Better Imaging Set-Up

[IanL]

Looking for a bit of advice from those who have been there/bought the T-shirt. Bear with me and I'll explain all in a long-ish post, rather than expecting you to be mind-readers! My current set up consists of:

- NEQ6 Pro (new one with the dual Losmandy/Vixen dovetail clamp), EQMod controlled via laptop/Stellarium.

- Meade LX10 8" SCT OTA (de-forked and mounted on an ADM Losmandy dovetail), Revelation Astro Crayford (non motorised, not low profile).

- Orion ST80 piggy-back mounted on the LX10 (using a cheap U-channel rail system with some outriggers, all metal bolts, non-adjusting scope rings).

- QHY5 guider and PHD.

- Canon EOS 500D uncooled/unmodded for imaging (also needed for daylight use, can't afford a second DSLR for modding or CCD), use BackyardEOS for capture.

The theme here, in case you hadn't spotted it, is "Cheap". I don't have huge funds to invest in gear; the SCT cost me about £1,200 sometime in the last century and since then the only major investment has been the new mount. Everything else is as cheap as I can get away with due to my other expensive hobby of having kids.

I am looking to spend a bit, but not very much, on improving my imaging. Here's my thought process:

- My main problem is time, or lack thereof. I can only get outside and image at weekends, mostly Saturday nights, and so taking in to account the poor weather, moonlight and light evenings in the summer, usable time is pretty limited, especially when I have to set up, cool down the SCT, polar align, collimate and get EQMod, PHD and BYE all playing nicely.

- On the plus side I have reasonably dark skies outside the back door (for Essex values of dark skies, which is to say not very but usable). I do plan to build an obsy eventually but that is a major undertaking and not going to happen this winter.

- As a set-up for planetary imaging it is okay but not brilliant. It is great for lunar and probably my most successful forays have been in lunar imaging. For DSO work, it leaves an awful lot to be desired.

- Getting usable, non-trailed subs is a pain. I know the odds are stacked against me, imaging at f/10 with a piggy back f/5 guider is asking for trouble to start with. The guidescope mounting is not exactly top end but I think I've done a reasonable job of limiting flexure by eliminating plastic screws, solid guidescope rings, etc. Mirror shift in the SCT is likely to be significantly greater than flexure anyway, and there is no mirror lock on this vintage of OTA and no practical way to retro-fit one. I get some good subs, but it is pretty hit and miss and many end up in the bin.

Given that I don't want to waste the very small amount of time I have constantly trying to debug issues, I think I need to spend some cash to make my life easier. So thoughts I have are:

- OAG - I know lots of people advocate the use of these with SCTs (for good reason), but I am doubtful it would be right for me. It is yet another thing to go wrong or to spend hours of frustration trying to get working and just feels to me like it would add to my problems rather than reducing them. I'd still be imaging at f/10 anyway, which is great for galaxies with the large DSLR chip, but pretty limiting for anything wider field, plus still have collimation and cool down hassle to deal with. (I do not usually have the luxury of several hours of preparation beforehand and then the whole night to image followed by Sunday in bed! More like "chuck the thing in the back garden and dash back indoors to deal with household tasks, and maybe get back outside for three or four hours later if it hasn't clouded over").

- Focal Reducer on the SCT - I haven't found anyone who says they have a successful set up using a Meade (or similar) 6.6 reducer with a non-low profile Crayford. Reducer to chip spacing is key, and I suspect the Revelation Crayford is too long to make this viable. I really don't want to go back to focussing without it for imaging, as the main focusser is not that precise and has a fair amount of image shift. Would result in brighter images in less time and probably much less trailing with the current guiding set-up, but still have the other SCT issues mentioned above.

- Use a DSLR lens piggy-backed on the guidescope (or even SCT). I have had some success using the 18-50 kit lens and a cheap Sigma 200mm zoom for widefield shots. They're not ideal though as they don't hold the set focal length that well and tend to shift readily under gravity. Was thinking of maybe investing in a prime focus, e.g. a Canon EF 50 mm f/1.8 II Lens can be had for about £75 and have heard reports that they perform pretty well if stopped down to f/4 or so. So might be good for wide-field shots, but still leaves me far from the action for DSOs. So an effective solution but pretty limiting in terms of what I can achieve.

- Invest in an Evostar 80ED DS-Pro OTA, plus a Skywatcher 0.85 focal reducer. That would get me down to f/6.37 which would make guiding significantly less of a challenge and provide a field of view that I think would work for me. Cost would be in the region of £500 which is pretty much the limit of what I can justify (to the Mrs!) at the moment. The other plus side is that I wouldn't have to invest a huge amount in additional mounting kit, the supplied vixen dovetail plus tube-rings seem adequate for now and could be upgraded later, plus I could (I think) piggy-back the ST80 (via the 80ED ring's camera holes) using its existing tube rings and cheap bar of some sort (maybe even DIY one).

I know there are some downsides; the focuser seems to attract criticism and I would think about replacing it later if needed. Should be okay for an un-modded 500D though, especially as it is mains-powered so no battery weight, just the body? On the upside, no collimation hassle, much quicker cool down, faster-f-ratio but not too fast, making for shorter useful subs, shorter focal length making for easier guiding without hours of tweaking PA and settings. In other words much quicker to set up and get working for good results.

- Of course the usual advice is to 'spend a bit more'. The Equinox 80ED Pro runs to about £520. It is already at f/6.25, and I assume the focuser is better quality to match the rest of the improved build? But in that case I'd still need to add a flattener of some sort, maybe another £170-200, plus I'd need a dovetail bar and some kind of additional side-by side or piggy-back mounting system for the ST80, so all in-all it is going to end up in the £900-1,000 price bracket, which is 'ain't going to happen' territory.

- Second hand - an option I suppose but I am wary of ending up with some lemon that has been used and abused.

So, I think that it is a choice between spending £500-600 quid on an Evostar 80ED or doing nothing (the money won't get saved for later, somebody in the house always needs a new pair of shoes/car tyres/school coat, etc.) what do you think? Would I see enough of an improvement in results per unit of available imaging time to make this a worthwhile course of action?

[Gina]

I have an Evostar 80 ED DS Pro with the SW .85 focal reducer and very pleased with it. I also have an SW ST80 piggy backed on top of it with a dovetail bar using the camera mounting points and the ST80 rings. I think the NEQ6 Pro mount came with two dovetails and I'm using the two but I might be mistaken - can't remember now. But the guidescope is really solid on the ED80 and I have never failed to find at least one good guiding star and usually several.

The supplied Crayford dual-speed focuser was quite adequate for a DSLR (particularly the relatively light 1100D) until I added a lot of extra weight to provide Peltier set-point cooling with a controlled humidity in a separate box. That nearly tripled the weight on the focuser and I needed to upgrade.

I think I can say that this set-up has been extremely satifactory and with patience and perseverance the kit has performed well.

[Helen]

I think getting a small refractor is a great way to reduce the hassle and increase the fun I did the same, going from a C8 down to a WO 90mm and started getting pleasing results nad having much more fun. It also gives you flexibility - you can image widefield, or do planetary and lunar on other nights.

I've tried OAG too, and actually as long as you set it up in the daylight to get the cameras parfocal it works fine. Also, on FR, you can get adapters that attach to the FR to make it fit into a standard 2 inch eyepiece holder ( google popped up with this one first http://www.optecinc.com/astronomy/catalog/17665.htm ). This will keep the FR - chip distance constant. So you could get your current set up to work better if you wanted to.

Helen

[IanL]

I have an Evostar 80 ED DS Pro with the SW .85 focal reducer and very pleased with it. I also have an SW ST80 piggy backed on top of it with a dovetail bar using the camera mounting points and the ST80 rings. I think the NEQ6 Pro mount came with two dovetails and I'm using the two but I might be mistaken - can't remember now. But the guidescope is really solid on the ED80 and I have never failed to find at least one good guiding star and usually several.

The supplied Crayford dual-speed focuser was quite adequate for a DSLR (particularly the relatively light 1100D) until I added a lot of extra weight to provide Peltier set-point cooling with a controlled humidity in a separate box. The nearly tripled the weight on the focuser and I needed to upgrade.

I think I can say that this set-up has been extremely satifactory and with patience and perseverance The kit has performed well.

Thanks Gina, good to know about the focuser as that was my main concern. I do like my ST80 and QHY5, it is the one bit of the set up I never have a problem with, always find I have a choice of guide stars no matter where I point. I am thinking of getting a cheap pillar drill as trying to drill anything metal with a hand-drill is hopeless - inaccurate and too fast, usually end up wrecking the bit due to drilling to fast and overheating. Pretty confident could fashion something similar to your set-up if I had one.

I think getting a small refractor is a great way to reduce the hassle and increase the fun I did the same, going from a C8 down to a WO 90mm and started getting pleasing results nad having much more fun. It also gives you flexibility - you can image widefield, or do planetary and lunar on other nights.

I've tried OAG too, and actually as long as you set it up in the daylight to get the cameras parfocal it works fine. Also, on FR, you can get adapters that attach to the FR to make it fit into a standard 2 inch eyepiece holder ( google popped up with this one first http://www.optecinc....talog/17665.htm ). This will keep the FR - chip distance constant. So you could get your current set up to work better if you wanted to.

Helen

Helen, the other option I was looking at was maybe a William Optics Zenithstar ZS71 ED 2013. Price is pretty similar to the Skywatcher 80ED, but I don't think the matched focal reducer is available yet. On the plus side the focuser looks like it might be better built from the images (hard to tell though). On the downside I've seen reports that the 80ED's optics are slightly superior to (other) comparable WO models, plus I'd have the same issues with needing additional hardware to mount the ST80. I think the (reduced) f/4.72 is probably a bit ambitious for a scope in this price bracket plus the really short focal length is probably too wide field. Still contemplating it though.

I wouldn't rule out getting an OAG at a later date to use with the SCT. I still like it even after all these years and it was as good (same!) as anything else Meade were putting on their more expensive mounts at the time. Despite being slow, for galaxies it has a good image scale on a DSLR-sized sensor so it will not be consigned to the junk pile. I just want to take a break from the frustration and get some usable data. I am a computer nerd and not having stuff to process when it is raining is disheartening!

I hadn't see that type of adaptor before, though I suspected something like it might exist. I just wonder if it would work without significant vignetting on a DSLR chip? I haven't measured the Crayford but the reducer would end up a long way back from the rear cell, it is a 2" tube. Might have to get my slide rule out on this one!