rnobleeddy

Having played with a few random old and new lenses, definitely do some research before buying. All lenses are not equal, and the cheaper zoom lenses that come with DSLRs have been pretty awful in my experience. On the flip side, some older prime lenses have performed well. If buying new, there are some threads here that cover some common good choices, like some of the Samyang prime lenses.

Thinking of consolidating my kit, for a number of reasons; I haven't really taken to imaging whilst travelling (or don't travel enough), and there's not enough clear nights to justify trying to keep 4 OTAs in rotation! I don't have an obsy (yet) so setup time is a consideration.

My most successful OTA has been my 130PDS - I built a shelf that I can install all the kit on, and so I can be up and running in 10 minutes from scratch.

Other main kit is an EQ6 that I leave in the garden, a Canon modded DSLR and a QHY163 mono camera with FW + the usual  7 filters.

So getting to the main question - what do people consider a good upgrade to the 130PDS? I'd like a similar/slightly shorter focal length, and nothing too bulky to make setup difficult.

My guess is that a 100-120mm APO refractor would be a good bet - would people suggest that this would provide a decent step up?

If so, is there much variation in imaging quality between the brands/designs - I know that a triplet is optimal, but I've seen good results from the ED doublets?

Obviously, I don't need to spend the cash I get from selling my unused kit on more gear, so just sticking with what I've got is also an option.

I personally love KStars/Indi/Ekos. I find the interface much easier than anything I've seen on Windows. I'm not sure I fully understand this thread, but if you just want a single Windows laptop connected to your kit, I guess NINA or APT is a better idea? 

I've used a VM before, but for £50, and as long as you can get a reliable network connection, I can't see any reason not to use a Pi as the INDI server, even if you sit next to it with a windows laptop.

A random Astrobiscuit video is the reason I got in to astronomy. 

Obviously his videos hide a lot of the complexity, but that means they're also a good watch, and IMHO, probably the best astronomy videos on Youtube.

I don't actually know who this dealer is, but it may well be the person who's bought the most items from me on ABS!

I tend to price items at 2/3 of the new price and don't care who buys them. If you're trying to help out a newbie by offering gear cheaper, then a first come first served model may not be best?

I'm amazed anyone can make a living doing this, but I can't see any issue with it, especially if they're generally open about it.

It probably depends on your eye for detail. It will certainly hold it, but I'd imagine there'll be tilt going on. I have similar cam + FW (no OAG) and I'm happy with how well it works.

It's pretty common to add a third screw to the focuser to help hold the camera.

I guess the OAG isn't really needed given the FL of the 130PDS, but if you have it, it makes sense to use it - all this is adding is presumably a very light guide camera?

1 hour ago, vlaiv said:

If your 200mm lens can go unguided - I don't see why your 432mm refractor can't be used unguided as well?

Just because something has 432mm of FL - you don't need to use it as 432mm of FL. You can use it as 144mm FL for example.

Lens have advantage that they are simpler to use (that is actually questionable - not sure how simple focusing is for example, or mounting of the lens and getting spacing right - maybe on DSLR, but not on astro camera), but have disadvantage of having optics that is not diffraction limited.

Scope has "disadvantage" of being "long focal length" - but in reality, that is not disadvantage - it is simply use case scenario.

What prevents you from taking your 432mm FL scope and making 3x3 panel mosaic with each mosaic pane being binned x3.

Result will be almost the same as using 144mm FL lens (differences will be that telescope image will be diffraction limited and that you'll get slightly smaller FOV due to overlap needed to stitch mosaic). Processing is a bit more involved, but result is the same resolution as using 144mm lens.

If you can use 200mm lens unguided - why wouldn't it work for 144mm FL?

I guess from my experience, there's a lot more to go wrong during acquisition, but I'd also argue that processing is quite a lot more involved. I'm not aware of any free/cheap software that makes this easy? 

Awesome stuff.

I picked up an F/4.5 300mm Photosniper lens on ebay (tair-3-phs) a while back and just got it prepared for the next clear night. 

My previous attempts with vintage lens always lead to disappointment in the end but I have high hopes for this one!

One more for indi/Ekos. I've used NINA too, but I find Ekos more intuitive.

Thanks. 

I got pretty nasty results with the flattener initially. Part of this was my electronic focuser had some play in it, so the auto focus routine led to bad results. 

However, what also let me down was making the assumption that this would have the same tolerance as the Newtonian coma corrector I use, which appears to have a 1-2mm region which produce solid results. Based on what I experienced so far, the 0.79x flattener  I have will need to be adjusted much more accurately! 

After using a Newtonian for the last year, I finally got around to having a go with a 60mm APO refractor I bought 2nd hand last year. It looks undamaged, but I'm having a lot of issues getting acceptable star shapes. I went back to basics and removed the reducer/flattener, and so wondering if anyone can suggest if these results are normal for a refractor with no corrector?

These are screen grabs of the data at full size. FL is 350mm and sensor is a 4/3 mono CMOS with a luminance filter. Short exposures (I think 10s) with the mount tracking.

I only captured 2 corners + the center, but the other corners show the same pattern, with the stars (for want of a better word) "flaring" out from the centre. The effect reduces as you go towards the middle and appears to be symmetric around the center.

I'm hoping that either looks normal or if not, perhaps it's obvious what the issue is? My mono camera + FW is heavy so there could be an issue with tilt, but I don't see how this would produce this pattern? Similarly, it's a doublet air spaced apo (photoline 60mm) so whilst color correction may not be perfect, I can't imagine this is related to that.

Top left

Approx central 

Bottom right

Bottom 

2 hours ago, vlaiv said:

As you say yourself - RA performance depends on where the mount is pointing.

RA error will be largest near equator - at DEC values close to 0°. Once you start moving "upper" to DEC values towards 90° - your RA error will stay the same in terms of arc seconds but it will not be the same in term of pixels on sensor. That makes sense if you think about it - if you point the scope at Polaris - you won't really be tracking as Polaris stays put - you'll be rotating your FOV at very slow pace - one full rotation in 24h.

For this reason it is best to calibrate your PHD at equator - close to DEC 0° - regardless where in the sky you'll be guiding.

Second thing that I'd like to point out would be that if you have 0.3" / 0.5", 0.4" / 0.4" and 0.5" / 0.3" RA and DEC guide values and you can notice star elongation in your images - well your guide setup is not measuring things correctly.

You are probably using very coarse guide setup - like very small guide scope with short focal length. Are you sure you entered guider parameters correctly in PHD2 (focal length and pixel size)?

Say you have 0.3" vs 0.5" error, you use 6" scope and have good seeing conditions of 1.5" FWHM. That is 12% elongation or 1.12 (one axis is x1.12 "longer" than other). Here is what that looks like:

Do your stars look elongated like that or more? With smaller aperture and worse seeing - they will be even more round as guiding performance will contribute less.

Thanks. I think I've jumped to causation when I really just observed correlation! 

I'm using a 9x50mm finders converted to a guidescope with 120MC/224MC - two separate setups with similar guide scopes give the same guide numbers with the correct settings in PHD2, although the internet suggests perhaps one of my 9x50mm guidescopes is 15mm shorter than the other, so maybe 10% out.

I'll dig out my maths textbook, but I naively assumed double the error meant double the star size. After some googling I realise this is wrong. At worst, perhaps I had 0.25" is one axis and 0.5" in the other.

I've looked back through the subs and realised:

- some of the worst subs in the position I thought was bad appear to have double stars that look like "jumps" in the mount, so I might have some differential flexure/movement in the main OTA that's not in the guide scope. It's a brand new setup with a short focal length (280mm with reducer) and the OTA dovetail mount I got to may not be optimal.

- however, even the best subs have some distortion in the corners but are good in the centre, so I think my reducer is too close. I hadn't realised the flattener spacing was so sensitive, or at least, so far away from the spec, because I measured very closely! It's textbook "too close" according to https://stargazerslounge.com/topic/340444-flattener-spacing-does-it-work/ and the software I use just showed me the top left corner, so the straight line stars looked like a tracking issue.

So I think I probably have a few different issues going on and I jumped to the wrong conclusion - thanks for the guidance. I'll just wait another month for a clear sky to try again

Having intermittent issues with my FW and before I give up or accept the occasional reboot, I thought I'd try the recommendation I found in a few places to ensure the firmware was upgraded.

However, since QHY changed their website, they don't appear to offer downloads for legacy kit, so thought I'd check if anyone has it?

I don't think it matters, but this is the CFW2-M-US version.

Tried a few different targets last night as part of testing a new scope. I realized that my EQ6 has different tracking performance depending on where in the sky it's pointing. That makes sense. However, when I started to look at some images I finally joined the dots and realized this is what's causing me to sometimes get oval stars. 

I can't remember what order this was in in terms of height in the sky (although I imagine it's easy enough to guess), but let's say I was seeing tracking of 0.3/0.5" in PHD2 in RA/DEC in one position, 0.4/0.4" in another, and 0.5/0.3" in another. Exposing for 5 minutes, I can see oval stars for either of the  0.3/0.5" combos, but perfectly round stars for the subs tracking at  0.4/0.4". 

Based on my knowledge of what's going on here, I have no reason to expect to get equal tracking, because the errors are caused by different things.

Is this something I have to live with, or do your mounts tend to track at the same rate? The error is pretty much regular noise rather than occaisional large jumps - so I don't see how shorter exposures would help?

It's an old EQ6 but tends to track pretty well (always below 1" RMS, and as low as 0.6"). No belt mod yet, but I have one that I'm waiting to install. I realize this may help DEC tracking, but it's not always going to help the imbalance.

I tried a 130PDS on an EQ5 and whilst it's possible to achieve good results, if I had a time machine, I'd go back and get a HEQ5 immediately (rather than a few months later). People do report success with EQ5s, but mine was a bit of a disaster in DEC. That said, I'm much better at polar alignment now, so  I do wonder how much better it'd perform if I could try again.

Not my area of expertise but these are going to be small. Check out astrobin e.g. https://www.astrobin.com/3my458/

Like others say, focus on a far way lamp post of chimney etc during the day. That'll get you close enough. Otherwise I often find that a guide scope or red dot finder is helpful when setting up a brand new scope. 

On 17/07/2021 at 19:33, Starwiz said:

Stratton was used for star removal from the SHO data.

I was unfamiliar with that software - but I guess it suffers the usual issue that it doesn't work with diffraction spikes. I'll give it a go anyway!

I don't it's possible to tell based on a graph alone. I don't consider myself that knowledgeable, but I can't see any reason why you should necessarily expect them to be similar, although obviously that's be ideal!

I'd guess you have good PA and so very little correction is needed in DEC. 

For RA there are two options - why is it mechanically worse (imbalance, play in the gears) and then separately, can you make the guiding better without touching the mount.

All of your RA corrections take two or three pulses to correct. I'd probably trust the guiding assistant over me, but Id start by dropping from 3s to 1s exposures and see if things improve.

8 minutes ago, Louis D said:

I haven't had a chance to try my recently acquired 20mm SVBONY 68 degree in my 127 Mak yet, but it does reasonably well in the central 50% of the FOV at f/6.  It should perform very well at f/12 for 75x.  They're £29.99 shipped from ebay UK.

Although the 6mm and 9mm SVBONY 68 degree eyepieces are well regarded for sharpness, field of view, and eye relief, they have a lot of kidney beaning (SAEP) going on, so keep that in mind if you're sensitive to it.

I'd recommend the 8mm BST Starguider for highest power viewing (188x) with the 127 Mak.  It does quite well in mine without SAEP for a bit more money.  I'd pair it with the 12mm for a bit lower power (125x).  Bought together, FLO offers a 10% discount.

At the low power end, a 32mm GSO/Revelation/Astro Essentials Super Plossl works fine to provide the max field of view at 47x in a 1.25" eyepiece without breaking the bank.

Perfect - thank you. I'll take a look at those in the morning

Can't see much below 30 degrees South from my garden, so I picked up a second hand Skymax 127 (https://www.firstlightoptics.com/maksutov/skywatcher-skymax-127-ota.html) as as a portable planetary imaging scope. It's also light enough to be a grab and go visual scope for use with the star adventurer when we're camping, but as I've never much been in to visual astronomy, I have no idea what eyepieces I'd need. 

Can anyone recommend 2 or 3 of budget eyepieces? Focal length is 1500MM, F/12.

No need to go for anything of particular high quality. It'd be good to get a decent view of planets, and whilst I realize the OTA isn't great at DSOs, I'm happy to have a go with it. 

I've generally found svbony hard to beat when you don't want to spend too much, so they'd probably be my default choice.

On 16/06/2021 at 14:09, Davey-T said:

You can attach DSLR lenses to ZWO cameras.

I'm waiting for my Asiair warranty to expire to fit an external WiFi aerial.

Another annoying thing is only being able to take flats, darks and bias calibration frames but a lot of folk are taking dark flats.

Dave

Assuming you mean the drop down is missing dark flats then that's the same as astroberry and is a little annoying. 

Fortunately I don't take fresh darks each session, so I can label the dark flats as darks without fear of getting mixed up!

6 hours ago, Budgie1 said:

Up here we have Sunrise at 04:28 and Sunset at 22:16 and 17 hours and 48 minutes of daylight for today. It's also Twilight all night at the moment, so never mind astronomical darkness, it doesn't even get completely  dark! 🥴

Still, on the bright side, it's been cloudy for the last 3 weeks so I couldn't have done any imaging anyway and it means I don't have to slather on the Smidge just to setup the scope!  

I'll be back imaging by August (hopefully) and in the meantime I get to see what everyone else is managing to do on SGL, finding handy tips for processing and swapping a bank balance for more astro kit, so it's not all bad.  

I have no sympathy - I spent a week on the Caledonian canal so I know the views more than make up for it!

16 hours ago, AbsolutelyN said:

We've had more clear skies since April than in the entire of last winter so I'm certainly making the most any clear skies I can get. I was unsure how possible it would be without proper dark skies and very short nights but so far so good and soon nights start getting longer again. This is 5.5 hours over two not very dark nights last weekend - approx 23:30 to 2:30. 

Really like target with a shorter focal length. May be the next thing I try - thanks!

I'd pretty much given up a month or so ago, but after selling a spare OTA to a more enthusiastic summer imager, I thought I'd recapture my "have a go" spirit and decided to collect some subs over the recent clear nights.

This was fraught with issues aside from the lack of darkness. My scope, having previously held collimation for months, was no long collimated. After some testing swapping spacers to a new OTA, I'd lost track of the correct coma corrector spacing. One night partway through the collection, the frame shifted by half a degree, but magically kept guiding. 

This is what I ended up with: approx 6 hours of narrow band data,  quickly processed. As expected, the Ha data dominates, and there's plenty to pick fault with. But I'm glad I tried - I would have thought this was magical when I started a year ago and it gives me something to benchmark against later in the year.

So just wondering if anyone else is still having a go - and if you want to share?