bobro

My EQ2 is the SkyWatcher/Meade type. The screw is M5 with the threaded part about 12mm long, though the length isn't critical. The screw head is an Allen socket type as that makes fitting the drive slightly easier.

My CC used filter holders with an internal filter locking ring that screws inside the holder. I used 2 of these, by SVBONY, to sandwich each lens, with careful positioning to centralise the lens.

You can see in the attached image that I too added a larger knob to the RA motor speed control. When guiding as the battery voltage reducing slightly, I would adjust the speed knob to provide a roughly equal number of slow/fast guiding pulses as they varied as the battery voltage dropped. Not critical though. Although it would be really useful, I don't think accurate slewing is really possible with this setup due to the DEC arrangement and the lack of precise stepper motors. The large gear was cut off in a bid to provide more space for the motor, though it wasn't really necessary as it turned out. Another mod I did was to lengthen the counterweight shaft to allow the weight to be moved slightly further out and achieve a balance. It pushed the EQ2 beyond its design limit, but it did cope. If you haven't already imaged the Pleiades, they are a lovely target that are easy to find.

That's a pretty good image for a 920mm FL reflector on an EQ2! Nice colours. Looks as though guiding is working well as it's difficult to get the simple RA motor to track accurately for 30 seconds. A longer FL guide scope will likely have a higher F# than the lens you are currently using, which means less light getting through to the guide camera, possibly making it difficult to detect stars. I initially used a Microsoft Cinema webcam so chose an Orion Mini 50mm guidescope as it has a relatively low F# of 3.2, which helped with detecting stars.

Hi @Flo94218, Good to see someone else having fun with getting an EQ2 to guide. Following on from using LinGuider, I went down the same path as yourself, using an Arduino and PHD2 for guiding - worked well as you have found. The lack of fine AZ adjustment does make polar alignment trickier. I used Sharpcap for this, and still do with my EQ5. Fitting the DEC motor was straightforward using a simple L bracket and flexible coupling - see attached image. There is plenty of adjustment on DEC, so it's just a case of setting the screw somewhere around the middle of its range. Guiding only moves the screw a small amount one way or the other, so there's no worry about reaching the screw's limit. In fact, the tangent arm DEC arrangement makes for very good DEC guiding as the backlash found with a worm and grub arrangement doesn't exist. I wish my EQ5 guided as well in DEC! To drive the motor either no voltage, +5V or -5V was supplied, depending on the guiding requirement from PHD2. The circuit board from the motor housing wasn't used for DEC. Looking forward to hearing how your dual axis guiding goes!

It does look as though the Omegon 130/650 has been designed for DSLR photography. The scope has an unusual focuser that is shown on the store website with a DSLR attached. It looks as though a couple of adapters have been removed from the focuser, allowing the camera sensor to come closer to the mirror to achieve focus. In any case, the OP's camera is mirrorless and has a flange to sensor distance of only 18mm (rather than a typical 44mm mirror DSLR). Bringing the camera to focus should be no problem. It looks as though the focuser has a standard 42mm thread for a T-ring. Assuming this is the case, a T-ring to Sony E-Mount adapter like this one would be required to attach the camera: https://www.celestron.com/products/sony-e-mount-t-ring Although the mount looks light and is likely to be a weak point, an RA tracking motor is available for the mount https://www.omegon.eu/drive-motors/omegon-eq-320-tracking-motor-set/p,65804, which should allow exposures of around 30 seconds to be achieved. This would be a useful way of seeing how well the scope performs before upgrading the mount and adding guiding/goto.

The OP's OTA is a 130PS (not the same as a 130P or 130 P-DS). The 130PS does not have adjustment screws for primary collimation as collimation is fixed. Although a 2X Barlow lens may allow a DSLR to come to focus with the 130PS OTA, an OTA more suited to imaging (short FL refractor, 130 P-DS or camera lens) may be the best way forward.

There are messages in this thread which may be confusing, so it's useful to go back to basics. In summary: The 'DC Motors' as mentioned for the EQ5 Enhanced Motor Drive are stepper motors. The drawback is that they are highly geared (to maximise battery life), which means they are much too slow for goto use. Nevertheless, they work well for accurate tracking and guiding with a suitable setup. Guide cameras do not have to be the route for sending guiding corrections commands to a mount - this can be separate to the guide camera. As an example, a programmed Arduino or similar USB-ST4 device can receive guiding commands and operate relays to guide a mount via ST-4. Nevertheless, a sensitive guide camera with ST-4 (e.g. ASI120) can make for a reasonably cost effective way to combine the two functions and may be a better solution than the (mature) ST-4 Guider and SV105 (discontinued sensor) mentioned at the start of this thread. PHD2 is a great way to guide and supports most hardware. The 'Enhanced Controller' has an ST-4 port for guiding corrections only. It cannot be used for goto.

Excuse me if I an missing something, but the guide log shows a guide scope focal length of 225mm, whereas the guide scope on the equipment setup looks closer to one with a 150mm focal length as it is much shorter than the 50ED FL of 242 mm. Something unusual about the guide scope?

Lovely image. The guiding RMS values suggest that guide camera pixel size and/or guide scope focal length may not be correct in PHD2 Advanced Settings. What guide scope and camera are being used and what values have been set?

For me this is the key to the Mono/OSC debate - if going mono then a good level of automation with a stable setup helps, otherwise it's easy to end up with uncompleted images. Having said that, an initial mono image of a target is a great way to gauge how it could work out. I went from modified DSLR to mono with a manual filter wheel. The manual wheel was probably a mistake as a motorised wheel could have been better, especially as current imaging programs control filters. With limited imaging time I'm tempted to revert to an OSC route, though a split between my wider FOV scope with the DSLR and the other narrower FOV scope with the mono camera is tempting, covering both worlds. Mono is just more complex, and can be a bit much if other parts of the setup (like mine!) aren't so good and are causing issues.

Good suggestion as it has the potential for a goto upgrade and can provide decent imaging with a scope that isn't too heavy.

If you have basic DIY skills, a 'standard' 130mm reflector on an EQ mount with motor drive will fit your budget and allow your DSLR to image with 30 second subs, perhaps longer occasionally. I started this way for £150, though prices have risen in the last few years. My setup was a Meade 130MD. I'm not familiar with USD suppliers, but here is one for a Meade 130 for $300 https://www.highpointscientific.com/brands/meade/meade-telescopes/meade-polaris-130-mm-german-equatorial-reflector-telescope-216006 though it may be out of stock. A basic motor drive is another $50. the catch is the metal scope tube needs to be shortened by around 35mm to allow a DSLR to come to focus as the sensor in a DSLR is back from the flange screw connection to the telescope. That pushes the camera focal plane too far out, requiring the camera to be brought nearer to the primary mirror by shortening the tube in some way. A Celestron or similar 130mm scope may be an alternative. This setup is very basic but can readily capture brighter DSO objects. It may be more appropriate to start out with better equipment, though this costs more. Depends on your resources and intentions.

Astrophotography is an unusual pastime. To improve (whatever that means) images isn't necessarily straightforward and can involve a number of things. For example (in no particular order): Better scope Better mount Better camera Better skies (usually means darker) Better imaging processing software Commitment/time/aims on the part of the imager Changing only one of the above may make no substantial difference to images. That makes it difficult when deciding how to proceed, hence a bit of thought needs to go into any change. So it's a balance. E.g. upgrading to a super scope on a poor mount won't make (or be a waste) in achieving pinpoint stars. Whereas upgrading a poor scope on a super mount could be worthwhile. Astrophotography can be complicated and take a lot of time/commitment/expenditure. Hence it's not a bad idea to become familiar with existing equipment and what it can achieve before deciding on a potential upgrade. Plus, it's worthwhile taking into account that image processing can make for surprising improvements before any equipment upgrade, and not necessarily at any great cost as free software is readily available.

Thanks for the clarification on the additional adjustment. My EQ2 had a similar weight capacity issue with the scope and guider mounted, so I screwed a short extension on the end of the weight bar to allow the weight to be moved further away from the axis and achieve balance. As your setup is already carrying a lot of weight, I suppose a guide scope and camera could be added on the counterweight shaft rather than on the lens side. If you haven't already seen it, this thread has useful info on startrackers https://stargazerslounge.com/topic/303949-imaging-with-a-star-adventurer/ There is a photo on page 2 of the thread with the guide scope on the counterweight shaft. A rough figure for guide scope/imaging scope combination that is often quoted is the imaging scope FL can be up to 10X the guide scope FL, assuming equal camera pixel sizes. Even staying well below this rough limit would allow for a useful imaging scope FL in a future setup. FYI - I use a guide camera with the same AR0130 sensor (colour version) as the ASI 120MM and a 162mm FL guide scope to guide my EQ5 with a SkyWatcher 150PL (1200mm FL).

I don't understand this. The iPolar should give correct alignment using alt/az adjustment without the need for any subsequent adjustments. What are you adjusting? Note: a mount does not need to be perfectly level as polar alignment points the RA axis correctly to allow tracking in RA.

Yes, guiding should easily allow 2-3 min subs. Guiding would be in RA only. Slow movement of the field of view isn't a problem as stacking software will de-rotate/align subs. Good polar alignment will help eliminate any movement as only RA corrections would be required.

Lovely detail!

Seems ok for a simple tracker intended for holding a camera or short FL scope. Shorter FL should allow longer subs without trailing. My tracked EQ2 mount could typically provide 30 sec subs with a 650mm FL scope. Depends on polar alignment and accuracy of tracker though a single sub will normally be much shorter time than overall imaging time - hence a bit of slow creep is ok. Guiding will not necessarily stop slow creep, especially if dithering is used, though it will improve single subs.

Could be hot pixels in different places due to dithering, though I can't see any in the single sub. What stacking method was used? (Kappa-sigma works well in eliminating hot/cold pixels when dithering is used.)

Your setup looks to be performing well - good star shape indicates good tracking/guiding. Longer subs of at least 4 minutes will help reduce the effects of camera read noise - if your setup can support this. One retailer suggests 10 min subs, but it will depend on other things such as the sky background (around Bortle 5 for Fareham) and camera used. Aim for a total imaging time of at least a few hours with this target. Seems a lot but the scope is slow at f#9 and the Canon 1000D not very sensitive. Flats are essential to get the best from an image. Good luck with your next image!

It is a very interesting discussion that I have been following over the days, though some points may be worth adding to the discussion: > When captured photons are reduced camera read noise becomes a bigger part of the overall SNR picture - that's why recommended minimum sub exposure time increases when filters are added. Filters cut down on the signal, whereas read noise is constant for a given camera setting. Increasing sub exposure time reduces the overall read noise (less subs) for a given total imaging time. However, there is no compulsion to go beyond a sub exposure time where read noise becomes low enough to be ignored, unless there are mitigating reasons such as too many subs required due to very long overall image exposure time. I've been experimenting with this on my setup using Robin Glover's calculations, finding that (not surprisingly) read noise shows when an Ha filter is used and also to a lesser extent with 30 sec subs. To keep things simple I've settled on 2-3 min subs as appropriate for my setup as guiding generally works fine at this period and few subs need be scrapped. Also helps with my non-cooled camera as it reduces the variations required in a darks library. > Plane or satellite trails are readily eliminated with kappa-sigma stacking, allowing these subs to contribute to the image. > Dust bunnies don't move around much, allowing flats to be used for a while. > Unless imaging is narrowband, modern cmos sensor dark current is so low that cooling isn't required in order to reduce camera noise - sky noise is usually the much larger source of noise. However, cooling (or rather fixed temperature operation) helps with providing accurately matched darks. I hope @MHaneferddoesn't mind, but I've gone back to the start of this discussion and reduced stars on the NGC7000 image using Starnet++, increased saturation and blurred the background to reduce the noise (hence the mottling) with a quick reprocess. It shows some interesting nebulosity, though still needs some work, especially on the brighter stars. Wish I has done as well with my first images!

Here's another working of your jpeg - using StarNet++ to remove stars followed by GIMP to reintroduce stars in a controlled way plus a bit of colour saturation increase for the nebula. The underlying image looks to have a lot of detail.

A couple of thin (1mm or similar) adhesive teflon type strips (from ebay) along the length of the inside of the focus tube can eliminate the wobble. 🙂

That's a good question and I will answer it as things seemed to me at the time - I couldn't find a definitive answer to what type of mirror the Meade 130 reflector possessed, although there was what looked very much like coma towards the edge of images (similar to your M27). I'm no expert on mirrors but understand that coma is a characteristic of parabolic mirrors rather then spherical mirrors. As there was apparent coma I went about making a coma corrector. The corrector made a big improvement but the result wasn't quite as good as I had hoped. I suspected the mirror wasn't the best and so installed the SkyWatcher 130 parabolic mirror. This produced the results used today. So I'm not totally convinced (but may be wrong and others may correct this) the Meade 130 did not have a parabolic mirror, though it may not have been as close to a parabolic shape as the SkyWatcher. @vlaiv is pretty good at explaining these sorts of things - perhaps he can advise regarding the mirror/coma in your images? If you wish to experiment, a simple way to improve images from both spherical and parabolic mirrors is to make use of an aperture mask. For example, placing a card with a 108mm diameter circular hole across the front of 130mm scope with 650mm focal length will change it from an f#5 to a f#6. A longer exposure will be require to gather the same amount of light, but the image improvement could be worthwhile. Star shapes can also be improved in software processing - very useful if a coma corrector isn't available.