Enceladus Dan

Further updates, I adjusted out as much backlash as I felt safe to do. The tight side of the worm was marked on a sticky label on the slow motion control. It left me with just under 180 degrees usable. 

I orientated it so I can put the usable area inline with the worm carrier bolt as a reference. It felt much better and after calibration I ran the guide assistant which managed to complete the backlash measurement. It came back as 20,366 ms with a recommendation to guide in one direction as mentioned by Onikkinen. 

I guess that is a little on the large side so I’ll contact FLO for recommendations as the mount is still relatively new. 
thanks for help and guidance everyone. 
 

regards

Danny

On 25/11/2021 at 09:31, Peter Drew said:

@EnceladusDan.   I think the easiest mitigation of the problem will be to do as you mentioned, tune the 90 degree potion of the Dec gear that is in most use.     🙂

There was a break in the clouds last night so I quickly set up and run the guiding assistant. Dec backlash measurement was aborted due to not enough south movement. I'm going to adjust to avoid using the worms tight spot and try again on next clear night. See how it looks if I only use part of the worm. 

Regards

Danny

1 hour ago, Robculm said:

Excellent 👍.

And I couldn't agree more regarding the "work life+ home life +British weather"!

Earlier in the week Saturday was looking promising but Arwen has other plans. 

51 minutes ago, ONIKKINEN said:

Guiding will make the backlash issues much worse, if not taken into account properly.

RA backlash is mostly irrelevant as the RA axis is under constant motion. Balancing east heavy makes the gears touch at all times= backlash irrelevant.

DEC backlash is a problem though. If yours is really bad you nay need to purposefully polar align not perfectly to allow DEC drift to be always to one direction and set DEC guiding pulses to only happen to that direction. You may also need to abandon DEC guiding completely if you lost the Skywatcher monday morning product lottery (i did).

Thanks Onikkinen, your posts in my last thread helped me figure out it was my tracking and not PA, also helped me decide to go guided. 

My First try guided was able to go 5 mins OK, I do need to try properly as it was a rush and skies were no good for imaging. I will try and get out before the moon phase goes into last quarter and use the time to practice and get measurements. I might even adjust dec and re-measure same night. 

I did think of swapping worms to pass my problem to the RA as I had read its less of an issue but was worried I'd make it worse. As for the SW lottery i feel I had a small win or break even as the RA is good now I adjusted out the binding. 

For the deliberate Polar misalignment I read it and get the idea but didn't quite understand the how. I assume it's the altitude is slightly out so it corrects one direction. 

Regards

Danny

Thanks everybody, 

I wished I had looked into the backlash sooner, being completely new I assumed it was a wear thing and being a new mount it was ready out the box and I didn’t need to check it…….. Lesson learned. 
 

it would have saved me a lot of time and stress, again being new I thought it was me and my alignment was terrible so I would spend hours trying again and again and end up just using 45 second and loose 50% of the to elongated stars. Now I adjusted RA to not bind I get 90 seconds easy. Now I’m just starting with guiding I’ll be flying and can’t wait to see how my images improve. 
 

I’ll pop back after clear skies (Saturday for me in the uk but it changes daily) with some measurements and hopefully some news. 

thanks Danny

7 hours ago, Peter Drew said:

@EnceladusDan.   I think the easiest mitigation of the problem will be to do as you mentioned, tune the 90 degree potion of the Dec gear that is in most use.     🙂

Thank you, at least I know that it wasn’t a stupid idea I had. I think my course of action will be to measure the backlash in PHD2 , I think I read the instructions right saying the assistant will measure it for me. From there I’ll contact FLO to see what they say, while I weigh up options I’ll adjust out as much as I can in the best potion and run some sessions to see how it goes. As my mount isn’t goto I assume I’ll use Dec axis less as I’m not slewing from target to target. 
 

If a replacement is an option I’ll need to think as my RA is pretty good and don’t fancy ending up with RA being like my Dec. 
 

thanks 
Danny

28 minutes ago, 900SL said:

I was incredulous when I opened up my Skywatcher.

Missing screws on the ring gear (I think they glued it..)

Congealed stiction grease

Aluminium swarf from the ring gear  

Pot metal poor tolerance 

Worked after I sorted it all out, shimmed, fixed and fettled. PE needed guiding.

Convinced me never to buy a Skywatcher product ever again, regardless of how good the HEQ5 Pro is  

After what I saw just by taking the worm carrier off I think I should have a go at a full strip down, clean and re-grease. Just need to courage to get on with it. I have no reservations with taking driveshafts and suspension springs out of cars, this is just that bit more delicate and I'm quite heavy handed lol. 

Also to clarify the movement from 12 to 1 is the rotation of the worm as seen by the slow motion knob before the Dec axis moves. 

I'm not sure if that is where I'm supposed to measure free play there or at the axis. 

20 minutes ago, 900SL said:

As a possible quick fix you could try changing the worm? Not guaranteed but could work

I did think of swapping the RA and Dec worms. I read that backlash is less important in RA as it is continually driving. Just a bit daunting where I'm new to all this and wasn't sure if I would make things worse.

I did pluck up courage to remove worms and clean and re-grease them. I used geoptic  grease, the grease I found inside was really sparse and had some metal pieces in it. Probably from the gears being cut at factory. 

4 minutes ago, Clarkey said:

If it is that much backlash there is seriously something wrong. I try to tune my mount until I can 'feel' no movement - and certainly nothing I can see. Are you sure everything else is right as this seems really excessive. It maybe there is a broken gear tooth or similar if it that bad. 

You can measure the backlash using various methods and software - but if it as bad as you are describing there is no need.

I think it's because both the worm and ring have areas that are tighter. I can reduce the backlash but I get binding. If the worm didn't have any tight spots I could adjust more out. I'll look into proper measurements to get real figure. 

Thanks

Danny

10 minutes ago, Clarkey said:

I think it will depend on what level of backlash there is. EQ5 mounts are built to a price and the QC is not the best. There will always be a little bit of play in the system, which in the case of my HEQ5 needs regular fettling. Certainly if it is excessive then contact FLO, but you probably need to quantify it first.

Thank you for a fast reply, is there a way to measure it? By eye imaging a clock face the free play moves from 12 to 1 maybe just after before any movement happens. 

Thanks 

Danny

Hello, Looking for some advice on my Dec worm gear.

Since getting my EQ5 deluxe in June, I have been having issues with tracking. I thought it was my PA, but I have found out both RA and Dec have tight spots. The Dec also has a point in every rotation of the worm that binds. 

After doing some adjustments to both I'm now happy with RA having no tight spots and very little backlash. However because Dec has issues with both the ring and worm I can't reduce the backlash as much as I would like without getting binding. 

As its only 5-6 months old should I tell FLO? My opinion from looking into this is most of the skywatcher mounts have these problems. I feel quite lucky the RA is pretty good. 

Or should I try and make a certain area of the Dec as good as possible and avoid the areas that bind? From what I have learned Dec worm normally moves a max 90 degrees. So if I mark the slow motion knob where the worms tight spot is I can set it to the opposite side before guiding. 

Regards

Danny

On 09/10/2021 at 15:51, ONIKKINEN said:

Are you autoguiding?

All mounts experience something called periodic error in RA where the tracking speed oscillates a bit above and under the ideal rate. Unguided exposures are limited by your RA drift rate, which varies quite a lot between different mounts.

 

Below is an example i just found online, the red line is your DEC, which in this case was spot on as it hardly moves in the long term while the blue line is the RA which is constantly in use. The steep drops and cliffs of the graph are where you experience bad subexposures, but just by pure chance you could have your exposure at the relatively even top section and not notice trailing as much. I don't know what mount (or even if it was a mount) this image is from but it gets the point across. My EQM35-PRO experiences somewhere around 8 arcseconds RMS of periodic error during one worm cycle, which is 8minutes on my model. In theory that would limit a 1 as/pixel resolution image to just 30 seconds, but in reality there are these same steep cliffs and drops in the graph, making unguided exposures not worth the effort.

How much you can get away with will depend on your mounts periodic error and the resolution you're imaging in.

My chart definitely wasn’t like this lol. It looked like my mount was having a heart attack. But even so it did guide 5 mins. I can only get better at the setup and get my error lower. My Dec was more like the RA in this pic, possibly the bad backlash in Dec. It doesn’t help the worm having a tight spot as well as the ring gear. 
 

thanks everyone I am over the moon now and eagerly awaiting clear dark skies. 

On 12/10/2021 at 07:52, Robculm said:

Hi Danny,

I see you've got lots of good feedback on this topic already, but I just wanted to add a quick comment since those elongated stars are oh so familiar to me!!!

I have the 200PDS on an HEQ5 mount & spent hours & hours optomising this & that, fitting the rowan belt kit etc etc... About 3 min was the max exposure length I could work with & even then I'd usually be throwing away 50% of the images (which is really really frustrating).

Autoguiding solved the problem.

I picked up a 50/200mm guide scope and an asi462mc, while testing my smoother RA I added them to my setup for a quick test. A bit finicky but I got there and the result was. Let’s say magical. 

I aimed for 5 mins but due to only setting up camera and IR remote not Wi-Fi to app on phone it was 5.5 mins. 

this one was 5 mins, happy as Larry. Now I can’t wait for a clear night without the moon. My biggest issue it seems is work life+ home life +British weather all playing ball at the same time. I do need to test some new balance now too as guide scope and cam made it rear heavy. 

Hello all, I thought I would come back with some updates. 

On 09/10/2021 at 16:52, rickwayne said:

Oh,  and the drift alignment stuff sounds correct. One thing, though, change the slewing speed on your mount so you can run longer exposures. It actually doesn't matter if you go off the edge of the frame so long as you get the timing right.

Perfect advice, I was able to do 3 minutes and the V was less than half my frame. 

On 09/10/2021 at 16:19, Ohgodwherediditgo said:

I think the HEQ5 has a worm period of about 8 mins, so that would rule out periodic error if you had a half hour with good tracking. The camera causing shake would cause it consistently ( i really doubt it's that ). Maybe a cable snag ? Or rough running RA bearing ?

Although I assumed out the box it would be nice and smooth, it turned out I had tight spots and backlash in the Dec axis and tight spots in RA. I stripped, cleaned and re-greased the ring gears and worms(wasn’t much grease there). The Dec axis some bad backlash and has a tight spots in the ring gear and the worm as it was getting tight every 360 degrees of the slow motion knob and about 120 degrees of the axis is tighter. In RA luckily it’s just the ring gear that got tight about 180 degrees was stiff and no backlash at any point. 
 

now RA has no tight spots and little to no backlash in the looser areas. But Dec has bad backlash and very sloppy in the looser areas, I may readjust to minimise in the loose areas and try and avoid the tight spots. The result? After a quick alignment and test exposure I have doubled my length from 45 secs to 1.5 mins. 

it’s over exposed even at iso 400 as the near full moon was high and bright. 

.

This is my entry of M42 taken on the 02nd of November 2021. I`ve only been doing astrophotography for 5 months and still and learning the ropes, I think I need to focus more on learning to post process. 

Taken in Bortle 5 with my 150pds on an unguided EQ5. My camera is a stock canon EOS M3, as it doesn't have the port for an intervalometer I used the canon camera connect app and an intervalometer app on my phone.   

60x 45 s lights at ISO 800

30x 45 s Darks

68x bias 

56x flats. 

Stacked in DSS and processed with Gimp. 

Thanks

Danny

With the weather being the typical uk weather I have been doing A lot of reading, in between making a storage box and case for my telescope and gear. I also made a diy dew heater controller and now trying out my own diy heater pads.
 

After much spiralling and going round in circles saying if I just go a bit more I can get…… getting way out of control.  I have settled on the following. 
 

ASI462mc with a ZWO 850 ir pass filter

Astro Essentials 50mm guide scope. 
 

the hope is that although an ASI120mm mini is cheaper and more than capable the ASI462 has very high QE ( I admit I had to google what this meant) at close to 100% in IR making it almost the same as a mono cam is used with IR pass and guiding with only IR light. Then I can also use it as a planetary cam with its fast frame rate( a lot faster than the gpcam 2 I was originally looking at) and also as a dedicated Astro cam for small targets with its high sensitivity. 
 

I will then get the M3 swapped for a 600d and send that for its mod to use on the large objects, lastly I’ll keep an eye out for a cheap second hand ASI 120mm just to guide my ASI462 when I use it for planetary and dso imaging. 
 

thanks for all the info everyone. 
Danny

On 13/10/2021 at 16:31, AstroMuni said:

Thats the approach I took and it turned out that the ASI224mc was less expensive than DSLR, so thats where I began to learn (and still learning) My journey is in the link on my signature. BTW, I can get around 60s unguided, so havent purchased guider etc. and managing with short subs of 30-60secs

Hiya Astromuni, 

How did the asi224 effect your FOV? I was looking to keep to APS-C sized camera as my current camera and the 150pds only just frames some DSO objects. I used astronomy tools to see what I would expect so was skepical about even dropping to a 4/3rd sensor. So I was planning to stick with DSLR for the time being while I figure things out. A 600d is pretty much free with trade in, then it’s just mod cost while I learn the ropes. 

Maybe the plan could be to keep the 600d for larger brighter objects and a 4/3rds dedicated for other objects. 
 

thanks 

Danny

56 minutes ago, Robculm said:

Ha, yes, tell me about it! But I guess if it was too easy it wouldn't be so rewarding / addictive!

Sorry, will need to defer to others on the camera question. I have the https://www.firstlightoptics.com/zwo-cameras/zwo-mini-finder-guider-asi120mm-bundle.html which to be honest I randomly selected, but it seems to work OK for me & it's light (200PDS is already a heavy scope for the HEQ5 without too much additional clutter!). I believe there are mathematically optimal guide camera / scope criteria to match with specific telescope / camera configuration... Nothing is as straight forward as it first appears in this business!

I will wait for advice as don’t want to jump in again with my own decisions and be wrong. I did see that bundle too and cheaper than the Astro Essentials 50mm f4 guide scope and GPcam2 I was planning on but if it works I can dual use the camera for planetary and guiding. 
 

thanks 

danny

On 12/10/2021 at 07:52, Robculm said:

Hi Danny,

I see you've got lots of good feedback on this topic already, but I just wanted to add a quick comment since those elongated stars are oh so familiar to me!!!

I have the 200PDS on an HEQ5 mount & spent hours & hours optomising this & that, fitting the rowan belt kit etc etc... About 3 min was the max exposure length I could work with & even then I'd usually be throwing away 50% of the images (which is really really frustrating).

Autoguiding solved the problem.

So just to highlight that you will almost certainly need to go down the autoguiding route, even if you upgrade the mount. It might be worth experimenting with autoguiding on your current set up to begin with, rather than spending out on a new mount & finding that while it may improve, it will not necessarily resolve the problem!

Good luck,

Rob

Hiya Rob, 

it’s good to hear my issue is solvable. guiding was on my cards, now it may be something to get sooner than planned. I’ve only been into this a few months and my collection of equipment is growing more than I initially thought lol. 
 

I had looked into a planetary cam to use for guiding too and had come up with the Altair gpcam2 290c, is this good for guiding as I read mono is better but if I can I want colour for planetary imaging. 
 

thanks

Danny

12 hours ago, ONIKKINEN said:

I am imaging with an EQM35-PRO (basically an EQ3 with extra marketing and an extra counterweight) and an 8 inch newtonian that weighs in at around 9kg with guiding and cameras on top. While it is painful sometimes and windy days are by default no-go it is far from impossible. Shorter subs and leaving DEC unguided are proving to be effective measures for me. I can get around 2/3rds of my subs under 1 arcsec RMS (generally regarded as good) if the conditions are average.

 

The payload and mount capability conversation has gotten really out of hand IMO. What do you suppose is "good performance" for the payload? Eternal sub arcsec guiding, no effects from wind, never loses a single sub? Looking at 10k mounts there. A more reasonable approach would be: More than half of the subs are good or usable and this you can already achieve unguided, so adding guiding will improve things drastically. In my opinion don't stress about this, its easy to get into a spiral of spending because of general opinions. The EQ5, especially when guided will be quite capable of handling your 150PDS. Wind will keep ruining your exposures but that is a problem that newtonian users just have to live with, regardless of mount used.

 

The "mount limited" concept is also in my opinion outdated and not quite true. Really there is no such thing as being mount limited, the system is being photon count limited and a better mount allowing longer subs will bring in more photons per exposure. But why not go the other way around and make sure that all photons count? Using modern dedicated CMOS astrocameras you can use exposures as short as 10s and stack 6 of them to get a result that is pretty much exactly the same as a single 60s exposure. I was in the same boat as you, looking for a mount replacement because i thought i had to take longer subs, but changing to a dedicated astro cam changed this completely. I am now looking for more storage space for my computer to allow processing thousands of subs. This applies to DSLRs as well, but you probably cant get quite as short in the exposures, but IMO 30s should be just fine.

 

Now having said all that i do agree that cheap mass produced mounts should probably not go over 50% of their rated payloads to get consistently good results, but since money is limited for a lot of people i just choose not to follow this argument.

Thank you, some good food for thought. I have much to think about now, but most importantly I know it’s not the alignment or camera. Now I learn to work with it and I don’t need to spend hours retrying polar alignment over and over. 
 

first I’ll trade the camera for the 600D and go guided, give myself some time to learn and see how much my laptop drains my power pack. At home I can use an extension but I’m limited to 3 hours from 1am to 4am due to street lights. I’m waiting on permission to go to some private land in a bottle 4 out of the city with no artificial lights around. 
 

next will be the leap to dedicated Astro cam, I’ll spend my time with the 600D looking at astro cams and if dropping to 4/3rds sensor size will be ok or save for APS-C sized one. Another subject I have much to learn about.
 

thankyou everyone, much appreciated

Danny 

5 hours ago, Richard Wesson said:

The 150PDS is really pushing it on an EQ5 for imaging and many would say is too heavy. This will have an impact on longer subs, esoecially unguided. 

Thank you, I think this was another error when I was first looking into what I should get. When I planned my set up I looked up the weight capacity on skywatchers website as 9kg and the OTA was 5.5 so I upgraded the EQ3 to the EQ5. Now looking again I see there are posts saying for AP we should not go over 6.5kg. 
 

so this will need addressing, I’ll keep plodding on with my journey and keep an eye out for a HEQ5 maybe second hand but at the moment the ones I see are only just cheaper than new. Could be because of waiting times for new. 
 

thanks

Danny

1 hour ago, ONIKKINEN said:

If you're planning on getting a new camera and planning on guiding one day, consider not buying a camera for now and getting a dedicated astro cam with the guide setup? Especially true if you're planning on spending more than a couple hundred on a used model.

A cooled, low noise astro cam makes a world of difference compared to DSLRs. The only downsides are price and a bit of an annoyance setting everything up every time, but the results are well worth it. Since you will need some sort of computer to do the guiding, adding the astro cam is no extra effort.

The thought had crossed my mind but I put a 4/3rds (based on a hypercam 294 pro camera) into the astronomy tools fov calculator and large dso objects like andromeda, orion etc don't fit. They just fit in my aps-c crop and astro cams with aps-c i found came in quite expensive to the hypercam. 

Worth their money I'm sure but too much for me now. 600D is almost straight trade for the M3 so just the modification cost. Or get some money off the 77D / 6D I'm tempted with. 

If I think sensibly, I should get the 600d for little actual cost and use it to learn more before diving in with a more expensive camera be it dslr or dedicated. But I've not been that sensible since I took this up in June lol.  

2 minutes ago, ONIKKINEN said:

The alignment is good. I don't see a reason to doubt polar alignment in this. I recommend you try shorter exposures and see where you have a good compromise between signal to noise ratio and failed exposures. The 60s sub in your post looks really good, actually unnecessarily good. If you can see the object in a single sub, then it is a really good sub. The 5 minute sub is actually overexposed, and you gain no useful data compared to taking a 1 minute sub 5 times. Something i would note is that 35 out of 60 subs being that good for unguided 60s subs with a newtonian is actually a decent result.

The elongation of stars is in the same direction as RA in this case, indicating that the tracking issue is entirely RA related.

Thank you, makes me feel better now. I thought I was loosing to many subs, eventually I’ll go guided but I want a better camera first then get it modified.

This was the reason for the 5 mins as my M3 has the hybrid AF sensor and when looking into cameras I saw lots of posts with strange dark lines caused by the hybrid AF. So I was trying to make my m3 do it to find out if it can be avoided. But I never got an image with the dark lines. 
 

now I’m looking for a 600D or a model after the 800D like the 77D etc. 
 

thanks

Danny