dan_adi
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Posts posted by dan_adi
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9 hours ago, kmaslin said:
Has anyone got experience of on-axis guiding, especially the setup from Innovations Foresight? Not cheap but wonder how it compares with offaxis guiding when using bigger scopes/smaller fov where it is difficult to do multiple star guiding
Hi, I 've used the ONAG gadget from IF on my SCT. It works fine, plenty of guide stars to choose from. But it takes alot of backspace, around 60 mm if I remember. Since the SCT I've moved on to a 8 inch refractor, and my field flattener has a backfocus of 90 mm, and I can't fit the ONAG+FW+camera in those 90 mm.
With the refractor I use Optecs Saggita 3 inch OAG that has a decent 12 mm prism and solid build quality, and I have no problems with guide stars (ASI 174 mini camera).
Overall it is a nice solution specially if you image at long FL, where guidestars could be rare.
Regarding the guiding in Near Infrared, from what I have read and experienced ,I don't see any important, earth shattering benefit over guiding using the full spectrum. Also the quantum efficiency of CCD/CMOS guide cameras is lower in the NIR. For example my ASI 174 mini has 20% QE at around 800 nm, that means my guide exposures need to be longer to get a decent SNR for the guidestar. Since I have a Mesu mount 5-10 sec exposures are just fine.
If your mount requires shorter guide exposures because you need frequent corrections, I suggest using IF own guiding software (Skyguide), because it can deal with lower SNRs in the NIR, much better than centroid guiding algorithms like PHD2.
A last note, if you go this route make sure you have enough backfocus space and search for a guide camera with higher QE in the NIR.
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Also great for Mesu friction drive mounts. Do you know if it has DC cables plugs 2.1 or 2.5 mm ?
PS: On their website they do have 2.1-2.5 mm option for plugs. Looks like a great way to balance a mount. Some high end mount have something similar in their own software
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On 28/05/2022 at 18:55, pipnina said:
When I first computerised my mount I expected this hobby to become a bit easier, and certainly for the level of automation to make me able to image more frequently and collect more & better data when I did. Sadly since I made the move to a cooled mono cam with this computerised setup my imaging life has been anything but stress-free.
Has the quality of my images gone up? Certainly. Has it introduced numerous independent problems that make me generally unsatisfied with my equipment, even though it has more than tripled in cost relative to last year? Unfortunately...
Whether it be poor flat frame calibration (neither 130-PDS nor TS-Photon 200/800 are free from this...) tracking/guiding woes, collimation challenges, suspicious levels of vignetting, filter reflections, computer errors, heavy mono cam & filters sagging the focuser or plain not sitting straight, the TS telescope not actually being compatible with their own coma corrector... It's all left me very sad and frustrated and with far less imaging time and lower-quality images than I expected if these problems did not exist.
When I finally got fed up with trying to tinker with my 130P-DS, and went for the only real option in my budget at the moment without sliding backwards in aprture and focal length (TS-Photon F4) I realised that while this scope solved one issue (PDS compression-fittingless focuser and barrel intrusion) it introduced several more such as the coma corrector pushing focus so far out, that the tube can't extend far enough and the corrector has to sit about 3-4cm pulled out, meaning from the stock of the focuser to the flange of my camera I now have a whopping 12cm gap, which is just ludicrous and creating a massive torque on the tube and focuser when my 1.5kg of camera, filters and CC are sitting in it parallel to the ground. This shows in my images as well as stars change shape throughout.
Then the filters, I adopted the "buy once cry once" approach and bought chroma 36mm, which are supposed to be an ideal fit for APS-C sized cameras. But while the LRGB filters seem to be working fine, the even more expensive narrowbands produce horrible reflections around bright stars, no matter the orientation:
As you can see the reflections are present in this 3nm Ha filter whether the coated side is facing the camera or the telescope (I flipped the filter wheel around). This is only a 60s exposure of arcturus. I guess my hopes of a good narrowband session near orion's belt are shattered now! This pattern doesn't show up in lum, so it's definitely something to do with the narrowband filters.
Then there's the suspicious vignetting (ADU in a flat or the background of a luminance frame) of about 50%! This scope advertises it's "90% illuminated zone" at being far larger than the diagonal of my camera... And I have already reduced the distance between my sensor and the filters as much as the 17.5mm backspacing built into my cam allows.
And perhaps most frustrating of all, my mount wants to just... turn itself off randomly as of late. Sometimes the INDI control panel says it's outside of its alt-az limits (even if I turn those limits off in EQmod, it still does it), sometimes it claims it wants a meridian flip, sometimes, just nothing at all. All I have to do is press the button in ekos to start tracking again but not having to babysit the scope was meant to be an advantage of computerising it! Plus the drift it causes means I have to re-create the framing all over again.
At this point I just don't know where to go with this hobby. It's so so good when things are running well, but oh so horrifying when getting death by a thousand cuts when so many thousands of pounds turns out to be not so well spent as expected... What do I do!? Where do I best direct my current astro-savings project money to?! So many problems and (after the computer and camera upgrades) not enough money to just splash out and hope high end gear will fix it.
If anyone has any ideas I'll gladly hear them, because this is getting ridiculous : (
Unfortunately astrophotography is hard. I went through the same frustrations when I started. 90% troubleshooting and almost no reward. Factor in cloudy weather and I almost gave up.
The only way it got easier for me was with a good refractor (CFF), OAG(Optec), focuser (Optec), and a good mount (Mesu 200). I don't think there is a magical way to improve a scope or a mount that is made to a price point, and I ve learned the hard way to adjust my expectations accordingly.
Bottom line, the better the gear, the easier it gets (this was my experience)
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True, I think they didn't think about the targeted audience. They should have made a profesional version for big observatories and have a trained profesional in PI hired for such a job, and a user friendly version for a simple workflow, intended for the amateur market. They did try and I ve appreciated the WBPP, now they could take it one step further for the rest of the work flow.
Overall when the learning curve is too steep, most will have a hard time.
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As Olly I found imaging with a 12 inch SCT disappointing even on a good mount as the Mesu 200. The amount of effort and tinkering made me spend more time troubleshooting than actual imaging, and the results were not that good for me.. SCTs are fine for visual, but for imaging I've switched to refractors. They do produce good results with planetary imaging though..most likely because planetary imaging is not very demanding on the gear
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For starters it would be good ideea to stick to refractors, low to mid focal lengths. I made the mistake of starting with a SCT and I've spend 2 years mostly tinkering than actual imaging. Last year I have switched to a refractor and I actually started enjoying the hobby. From your location you can do LRGB and narrow band with no problem
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5 minutes ago, Moonwrecker said:
Cheers Dan,
I’ll have a look. 👍
I've been using it for 4 years with no problems, now I use it on my refractor. I find it better than the stock FeatherTouch, at least for astrophotography... For visual the FT is ok.
It has 80 nanometers per step, doesn't get more precise than this. Also for the SCT I recommend using it's temperature compensation routine if you image.
Clear skies!
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On 14/05/2022 at 09:59, ollypenrice said:
...to whom do the authors of this menu think they are talking? If they are well entrenched on the Asperger's continuum they won't care...
However, terms like opacity, feather, erase, select, minimize, maximize, etc etc, though used metaphorically to describe mathematical manipulations, make intuitive sense to me and create an analogue processing experience.
Olly
I thought I was the only one finding PI made for mathematicians :)).
I even complained on their forum about making the software more user friendly, but the moderators didn't take it very well
My opinion is that software needs to be user friendly and automated as much as possible. If you have to take paid courses like those by Adam Block in order to use it, the design is simply bad, like in the old days in Linux when you had to use a terminal and learn commands to copy a file from one place to another....
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On 19/05/2022 at 23:52, Moonwrecker said:
I really need your help folks!!!
This feels like a prayer
I am trying to solve an ongoing brain teaser that is actually starting to drive me nuts. I want to get an ASCOM compatible (preferably ZWO EFA) Auto focus onto a Meade LX10.
Yes, I know it's an older scope, but the optics are good (scopes never really been used before I got it) and I am about to de-fork it and invest in, and whack it on an EQ6 PRO Mount to future proof my astronomy for the medium term.
I am going round in circles and I feel like a dog chasing it's tail.
Question 1 - Can I get the original focus knob of off the scope? If so how? And after the two visible allen grub screws are removed does it screw off? Once off what size is the spindle.
Question 2 - Once the knobs off, will the ZWO kit for use with Celestron 9.25 (with the flexible adaptor) fit straight on?
Question 3 - If not is there a belt drive system that will work? If so, any idea what components are needed?
Question 4 - If questions 1 - 3 are unanswerable or simply don't work, I could stick a Crayford style draw tube on. Right? - This leads to Q5 onwards????
Question 5 - Dual speed Crayford, without spending a small fortune on an old scope. Which one will take the EAF?
Question 6 - I've looked TS optics 2 inch SCT dual speed - Link Below. In conjunction with the Wega 3D printed bracket. But don't know if the two are compatible???
https://www.astroshop.eu/focusers/ts-optics-focuser-crayford-2-/p,11264#tab_bar_0_select
Apparently they are from the description but it's not exactly clear from the description - Your'll see what I mean.
Question 7 - Will the Skywatcher (or equivalent) Dual speed Focuser work with the ZWO EAF if so How to I attach it ?
Question 8 - If all else fails - has anyone seen or used this product? See below link - If so is it any good?
Looks like a perfect solution and exactly what I am trying to achieve but I don't want to Shell out on something that turns up having been made by someone in their garage and wish I'd have answers Q1 through 7 and got a better result.
If you are able to help before my head implodes I would be eternally grateful.
Amen!
CR
For an SCT you could use the Optec Leo low profile focuser. Very good focuser
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1 hour ago, tomato said:
It’s definitely worth contacting Lucas as the Mk 2 Mesu doesn’t have the same encoders as the Mk 1 and uses the Sitech 1 unit. It might be possible to ‘dumb down’ your Mesu to run with the Sitech 1. I have seen a used Mesu 200 for sale with one encoder disconnected from the Sitech 2, presumably because the encoder had stopped working.
With modern quick and reliable plate solving, absolute encoders are not essential.
Neither Mesu Mk1 or Mk2 use absolute encoders. The Mesu 300 is fitted with Renishaw absolute encoders on RA and DEC, most likely the common 26 bit ones (that is 2^26, or ~67 million tiks per rev, or 51.78 ticks/arcsec that gives a resolution of 0.019 arcseconds per tick)
Indeed absolute encoders (Renishaw) are not essential, but they do improve tracking and pointing substantially on any mount design, and most importantly give you more time to focus on imaging. Pair that with a good pointing/tracking model software like PointXP (in case of sitech or planewave) and autoguiding is no longer needed for subs ranging from 5 to 20 min or so. Expose longer than that and you will have to guide, but the guiding will be very gentle (low aggression and rare, like 10 sec exposures once or twice a minute). But with new, sensitive CMOS camera who exposes for 20-30 min per sub these days anyway ..
When I get my Mesu 200 fitted with Renishaw 26 bit encoders I will give a more hands-on experience, besides the usual theory, but I have to say I haven't seen anyone complain about using absolute encoders ...
This is a great presentation by Dan Gray from Sitech about improving mounts:
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1 hour ago, Skipper Billy said:
Thanks for the info dan_adi but I am severely space limited - it has to fit in a 4' x 4' box!
My current setup just fits.
Then maybe it's time for upgrading to a obsy 2.0
in order to make a little more room for a new scope. My refractor barely fits in my obsy too, but I don't see myself upgrading from a 8 inch frac to a 10 inch one, although one can dream :).
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Another vote for Mesu 200. Reliable mount, no maintenance.
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https://www.optecinc.com/astronomy/catalog/oag/19340.htm
I have this one and it's great
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When I wanted more focal length, I purchased a 12 in SCT and put it on a Mesu 200 mount. Without going through all the story, I got rid of the SCT and got a longer focal length refractor from CFF. It is plug and play, no hassle, great optics. Last summer I finally started imaging with the 8 inch refractor, after 2 years optimizing/tinkering the SCT. I can't wait for the weather to calm down and start imaging again
My recommendation: stick to refractors. If the cost is prohibitive, then at least try to get a 10-12 inch RC from CFF or one of those 12 inch Planewave CDKs.
The image below is a test image with a 1300 mm FL , 8 inch refractor. Target is Abell 2218, around 40 hours exp time in Luminance. Just some DBE and stretch, nothing fancy yet ... much to learn in PI . There are lots of awesome small galaxies and by the the end of summer I hope some gravitational arcs in the middle
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@BCN_Sean, found two bugs.
1st in device.py, line 12, Central obstruction should be converted from mm to meters.
2nd in ETC.py, functions ExposureTimePoint and ExposureTimeExtended, pixel surface should equal imageScale **2, because I've already included binning in image scale computation, so delete * binning **2
I didn't catch the bugs early because I've tested with CO=0 and binning=1 😁
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6 hours ago, BCN_Sean said:
@dan_adi, I've had a look under Monterey as well, and it's working the same as on the other one.
Also (don't kill me for this!) I've had a bit of a noodle around in the code by adding a function to detect whether MacOS is running dark or light, and set the colours accordingly.
On the contrary, thanks a lot ! . I am not a professional programmer so any help is greatly appreciated. Like you I use python at work from time to time. This evening I took a look at the app on windows and ubuntu. I have to change the look a little bit in every OS, so it will take some time to finish everything. Also I was thinking of adding the 'reverse' option, meaning the user can input the exposure time per sub, the number of subs to stack, and the app will compute the resulting SNR stack.
PS: on a Mac button instead of bg=colorBackground I should have used highlightbackground=colorBackground. Now the universe makes sense again! 😀
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1 minute ago, alex_stars said:
Given all other observing conditions equal (light pollution and such) isn't this the telltale sign for the refractor having a lot more contrast than the SCT, due to its design. I'd argue it is 👍
Most likely this is a valid explanation. It's nice to see the theory go hand in hand with observation. That said, there is no perfect telescope.... refractors come close, but going up in aperture comes with lots $$$ and becomes impractical for both amateurs and professionals. Also I see very few, if any, comparisons between high quality reflectors and refractors. Ultimately one has to decide what they want to image/observe, and choose the right tool for the job with the best quality they can afford (taking into account the local conditions - light pollution, seeing).
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8 hours ago, BCN_Sean said:
I wouldn't say I'm proficient at it, just have it about for working with the occasional script and whatever that pops up; and after looking up a couple of other dependencies I didn't have here's the result. What did interest me, though, was tkinter not accepting the fg setting,
Not got time to look in to it further tonight, but have had a couple of runs with it, and nothing noticeable error wise popped out (aside from a memory page error generated by Python, but that isn't an error at the moment as the rig is rendering a heavy video at the same time).
So far it looks good, and when I'm caffeinated tomorrow, and got a couple of hours to dedicate to it, I'll have a deeper look in to it and I'll have a look on the other machine (running MacOS12) as well.
Nice to see that it is working. Good job!
For your simulation, with such a bright star, you ca go to a SNR of 100 or above, otherwise an exposure time of 0.013 seconds will be too low for practical reasons. The dark banding around the lower buttons only appears with macOS Dark theme enabled, must be a bug in Tkinter...
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1 hour ago, BCN_Sean said:
Not working on 10.15.7 with Python 3.9 installed; it's throwing up an error that it can't find the runtime locations.
Thanks for trying, I will search for a fix. If you have python installed, and I presume you know how to use it , I will link the source code.
The main program is ETC.py
The files device.py and utility.py are modules imported in ETC.py.
CCD.csv contains QE data for the sensors.
All the files need to be placed in the same folder. In utility.py at line 98 and line 247, you will need to modify the file path to the CCD.csv file, in order to point to your desired file location. Example: '/Users/yourusername/Documents/ETC_folder/CCD.csv'
For compiling you will need the synphot library and astropy library:
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I've added a couple more cameras, and I've compiled it for MacOS. If you are a mac user, please select Light theme from system preferences. Don't know why, but with a Dark theme, there is a weird banding ... Browsing the forums for this error, I think there is a bug with the Tkinter library in python, so not much I can do to remedy it.
Anyway, if someone uses a Mac, please test the app. Unzip, then run it.
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On 21/02/2021 at 19:18, alex_stars said:
Kind of don't want to let this thread die, so here is the long ago mentioned comparison between a C14 (planetary imaging favourite) and that 7 inch Mak.
- A C14 is equal to a 248 mm (9.76 inch) refractor and the MTF50 value for both scopes is at 0.91/arcsec or at 1.09 arcsec.
Looking forward to the next round of comments
Pretty much nailed it. I don't have a C14" and a 9.74" APO, but I have a Meade 12" SCT and a 8" APO. In my limited visual experience with the two, the details on Jupiter where kind-off the same, but sometimes the 8" pulled a little bit ahead (maybe the seeing, maybe the collimation in the SCT, maybe the temperature ... or simply the focus ). Overall the viewing experience was in favor of the refractor but it's subjective to quantify by how much. Also I noticed the background sky was darker in the refractor, while being grey-ish in the SCT. When observing the Orion nebula the grey-ish background in the SCT made it harder to distinguish the subtle shades in the nebulosity, and I found the image in the refractor better. Again these are not earth shattering differences, but they are there.
With regard to DSO imaging, the refractor wins.
Interesting thread!
PS: Don't take away from this that I am bashing SCTs. I simply found the refractor to be a better tool, in my case.
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"I am definitely confused now, but it is starting feel like the point of this thread is telescope bashing (refractors in particular) and rubbishing people's gear.
I stopped using cloudy nights because of this type of carry on...pity."
I don't think anyone is bashing refractors. Ultimately the best scope is the one you use 🙂. From an imaging perspective I've switched from bigger 10" newts and 12" SCTs to a smaller 8" apo (if you can call an 8 inch refractor small ) and I am more than happy with it. Things like collimation instability, lower quality optics, obstructions, and the endless lost nights of tinkering drove me to the refractive design (actually drove me nuts 😀). Sure smaller aperture means more integration time needed per target ... but that is something I can live with. There are more important benefits that a quality refractor brings to the table.
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10 hours ago, BCN_Sean said:
That looks a great little too. Is there any way for the user to add their own sensor data to it? It's quite often I've stood out the back with one of my cameras (all SLR, so may be tricky to find the sensor data) and pondered how long something is going to take.
Sure, you can click on the numbers and change them as you like. I will browse telescope-express or FLO and see what other cameras I can add.
PS: I see you mentioned dSLR cameras ... I included CCD and CMOS mono cameras, I'll have to find some DSLR sensor specs and see if it works, or if the results make sense. Given that they already capture color data, the color filters won't make sense, but for luminance and narrow band maybe ...
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13 hours ago, SlimPaling said:
Well ... I am interested ... especially if you get the time to do a version for my Win10 PC and my Moravian G2 camera 🙂
Mike
Ok, I will add the Moravian G2 8300. Yesterday I've compiled a standalone version for Mac OS. The only issue I found was with Dark Theme enabled on IOS, the text on the buttons and the buttons are white, so the user can't read the text. With the Light theme, the problem doesn't show up, so it must be a bug with the standard python TKinter library and Dark Theme in IOS. It won't be such a big problem since the user can switch to the Light Theme momentarily.
The only windows machine I have is the small PC that runs the observatory, and I have to install all the tools to compile it on Win, it will take some time, but it's doable.
RC vs Edge HD
in Discussions - Scopes / Whole setups
Posted
If you plan to image with an SCT, I don't recommend them. I've had nothing but headaches with it. Mirror moves, corrector plate=dew magnet, cool down is slow, it focuses by moving the mirror ... don't really know why people still buy them. Maybe because on paper they seem to tick many boxes, but the actual experience for me was a waste of money and time.
I have replaced it with a quality refractor, and never looked back. I can actually enjoy the hobby with a frac ...