Polar Align Comparison - iPolar versus NINA versus Sharpcap
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- เผยแพร่เมื่อ 23 มิ.ย. 2024
- In this video for amateur astronomers I go through an exercise of comparing Polar Alignment done first with iPolar, then NINA and lastly Sharpcap. At the end I share from my recent imaging sessions the Pelican Nebula and the Elephant Trunk Nebula. Enjoy!
Here's some equipment I'm using for my setup:
Note: I am an amazon affiliate. If you follow any of the amazon links and make a purchase, it helps support my channel.
William Optics RedCat 61 WIFD f/4.9 Petzval Refractor Telescope
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Sky-Watcher EvoStar 100 APO Doublet Refractor Telescope
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ZWO ASI183MC 20 Megapixel USB3.0 Color Astronomy Camera for Astrophotography
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iOptron GEM28 Mount - Head with iPolar in Hard Case
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ZWO M48 to M48 Extender / Spacer Ring with 16.5mm Extension # ZWO-M48-EXT16.5 (used to obtain precise back focus with field flattener)
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ZWO Filter Drawer with M42 & M48 Threads - For 2" Mounted Filters # FD-M42
agenaastro.com/zwo-filter-dra...
2" Baader Neodymium Moon & Skyglow Filter with IR Cut
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Optolong 2" L-Enhance Dual Narrowband Light Pollution Filter (H-Alpha and H-Beta/O-III)
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This eyepiece is awesome for visual astronomy with its wide field of view.
Alpine Astronomical Baader 76° Morpheus 17.5mm Eyepiece (1.25"/2")
www.bhphotovideo.com/c/produc...
This is a very well made barlow lens I've been using for visual astronomy. I found thought that this doesn't seem very compatible for astrophotography for my setup unless using the diagonal (only way to get camera focus).
Celestron 93436 Luminous 2-Inch 2.5x Barlow Lens (Silver)
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This is a must have for astrophotography purposes.
Sky-Watcher S20201 Reducer / Corrector
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Astromania M48X0.75 (2" Filter) Female to M42X0.75 T / T2 Male Thread Telescope Adapter (to achieve back focus with reducer/corrector)
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Alstar Astronomical 2"/M48-extension Tube Kit for Cameras and eyepieces - Length 5mm 8mm 10mm 20mm 30mm - M48x0.75 on Both Sides (adapter to use with tubes for achieving back focus with reducer/corrector)
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SVBONY Bahtinov Mask, Aluminum Alloy Bahtinov Focusing Mask, 85-120mm Caliber Fixed Diameter 80-135mm
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I find this lightweight cart handy for hauling in/out a stack of organizer boxes and the mount case.
Leeyoung Folding Hand Truck and Dolly,309 lb Capacity Aluminum Portable Cart with Telescoping Handle and PP+EVA Wheels
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Some gear for cleaning purposes:
UES Air Blower Dust Blaster for Digital, DSLR, SLR Cameras Sensor Lens Cleaning, Rubber Bulb Air Pump Dust Blower Cleaner - Black
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UES APSC-16 DSLR and Mirrorless Digital Camera Sensor Cleaning Kits for APS-C Type CMOS and CCD Sensors (14pcs APS C Sensor Cleaning Swabs and 15ml Sensor Cleaner)
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UES Lint Free Microfiber Cleaning Cloth for Lens, Eye Glasses, LED (8 Packs - 15cm x 15cm)
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These are great for making sure you don't have any dust or dirty spots on your CMOS of your camera.
Beileshi Watch Repair Magnifier Loupe Jeweler Magnifying Glasses Tool Set with LED Light with 8 Interchangeable Lens-2.5X 4X 6X 8X 10x 15x 20x 25x
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If you have to transfer images/files from your laptop to another computer for further processing, this external drive is very fast compared to something like a thumb drive.
SAMSUNG T7 1TB, Portable SSD, up to 1050MB/s, USB 3.2 Gen2, External Solid State Drive (MU-PC1T0H/AM), Blue
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To avoid unrolling and rolling up power cables for each imaging session or setup where there's no outlet to connect to,, this is very convenient.
Jackery Portable Power Station Explorer 300, 293Wh Backup Lithium Battery, 110V/300W Pure Sine Wave AC Outlet
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If you want to share your astro images so I can feature them in a future video, send them to my email:
marksastrojourney@gmail.com
Dehancer set me up as an affiliate. If you want to buy the desktop application instead of the iPad/iPhone app and use the following discount code, you will save 10% and I will also earn a small commission:
Dehancer Discount Code for a 10% Discount: DEHANCER-MAJ
Dehancer website: Dehancer.com - วิทยาศาสตร์และเทคโนโลยี
I've been doing polar alignment for almost 4 years, and iPolar is BY FAR the best.
Thanks for sharing your experience and some helpful suggestions for getting the best results! Clear skies!
I’m in the southern hemisphere (Sydney, AU) and mobile (and mostly image within a 40 min drive from the centre of the city so around SQM 19.9 to 21). Setting up each time, you want something simple and fast. I like the PoleMaster camera as it just clicks into place on the mount’s body, in the centre of the RA rotational axis and you don’t have to worry about focusing. The polemaster app is a pain so don’t use it. I use sharpcap polar alignment routine with the Polemaster camera. All this can be done just when stars appear. The setting up NINA, main camera, focus etc is all done next after polar alignment is finished. I think it would be interesting to use a drift alignment method (as you suggested) and compare others to that. I’ve been told an app such as PemPro would speed that up.
it sounds like you’ve worked out a great solution for your grab and go setup. I was looking at phd2 guiding’s drift align, but could tell right away it will take some experimentation to get the hang of it. Clear skies! It’s great to hear from the Southern hemisphere!
Hey Mark - We pretty much have to use software down here in Australia. I've always found Sharpcap a great tool for this. Nice comparison video very useful 👍
It's great to hear from someone in Australia! I can see why you like Sharpcap's Polar Align feature - overall Sharpcap gives a lot of options to allow us to control the different tools. Thanks for watching and wishing you clear skies!
Hi Mark, great video! I have an iOptron GEM45 and have been satisfied with the iPolar allignment when using NINA to capture images. The thing I really do not like with this mount is the fact that when you tighten down the mount your alignment shifts a little and you have to correct it again. I love my GEM45, but there has to be a better way to lock down the mount after you have aligned. Clear skies!!!!
I agree with you about the screws used to tighten down the mount. Mine requires an Allen wrench. Also, just as you said and as was obvious in my video, tightening them down slightly undoes some of the your polar alignment adjustments. this probably could be better engineered so that the locking mechanism doesn’t shift the mount any. Clear skies!
same with my cem40, so I tighten the screws a little, realign then tighten fully.
Any of them are fine, they all will easily get you within what is needed for proper guiding for pretty lengthy exposures with a decent mount. Even if you run the same application twice your going to get slightly different results on each run.
thanks for sharing your observations! I also think if the mount is on a tripod instead of a pier, one of the tripod legs can shift ever so slightly and throw it off after it’s polar aligned. The equipment cools and warms over time and it seems like that’s a factor as well. Clear skies!
Good thing that nina and sharpcap were saying roughly the same deviation. this is reassuring. I have recently re calibrated my ipolar (changed the x-y values) after I performed a drift alignement . The circle and cross were close but not right on. I am planning to compare also with nina and that similar routine in APT. Let's keep in mind here that PHD will give the polar error of the guide scope , which may not be perpendicular to the mount's axis.
Thanks for the video.
it’s good to hear your experience and I’m glad you enjoyed the video! Clear skies!
I do 5 calibrations back to back, then average x,y positions of the center of rotation and enter those averages in settings. This way, the polar alignment is as good as it could be with respect to the hardware limitations.
Thanks for watching and sharing what you've learned to work well with Polar Alignment! Clear skies!
With no sight to the north and limited sight to the rest (Have only my balcony in a urban region), NINA is the best solution for me. It take a bit to bring it down to ~1 Arcmin, but I get great results with 5 min exposures.
That’s a pretty good outcome considering the limitations of your site! Clear skies!
Why are you using the HA filter in NINA to PA @ 30 second exposure? This is far too long, change to the luminance and use 5 second exposures. I also find that no matter which PA app I use they always tend to differ which PHD2 when running Guiding Assistant
that’s a good catch on the filter, I didn’t even notice it - thanks for pointing it out! Thanks for mentioning the discrepancy you usually see between these PA utilities and PHD2 guiding assistant as well. Clear skies!
I have an AVX mount with a C8 SCT, focal reducer, ASI071MC Pro. My AVX has a polar scope with a pattern showing the NCP and using an app on my phone, PS Align Pro, I get a better starting point for NINA polar alignment.
I use NINA for polar alignment. I can usually get below 30” but sometimes below 10”. I’ll then run the polar alignment a second time. Once it finishes the slews and plate solves, it never reports the same. I make sure after tightening the Alt/Az screws to verify the polar alignment hasn’t changed or if it did it’s just a few seconds off prior to the tightening.
Another verification check for polar alignment is in PHD2 Guiding Assistant the polar alignment error is reported. It’s usually way off from the NINA results.
My understanding is the reason to get great polar alignment is for better guiding and I guess with my mount there is still too much drift and PHD2 somehow can figure out how far I’m off. I don’t bother with Guide Assistant anymore just to save time.
Despite these issues I can usually use 3 minute exposures successfully enough to get, for me, decent galaxy images.
Have you been satisfied with your iOptron. I’m researching an upgrade to a new mount. I’m not sold that strainwave mounts are the best choice for an SCT at 1442mm and 2032mm due to their periodic error.
Thanks
Thanks KJ for sharing your experience! With my Gem28 ioptron mount, I feel that 3 min exposures are about the most I can push it. If I try to go for 5 mins, I usually have too many issues with distorted stars. If you want to step up to 5 min exposures, I wouldn’t recommend the Gem28. Clear skies!
I’d probably look at a GEM45 or CEM40. The EQ6 mount has a great reputation but the mount head is too heavy. I’m not sure strainwave mounts are good for higher focal length guiding. Thanks.
It'll be interesting to hear how one of those works out for you once you have it. Hopefully, the tracking will be better to help you get the longer exposure time you're after!
I used to have an EQ6 Pro with a polar scope that try as I might to adjust the internals, was always 10 arc minutes of the pole. It guided fine for 3-5 minute exposures. Now I'm bummed if Sharcap only grades me as "Good"alignment, like 35 arc seconds of the pole.... lol. Ignorance is sometimes bliss. I always use Sharcap now. My new Nyx 101 mount does not give you a choice.
that sounds frustrating about the polar scope not being able to be adjusted to be aligned with the mount itself. Do you find the nyx 101 mount to be superior to the eq6 pro?
maybe you could test with the PHD2 guiding see which method is the best
thanks for watching! I may give that a try to see what it shows. Clear skies!
SharpCap is the best. It was checked on 10 micron mount after 30-point sky model.
Is that a published test/finding you're referring to or your own? Feel free to post the URL if it was a published article. Clear skies!
I've had great results with it. Can believe I wasted money on that QHY polar camera system.
Thanks for sharing that - it might save some others wasting their money. Clear skies!
Don't know or want to learn NINA. I use Sharp Cap Pro polar alignment on the Sky Watcher Star Adventurer GTi. Bad back, so can't use built in polar scope. Don't use any tracking. Don't need it for E.A.A. and don't do any post image collection work at all. To lazy. Only use one shot color cameras and dual band filters on emission nebula. Happy with results.
Thanks for your insights and experience! I can see how a bad back would make some equipment more challenging. It’s great you adapt and find ways to still enjoy your hobby! Clear skies!
I find the better my polar alignment, the better my guiding is. my best alignment was at 1 arc sec, using asi air. but I bet if I had repeated the polar alignment again, it would have shown a different error
That’s a good outcome, only 1 arc sec! I’m finding once I get down to around 30 arc seconds or less for polar alignment, it’s challenging to adjust without over correction. It might have something to do with how the mount bolts and adjustment mechanism is designed. Thanks for sharing your experience!
Interesting vid. You could have tested each alignment by doing a exposure for the duration of your worm period to see the drift.
I’ll have to look up the duration in the specs. I seem to recall it being something like 10 minutes. But that sounds like another interesting twist I could do for this exercise. Clear skies!
@@marksastrojourneyThe GEM28 is indeed 600 secs. Should be more than long enough to show any Dec/RA miss alignment. I use a CEM70 and iPolar. I try my best to get the cross concentric to the circle and the Dec tracking is pretty good. No consistent adjustments in 1 particular direction. I tried the 3 star alignment on APT and got terrible results so I stick to iPolar.
It's good to hear that some people are having good success just using iPolar! I've never owned a CEM70, but guessing that name means it can support a 70 lb payload. If that's right, I'm thinking your mount is heavier duty than mine. Do you see issues on the CEM70 with tightening the mount screws down affecting your polar alignment and having to do another final minor adjustment to correct that? Clear skies!
@@marksastrojourney The CEM70 does carry 70lb of load. There's no bolts to tighten down on the mount really. The azimuth is adjusted by 2 push bolts and I move the altitude with threaded feet on my home made tripod. There are 2 clamps on the mount to secure the altitude adjustment (which could shift the alignment) but they're always clamped down on my rig.
@alanjs1 That sounds like a good setup!
Many possible issues here. First, the ipolar must be perfectly installed, flush against the mount with no tilt for best results.
Second, try nina and sharpcap thru the ipolar.
Using the scope to polar align setups up possible cone error unless the scope is properly pointing straight using adjusting rings instead of the clamshell clamps.
Personally I use ipolar but a good possible test of your alignment is to leave ipolar open on green after your alignment. Then slew 90 degrees east and then west to see if the alignment stays green, or close enough, thru the entire slews.
Thanks for the tests.
Thanks for sharing some ideas! The polar scope came installed from the factory and I never have assessed whether or not it might not be installed properly. But it does appear to be fully flush to the mount as you mentioned. Interesting suggestion regarding slewing. Clear skies!
30 seconds for platesolve?lol
Not in my case. To avoid people having to wait through while the software is imaging/working, I didn’t show the entire wait time. It usually takes a few minutes in my case as I have to break down my equipment each time and set it all back up the next time.
Your screen shows 30s exposure in Nina , for platesolving ... 15s on sharpcap