symmetal

You need a much longer exposure to get a good bahtinov image with narrowband filters, around 10 times that used for wideband. Also depending on how good your optics are the triband filter will effectively produce a separate bahinov image for each band and the optimum focus setting may not be the same for each band. The wideband image will be an average of the different colour bahtinov images while the tri-band will have 2 or more distinct images superimposed. Alan

I have a Ctek MXS 7.0 charger/conditioner. Here's the manual which shows the voltages applied during the various charging/conditioning phases. Once fully charged it switches to 'float charge' mode where it just maintains 13.6V output so little or no current flows into the battery unless you start discharging it or it begins self discharging after a while of unuse. So it can be left connected to the battery permanently if you wish without causing harm. They do models with lower maximum charge currents at a lower price. There are other manufacturers which do a similar product but Ctek seem to have a good reputation. Alan

To save having to create a new file for the copy. Select the layer of your RGB image and hit Ctrl-3, Ctrl-4 or Ctrl-5 to select the R, G or B channel. Hit Ctrl-A and Ctrl-C to copy that channel. Click 'Create a new layer' icon (next to the trash icon) at the bottom of the layers pane to create a new layer above your image layer. Hit Ctrl-V to paste the selected colour channel in the new layer. Done. Alan

The ZenithStar 66SD Manual does say it has a 1.6" focuser and if you want to use 2" accessories you need their adapter. The field flattener for this scope has a 2" nosepiece which is internally threaded with an SCT-type thread which will screw directly onto the ZS66 SD focuser. Picture posted by David Taurus above. Alan

Rapidobat Column Formers in the UK are similar to Sonotube. I don't know if they sell single tubes but you could email them. I did buy a similar pvc lined cardboard tube about 15 years ago for my pier. 12" diameter and 6 feet long. Can't remember who I bought it from but they were happy to supply a single tube and it arrived on a flat bed lorry a couple of days later. Can't remember the cost but it wasn't excessive. Alan

The likely reason why dew straps fail where the cable is attached to the heating strap is because so many use screened audio cable for the phono cable and unless you're really careful during construction when attaching it to the heater, a strand of screen can easily break loose when manipulating the strap and float around, coming into contact with the 12V at some point. This single strand across 12V will heat up very quickly causing the smoking problem seen. I shorten the cables on my dew straps to more convenient lengths and fit my own phono plugs. The Astrozap straps used screened cable so am always cafeful to not move the cable to much where it enters the strap. The last few straps I bought have been from dewheater on ebay who sells W&W Astro straps which she makes. These actually use fairly thick 2 core flexible cable moulded to the phono connector and not screened cable so is a more reliable solution in my opinion. Alan

Glad that's all it was. I had my grub screw work loose which caused a similar problem. You need to ensure the grub screw is tightening on the flat section of the focus shaft. As you tighten the grub screw wiggle the coarse focus knob on the other end to ensure it's sitting in the middle of the flat section. Alan

Check the Lakeside motor unit is firmly attached to the focuser shaft. A grub screw can work loose causing severe backlash. There should be no movement when trying to lightly move the coarse focus knob on the other end of the focuser shaft and a small amount of movement (around 5-10 degrees) when the fine focus knob is gently moved. To check the amount of focus backlash compensation needed to be set in APT, it can be checked by commanding the focuser to move out and then in by say 20 steps. If you see the fine focus knob rotate a little after the focus in command then your backlash is overcome by the 20 steps. If it doesn't move increase the distance you move in and out each time until it does show inwards movement of the fine focus knob. This is the distance you need to set in APT for the backlash value. I assume there is an option in APT to force compensation in one direction only (normally inwards) so that the autofocuser always finishes movement in an inwards direction. This way it ensures the teeth are fully engaged driving the focuser in an upwards direction, (against gravity). There's no problem with setting the compensation too high, it just means it takes a bit longer to do the compensation as it has to travel a bit further each time. I use SGP but assume APT has similar backlash settings. You can set backlash compensation in the Lakeside Astro driver but it's easiest to let APT do it as it's quicker to change the value. The focuser current position is stored in the Lakeside Astro controller so after turning it all off and back on it knows the focuser position, (assuming you don't move the focuser while it's turned off. Alan

USB 3.1 Gen 1 is apparently the 'new' name for USB 3.0 so works at the 3.0 speed of 5 Gb/s compared to the 10 Gb/s of USB 3.1. Data Transfer only means it won't supply much (or any) current for powering devices. It's possible the 5V pin is not even connected to 5V. A reply on the HP forum from their technical advisor says So it seems it may supply some current. Alan

I didn't read your first post clearly enough to realise you were doing solar imaging so polar aligning using Polaris isn't much use unless it's left out from the night before. As others have said you can use the Sun instead for alignment with Sharpcap though I haven't tried it. For my solar imaging on an EQ3 Pro I don't do any alignment, just place the tripod N leg to North(ish) and set my latitude on the mount scale. This good enough to keep the whole Sun's disk in the view of the camera for about 3 minutes before I need to nudge the scope to recentre the Sun before the next video. If your scope/camera combination has a narrower FOV and you can't get the whole Sun in the image then the Sun will appear to move faster in your FOV so more accurate polar aligning may be necessary. Getting good focus is the main step to a clearer sharper image. The short video frame exposures of around a few milliseconds means the slow drift of the Sun during the video exposure won't affect the sharpness of the result as long as the area you're interested in stays somewhere in the frame during the video. The Earth's atmospheric turbulence causing the image to continuously jiggle about and go in and out of focus is the main problem to getting a sharp image. Stacking the many video frames to only select those frames that are momentarily in focus is the key to getting a sharp final result. Alan

I assumed you knew this was barebones and components would need to be added but maybe I was wrong. I have an earlier discontinued model of this mini PC. Having an SSD already installed along with Windows 10 Pro the price is pretty good. There is space to install a SATA 2.5" hard drive too but that wouldn't be necessary for your usage. Alan

Yes, that should be fine. Not much processor power is needed just for acquiring the images. I have a mini PC on my dual rig scope running two instances of SGP, PHD2 and CdC with no problems. Having an SSD is the main benefit for speed, especially if you are doing planetary video imaging as it can write to the SSD very quickly so the limited RAM size isn't a problem. There isn't a serial port on the PC. The D connector is for a VGA monitor if you don't have an HDMI one. Alan

To use the Sharpcap polar align, which is very quick to do once you've got the hang of it, it needs a fairly wide angle view of the polar region in order to plate solve the image, (work out the star positions and so determine where the scope is pointing to). To get the wide angle view a finderscope is ideal or a guidescope of a similar FOV. Once Sharpcap's plate solved it just rotate the rig through approx 90 degrees RA and it indicates your polar align error by a line from where your mount RA axis is pointing and where the real polar axis is and you just move your azimuth/altitude bolts on the mount to minimize the length of this error line. Your main scope FOV would be too narrow for Sharpcap to be able to plate solve as there won't be enough stars in view. The benefit of this method is that the finder/guide scope doesn't have to be accurately aligned with the mount axis. The 90 degree rotation you do is via the mount so the centre of the rotation tells Sharpcap where the mount is currently pointing to. As has been mentioned you only need accurate polar alignment for long exposure deep sky work. For planetary, sun, moon etc. short exposure videos are taken so trailing due to polar mis-alignment is not so much of a problem. If you just point the N leg of the tripod reasonably close to North and set your altidude on the altitude scale of the mount this can be good enough for planetary imaging. This is probably why you didn't see people accurately polar aligning on the Youtube videos, and putting the camera directly on the main scope to image the target. The further out of polar alignment you are the quicker the target will move across the scope FOV so you'll need to account for this by moving the scope RA and DEC controls to keed it in view during the video. Alan

Tried the framing wizard last night and it was all working again. Also tried the new 3.1 beta version of SGP and the framing/mosaic wizard is in colour now. Much easier to see the results compared to the old low contrast B/W images. It also returned the results faster too. Alan

SGP gets me within 10 pixels within 2 or 3 goes, often within 2 or 3 pixels. If it refuses to get any closer to your requested distance, clearing out the pointing data in Eqmod usually solves it. Alan

This is posted on the SGP forum and it is a server problem. Ken the deleloper of SGP has posted that they were looking at changing the source of images from Aladin/HIPS to Skyview, but Skyview is not so versatile. A beta release of SGP 3.1 has just been released with changes to the wizard. changes-to-mosaic-and-framing-wizard-in-3-1 Alan

Just tried it and same here. Looks like the remote image server isn't working. A similar thing happened a year or so ago when the server changed the search string format slightly leading to the same problem. SGP developers then released a program patch to fix it. Alan Thouight this was a new thread so my reply saying this happened previously was a bit redundant.

Well that told me didn't it. Thanks vlaiv. So LP puts no restriction on how much faint detail you can see. It just means you have to allocate much more imaging time to be able to reduce the significantly more noise contributed by the light pollution in order to see that detail. And deal with the gradients of course. I stand corrected. So hypothetically, if you had a camera with sufficient well depth that it didn't saturate, you could do DSO imaging in the daytime if there were no clouds, (and you weren't pointing at the Sun). Alan

Good point. Forgot about the scattering. The OIII would be scattered more so would add to the sky background pollution. I appreciate the improvement in SNR where longer imaging in LP skies will produce the same result as dark skies, but surely only for areas of the image which are brighter than the skyglow. Are you saying that you can get an image of say a mag 21 object with a skyglow of mag 18 if you image for long enough. For every 16 photons from the skyglow you'll get 1 extra photon from your target once the noise has been reduced to an insignificant level by enough imaging time. The problem I see is that the skyglow isn't a constant value which can be subtracted out once the noise has been made insignificant by sufficient exposure duration. It varies continuously for many reasons, some predictable and some not. Different areas of every sub will likely have a different 'average' skyglow value, so determining if a 1ADU variation of a pixel came from the target and not from somone a mile away turning a light on is difficult. Standard calibrating and stacking would be insufficent and each sub would need to be calibrated with its own unique sky glow to achieve that I'd have thought. Alan

Surely if you have Bortle 9 (18 mag) skies caused by moonlight which is broad spectrum, you can't image anything darker than 18 mag. You can reduce the noise caused by moonlight by greatly increasing the number of subs but the moon's light pollution 'signal' will still swamp the fainter areas of the target which are less than mag 18. Only Ha imaging is successful in moonlight, other narrowband frequencies seem to be significantly affected, and it seems to be accepted that SII and OIII are best carried out on moonless nights. Admittedly, Ha filters are generally a bit narrower than the others which helps. The spectral response of moonlight which pretty much matches sunlight shows a dip at Ha which I assume is part of the reason Ha imaging works. The Sun's spectrum has a dark Fraunhofer line at 656 nm, (the C line) which corresponds to Ha. The Sun's photosphere produces these lines by absorbing energy at those wavelengths. Ha images of the Sun would be even brighter if this absorbtion didn't occur I would imagine. SII at 673nm and OIII at 502nm have no corresponding Fraunhofer absorbsion lines so imaging them are more affected by moonlight than Ha. That's my take on it but am willing to be proved wrong. Alan

The 66 to 88 mm adjustment distance is only correct if the sensor is mounted 55mm from the flattener rear, the standard distance for mounting a DSLR and its T2 adapter. So your ASI camera sensor should also be mounted 55mm from the flattener. If you don't have the correct spacers to fit your ASI at 55mm you can use the FF adjustment to correct this. If the camera is say 52mm from the FF you can increase the FF adjustment by 3mm to make up the difference. The body doesn't revolve as the FF is adjusted. The FF lenses just move along runners in the FF. The focus is affected if you adjust the FF so you'll have to refocus each time it's moved. As others have said the actual FF adjustment distance is only dependant on the scope used so if you don't have a WO scope listed you'll have to use trial and error to find the optimal distance for your scope. This is fairly quick to do, just make say 1mm adjustments, refocus and take a test image. No messing about with variable spacers. Alan

Yes, as Tomatobro says, pin1 is Ground, pin 2 is +12V. Alan

Good luck Andy. When you first plug in the EQDirect cable check what COM port windows assigns to it using Windows Device Manager. Then put that COM port number on the Eqmod setup screen. Don't use the Eqmod Auto search option for the COM port as that doesn't always work. The other COM port parameters can be left as their defaults. One other point is when Eqmod is parked in the standard home position with the weights down Eqmod will still report the RA as being 6 hours out. This is not a problem as whenever you unpark and slew to a target using CdC or whatever, Eqmod will altomatically correct this 6 hour difference by effectively rotating the RA through 90 degrees (6 hours) on your first goto from the home position. When viewing any target on the meridian the counterweight bar is always horizontal. The celestial pole however is the only target on the meridian where the counterweight bar can be in any orientation and still point at the target, because all lines of RA coincide at the Celestial Pole. (Merlin66 also just posted this as I was editing this post. ). With Eqmod the home position can be set to be pointing to anywhere in the sky using the set Current Position as Home Position (or similar wording) on the Eqmod expanded screen. This is useful if you have an observatory with a low roof that may hit the top of the scope when in the conventional Home position. You can set the scope horizontal and set this as your new Home position from which all gotos will start from when you unpark. If a new Home position is not set it will assume the scope is in the standard Home position when you turn it on. Alan

The sync is only to inform the mount that the telescope is pointing to the target the mount 'thinks' it is pointing to so the mount can update it's pointing database. If you had perfect polar alignment then only 1 sync on a star is needed. If your polar alignment is out then 2 or three syncs on different stars can correct for this error. The home position is just a starting point that the mount believes it's pointing to when the mount is turned on so that it knows where to slew to when you select a target. This home position may not be accurate (it doesn't have to be that accurate) which is why the first sync is performed to correct for this home position error, as well as any polar alignment error you may have. I've found that when you use Eqmod for the first time after previously having used the handset, and your scope is in the home position when you turn it on, you need to tell Eqmod to park the scope, ie return to its 'home' position. Instead of staying still it will rotate the RA through 90 degrees so the counterweight bar is horizontal and then report 'Parked'. This is incorrect, so release the clutches and put the scope back in the proper home position, weights down, and pointing to the North Celestial Pole (near Polaris). As I mentioned above this doesn't have to be done very accurately as your 'sync' commands will correct any home position error. 'Unpark' the scope through Eqmod and the scope will stay where it is. It takes the current 'proper' home position as the Eqmod home position from then on and your good to go. Slewing via CdC etc should get you very close to your target and you can centre the target (in the eyepiece or via the camera if imaging). When centred just click the 'Sync' button in CdC to get everything in agreement. When you've finished your session just click the 'Park' command in Eqmod and the scope will return to the Home position. Then turn of the power. Next time you use the scope ensure the scope is in the Home position before you turn on its power. Then Eqmod just picks up from where it was the previous time after you hit park and shut the system down. As you can see hitting 'sync' when in the home position causes Eqmod to get itself in a twist so don't do that in future. If you do make a mistake and hit sync at the wrong time you can delete Eqmod's scope pointing database by clicking the button on the Eqmod expanded screen. Then click 'Park' and when it's done release the clutches and put the scope back in the home position. You're good to go again. Alan

In the home position Eqmod will show your RA as being 6 hours out (90 degrees). This is normal as the counterweight bar is not in its 'viewing' position. The text with the image says you synced the home position and the statement you wrote that I quoted also says you synced the home position. You must never do this or you will end up pointing 90 degrees out with CdC/Eqmod. When you were using just the handset you wouldn't have synced the home position as it wouldn't have asked you to. The handset only asks you to sync after it's slewed to a star. Alan