Robculm

Thanks Alacant, Thanks Clarkey, Will definitely keep the EQ6 in mind. Hopefully I might get a decent resale price on my HEQ5 pro (with belt mod)! In the meantime, will work on my 200PDS. I already have the mirror glued & upgraded screws. Will look at getting a 500mm Losmandy plate & aluminium bar for the top (on which also mount the guide camera. What's the advantage of upgrading the focusser? I don't tend to see any change in focus during a session, so don't think I'm getting any movement from the stock focusser. I do see that my collimation drifts a little depending on the scope orientation, but I assumed that's down to flex in the tube or the weight of the secondary on the spider vanes. Cheers, Rob

Thanks Alacant. If I was to upgrade the current vixen style bar to a Losmandy, I guess I need to change the tube rings too (wider spacing where it mates with the bar), any suggested bar & ring sets at a reasonable price!? I would then look to move the curent vixen bar to the top of the rings & mount my guide camera there (as I've seen in some of your previous set up photos). Regarding the mount, I hadn't really considered the EQ6-R as although it's belt drive (and I've already belt modded my HEQ5 pro) & higher load capacity, I assumed it would still have the poor worm gear issues of the HEQ5 pro? Is it really a significant upgrade, in comparisson to something like the iOptron GEM45 (which for sure is somewhat more expensive). Cheers, Rob

Hi Lucas, Just to say your website is great! Some fantastic images. My 'future targets list' has just got quite a bit longer! 👍 Cheers, Rob

Thanks for your comments Onikkinen & Steve. Yes, that's a good point Onikkinen, for DSO's the mirror quality probably isn't of such importance compared with tube stability and mount / guiding. The TS Optics options do look interesting & worth to keep in mind for the future. I guess for now I will keep 'fettling' the 200PDS and maybe move a better mount further up my wish list! Cheers, Rob

Hi All, As you know from my profile, I'm currently using a standard Skywatcher 200PDS. I love the 'light gathering' capability of reflectors & despite the immense frustration of collimation etc, my feeling is to stick with them, rather than switch to a refractor. However, it does frustrate me that unlike refractors, where there are stacks of choice & a relatively straight forward link between price / performance, it's definitely not so clear cut with reflectors. While I've seen some great images with low cost tubes like the 200PDS, there's no guarantee of optical quality compared for example with buying a Takahashi refractor! Just wonder what people's thoughts / recommendations are for 'higher spec' reflectors. As I see it, there's the PDS and various low end equivalents. The Skywatcher quattro & equivalents, but it's essentially the same in terms of optics. The Vixen R200SS which almost certainly has better optics, but has enormous diffraction spikes due to the heavy duty spider vanes & similar for the Takahashi Epsilon. Don't get me wrong, I'm a fan of diffraction spikes, but both of these are a little too much IMHO. I've considered the Orion Optics AG8, almost certainly great optics, but very expensive & not sure of the quality aside the optics. Aside that, I guess there's the option of a 'standard' tube, such as the PDS or quattro and upgrading the optics (again for example Orion Optics or I see some TS options). Anyway, thoughts / suggestions welcome please. Also to note, I think 8" is adequate in terms of aperture, certainly for my HEQ5Pro, longer term I'd like to upgrade that, iOptron perhaps, but aside the mount tube weight just from an ease of handling perspective is just about right, for me at least! Cheers, Rob

Yep, that's it. Camera is just 'rotated' compared with mine. Here's a single 'sub' which I've rotated to match the orientation of your image & cropped a little. Not sure your exposure time etc, but the star shape looks pretty good 👍

Thanks John 😀. Yes, I was pleased with the colour in general and it was straight from the 'default' on startools, no tweaking! It's definitely a worthy target, but doesn't seem wildly popular!

I'm still trying to solve some problems with diverging diffraction patterns on bright stars, so thought I'd try a target without any! Definitely some room for improvement on the processing, but generally speaking I'm quite pleased with this so thought I'd share for comments / suggestions please! On this version I've kept the stars quite 'bright', as although they distract a little from the galaxy, it's such a beautiful 'foreground', seems a shame to suppress it! It's around 6h of data, 300s exposures.

2021 was my first year of imaging. Still a lot to learn & hoping for a significantly improved set of images in 2022! Anyway, here are my favourite 5 in chronological order, all with 200PDS & EOS800D. M42, NGC4435 / 4438 (Markarian's chain), M16, NGC6960, M33):

Hi Stu, The mirror cell is effectively 'floating' on the 3 springs / pull screws. The push screws are just for 'locking' after collimation. I see what you're saying, but without the spings it would be very difficult to make adjustments. To be honest I don't make much use of the locking screws. With good stiff springs they are not really necessary IMHO, but I'm still very much a beginner & don't always get imaging results I'm happy with (i.e. take everything I say with a pinch of salt!).

Hi Stu, I used these for my SW200PDS & they seem OK, albeit a tad expensive for what they are and they are not 'ground flat' on the ends. https://www.amazon.co.uk/gp/product/B08FDWWBZK/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&th=1 Rob

And yes, colours are a bit subjective! I'm using the UHC filter so there shouldn't be much green there to begin with, so just my processing that's to blame on that one!

Thanks both for your comments. Camera was removed between sessions & of course re-focussed each time, so must be something 'fundamental' in the set up, not specific to these sessions. Spider vanes all look good, so I'm still at a loss on the root cause here! Any other suggestions welcomed. I will try to set up a very bright artificial star test & see how it looks... Cheers, Rob

Finally some clear skies and managed a couple of sessions on this area with the modded camera (also using ES UHC filter). Both are ~ 3h total integration (5min exposures). First image was early Feb, with no moon, 2nd image (where I've also tried to frame in the flame) was this past week, with ~70% moon. Alnitak makes this quite a challenge and I'm wondering if anyone has any thoughts as to why I'm getting these very long double diffraction spikes? Cheers, Rob

With small periods of 'star lost' (like I'm having tonight here in Devon), the AAP picks up the star again as soon as it's cleared & continues as normal. I'm not sure for longer periods though (I'm hoping we can avoid them tonight as it's the first clear one for months!!!). One thing I've found very useful though is that if you make adjustments to the centering (i.e. changing the framing of your target away from the default), you can save that (add in favourites & use current mount position), so that you can come back to the same point again. I regularly use this so that I can re-focus or come back to the same exact position on another night.

Hi All, Just a word of warning on the silicone method (albeit on my 200PDS not the 130). Do be sure to only use 'dabs'. I got a bit carried away & siliconed around the complete edge which resulted in significant primary astigmatism, which took quite some time to figure out & it wasn't much fun cutting the mirror out again! For now I've reverted to the clips. Given how thick these mirrors are, it's really surprising how much stress the clips introduce, you really have to tighten them the bare minimum, just enough to secure the mirror in place. I will be taking another shot at the silicone approach in future as it did for sure remove some of the 'artifacts', but for now I'd just be happy with some imaging of any sort if the weather ever improves! Cheers, Rob (from cloudy Devon)

Thanks 😀. I hadn't considered that option. 👍

Thanks Vlaiv, an excellent explanation as always 👍 Ha, yes, I've seen from other posts that the planetary imaging is 'very different'. It's not something for which I have a great desire, but they jupiter is always so bright & tempting! Maybe I will explore the Barlow (perhaps a higher power) just for some 'visual' kicks for now. To be honest, I think I'm just getting itchy fingers as the weather is so darn rubbish and I can't get a decent imaging session on anything at the moment!!! Thanks again, Rob

Coming back to this topic, but from a slightly different perspective. I'm contemplating getting a Barlow lens to 'increase magnification' for smaller targets. Possibly planets (something I've not really attempted yet), but certainly smaller deep sky targets. So how does this work in terms of gathered light / image resolution etc... The Barlow (lets say x2) gives me 1/4 of the field of view, but does 'all' of the gathered light make it in to that 1/4 area or am I again missing something on the mathematics here! And in general, thoughts on using a Barlow (this would be with the 200PDS) for imaging? Don't seem to see much reference to this, so not sure if it's common? Many thanks Rob

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

Thanks Vlaiv, yes, that's much clearer 🙂 Key point is that I need to think very carefully about the targets I want to image & that I should probably persevere trying to optimise my 200PDS performance for now! Thanks again, really appreciate your time explaining in such detail. Cheers, Rob

Thanks for the comments. Hi Vlaiv, the headline number (~82%) sounds good - Thanks. But still not really clear to me how we get to that. Yes, using the 800D, so 3.7x3.7um pixel size. With the 200PDS, forgot to mention, I have the Skywatcher coma corrector, which is also a 0.9 reducer, so actual f is ~900mm. The astrotools FOV calculator tells me that's a resolution of 0.85x0.85" pp, FOV 1.4x0.95deg. For the 100ED, 1.39x1.39" pp (FOV 2.32x1.55). So around x2.67 more sky area, and around x1.93 resolution per pixel. I understand that from a sampling perspective, .85x.85 is 'oversampling' and I'm binning 50% in processing (software) , 1.39x1.39 is a much better sampling rate and possibly doesn't need binning? When you say can only compare if imaging at the same resolution, can I basically say that if I imaged the same target, let's say this M33 image for example, and I cropped the 100ED image to the same size as I have here from the 200PDS, I'd have lower resolution and ~ x4 worse signal to noise? So the 100ED only makes sense on larger targets where I'm using the 'whole' image? Apologies again, maths is not my strongest suit! Thanks, Rob

Hi, apologies for what's probably (to some) a very obvious question! I'm tentatively looking at APO's, such as the Esprit 100ED as an 'alternative' to my 200PDS. The Esprit 100ED in particular as I'm looking for a slightly bigger FOV (but not too much), it's a good weight (little less than the 200PDS so should be OK on my HEQ5) and price isn't 'too' crazy. Back to the key question though, is my understanding correct that I basically get about x4 less 'light gathering' with the 100ED than with the 200PDS. OK, presumably a little less as there's no secondary obstruction, but even so, it's quite a significant number. I'm sure there are some factors related to the f number etc that I'm missing here?! But in general, does this mean I need x4 imaging time to achieve similar results? Main reason I'm considering this that I'm constantly battling collimation / star shape with the 200PDS. But I don't want to spend £2k on a new set up only to be dissapointed with what I can achieve! Aside star shape, I feel I'm getting some reasonable images! Would very much appreciate advice / comments please. Note, here's my latest example, 2h of data on M33. So this is my 'starting point' as such and of course looking to improve upon!

Yes, I'm definitely thinking now is the time to focus on more wide field targets & save investing on a higher magnification, narrow field of view set up for later as things get busier!

Since we all have to increasing endure these ruined exposures, rather than just angrily consigning them to the trash, I thought perhaps we could at least gain some minor enjoyment from comparing them! I was particularly impressed with the symmetry of this one in a single 3min exposure!