, you are using what is termed an “afocal” system, which simply means that one complete optical system (the iPhone) is looking into another complete optical system (the telescope), each having its own objective lens and eyepiece (ocular).  I recommend focusing the telescope and the phone at the same time.  But initially, set up your optical system/telescope with the NVD or glass eyepiece and focus it.  Then apply your phone in its bracket to the eyepiece or NV ocular (you may need to remove the rubber eye guard on the ocular for a firm connection between you phone bracket and the NVD or eyepiece).  

IMG_7022.jpg
 

After opening NightCap in the main screen, I go to “Settings” (tap the gear icon at the top of the main screen) and usually make just three adjustments.  I turn on the shutter release delay and set it to 3 seconds.  The delay button is turned on at the timer clock icon found about half way down in the settings menu.  Touch it so that it turns green.  Then touch the “3s” box.  This gives the telescope assembly time to settle vibrations before taking the photo and NightCap provides three beeps to alert that a photo is about to be taken; the volume of the beeping sound is controlled by the volume up/down buttons on the side of the phone.  Trust me, touching the shutter release button is enough to cause vibrations, resulting in image blurring.  The 3 second shutter delay is adequate for my mount/scope combination.  A mount/scope combination that allows for increased vibrations might require the 10s delay.  The option to this, is a blue tooth remote shutter release button available for about $8 on-line.  I’ve tried this method and found it just a little cumbersome.  It adds another device to carry and fumble with in the dark.  The 3 second delay built into NightCap is ALWAYS there and works just fine for all of my optical+mount systems.  

 

Then I adjust the Interval Programmer, just below the shutter release delay button.  First touch the button on the left side of the settings screen so it turns green, which then allows control of the Interval Programmer. The Interval Programmer performs three distinct functions.  It can control the number of images taken, from 1 to infinity (the first set of boxes under the Interval programmer button).  This should be set to “1”, otherwise you will end up taking more than one photo with exactly the same settings.  This is OK if you are taking several sequential shots like during a lunar eclipse.  But for taking a single photo, set this to 1.  The second box under Interval Programmer is the EXP (Exposure) box.  The sliding button that appears under this box does not actually set the exposure for the image, it sets the number of seconds that the application will take pictures for averaging.  So if you are taking a 1/5 second exposure for 10 seconds, you are setting NightCap to take 50 pictures to average… 5 pictures per second for 10 seconds.  Touching the EXP box reveals a slider button beneath for adjusting the number of seconds or minutes you desire for averaging.  Set the slider button to 10s to begin (more on this later).  The third function that is controlled by the Interval Programmer, is the photo delay between multiple photos.  NightCap can take several photos equally spaced by adjusting this setting, so that multiple images can be automatically timed, like for a lunar or solar eclipse.  But for a single long exposure, this setting should be set to zero.  For a single, averaged, long exposure photo in NightCap, only adjust the EXP box, and understand that it controls the length of time in seconds or minutes that photos will be taken and averaged.  

 

I do use the ISO boost at the bottom of the settings screen to give a greater range of ISO settings.  With the ISO boost setting off, NightCap Camera app is limited to the default ISO setting in the iPhone camera.  My iPhone XR, has a maximum ISO of 2,500.  When ISO boost is set to “Low”, the maximum ISO jumps to 5,000.  On “High” boost, it increases to 10,000.  The newer iPhone 11 will max out at 12,500.  My older iPhone 6+ maxed out at 6,000.  I do find boost useful, and it works surprising well with the Long Exposure mode, as long as sufficient time is given in the EXP setting of the Interval Programmer.  But it’s a balancing act; higher ISO settings require additional averaging to smooth out the noise (graininess) introduced by a high ISO.  

 

This photo shows what my NightCap settings look like:

IMG_7023 3.PNG
 
Return to the main screen in NightCap by touching the gear icon at the top of the settings screen.  Now, you might think that you have made the necessary settings, but they are not actually activated yet.  To activate them, click on the star icon at the lower left of the main screen, which opens the Photo Camera Options menu.  Next, touch the star adjacent to “Long Exposure”; with a short delay, the small red button below the star will turn green.  Now your settings are active.  You might also touch the sun icon at the lower left in the same menu.  It is a light boost, separate from ISO boost and it’s level of control is adjusted using the slider button near the top of the settings menu.   Now touch anywhere on the screen to close the Photo Camera Options menu.  Below is what that menu looks like when open:
IMG_7034.PNG
 

NOW, you are ready to set the White Balance (WB), ISO, exposure (shutter speed) and focus… one at a time.  Before adjusting these functions, it is best to temporarily set the Exposure to about 1/10 second.  When the photo screen opens, NightCap will make adjustments automatically.  Because the image is usually pretty dark, even with NV, NightCap will slow the exposure (shutter speed) to one of its slowest settings.  This means that if the exposure has been set to 1/2 or 1 full second, it will take that long for the screen to re-fresh; it is very difficult to make the appropriate settings when there is such a delay for changes to show on the screen.  By setting the exposure to a faster setting of about 1/10th second, adjustments to ISO, Focus or WB appear almost instantly as you move the sliders.  I have found that a 1/10th to 1/15th second exposure setting makes the other adjustments a lot easier.

 

If you are using a white phosphor NV tube, changing the WB has a dramatic effect on the color of the photo.  I have found, for my taste, that I prefer a slightly blue tint, which means that I set NightCap WB between 4000 and 4200.  Setting it higher will begin to change the tint to green; lower and it turns to a much darker blue.  You can experiment with WB to find a tint you prefer.  If you do not set the WB, NightCap will set it automatically using default settings from the phone, which sometimes works, and sometimes doesn’t.  Often, if left to the automatic setting, it will go to a greenish tint when using NV.  The choice is yours though.  With glass eyepieces, I do allow NightCap to select the WB setting which comes out much better.  WB is set manually by moving a slider button that will appear temporarily at the top of the screen, when you touch the main (photo-taking) screen.  Once you have found a WB setting you like for NV photos, remember the number for future manual settings. 

 

Now move to the left side of the screen to adjust the ISO.  With a long pass filter on your NVD, a higher ISO is required than going filterless.  With a narrow H-a bandpass filter, even more light is suppressed, thus requiring an even higher ISO setting.  For now, find a setting that is bright enough so you can focus stars.  You will come back to ISO settings while adjusting the Exposure.

 

Manual focus adjustment is the slider button at the bottom of the main screen in NightCap.  This button focuses the phone camera… not the telescope.  Precise focus of stars in an astro image is critically important.  For a long time, I used 3x reader glasses from the drug store to focus stars on the phone’s screen.  But there is an easier way to use manual focus in NightCap.  On the very bottom of the main screen, on the right side of the shutter release button, is a separate slider that can be moved to the right or left to zoom.  Make sure you’ve got at least one star visible on the screen when you zoom in.  Next, use your telescope focuser to focus stars to their smallest diameter while watching the screen.  Now, slowly move the focus slider button at the bottom of the phone screen and watch the focus on the screen; stop when it looks perfect with the smallest points of light.  You can return to the scope focuser to re-focus it… when it is perfect, lock the focuser draw tube so it will not move accidentally.  If you refocus the telescope, be sure to finish by moving the focus slider on the phone screen as a final adjustment.  When focus is reached, remember the number which can be found at the top of the screen… it will be needed again if you leave this main screen, for instance, to review an image that has been taken. When perfect manual focus has been achieved, you can zoom back out.

 

Alternately, you can move the small floating box in the main screen to allow NightCap to automatically adjust focus; just touch it with your finger and slide it over some stars .  The red light in the box will turn green when focus has been achieved and is locked.  I have found that placing the box on medium sized stars about half way between the center and edge of the image is the best position for the autofocus box.  Sometimes, especially if the image is very dim, autofocus will not function properly.  I always adjust focus manually to avoid this issue.  

 

Next, you are going to set both the ISO and the exposure.  Keep in mind that a lower ISO is always better; a lower ISO produces less noise than a higher ISO.  So you might start by setting the longest possible Exposure at 1/3s, 1/2s or 1 second (currently the maximum exposure/shutter speed for different models of iPhones) and then adjust the ISO, so that the image is not too dark or too bright.  These two settings work together in a uniform way.  Once you have found a suitable brightness for the image, further adjustments can be made by moving both settings in opposite directions to achieve similar results.  These are your final settings.  

 

This photo shows the four slider buttons that control WB, ISO, Focus and Exposure at the main screen perimeter.  The small floating box near the bottom is the auto-focus box.  A readout of your settings is found at the top, under the icons (too small to read in this low res image).  The slider adjustments are shown briefly when you touch the screen.  Be careful not to move your finger too close to the center of the screen, lest you change a setting that you've already made.  In other words, keep your finger close to the edge of the screen where the slider lines appear.    

IMG_7033.PNG
 

At the bottom of the main screen, just left of the shutter release button, are three red lights followed by FOC, EXP and WB.  As you make manual adjustments to these three settings on the main screen, the red lights will change to green.  The green color means that those settings are locked and will not change unless you make an additional manual change to them.  If you touch the FOC, EXP and WB, a menu box will open showing these same elements but larger.  You can lock (green light) or unlock (red light) any of them by touching each element.  Close this menu by touching anywhere on the iPhone screen.

 

Now push the shutter release button at the bottom/center of the main screen.  The phone will beep during the 3 second delay and then NightCap will take your photo.  During this initial photo, you have 10 seconds (the time you previously set for averaging) to look at the screen, see the settings at the top of the screen and try to remember the ISO and exposure time, the white balance setting and the focus number (between 1-100).  Why?  Because if you leave this main screen to review the image (by clicking the stacked boxes icon in the upper left corner of the main screen), the four settings (WB, ISO, Focus and Exposure) will be deleted because  Long Exposure mode will revert to automatic adjustments.  Chris, NightCap’s developer, can’t do anything about that; it’s an Apple issue over which he has no control.  So when you return to the main screen after reviewing an image you took, you will need to re-set those four settings.  Knowing what they should be makes re-setting them a lot faster.

 

When the image is being taken, it is important to keep your eye on it as it is being built in NightCap during the averaging process, especially just before it is complete.  If you see too much grainy appearance, if the brightness of the object or the background sky is too light, or if you want to change something else in the photo, make the adjustments to WB, ISO, Focus or Exposure, or return to the settings menu to increase averaging time (EXP box) and immediately try again.  If the image shows a lot of noise, lowering the ISO can help, but only if you can also slow the exposure to achieve the same image brightness.  If you cannot change the ISO/Exp, then return to the settings screen (gear icon) and increase the averaging time in 5 second increments.  Toggling between the main screen and the settings screen does not delete your locked settings, so click on the EXP box again and slide the button for another 5 seconds (now 15s total).  You might have to reach 20 or 25 seconds before the grainy appearance of high ISOs is managed to your satisfaction.  The longest I have needed at ISO 10,000 is 35 seconds (using 1s exposures) with my NVD used as the eyepiece.

 

Every time you make an adjustment to the optical system, like changing filters or eyepieces in afocal or adding a reducer, flattener or barlow, you must re-focus the telescope and then check or re-adjust the four primary settings of WB, ISO, FOC and EXP.  I am used to this process and it goes very quickly for me.  

 

As long as you remain in the main screen or the settings screen of NightCap, and your phone does not shut down in Auto-Lock, your settings will remain locked.  If you are using a GOTO mount, you can leave the WB and Focus settings alone and just make minor adjustments to ISO/Exposure for really bright or dim subjects.  I have taken up to 34 images of different subjects this way in less than an hour, and not felt rushed.  By making a list of what I want to photograph in advance of the session, it goes very fast.  

 

You can mix visual NV and phonetography, but it is a lot slower if you are constantly removing the phone/adapter from the NVD each time you want a visual comparison; and, you will loose your settings when the phone is turned off.  Splitting your time between NV visual and photographic use seems much more productive; when taking photos, I take them consecutively until I’m done.

 

If you want to use your iPhone with NightCap, without night vision… follow the same instructions above in Long Exposure mode, using your glass eyepieces with your phone.  Point light sources from clusters, bright double stars and colorful asterisms are usually the best subjects when taken from a dark site.  Luna and the sun (with proper filtration) are very bright subjects that mostly do not need the Long Exposure mode, but images of these two subjects do improve with judicious use of manual settings in NightCap.  Filters can be used, but any filter reduces light throughput, requiring a longer exposure, higher ISO, or longer averaging time.  Making appropriate settings really amounts to a balancing act; the higher the ISO, the more averaging time will be needed to smooth out noise in the image; the longer the exposure time, the longer the averaging time needs to be for an appropriate number of photos to average… to average 40 one-second photos takes 40 seconds, whereas to average 40 one-quarter second photos takes only 10 seconds.  Balancing the ISO, Exposure and Averaging time is the key to the Long Exposure Mode in NightCap.  

 

One of the great benefits of using NighttCap’s Long Exposure Mode, is being able to see how the ISO and exposure adjustments you make effect the image you intend to take.  After you’ve taken a few images, you will watch the screen as those two adjustments are made.  Generally, for the lowest ISO setting, you are going to use the slowest exposure setting.  Remember that once you have slowed the exposure setting to 1/2 or 1 second, making any other adjustments will take longer to show up on the phone screen.  AND, the slower the exposure is set, the longer the averaging time will need to be for greatest effect.  Generally, I want at least 35 exposures to be averaged, which means that the EXP box in the settings menu needs to be set accordingly; 1s exposures will require 35+s of averaging, 1/2s exposure will require 15-20s of averaging; 1/3s exposure will require 12-15s of averaging, and so on.  Very bright subjects requiring a faster exposure of 1/10th second at the lowest ISO setting do not require the Long Exposure mode.  

 

 

 
 
 
 

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#2 GeezerGazer

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Posted 08 February 2020 - 12:56 PM

Example:  The Rosette Nebula with NGC 2244, the central cluster, taken on 1-24-19, using an Explore Scientific 208 Newt with ASA .73x reducer at f:2.8 and 7nm H-a filter, at ISO 4000, 1/2s exposure averaged for 10s in NightCap-Long Exposure Mode:

IMG_3686.jpg
 
Now that you understand how Long Exposure mode works and why manual settings are important, here’s the simple version for using NightCap in Long Exposure Mode:

 

1.  Reduce iPhone screen brightness to <25%

2.  Increase iPhone Auto-Lock to >3 minutes

3.  Focus telescope with eyepiece to be used

4.  Apply iPhone (in bracket) to eyepiece (or NVD)

5.  Open NightCap, open Settings (gear icon)

A.  Activate shutter delay and set to 3s

B.  Activate and set Interval Programmer, EXP to 10s or more

C.  Set ISO boost to high (touch gear icon to close menu)

6.  Main screen, open Mode settings (star icon) 

A.  Turn on Long Exposure mode (star icon)

B.  Turn on Brightness mode (sun icon)

7.  Set Exposure to 1/10s or more, then set

A.  White Balance

B.  Focus telescope, then focus iPhone, repeat as necessary; lock focuser

C.  ISO (lowest possible) and Exposure… watch screen as settings are adjusted

D.  if needed, go to Settings to increase EXP (time for averaging)

8.  Take photo and watch image; remember settings

9.  Make adjustments and re-take photo, or go to next subject

 

Night Vision is a remarkable tool for amateur astronomy.  To learn more about Night Vision, visit the Specialty Forums, EAA (Electronically Assisted Astronomy) forum, BEST of NV thread.  It provides a list of NV topics with links containing useful information.

https://www.cloudyni...842-best-of-nv/

 

I’m hoping that others who have experience with NightCap in Long Exposure Mode will add any shortcuts or discoveries they have made.   While other modes within NightCap are pretty straight forward and even automatic, Long Exposure Mode really does require an understanding of how it works to perform its best.  

 

Clear Skies

Ray

 


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#3 PhotonHunter1

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Posted 09 February 2020 - 06:08 PM

I love this app, and this thread is excellent. It will definitely help me maximize the use of Night Cap when I'm camping and didn't schlep all the gear. Thanks for taking the time to draft and post!


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#4 RMay

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Posted 03 April 2020 - 01:59 AM

I’ve just started using this app and will be doing some close coupling to my Questar 3.5. Looking forward to playing with it...

Thanks for an excellent tutorial.

Ron
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#5 Lofapco

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Posted 26 April 2020 - 07:55 PM

Awesome review.. I downloaded this app tonight and can't wait to get my Iphone adapter for my Oberwerks 25x 40x 100mm Binoculars! I live in a designated Dark Sky community and if I need darker it is only about 15 miles to the desert trails with no other lights. This is going to be a fun app to get some great shots with my Iphone!. I also see it works good with daytime and night shots other than astro. Can't wait to start shooting!

 

OW 2a

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#6 FredOz

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Posted 04 May 2020 - 04:55 PM

RE:  NightCap Camera App in Long Exposure Mode for Phonetography

Ray Taylor

 

Thanks for posting this.  Some questions:

1)  What do you mean by night vision device (NVD)?  Is that a telescope or binoculars?

2)  You use a GOTO- tracking mount.  Would this work by taking a series of exposures and then stacking them?

3)  I find it difficult to get an image on my camera (iPhone 6) with an eyepiece of shorter than 15mm (80x on my Skywatcher 150).  How do you avoid this problem?

4)  The alt-azimuth (Dobson) mount is also awkward for telescope aiming with a camera.  Any suggestions?

 

I've been able to take reasonable pictures of the moon with my setup but Venus is difficult and frustrating.  I've not tried a deep-sky object, like a cluster yet.  Also, with my phone (not yet using NightCap), I get a better photo without a delay.  Here's my best Venus picture so far.

 

--- Fred

Venus 22 Apr.JPG

 


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#7 GeezerGazer

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Posted 05 May 2020 - 12:58 AM

Awesome review.. I downloaded this app tonight and can't wait to get my Iphone adapter for my Oberwerks 25x 40x 100mm Binoculars! I live in a designated Dark Sky community and if I need darker it is only about 15 miles to the desert trails with no other lights. This is going to be a fun app to get some great shots with my Iphone!. I also see it works good with daytime and night shots other than astro. Can't wait to start shooting!

 

You are a luck astronomer to live in a designated dark sky community!!!  You'll be limited to very short exposures with an alt/az manual mount; go for the very brightest subjects first.  Terrestrial daytime shots should be a breeze using the regular iPhone camera.  


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#8 GeezerGazer

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Posted 05 May 2020 - 02:24 AM

RE:  NightCap Camera App in Long Exposure Mode for Phonetography

Ray Taylor

 

Thanks for posting this.  Some questions:

1)  What do you mean by night vision device (NVD)?  Is that a telescope or binoculars?

Hi Fred, thanks for your questions.  I'll do my best to answer. 

NVD is a light intensification device, used by the military and hunters more often than astronomers.  But it is being used more and more, primarily to overcome light pollution.  It easily doubles the reach of just about any telescope.  I'm 71 and don't want the burden of a large Dob.  So I use night vision device primarily with my camera lenses and an 8" Newtonian.  Currently, the Night Vision forum is included with EAA (Electronic Assisted Astronomy) in the AP (Astrophotography) forum... just look for the NV tags in posts there.  But a good way to understand what it is and how it works would be to visit the BEST of NV thread at the beginning of the EAA/NV forum.  Click on it to reveal an index of topics; then click on one of the topics that might interest you and you will be taken to a list of prior threads about that specific topic. It's easy to use and contains almost everything you could possibly ask about NV.  NV is not inexpensive, but it's a whole lot less than jumping from a 140 APO to a 280mm APO refractor!  Here's a direct link to the BEST of NV: 

https://www.cloudyni...842-best-of-nv/

 

2)  You use a GOTO- tracking mount.  Would this work by taking a series of exposures and then stacking them?

NightCap does not perform "stacking"... stacking aligns photos using one or more registration points within several photos and it averages photos.  NightCap only averages photos; it will not stack & align them.  To average photos with NightCap, a tracking mount must be used.  The tracking mount keeps the subject in exactly the same place within a range of photos so they can be averaged.  Depending on your computer (PC vs Mac) there are programs or applications that can be used to stack and average a series of individual photos, or like some of the phone photography being done now, using the individual frames from a phone video taken through the eyepiece of a telescope.  This technique of using video files might be your best option for use with your existing equipment.  I do not use that technique, but some have produced very good results.  

 

3)  I find it difficult to get an image on my camera (iPhone 6) with an eyepiece of shorter than 15mm (80x on my Skywatcher 150).  How do you avoid this problem?

There are several potential problems that occur as magnification is increased.  First, the image becomes increasingly dim because essentially, the focal ratio is reduced, like on a camera.  Then there is the problem of unintentional scope or mount movement which is more "touchy" at higher magnification.  Little vibrations show up more easily at increased magnifications.  Most of my images are taken at 10-30x but I have to bump it up to 60x for some globulars, doubles, planetary nebulae or especially galaxies.  But keep in mind that using NV greatly enhances the visual image, so I have it a lot easier in terms of imaging with a phone.  

 

4)  The alt-azimuth (Dobson) mount is also awkward for telescope aiming with a camera.  Any suggestions?

There are tracking mounts made for Dobsonian scopes.  It is probably less expensive to purchase a new Dob that already has tracking ability.  Several of the major companies have GoTo/tracking Dobs in 8" to 12" (and larger) models, like the SkyWatcher SynScan, or the Orion SkyQuest.  If your aim is to get into astrophotography, then you should visit the beginning AP forum for suggestions.  If you want to take snapshots with your phone using a manual mount with a Dob, you will need to keep magnification as low as possible and your exposures will need to be very short... limited without tracking to about 1/2 second.  

 

I've been able to take reasonable pictures of the moon with my setup but Venus is difficult and frustrating.  I've not tried a deep-sky object, like a cluster yet.  Also, with my phone (not yet using NightCap), I get a better photo without a delay.  Here's my best Venus picture so far.

Your photo of Venus is quite good actually.  It is a tough target because it is very bright.  You might try using a polarizing filter if you have one available.  If you visit the Beginning AP forum, the thread titled "Smartphone Astrophotography" page 40, post 978, you will find an image of Venus taken using this method.  Here's a link:

https://www.cloudyni...strophotography

I hope this helps.

Ray

 

 

--- Fred

attachicon.gifVenus 22 Apr.JPG


Edited by GeezerGazer, 05 May 2020 - 02:32 AM.

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#9 joelin

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Posted 25 May 2020 - 08:35 PM

This tutorial really helped me yesterday when I was doing some dark sky night vision astrophotography! 

 

 

Some observations:

1) This tutorial is absolutely essential. Coming from someone who is pretty proficient as DSLR astrophotography, the app is quite hard to use. Many of the various functions don't have labels or detailed descriptions which leaves you guessing what they actually do. I wouldn't recommend someone try to figure it out on in the field, especially when dark sky time is precious. 

2) Is it better to go with short exposures like 1/20 with higher ISO or longer exposures like 1/2 with lower ISO? I didn't test various combinations so I don't know. How do you know when your image is bright enough?

3) I couldn't get auto focus working. I would tap on the stars but nothing would happen. Finding the exact focus point is quite hard, especially considering this is afocal so you have to focus two independent systems. Next time I might try using a Bhatinov Mask. 

4) I had the app take 3 pictures one after another in the settings. This is because the mount after slewing took some time to settle so the first two images had some star streaking. 

5) The camera settings are lost after opening up the photo albums to preview so I rarely do that. It's a bit of a hassle to reset them. However, you can still get a preview of the result by watching the image build during the exposure, that is how the stars were streaking. 

 

Overall great app. My setup was the 8" Edge SCT with 0.7x reducer. The mod 3 was in prime focus. No filter was needed as I had nice dark skies about 21.3 mag on the SQM. 

 

See some of my results here:

https://photos.app.g...p6JJnnAShw7ECM9


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#10 GeezerGazer

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Posted 26 May 2020 - 12:38 AM

This tutorial really helped me yesterday when I was doing some dark sky night vision astrophotography! 

 

 

Some observations:

1) This tutorial is absolutely essential. Coming from someone who is pretty proficient as DSLR astrophotography, the app is quite hard to use. Many of the various functions don't have labels or detailed descriptions which leaves you guessing what they actually do. I wouldn't recommend someone try to figure it out on in the field, especially when dark sky time is precious. 

2) Is it better to go with short exposures like 1/20 with higher ISO or longer exposures like 1/2 with lower ISO? I didn't test various combinations so I don't know. How do you know when your image is bright enough?

By reducing the screen brightness to 20% or so, and watching the image as you adjust settings, you should see how bright your image will be.  Averaging does not effect the image brightness; averaging only reduces electronic noise caused by higher ISO settings.  

 

Joe, I did not find the Long Exposure mode to be intuitive.  The symbols are used as an abbreviation for their function, but could probably be refined for better recognition.  For example, the EXP box in the Settings Menu is short for EXPosure, but should probably be named TIME or AVEraging, because it does not specifically impact the exposure of the image, which is set on the main screen with the right side slider.  Concerning this question (No. 2) the combination of exposure, ISO and averaging time is very much a balancing act.  As a photographer, you know that the lower the ISO, the less noise is introduced, and with the very small pixel size of the phone camera sensors, low-light noise is still a problem.  During some correspondence with Chris, the NightCap developer, he suggested always using the longest exposure with the lowest ISO for best results.  But the averaging function of the Long Exposure Mode in NightCap requires more time to average longer exposures.  I have found that with very bright objects through a night vision device, like globular clusters, successful results can be achieved with a faster exposure (1/5 to 1/10 sec) with a correspondingly higher ISO... because a shorter exposure allows for more photos to be taken in a given amount of averaging time.  For instance, my tracking mount (AZ Pro) is not made for long exposure AP, but its tracking is adequate for short durations.  So I try to keep my averaging time (the EXP box in the settings menu) lower than 40 seconds.  A 1 sec. exposure requires 40 sec. to average 40 images.  But if the wind has come up, or there are gusts, I try to keep my averaging time to a minimum, 5-10 sec.  To do that I must boost the ISO and shorten the exposure, so if I set a 1/4 sec. exposure, NightCap is averaging 40 photos in 10 sec.  The less time the camera is collecting photons, the less chance there is of a wind gust causing movement of the objective or mount.  

 

My XR has a possible ISO of 10,000 if the ISO boost is turned on in NightCap.  I have found that noise is nearly always present in the image when ISO is set that high.  Averaging performs very well to reduce noise, but averaging time also needs to be increased when using the highest ISO settings.  Of course, this also depends on the speed (focal ratio) of your optical system. Faster systems, deliver more light to the sensor, while scopes with slower focal ratios deliver less light.  This is why I say it is a balancing act.  

 

I encourage you to experiment with different combinations of exposure, ISO and averaging time to find the perfect combination with your scope.  

 

3) I couldn't get auto focus working. I would tap on the stars but nothing would happen. Finding the exact focus point is quite hard, especially considering this is afocal so you have to focus two independent systems. Next time I might try using a Bhatinov Mask.  

I tried a Bhatinov mask for focusing on both my Newt and refractor.  Although they provide a solution for perfect focus, they are one more thing to take and use in the dark.  I preferred using the zoom function within NightCap to see when I reached perfect focus, both with the telescope focuser and the camera focus slider.  

 

4) I had the app take 3 pictures one after another in the settings. This is because the mount after slewing took some time to settle so the first two images had some star streaking. 

5) The camera settings are lost after opening up the photo albums to preview so I rarely do that. It's a bit of a hassle to reset them. However, you can still get a preview of the result by watching the image build during the exposure, that is how the stars were streaking. 

This problem exists because of iOS restrictions and cannot be fixed by 3rd party developers.  It is annoying!  I typically preview photos until i have a satisfactory image, then I take a series of images in succession.  I usually make a list of subjects I want to image before I start.  With a GoTo/tracking mount, dozens or even hundreds of images can be taken in a single session.  

 

Overall great app. My setup was the 8" Edge SCT with 0.7x reducer. The mod 3 was in prime focus. No filter was needed as I had nice dark skies about 21.3 mag on the SQM. 

 

See some of my results here:

https://photos.app.g...p6JJnnAShw7ECM9  Your images look great! 

 


Edited by GeezerGazer, 26 May 2020 - 12:39 AM.


#11 calerner

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Posted 16 July 2020 - 11:18 AM

Thanks for all of the information in this thread.

 

A couple of aspects of nightcap are not clear to me.

 

Is there any difference between taking a picture in long exposure mode with interval programmer activated and exposure set to 10 seconds versus taking a picture in long exposure mode with interval programmer not activated, but pushing the shutter button to begin the image and then pushing it again at 10 seconds to stop the image?

 

What is the difference between long exposure mode and light trails mode and star trails mode?

 

Thanks for any clarifications and sorry if these questions can be answered in any of the information in the thread already - I may have missed it.

 

Charles


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#12 GeezerGazer

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Posted 03 September 2020 - 09:02 PM

Thanks for all of the information in this thread.

 

A couple of aspects of nightcap are not clear to me.

 

Is there any difference between taking a picture in long exposure mode with interval programmer activated and exposure set to 10 seconds versus taking a picture in long exposure mode with interval programmer not activated, but pushing the shutter button to begin the image and then pushing it again at 10 seconds to stop the image?  I never tried that, so I'm not sure if it uses the same mechanism within NightCap.  Since exposure and ISO is set on the main screen, I suspect it would work in "star trails."  But star trails might use the ISO boost or light boost automatically instead of offering manual control on the slider button in the settings menu.  You might be best served by asking the app developer, Chris.  He usually responds within a day or so of receiving an email.

 

What is the difference between long exposure mode and light trails mode and star trails mode?  I don't think there is too much difference between them, except in their intended purpose.  And since they are included under a separate button, I'm guessing they each provide slightly different automatic phone camera settings.  For instance, Light Trails might not use the light boost function at all, while Star Trails probably does.  The nice thing about Long Exposure mode is you are not touching the phone for the start and stop function, which means you are not inducing vibrations, especially noticeable at high magnifications, and you retain manual control over the light and ISO boost functions.  Long Exposure is intended to be used with a separate optical system and a tracking mount, whereas, Light trails, Star trails and Meteor mode are all intended for stand alone phone camera operation on a non-tracking mount.  

 

Thanks for any clarifications and sorry if these questions can be answered in any of the information in the thread already - I may have missed it.

 

Charles

Hi Charles, 

My apologies for not responding earlier.  My answers are above in red.  I've never been interested in taking images of star trails or terrestrial light trails at night.  But one day, I might try the Meteor mode! 

Best Regards,

Ray


Edited by GeezerGazer, 03 September 2020 - 09:04 PM.


#13 CowTipton

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Posted 03 November 2020 - 11:42 AM

Thanks Geezer, you're the best.

 

I love that I can activate the shutter with my apple watch so I don't even have to touch the phone once it's ready to go.


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#14 FredOz

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Posted 03 February 2021 - 03:24 PM

This tutorial really helped me yesterday when I was doing some dark sky night vision astrophotography! 

 

Some observations:

1) This tutorial is absolutely essential. Coming from someone who is pretty proficient as DSLR astrophotography, the app is quite hard to use. Many of the various functions don't have labels or detailed descriptions which leaves you guessing what they actually do. I wouldn't recommend someone try to figure it out on in the field, especially when dark sky time is precious. 

2) Is it better to go with short exposures like 1/20 with higher ISO or longer exposures like 1/2 with lower ISO? I didn't test various combinations so I don't know. How do you know when your image is bright enough?

3) I couldn't get auto focus working. I would tap on the stars but nothing would happen. Finding the exact focus point is quite hard, especially considering this is afocal so you have to focus two independent systems. Next time I might try using a Bhatinov Mask. 

4) I had the app take 3 pictures one after another in the settings. This is because the mount after slewing took some time to settle so the first two images had some star streaking. 

5) The camera settings are lost after opening up the photo albums to preview so I rarely do that. It's a bit of a hassle to reset them. However, you can still get a preview of the result by watching the image build during the exposure, that is how the stars were streaking. 

I agree that the tutorial is useful.

 

RE: "Many of the various functions don't have labels or detailed descriptions which leaves you guessing what they actually do." 

 

I've had that problem too.  A couple days ago, I sent a request to <support@nightcapcamera.com>  (No reply yet,)

 

Here's what I asked:

I'm still puzzled by several of the Settings Menu controls.  I have not seen in any of the documentation a picture with labels explaining what the controls do.  Indeed, I do not recall seeing anything about the settings menu.  Some controls are fairly obvious, like Jpeg vs Tiff.  But others are not.  Please see the attached which shows some labels as I (think I) understand them plus a few labeled ? that I've not figured out.

 

I also suggest a bit of explanation on what I call the Integration Time control, including saying that Night Cap averages for noise reduction but does not stack exposures as can be done in Deep Sky Stacker.

Also, I suggest explaining the x1.0 control on the main panel.  I think it's purpose is to enlarge the display as a focusing aid and that it does not affect the picture taken.

 

One other idea -- why not a pop-up window to explain a control when it is pressed for ~2-3 seconds?

 

FYI, my application is afocal photography through an untracked telescope (Dobson mount).  I've been struggling to get decent pictures of the Pleiades, Double Cluster & Orion Nebula.  I've not (yet?) tried a galaxy, not even M31.  I did get a decent photo of the Jupiter/Saturn conjunction except Jupiter was somewhat overexposed (no bands are shown).  The Moon is easy, even with the normal iPhone app.

 

--- Fred

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  • NightCap.JPG

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#15 FredOz

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Posted 10 February 2021 - 11:02 PM

Chris from NightCap Support was kind enough to add some annotation to my photo above.

 

Contrary to what NightCap says, I seem to get better results with my iPhone 6s than with the older model 6.  The 6s supposedly has smaller pixels that do not respond to dim light as well but my 6 produces "blotchy" pictures and even blotchy dark frames.

Attached Thumbnails

  • NightCap.jpg

Edited by FredOz, 10 February 2021 - 11:03 PM.

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#16 GeezerGazer

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Posted 18 March 2021 - 04:25 PM

Thanks Fred for adding the annotated menu screens; very helpful. I should have thought of that!  



#17 GeezerGazer

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Posted 18 March 2021 - 05:03 PM

Fred, the single biggest improvement in my phone images occurred when I switched to a tracking mount, because "integration time" was dramatically increased.  I went from a single photo of 1/2s or less, up to 60 photos that were averaged in 30s.  It was a huge difference.  The second biggest improvement came when I upgraded from my iPhone 6+ to an iPhone XR, which increased from 8 MP to 12 MP.  I now use an iPhone 12 Pro Max which has a larger lens and sensor for the 1x lens.  Image quality improved modestly with the larger lens and sensor.

 

The 1x magnification slider button on the main screen is a digital zoom.  Not recommended except for finding best focus.  Using the digital magnification creates increasingly higher levels of noise in the image.  The smaller "x1.0" that appears above the slider button shows exactly how much magnification has been applied to the image from the lens that is chosen for use to take the photo.  

 

The new iPhones have more than one camera lens.  NightCap allows you to choose which lens you want to use.  On the main screen, to the right of the magnification slider button, is "1x".  On the iPhone 11 or 12 Pro which have three lenses, you can choose the 1x wide angle, the 2x telephoto or the .5x ultra wide angle lens just by tapping on the "1x".  This must be selected to make sure the phone camera uses the lens you have centered on your telescope or optical system.  


Edited by GeezerGazer, 18 March 2021 - 05:10 PM.


#18 joelin

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Posted 18 March 2021 - 07:27 PM

Fred, the single biggest improvement in my phone images occurred when I switched to a tracking mount, because "integration time" was dramatically increased.  I went from a single photo of 1/2s or less, up to 60 photos that were averaged in 30s.  It was a huge difference.  The second biggest improvement came when I upgraded from my iPhone 6+ to an iPhone XR, which increased from 8 MP to 12 MP.  I now use an iPhone 12 Pro Max which has a larger lens and sensor for the 1x lens.  Image quality improved modestly with the larger lens and sensor.

 

The 1x magnification slider button on the main screen is a digital zoom.  Not recommended except for finding best focus.  Using the digital magnification creates increasingly higher levels of noise in the image.  The smaller "x1.0" that appears above the slider button shows exactly how much magnification has been applied to the image from the lens that is chosen for use to take the photo.  

 

The new iPhones have more than one camera lens.  NightCap allows you to choose which lens you want to use.  On the main screen, to the right of the magnification slider button, is "1x".  On the iPhone 11 or 12 Pro which have three lenses, you can choose the 1x wide angle, the 2x telephoto or the .5x ultra wide angle lens just by tapping on the "1x".  This must be selected to make sure the phone camera uses the lens you have centered on your telescope or optical system.  

Ray, with the multiple lenses, do you find a use for the wide or telephoto when using NightCap?


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#19 GeezerGazer

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Posted 20 March 2021 - 02:51 PM

Ray, with the multiple lenses, do you find a use for the wide or telephoto when using NightCap?

I typically only use the 1x lens on the iPhone because it provides a complete circular image from the telescope as seen on my night vision device's phosphor screen.  I have been meaning to try the 2.5x lens but my suspicion is that with Night Vision, it will zoom in on the phosphor screen to show every potential defect.  It would however, decrease the FoV... meaning that smaller subjects like planetary nebulae or galaxies would appear larger in the image produced by the iPhone.   Perhaps the added scale would be offset by problems associated with magnifying the phosphor image.  Using the .5x iPhone lens would only reduce the diameter of the image presented by the phosphor screen; the increase or decrease of field of view, offered by the iPhone's .5x and 2.5x lenses, is only acting on the image presented by the NVD phosphor screen.  

 

I have not attempted using the iPhone's 2.5x lens attached to a glass eyepiece mounted to a telescope, but that is something that should be tried.  Perhaps soon!  




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