rnobleeddy

Any views on a baader fringe killer instead of an astronomik L3 filter? Aside from the weird behavior in the lower wavelenths, it doesn't like the baader would be terrible? Asking only because FLO is out of stock on the L3, and whilst it'll inevitable be cloudy when I get there, I want to take it with me for the holidays!

As weird as it sounds, in a similar situation, I had good success with a jar opener tool - effectively a grip with a rubber insert to grip the thread.

The last week ha been a mixed bag of weather. I left the kit imaging but cloud periodically ruined subs, sometimes just 1, sometimes 10 in a row. I have 180 frames in total to stack in DSS. About 10 are totally clouded out. The rest get scores ranging from 0 to 5900, with a large number around 4000. I know it's a trade-off between SNR and quality - but does anyone have an approach to choosing the cutoff scientifically? I tend to work something out based on the data - I remove any low outliers, or if the scores are more normally distributed, I'll pick perhaps the best 80%. I will err on the side of more data. Obviously I could (and might) try stacking different numbers and seeing what happens. But I also wonder if the computer couldn't do this for me - rather than stacking the best n%, software could work out the # of images that resulted in the best stacked image. You'd just need a good measure of quality and a lot of CPUs!

It's an interesting comparison with other hobbies. I cycle a lot. Whilst I don't enter races, I was recently told about the guy who won the local clubs hill climb - he chose not a super lightweight carbon bike, but an older heavy bike that was a large disadvantage. He just happens to be on a different level of fitness to the other members. That never happens with deep sky astrophotography. You can do very well with limited kit, and there is definitely a lot of skill involved, but the laws of physics dictate that my 6" newt in my back garden will never be able to produce better images than the 12" newt on the top of a mountain in Chile. This was most apparent on a recent trip to an astrophotography exhibition in London. I was pleasantly surprised how little kit some of the winners needed in some categories, e.g. for earth based images of aurora, or for the more artistic images. There was some planetary and solar images that were taken with kit many people here will have. But move to DSO's and almost without fail, they were very long exposures with very large telescopes in very dark places with very good seeing. I don't disagree at all - but there are limits!

Definitely still enjoying it. I guess I maybe caught in the cycle of buying new equipment at a rate that exceeds the number of clear nights we have! I don't think I'm the only one, and the 2nd hand sales here and ABS make it pretty affordable, as long as you periodically part with the stuff you don't use!

Similar here. I haven't had a lot of luck with the meridian flip even though others with the same equipment have. I tend to choose a target that is past the meridian before I go to bed. I'm very cautious about weather forecasts (multiple apps, no clouds etc) but one day I will be caught out!

I think integration time is main factor I underestimated. Of course there are exceptions to everything, but the difference between 2 hours and 20 is massive, and many of the images I struggle to match have at least 2x the integration time. I've tried to be less greedy with the number of targets I try to work on at once!

Thanks - that at least makes it a really easy choice!

I managed to get one of these 2nd hand (after also getting a Samyang - I'll compare and contrast, and sell one at some point!). Any recommendation on an L3 filter?

Been at this for about 18 months now. Enjoying it, but trying to work out what to focus on in the longer term. A recent observation is that it gets harder and harder to make improvements, and so I wondered what others take on this is? I started with a 130PDS and a modded DSLR. Over the course of a few months my images progressed from terrible to acceptable. As it happens to help with this comparison, towards the end of my time with this kit, I imaged M33 and it was one of the better images from the time. Fast forward a year - I have an (older) cooled mono CMOS, filter wheel, narrowband + LRGB filters and a couple of decent APO refractors. I had some mount issues that I recently resolved, and so as a test, M33 happened to be favorably located. I collected about 4.5 hours of LRGB data. I'd like to add some Ha to the image too, and get more/less moon impacted L data, but the comparison is not clear cut. I probably prefer the older one! The new one has more color (probably too much, given they quick processing) but maybe over processed. Given the cost ratio of the setups (a £200 OTA + £150 camera vs a £1K OTA and a £1K of cameras and filters) I'd certainly choose the earlier image for the value for money award! The point isn't these two images in particular - but that it seems to be getting harder to get better. Does everyone experience this? There are other benefits of course. I love narrowband images and the new setup is far more consistent - I never get to the end and regret the fixed pattern noise of the DSLR anymore. But I might also be happier with the cheaper setup - that way if I leave it out overnight and it gets rained one, it's not quite as big a deal!

Found them. Agree the prices are good, although it appears a couple of places will recoat the one I have for closer to £80. Of course, I'd actually forgotten how much a new 150mm Newt would cost, so it appears both options are in budget! I'm new to worrying about mirrors - do you have any tips for trying to polish it?

Thanks - both good points! I know the general suggestion is that mirrors can be pretty bad and still produce good results, but I guess convincing yourself of that is harder. It's certainly free and easy to both try a more aggressive cleaning approach (rather than soapy water) and try using it. The secondary is in good condition and cleaned up nicely. I can put up with the ropey single speed crayford focuser, so it is entirely usable.

I bought an old TS Optics 150mm Newt in a pretty poor condition (but priced accordingly) as a project to get more acquainted with taking scopes apart and making mods. I knew the primary mirror was probably corroded, and that has been confirmed when attempting to clean it. The original model is uncertain (TS150, perhaps F/6) but I don't anticipate the quality is/was particularly good - I'd expect it to be on par with the mirrors you'd find in a Sky-Watcher 150PDS, for example. With that in mind, I just wanted to confirm: - although the pics are poor, that the mirror is beyond use? - re-coating is going to be uneconomical? And if so - does anyone know a good source of replacement mirrors? Obviously the aim here isn't to save money, else I wouldn't have started, but if the cost starts to approach that of a new 150mm Newt then I may start to question my choices! I guess the fallback is to put wanted ads here and on ABS and just wait. I have patience!

To reply to myself, this pretty much came down to belt tension. From my experiments there was a (relatively) forgiving range of worm end tightness and worm meshing in which good results were achieved, but insufficient belt tension was a killer. I'm unconvinced I'm any better off than before the belt mod - DEC backlash still measured between 0.8 and 1.9s but that's within the range that PHD2 appears to be able to mop up with backlash compensation. I didn't measure this before though!

Thanks both. Based on a quick look on eBay, there aren't many used Samyangs, so cost is similar apart from the L3 filter. I'll do some research at the weekend - I'd guess the longer focal length will be my preference, but there are plenty of good images with the Samyang too.

Had a bit of a nightmare belt mod with my EQ6 but after a lot of work, got it back together and there was just about enough clear sky to see how it guided. The answer is worse than before! Just wondering if anyone has any additional ideas for this large backlash in DEC (which amounted to 12s!) : The easy things to try are: - make sure the worm shaft is not too tight (or too loose, but it isn't!) - ensure the pulley tension is sufficient After that, and most likely, I guess its the worm gear itself meshing with the shaft? There is no free play by hand - can this be true and lead to such bad backlash? The RA gear was worn and had some minor damage on a few teeth, so I swapped RA/DEC over but I didn't do too much to file the burrs/rough bits on what is now the DEC cylindrical gear. It's not as tight as I'd like but I just got to the point where there was no free play by hand and it didn't bind on a full rotation. It would go a lot tighter and not bind most of the way round, but would bind in one spot. Does anyone know if the binding tends to be caused by small defects on the gear itself (which I can file) or manufacturing tolerances relating to roundness etc of the whole part? If it's the former, I can take it apart and work on filing it. If the latter, I guess I'd do better swapping the RA/DEC cylindrical worm gears back? In general, if one gear has some damage and a replacement is not easy to find, is it better on the DEC or RA axis?

Great thread - I'm looking for something with a focal length in this range and this seems like great value when compared with other scopes and even other Askar products. Wondering if anyone has direct experience of this vs the Samyang 135mm f/2? I know they're slightly different beasts, so whilst I can't imagine the Samyang is better, the advantages of the Samyang for me are that it doubles as a camera lens, and there's a realistic chance of finding a 2nd hand one. I'll dig through the Samyang thread too, but with so many variables in play, it'd be great if anyone has direct experience of both?

Going to get a wedge to be able to use an AZ-GTI in EQ mode. Assuming stock exists, all I can see to choose from is the Skywatcher wedge (I've owned one before, it was fine, but a bit flimbsy) for £62 (https://www.firstlightoptics.com/skywatcher-star-adventurer/skywatcher-star-adventurer-equatorial-wedge-white.html) or the Williams Optics for £180 (https://www.firstlightoptics.com/william-optics-mounts/william-optics-wedge-and-extension-bar-for-skywatcher-star-adventurer-and-ioptron-skyguider-pro.html). Just wondering if anyone has an opinion or other options? Is the WO wedge worth the extra? Does anyone have an opinion if the Skywatcher is likely to be the weak link?

I have an old, old EQ6. Provenance unknown, it's black with the words "Heavy Duty" on it. But it's been guiding at about 0.8" RMS for the last year, so I decided to belt mod it. It didn't really want to come apart, but with a lot of tapping out of bearings what were stuck on shafts, I eventually dissembled it. The problem I face now is that the large, cylindrical brass worm gear won't fit back in the mount. Whereas in the various guides and on the attached video (~3m 50s in), the RA axis just slots back on the mount, for me, the brass cylindrical gearing won't even fit back in the mount. I've taken a short video showing just the brass section not fitting in the mount - https://photos.app.goo.gl/XiXf9tHPEPWxuH528. I'd previously fitted the RA axis with a little tapping, but it was locked solid, only moving when the worm drive was engaged. The RA axis was previously stiff, but did move. Aside from the obvious approach of sanding/smoothing, am I missing something obvious? It's hard to understand how the RA axis used to rotate, but now won't even fit together:?

One of the difficulties I've found is comparing mounts - the skywatcher mounts are used frequently enough that you can get a reasonable read from comments online, but I don't think that's true of any other brands/models. Based on what I have read, my expectation of an ioptron would be that it will probably guide as well as a decent example of an equivalent skywatcher mount, but that the quality control should be better, so I'm less likely to need to get out the toolkit on the first night.

There are numerous issues reported with the zwo usb2.0 cameras on Linux. Some people reported success with different firmware, but I just swapped for a usb3.0 model.

I have some of these on the way. Doug seems like great guy!

I have had a similarly difficult job getting the RA out - did yours go back together OK? Mine feels incredibly tight fitting.

Always worth googling:

My 18 year old EQ6 (black, labelled heavy duty) has run into a few issues during a recent attempt to fit a belt mod. I manged to get a free a seized shaft and bearing without too much damage, so all I'm short of is some PTFE shims that were spacing the RA axis. Has anyone found a reliable source of these? Otherwise I wonder if a plastic milk bottle and a stanley knife will suffice.