ONIKKINEN

I will be looking for new tube rings soon(ish) to fit to a roughly 235mm outer diameter tube to replace the VX8 rings i currently have. Big knurled screws and hinges are a must have, since i will be using the scope almost exclusively with thick gloves and will want to change between visual and imaging tube orientations easily. If its not easy it doesn't get done and im not ready to doom my scope to be a full astrograph just yet (would need a second scope first, a thread for another day and another few paychecks). They also need to have flat contact surfaces for a losmandy plate on the bottom and a vixen one on top.

I know of:

GSO rings: https://www.teleskop-express.de/shop/product_info.php/info/p1198_Pipe-clamps-for-tubes-with-D-230mm---Set-of-2-pieces.html

Orion (US) rings:https://www.teleskop-express.de/shop/product_info.php/info/p987_Orion-tube-ring-set--two-pcs-----for-235-mm-tube-diameter.html

Skywatcher rings (similar to Orion ones, maybe the same?: https://www.firstlightoptics.com/tube-rings/skywatcher-telescope-tube-rings.html

Primalucelab rings, apparently made of gold according to the price: https://www.teleskop-express.de/shop/product_info.php/info/p10614_PrimaLuceLab-235mm-PLUS-support-rings.html

Which of these, or some other would you think is the best or are the low price ones all the same? I dont think the rings themselves need to be spaceflight-quality since the bottom and top rails will be the rigidest structures at play here and will make the rings a bit trivial, thoughts?

Basically anything other than the rings i currently have is on my mind. I also know that OOUK makes higher quality CNC rings for a solid-gold pricerange but since in not convinced about the mechanical quality of my current OOUK rings im not going to risk it with the higher cost ones.

Love it! Especially like the tight crop of the center. Makes the core feel "alive" and dynamic somehow.

1 hour ago, pipnina said:

my cam to cool at -10 or -20c caused the AR window to fog up after a certain amount of time, apparently in this 70%+ weather I can only do -5c at most.

Is this with the rising cam 571? Fitting a ZWO sensor window heater solves the issue, but actually no need to cool down so aggressively since the dark current produced is so low.

I have done some tests on mine and even at +10 it still takes 140s for every 1 electron of dark current per pixel to build up. Since astro darkness is out now, i reckon its safe to say you have enough sky brightness to swamp the tiny little dark signal to oblivion and back even from normally good skies and a much warmer sensor than you currently shoot at. At 0c the dark current buildup would be around 275s per 1e, at -5 its 510s per 1e and at -10 its a silly 1945s per 1e!

2 minutes ago, malc-c said:

probably down to all the listening its doing and sending it all back to Google so as best to taylor your next youtube experience

And which ads to show you and when to make a profit on peoples personal data...

Aside that, the YouTube algorithm is actually scary how good it is. I dont really subscribe to any channels since YouTube will know what i want to watch anyway so no point in doing that. Somehow it has profiled me perfectly and i rarely if ever see a video in my home page that i am not interested in at all.

The newest PBS space time video has a topic about the commonly ignored issues of interstellar travel regarding problems other than just reaching a speed that doesn't make the trip a thousand year one, i found it pretty interesting.

https://www.amazon.de/-/en/Super-Lube-21030-Synthetic-Grease/dp/B000XBH9HI/?_encoding=UTF8&pf_rd_p=679c5c41-3ec0-4d4f-8104-048309a30e62&pd_rd_wg=mjCcb&pf_rd_r=1DXNHZZQHWQ95GDE016Q&content-id=amzn1.sym.679c5c41-3ec0-4d4f-8104-048309a30e62&pd_rd_w=kooaf&pd_rd_r=17069755-939b-43e4-af09-81d30f6d82a0&ref_=ci_mcx_mr_hp_atf_m

This one maybe?

1 hour ago, Adam J said:

Most quote half the resolution of a mono camera for OSC but this is wrong. 

Ill explain with a diagram at lunch.

Adam

Something to do with higher resolution in green compared to red and blue no doubt? I was under the impression that the resolution of an OSC image is still only the resolution of a single channel (unless dithered every frame and bayer drizzled), but it just so happens that there are 2 green channels which just increases green SNR, but not really resolution. Anyway, very interested in seeing a technical explanation for this.

5 hours ago, Lotinsh said:

Yeah imaging indeed isn't cheap, hence I'm looking at the used market. I know I don't have enough funds to step up the game yet, but my plan is once a while make an upgrade once I can. For now my budget is <100 Eur, not much. Especially with the inflation.

Are there perhaps other upgrades I could do to improve exposure time or something that helps imaging for my budget?

Incremental upgrades of not that great purchases do not add up to one great purchase over a longer period of time in terms what you get for your money, so i would probably try to save more money at first and then figure out what to buy next. Its very easy to make bad purchases when trying to save money and only end up having to spend more over a longer period of time, i fell into this trap when beginning and ended up spending around 50% more than what i would have had to spend if i just made the right purchases in the beginning.

Guiding is perhaps the most important part in astrophotography so you should look into ways you can make that happen. Maybe you have to split the budget in 2 and get a motor kit (like on step) that can be guided just for the RA axis and then save up money for a camera that can be used for guiding. I bet there are a thousand un-used old webcam-guidecams and guide cams like the 120MM that someone is looking to get rid of and you could fetch one for a good price.

Both cameras you have in mind have tiny pixels, which you probably wont be able to make use of with your scope in DSO imaging (without binning), and for planetary imaging there are better and cheaper options available. You can of course bin to reach better sampling, but it would be better to have bigger pixels to begin with. The 183 on paper seems like a bit of an old tech camera in terms of its technical specs, so that's a hard sell in my opinion. The 2 cameras you have in mind also have much smaller sensors compared to any DSLR, so you would lose a lot of field of view to that. I dont think either camera would give you the improvements you are looking for when compared to DSLRs, other than much higher QE, but that coupled with smaller pixels could actually take you to the opposite way in terms of imaging speed.

At around the budget you have you could look into modifying your existing DSLR instead, or looking for a premodified one from the used market?

The Galileo spacecraft had an even weaker signal at first because of its failed antenna deployment, quote from the Wiki article:

Quote

the high-gain antenna was to have transmitted at 134 kilobits per second, whereas LGA-1 was only intended to transmit at about 8 to 16 bits per second. LGA-1 transmitted with a power of about 15 to 20 watts, which by the time it reached Earth and had been collected by one of the large aperture 70-meter DSN antennas, had a total power of about 10 zeptowatts.^[97] Through the implementation of sophisticated technologies, the arraying of several Deep Space Network antennas and sensitivity upgrades to the receivers used to listen to Galileo's signal, data throughput was increased to a maximum of 160 bits per second.^[98][99] By further using data compression, the effective bandwidth could be raised to 1,000 bits per second

so between 16-160 bits per second without data compression, yikes!

If you polar align very accurately and shoot at higher declination targets with short subs you can get away with not guiding in dec at all.

Have a look at targets at around ursa major and such, plenty of them are far enough north that dec drift can be trivialised.

57 minutes ago, AstroMuni said:

I was of the understanding that the background extraction capabilities of Graxpert are now integrated into Siril. So am I missing something here?

I have not heard about this, do you have a link to some reading? I have some old version installed and that has still the old extraction tool, but this would be great news if its the case for a new version.

6 minutes ago, Dam said:

You are very correct sir and it is an ebay sale so am.hoping am having some kind of cover via paypal but wouldn't hold my breath as seller did state no returns so will dispute it as not fit for purpose . However i wonder if i should attempt to take a ring out and inspect as it seem to be a IR clear filter from what i can tell  so hopefully there is no damage to sensor but dont want to expose sensor to dust.

The proper tool for the job of opening the retaining ring would be a lens spanner:

You can also use circlip pliers or needle nose pliers, but that can be finnicky depending on how tight the retaining ring was tightened and im guessing the previous owner used something like that and had some trouble judging from the scuffs. If the marks are on the glass filter only and are not actual scratches but some kind of dirt then i guess you could just try to clean it with some isopropyl alcohol and something that doesn't have a risk of scratching the glass, like some cotton wool. You should do this in as dust free of an environment as possible and have something nearby to immediately cover the sensor once you remove the glass. And check that what you cover the sensor with is not dusty itself actually. If you're lucky you wont get dust inside the sensor, but household dust suspended in air can easily make its way onto the sensor.

I dont know how this particular camera is built, but if it has desiccant tabs integrated somewhere inside the glass window (like mine), you could also accidentally saturate those if you have high humidity indoors and have a risk of dew forming on the sensor later. That is part of the reason why certain camera manufacturers dont want people poking inside.

10 minutes ago, Dam said:

Yes bought it as used unfortunately and am guessing am stuck with it now. Yes looks like it a very nice improvement 😄 overall. Wonder if this filter can be replaced with new one? Any thoughts? 

Above all else i would try to return the camera to the person you bought it from. If they have any shame they would agree to cancel the deal, but i wouldn't hold my breath on that. I dont know about UK laws so cant advice on that but i think this can be interpreted as a fraudulent sale from the looks of things. The previous owner has obviously opened the camera and done that using tools not fit for the purpose (the marks on the ring) so this paints a picture of a complete moron doing something to electronics with no experience on the matter at all. After doing whatever they did to the camera they left some crud possibly on the sensor itself (hard to tell from the image where the mark is, the sensor, the sensor window inside or the outside), which is very difficult to clean. Basically if you dont have a clean room you will get a dust particle or two on the sensor.

25 minutes ago, Dam said:

Just a quick update i took my train apart and found this on camera glass😱?? Is this damaged  coating or just a dirt? Not sure if this is culprit but looks very bad.

If you just bought the camera, stop before doing anything to it and return it to the seller. If bought used, good luck, but if bought from a retailer of any renown you will get a new one. From the looks of things it looks like someone has "improved" the camera and left their watermark to where it should not have been left.

I left the camera running overnight, but it looks like my mini-pc shut down after 9 subs, so here is 9 hours of darks with 1h subs at -10c with my rising cam IMX571 OSC camera. I did not debayer the subs and stacked with pixel maximum in Siril. To my eye it looks like there are far fewer hits than with the previously posted shots, even considering differences in exposure times. The linked paper mentions pixel height as well as pixel pitch, so maybe a modern CMOS sensor has a very shallow pixel as well as a smaller pixel pitch so there are fewer hits?

Also answered my own question about the dark current of the camera, at -10c there is 1 electron per roughly 30 minutes of exposure of dark signal.

43 minutes ago, wimvb said:

Imo, this isn't a gradient. In this case your gradient removal tool removed valid data as well. Careful marker positioning, as you already noted, should resolve this issue.

Yes, i have killed a not insignificant amount of the faintest nebulosity with the process. Most of the red blobs i would imagine are real signal, but the other blotches are kinda all over the place still and looks sort of familiar to my background prior to focuser upgrade, flocking and some other improvements to mechanics on my OTA, hence the gut feeling that there are issues not related to OPs processing skills.

I did 2 processes with the data, a simple 2 minute process with Siril, https://www.graxpert.com/ and ASTAP. First binned x2 in ASTAP, then gradient removal in Graxpert, then photometric colour calibration in Siril and lastly a simple stretch and a bit of a resolution reduction.

Then the one where i spent a bit of time in Photoshop with layer masks, starless processing and general fiddling around with saturation, sharpness, noise control (with and without TopazAI):

I dont image nebulae myself so im definitely not an expert in processing them, but i think your data is very nice and was quite easy to work with apart from the gradients which you struggled with too. Thankfully Graxpert makes short work of it and outputs a mostly gradient free image. I didn't do the sampler placements perfectly because the areas inside the heart nebula came out darker than the outside, so it could be improved. Below is an image of the compålex background model that Graxpert removed:

As you can see its a very complex and messy gradient and not one that can be explained by just light pollution or something normal during capture. Im going to guess you have light leaks and problems with the flats, not sure how else to explain the gradients but i would need to have a look at the flats and subs to say yay or nay more of that. But Graxpert works very nicely with flawed flats and you can salvage a very cursed image with that, give it a try!

As for why i think you struggled with the colours in the image is that the CLS filter clips most of theyellow-red areas out and really leaves only blue-bluegreen and then skips all the way to H-alpha. That makes your background noticeably blue and leaves all of the other detail as red from H-alpha. The photometric colour calibration tool in Siril attempts to create real colours but really it cannot since not all of the spectrum was captured. The result can look a bit off and that may be the issue if you try manual processing in PS. Overall i would recommend you ditch PS as soon as possible for early processing and do the core parts with something more dedicated to astrophotography, like Siril. With Siril you can create the first image in this post in a couple of clicks, no guessing fiddling required!

26 minutes ago, inFINNity Deck said:

That would me quite interesting! Could you please post your findings here?

Nicolàs

Sure, im going to give it some time to get some sort of meaningful average over some period of time. I am also interested in getting real world data on how much dark current my camera produces so im going to take at least 5 subs to get some meaningful amount to sample from.

22 minutes ago, vlaiv said:

I've found that majority of impacts in darks are not in fact cosmic rays but of earthly origin.

Once I created set of darks near some tools used to clean wood stove - bucket and small shovel and since those had some ash residue on them - I got much higher incidence.

Conclusion was that it was due to radioactive decay in ash (wood absorbs radioactive material) - quite possibly from Chernobyl era.

Btw - take any set of darks and stack them with max operator instead of average and you will in one image how many hits you had over whole session of taking darks.

The ash thing sounds perfectly plausible to me. Mushrooms for example are still quite high in Cesium-137 from Chernobyl fallout and there are regions here where its not recommended to forage wild mushrooms and eat all that many of them.

Very interesting read both @inFINNity Deck and @VectorQuantity. Seeing as i have nothing better to do i am now taking 3600s darks to see how many on average would hit my sensor. Doubt i will do anything with the information but im just curious how common this is.

1 hour ago, Pitch Black Skies said:

How do I integrate short exposures of the stars into the main integration. I tried to do it with M42 before but was unsuccessful. I was using DSS and it gave an error message stating the exposure lengths differed. I've seen a few people mention Affinity Star but haven't gotten round to checking it out.

If you have one of the newer low noise and high full well capacity cameras you will probably find that this trick is not necessary (did you have the 533?). Its actually quite difficult to saturate stars to a point where they look bothersome in the stacked image and the double exposure thing is probably not worth the effort. Some stars will always saturate in an image but these will look out of place if you try to un-saturate them with the double exposures thing. Anything but the brightest stars will probably not saturate if you expose for the 3x read noise swamp thing.

But an easy way to combine the 2 would be with layers in photoshop. Stack both datasets separately and then combine them later in processing, just do early processing the same way for both stacks (colour calibration mainly, so that the stars and the main image have the same colours). You can use layer masks and other easy to do trickery to combine the 2 images the way you like, for instance only blend in the brightest very saturated stars and leave the medium brightness stars as they are.

12 minutes ago, ollypenrice said:

And platesolving always works and never acts the goat? My robotic clients will be delighted to hear this. When did this miracle occur? 😁

Olly

Definitely doesnt always work, but what does? None of my kit works all the time but then again its not a remote setup so doesnt have to.

Isnt goat short for greatest of all time? In that case we agree 🤣. Just joking, wouldnt try to convince you that platesolving is good even if i was paid to do that!

On 13/06/2022 at 19:17, malc-c said:

I agree.  Same goes for me.  Not knocking the product, but just pointing out that there are lots of cheaper alternatives that do the same thing.  

I dont agree that the alternatives offered in this thread are the same thing as the Prologic meter. I think i laid out at least decent reasoning in my previous comment as to why the price is (justifiably) higher. Can you link a well made and durable meter that does the same but for cheaper?

Its not a rhetorical or snarky question, i would genuinely be interested in one that does the same (and does not need AC power).

3 hours ago, Shimrod said:

Prices are already on the FLO website as well - the 678 is £319

Price seems very nice actually. I would have expected more.

the 678 looks like it could be a good all-rounder for guiding lunar and planetary. For guiding needs to be binned but the read noise is very low so no problem, for planetary and lunar the 2 micron pixels sound very enticing.

Damn it ZWO, dont announce these things when im broke!

5 minutes ago, vlaiv said:

Having standard orientation of sensor allows for markers on camera / ota for quick alignment.

0/90 can also be easily aligned without plate solving - with drift exposures (drift is in RA direction and bright star that drifts in exposure will leave a line - if that line is either horizontal or vertical in frame - you are aligned).

Slewing during a short exposure or taking a long enough exposure to have obvious trails takes the same amount of time as platesolving a short exposure. I have used both and really its not a big deal and i wouldnt want to discourage someone from using whatever framing they want.

That said, 95% of targets are fine at either 0 or 90 degrees so marking those on the focuser takes the least amount of time. But also no reason not to mark 75 degrees if one has a project that needs it.