ONIKKINEN

Some rotation after a meridian flip should be expected. If your polar alignment is less than perfect = which it almost always is, your DEC and RA are not perfectly 90 degrees from each other (also the case), your camera is not perfectly level etc you will have this kind of rotation.

This looks pretty mild to me actually.

33 minutes ago, vlaiv said:

How does sharpcap measure e/ADU displayed in the table?

No clue, could be magic for all i know.

The measurement process itself goes like this: Constant illumination on the sensor, i used a flat panel on my telescope. Then sharpcap chooses a small area on the sensor to do the measurements on and goes through all the gain values while taking exposures and measuring something? Really dont know how this works.

The Rising Cam aliexpress store also reports similar values: https://www.aliexpress.com/item/4001359313736.html?spm=a2g0o.productlist.0.0.6f047164JGhOx6&algo_pvid=88c7fc7f-59b2-4b58-9bdc-a75b08237944&algo_exp_id=88c7fc7f-59b2-4b58-9bdc-a75b08237944-0

Pixel orders from fits files can be read from many directions, and depending on which direction the frame is read the order can change. My camera is RGGB in most software that care about bayer matrix order but if i split the colour channels before debayering in some software it comes out as GRBG so both can be correct.

I dont have the same camera as yours but from what i can gather the pixel orders would be similar, so try setting it to RGGB and GRBG and see which is right?

Below is a fine artwork i made myself that maybe shows this better. If the pixels are read from top to bottom (and then change of row once all read) it comes out as RGGB, if from bottom to top it comes out as GRBG.

2 hours ago, vlaiv said:

I've never seen that low read noise. Best planetary camera in use today has read noise of ~0.75e (small sensor - imx224).

This is my Rising Cam ATR3CMOS26000KPA, or more commonly known as the Rising Cam IMX571 colour camera. Measured with sharpcap pro sensor analysis.

I dont know what ToupTek (manufacturer for RisingCam products) does differently with their electronics compared to ZWO or QHY offerings but this is how it is with this particular camera. Could be an option for OP if the absolute lowest read noise is a must have with a decent sized sensor, this one being APS-C. Framerates are low, like with all IMX571 sensors so shooting in 8-bit mode might be needed.

Of course if shooting in 8-bit mode you lose the low read noise in low gain values, so not sure if worth it. Below is the same analysis but in 8-bit mode.

The AZEQ6 has encoders on both axis, so you can loosen the clutches and manually move the scope around and have SynScan be aware of those movements. Not sure how useful this is to be honest but the feature is there.

Compared to the EQ6R the altitude adjustment system is better, at least that's what i gather from reading user experiences. In the EQ6 you have this weird springloaded ratchet system looking bolt that many think is a pain to use and some have even stripped theirs and needed replacements, in the AZEQ6 the altitude adjustment system is completely different, and in my opinion quite smooth and easy to adjust.

The AZEQ6 is also a tiny bit lighter, but that's about it. The main selling point in here would probably be the ability to use the mount in alt-az mode as well as eq mode. You can also mount a second scope in alt-az mode if you want to. So if you do enough visual to justify the price you may find the AZEQ6 better for your needs.

22 hours ago, The Lazy Astronomer said:

V2 does have an option to remove stars on "linear' data (inverted commas because it does it by doing similar to as you described above - stretching>removing stars>restoring to linear)

Doesn't seem to work with 32-bit files though.

Very interested in seeing the results in the end.

Doesn't seem that difficult to do either, might have to look into doing this to my EQM35 whenever i have the time for it.

14 minutes ago, newbie alert said:

Large pixel camera's? Pixels have been getting smaller.. I do hope that they revert to getting bigger but as the  cmos market dictates what sensors are available they can only use what's being produced... most camera's that are being used are under 4um...that's not big

Smart phone cameras have pixels as small or smaller than 1 micron, so i think its safe to say the general trend of pixels getting smaller will continue, since daytime/normal photography needs and wants are what sensor manufacturers will focus most on. If read noise and other camera noise sources continue improving along pixel sizes i could imagine a 1 or 2 micron pixel camera to be quite convenient. You could BIN the camera to work at any resolution you want with a wide variety of scopes were this the case.

44 minutes ago, ollypenrice said:

Anyway, when are we going to hear chapter and verse on the guiding RMS of the EQ3 Pro? It's time for an infusion of facts into this conversation!! 😁 I've no idea what this mount can deliver since I don't even recall seeing one in the flesh, but if it's good enough to run at half the pixel scale of its imaging rig (or thereabouts) I'll gladly doff my hat to it.

Olly

PHD2_GuideLog_2021-09-02_005223.txt

Since there are no others interested in sharing theirs, ill share mine. Note that this is not from the EQ3-2 but the EQM-35PRO which has a slightly improved RA axis (but the same DEC axis) and a steel tripod.

I dont remember exactly what happened during this session but it was one of the last times i shot towards low declinations (this was M33 at dec 30). Payload was within advertised limits, so around 8.5kg/10kg. For what its worth FLO seems to have a more reasonable estimate of 7kg in imaging payload for the mount, although i would be wary of suggesting someone mount a 7kg imaging setup on this thing.

I bet you've never seen periodic error in DECLINATION 😎. Well not really periodic error, but if you inspect the log you see it goes off on a trip somewhere after every dither in RA or any other anomaly in RA guiding.

Total RMS of 1.37'' in RA and over 3'' in DEC, but short exposures can be used since DEC does whatever it wants anyway and wanders off occasionally. Unguided is not a wise choice since the P2P error in this case was 45''. So while its not good, it looks like a very wide 6 arcsec/pixel setup would not care about the hiccups. And the hiccups would probably not be as bad and declination would also be usable, so i do think it can work for very low resolution imaging just fine. But thats not really the point, the point is this thing is just a waste of money for someone who wants future proofing.

Did some tests with the new starnet compared to StarXterminator, i dont have the original starnet so wont be testing with that. This particular image is very noisy when stretched this far and so shows remaining artifacts very easily. Very pleased with how the new starnet reduced artifacts! Both run on the same 16bit stretched file.

StarXterminator:

Starnet V2:

Its not artifact free, but very close. The brightest stars still have a background patch of blue behind them, but much better than with StarXterminator.

9 hours ago, Stuart1971 said:

I totally get what you say here about pixel size, but many people moved from CCD to CMOS which have always had smaller pixels, yet one of the main things I read from people was “you only need short exposures with these camera 1 or 2 mins, but lots of them” well I get nothing in a 2 min sub….and need to use 5 mins at least, 🤔🤔🤔🤔

so we’re all those people referring to mono CMOS cameras, I suspect many were, but not all, and when they say “You need a lot of subs” how many is a lot….100, 200, 500…..?? 
I see regular images with my make and model of camera that are superb, with say 2 hours of data….this is when I get disheartened….

Thought i would mention that its not necessary for the single sub to look good, so you might be chasing something that doesn't need to be. Of course the data must be there somewhere and you have to have some sort of statistics to tell you the sub was decent (basic stuff, FWHM, number of stars, etc), but it doesn't have to be visible in a single exposure. Not a bad thing if the single sub looks good of course.

Below are 2 example pictures, one single calibrated and stretched/colourbalanced 30s sub and an image consisting of several hours of subs exactly like this one or slightly worse (picked one at random from hundreds). I am not sure how many hours is in the stacked/processed shot but i think it is either 5 or 6 hours of only 30s exposures, its a work in progress for at least triple this time to wrestle the IFN cleanly out of the background...

There is not even a hint of many of the smaller galaxies in the single sub, even the biggest ones are just a couple of pixels above noise. Never mind the IFN which only showed up in the negative version of a 2h stack and i could never guess that it existed in the single exposure. I am actually amazed myself that stacking somehow makes these structures come out from what looks like a mess of nothing at all, but i trust the technology in this case.

Point is: Its not important for the single sub to look good if the data is there. Photons go in the camera, picture comes out in the end.

5 hours ago, powerlord said:

aye, there used to be an excuse as you say - where would you learn to do better - but now nearly everything is a few clicks away. there's no excuse really. And yeh mechanics who don't use torque wrenches and swear they get it right by feel (though you can bet they have never actually put it to the test) are a bugbear of mine for sure - from wheel bots nearly welded on, to stretched head bolts, etc. arg...

Wheel bolts tightened with a 1m extension as leverage "just in case" 🤣. Never getting that off cleanly again.

This thread was IMO never going to reach a conclusion that everyone agrees with.

People have differing opinions and so give differing advice, isnt it up to the person asking the advice to decide what route to take through the jungle of forum posts? 

I fail to see how a cooled camera + lens + cheap mount is a better alternative to an HEQ5+200P,DS or maybe 150PDS.

Example: 533MC + samyang 135 + AZGTI = around 2000e. Not usable for visual, not usable for planetary/lunar, not usable for medium or small DSO. Only usable for wide field, but very good for that. Mount and lens must be ditched when upgrading = half the money spent is gone.

Example 2: HEQ5+cheap newtonian+Cheap DSLR + some coma corrector = also around 2000e. Usable for visual, usable for planetary, usable for almost all DSOs. Only the DSLR will be upgraded from these, and even that is not a must have upgrade. Worst case scenario is that the cheap synta newt has a lemon of a mirror and will have to be swapped, but tge most expensive and important part: the mount can stay. Will a beginner produce APODs with this? Of course not, but its a learning experience for anyone in the beginning.

For what its worth most beginners can afford neither (from what i have seen), so some compromises will be made in both cases.

Looking at the site you see a picture of what looks like an ion thruster of some kind (blue sci-fi looking thing), which is a curious detail. Ion thrusters have inherently very low thrust so they will need days or weeks to accelerate to the few km/s needed to reach a final orbit after the initial push from the launcher.

But gravity will give you 10 minutes tops, so not something that will be usable. Whatever small cubesat gets put into the projectile will still need to be about 50% chemical high thrust propellant (IE no ion stuff, solid or liquid propellant of some kind) to be fast enough to reach orbit.

If this is somehow made to work so that only minor repairs are needed per launch + new projectile it could be cost efficient for very small satellites

Edit:hmm, not sure where i got the ion thruster idea, cant find it anymore in the site😀. 

8 minutes ago, AstroKeith said:

Whilst I sympathise, the problem is I think more fundamental.

The typical level of technical knowledge isn't up to maintaining such kit. Most people haven't heard of circlip pliers, or the difference between imperial and metric. So they aren't going to go and get some.

Even if someone is aware of their shortcomings, there are no service centres. I spend (and enjoy) quite a lot of time at star parties 'fixing' kit.

I'm personally frustrated by people who refuse, even when explained, to appreciate ohms law. They insist on pulling 6 amps through metres of thin wire and then complain that their batteries rent any good.

"check the connections once the smoke clears out" is a saying mechanics tell as a joke(?) when learning.

In mechanic school (for cars) we had test engines that were not going to be used for anything other than learning at school. Our teachers encouraged us to over tighten some bolts to see what happens and how easily, and then teach how to fix that destroyed thread. Most didn't need any special encouraging, but just accidentally broke some threads as there is really no way for someone to know how easily you can do that. I dont think there is any real way to learn mechanical skills without making all the mistakes one could make and so i will be wary of second hand kit that has a chance its been "improved".

12 minutes ago, wuthton said:

Post #3 - "I don't think 500 eur is going to be enough for any astrophotography mount"

This would be mine, and i still stand by this advice. Well its not really advice the way its said as a personal opinion but it works as advice in this context. I personally think 500eur is not enough for an astrophotography mount (= not tracker). In that thread looked like OP had started the path that i and many others took as beginners and tried to look for the cheapest solution available, which in my opinion leads to ruin more often than not.

AZGTI, Star adventurer, SkyguiderPro are all over 500e with tripods and wedges and whatnot.

Others had better out of the box ideas with DIY solutions in the end.

1 minute ago, vlaiv said:

Well, interesting thing about mounts and tracking is that tracking error in pixels decreases with declination.

It takes Polaris 24h to move 4° in pixel space (it is about 38.5 arc minutes from NCP and circumference of the circle is 2*r*pi so that is about 240 arc minutes or 4°). If you image at 8"/px - than that is about 450px of motion in 24h or 18.75px per hour, or 1px in 3 minutes.

Even if your mount does not move at all - at that declination and that resolution stars will stay mostly round in 3 minute exposures.

In order to really test your mount - you need to track at meridian and then see how well it behaves (same goes for guiding).

I am well aware of this, i had to use this knowledge once i realized the EQM35 was not going to work the way i wanted. After realizing this i looked at targets in very high declinations, like 65 and above and only shot those. And to be fair i was able to get reasonable performance at these latitudes, but this is to be expected. I am fairly confident in saying that if someone absolutely must use an undermounted system, or some obscure DIY solution, shooting high in DEC is the way to go.

The Astromaster pic was on M31, so fairly south. Took me 45 minutes to fiddle with polar aligning and the RA motor speed though (stepless speed adjustment).

3 hours ago, centroid said:

If I can get somewhere near this with a CMOS camera, I will be both convinced, and happy.

I this took this image back in January 2012  with a SX  SXVR H16 CCD, (Kodak sensor), with a 110mm f/7 refractor, albeit separate LRGB. All in one evening, and not one night per filter, as someone mentioned on another group, that is how he uses his CMOS camera to get decent results.

Comment:  for some obscure reason it displays excessively bright posted here, but not on my calibrated PC monitor, or on my website.

Isnt LRGB like (at least) 50% faster than OSC? And the pixel sizes between that camera and your current one are also wildly different so i dont know if these 2 could be compared. Youll probably need 2 nights to reach this if the shooting conditions are the same as they were then, and more than 2 if they have gotten worse.

3 minutes ago, gorann said:

I have to say that the Artesky one is really good looking but then I saw the nobs. How do you get a grip on something looking that smooth? Design over practicallity?

Is this picture really true? Looks like the mount only goes to 50 degrees of latitude?

I was going to comment that those knobs are not really usable with thick gloves in wintertime but looks like they solved the issue by having the mount be restricted to areas around the world that do not get winter 😎.

12 hours ago, wuthton said:

If what you mean by huge mega pixel camera is a camera with huge pixels then yes there is a lot of point. At a short focal lengths, high precision mounts make absolutely no difference whatsoever. My trusty, old Atik 314+ and Samyang 135mm has scale of 8.25"/pixel and I'll do the Daz doorstep challenge with that on the cheapest tracking mount you care to name vs a DSLR on a HEQ5.

My very first astrophoto was taken with a Canon 550D and a kit lens at 100mm fl piggybacking on an Astromaster 130MD with the motor running. Took 12s exposures and stars were very much round, so i think if the astromaster can handle an 8 arcsec/pixel resolution any mount in the universe can.

Wasn't a good picture of course, but point is at this kind of resolution i doubt you can find a mount that just flat out fails to work.

14 minutes ago, wimvb said:

ZWO, Sharpstar, Pegasus Astro, Rainbow Astro, Artesky, and possibly Rowan Astronomy. Why suddenly the hype? Is everyone going portable all of a sudden?

I reckon some harmonic drive manufacturer just came up with a conveniently sized and priced package that all these different manufacturers can implement on their own mounts. I find it difficult to believe that all of these would be unique in-house designs just launched at the same time.

Orbital speeds wont be happening from atmospheric launches, whether it be from sea level or from the summit of Mt Everest. Or maybe they could, but it wouldn't be efficient and the satellite would still need to do a several km/s insertion burn at apogee. In an airless world you could point the launcher sideways and just a small correction would be required at apoapsis, but from an atmosphere you do want to launch at a fairly high angle, or the projectile will either burn up or slow down before escaping the atmosphere. The atmosphere acts like a soup made of brick walls at hypersonic speeds in the thick parts (below i dont know, maybe 30km?).

Launching at an angle of lets say 45 degrees could work, but then you would be going 45 degrees to the wrong way once in space, and you're actually probably only half way to orbital speed at apogee. If you just launched the projectile faster you would still be going the wrong way, but now faster and the apogee would be pushed higher, so still a problem.

If this is the projectile in question it would fit a decent sized mini-satellite that could have enough propellant of its own to reach orbit, but not sure if all this trouble is worth it to make sure the satellite can survive the G forces and all the design decisions that come with it.

Anything coming out of the launcher tube will be a mist of atoms as soon as it hits the atmosphere at those speeds. This would be neat on the Moon though, if a base ever gets built. It could be orientated so that it gets put into Earth atmosphere intercepting orbit straight from the Moon with no propellant used. Not really usable for human transportation unless the centrifuge is absolutely massive in size to reduce G forces to crew, but if you wanted to move payload from the Moon surface to the Earth it would be pretty cool.

What would you want to shoot back to Earth though? Minerals? Rocks? Whatever someone figures out can be mined from the Moon for profit i guess.

1 hour ago, Bukko said:

In the early part of this thread, it is mentioned that newcomers to AP sometimes have limited budgets and no sound idea what they would like to concentrate on...

And we need to think "out of the box" to come up with ideas and possible solutions.

I am interested in where the forum is with regards proposing the use of a remote imaging site instead of purchasing hardware?

Different scopes, good cameras and mounts and with a budget of a few hundred pounds, could probably get quite a lot of quality imaging runs for the money -  good value for money, compared to how few clear nights we often get in a year..

Gordon.

 

 

I think one of the best parts of astrophotography is the part where i can look at an image i took and say "i did this". Every step of the way was something i learned to do through research online, trial and error by myself, nights spent out with the telescope. Pack all my stuff into my car, drive to a location, setup the gear as best as i have learned, start the session, troubleshoot at least 1 unforeseen issue per night, its always a lot of work. Sometimes the trip is a complete waste and i feel like a clown for doing this, but when the result gets put to an image in the end its all worth it, i still cant believe its possible for me to take pictures of galaxies with amateur gear in very much amateur conditions.

Buying results taken with some other persons equipment in a desert somewhere out of my reach wouldn't feel the same to me at all and i doubt i would really care about the data quality then since it wasn't mine to begin with.

5 minutes ago, wuthton said:

I've got a Moravian G2 8300 screwed onto a Redcat 51, would I see any improvement in my images upgrading say from a EQ3 pro to a HEQ5?

Having imaged with an EQM35 (similar to EQ3, a bit better) for a bit more than a year i can wholeheartedly say that i recommend absolutely nobody ever buy the mount. There is nothing but regret in my voice when i say that i bought the mount and tried to make it work while also believing all the time that its a waste of money and time. I ended up buying an AZEQ6 for 1900e to get a mount that works better, but thing is the AZEQ6 actually cost me 2650e considering the price of the EQM35 so did not in fact save money. Doubt i will be able to sell the EQM35 for more than half the price i bought it, if even able to sell it at all. In your case, the difference would probably be small or nonexistent with the little 50mm scope but once you put a telescope larger than a finder scope on the mount you will see the difference. I dont think im too far off when saying that most folks will want to move on to bigger scopes sooner rather than later regardless if thats a good idea or not.

You can use the EQ3 with the redcat51, you can also use the HEQ5 with the redcat 51. Difference is one is upgradeable with a bigger scope and one is really not. I think putting emphasis on the mount is very good advice for beginners, and advice that i ignored and now understand why it is so.

1 hour ago, Stuart1971 said:

Flats are not good with CMOS cameras if under around 1 second, best to do between 3 and 5 second flats, so you need a dimmer light source…👍🏼

I too found that 50ms flats calibrated my lights well with my Rising cam OSC. They were so fast because i was experimenting with different gain settings, i dont usually use so fast exposures for flats. But usually mine are somewhere around 130ms and also work well.