AKB

The first question is really: “how good is your current guiding?” Assuming that your new scopes are not significantly heavier than your existing one, then your guide performance should be similar. The second question is: “what image scale will your new scope/camera combination yield?” As long as your guiding performance is around twice as good as your image scale in arc-seconds per pixel, then all should be well. Tony

Just a brief window before the clouds last night, so took a quick peek to the west and glimpsed the comet. New scope is still not adjusted for collimation / backfocus / filters / cable diffraction, but as this is something of a transient target, undergoing various outbursts from time to time, I thought it worth a go. This is with a RASA 11 and an ASI294MC colour camera, but binned x2 in mono, over just five minutes. Subsequently, I processed them offline in colour, just for a comparison. I like this mode of working: EEVA is fast and easy with a smaller mono image, but you can return in higher resolution and colour later, if desired. Best of both worlds! Tony

... "because you're worth it", to quote an advertising campaign.

Ooh, that must have changed your online life! Certainly did mine. Just the thing for big images (like this) and system updates. Tony

I'm a huge fan. A couple of layers of foil-backed bubble wrap seems to work well. Did it for my Hyperstar, and now for my RASA... Tony

Up to (or, down to) a limit, surely. Arbitrarily reducing the pixel size much below, say, the spot size (or Airy disc?) isn't going to help. How about “p ratio” ?

Over the last few years, I've used a 9.25" Hyperstar and a small (or small ROI) camera to do EEVA. The thinking is: aperture is king. Of course, image quality also matters and, despite all the tweaking, it has to be said, that a Hyperstar is not the highest optical quality... although perhaps good enough? I've certainly been happy with my results. But it's time to move on, and I've gone (hopefully) a bit bigger and a bit better... a RASA 11. Of course, before it can be used seriously there are a few adjustments to be made. FLO was brilliant in helping me sort out a problem with the focuser motor, so now all I need to do is sort collimation, tilt, and back focus. The collimation itself seems good, although not perfect, I'm leaving it alone at the moment. One thing to remember is that the optical axis need not be aligned with the physical axis, so it's not worth trying to sort that out. I've made a start with tilt, but last night was cold, and short-lived since the freezing fog came in quite quickly. Nevertheless, I made a first pass on tilt. I think I have more to do (I know I have) and back-focus is certainly still off, but I'm starting off with evaluating this against some rather well-known, bright, and generally large objects, so that I can make easy comparisons as adjusments progress. One thing is already clear: this is certainly a fast system. Here's some examples from last night (using only a clear glass filter – other options yet to be evaluated, as has the choice between mono and colour.) But will it be any good on more distant, smaller, and fainter objects? The specs say it has a spot size of around 4.4 microns over the whole imaging circle, and I won't be using anything like that. So I have high hopes. Tony

Could this be slag? https://sites.wustl.edu/meteoritesite/items/slag/

In the process of commissioning my new scope, a RASA 11, so, indeed, trying to make the most of it. Having had a nightmare getting the Celestron focus motor to work when pointing towards the zenith (worked perfectly when more horizontal) I now need to climb the collimation / tilt / backfocus hill. However, couldn't do all that this evening, so with everything wrong (no pixel peeping!) and in white light (no filters at all) I had to try out briefly (very briefly) the odd galaxy and nebula...

No!! Temporary, or permanent? I still love my M-Uno, and had been using it whilst my Mesu was in disrepair (servo controller, not mechanics.) Tony

Absolutely fantastic. Functional and beautiful. You should go into business. (Although, perhaps there aren’t that many customers for this particular scope!) Tony

Yes, exactly. This, for me, is the litmus test on this target.

This seems to happen to me fairly regularly, but as it really doesn’t affect anything I’ve not dug into it. I think we’re using the same mount, Mesu? Regularly guides at 0.3” – 0.4”. I’m using a really basic ASI120 as the guide camera, and I’ve noticed, outside of the guiding context, that sometimes an image is shifted wholesale across the frame, reverting to normal on the next. Not sure if this is a camera or USB thing, but it would certainly cause the guide stars to be missed… Tony

Loving the tube rings and dew shield on the RASA… what are they? I’ve been struggling to find a decent dew shield – does it have an end cap too? Tony

My first EAA results were from an 8" F4 Newtonian (Quattro) using a small, uncooled Ultrastar mono camera. Some examples of results here: Tony

Well, you need to be a bit conservative when it comes to design parameters when imaging… I used to have a dual-mounted C9.25 Hyperstar and Esprit 120, which was pretty heavy, but I’m initially going for an 11” RASA, which is a bit of a beast itself. I used to say that I’d never have a scope that I couldn’t lift, but I think I’m getting weaker in two ways: physically, so that limit will be ever decreasing, mentally, in terms of not being able to stick to my own guidelines. …so who knows what will happen?

A final update on this, for any who may be interested and/or have helped on the way. The long delay in fixing my mount (since January of this year) has been down to my laziness and the fact that I have a very serviceable alternative mount (Avalon M-Uno, albeit with a lower load capacity). I've had very attentive responses all the while from Lucas Mesu, and, since I contacted them, SciTech. The remote diagnosis from SciTech confirmed the servo controller itself as the issue and they sent me detailed board layouts and some instructions to try and identify a failed component. I checked all I could: resistor values, track continuity, connectors, re-soldered some joints, but in the end was unable to resolve this. Despairing of the paperwork to send the controller for repair to the States, and to get it back again, I finally bit the bullet and bought a new one. The unit currently costs $400, and I'd been warned of a hefty price rise coming in the new year. In reality, the costs in round numbers worked out at: item cost £350 shipping £50 VAT, import duty, handling charge £100 ...for a grand total of ~£500. Ouch. But to put it in perspective, having the 100kg load carrying capabilty of the Mesu back online does allow me to consider buying a bigger scope, so the cost of this repair will no doubt pale into insignificance... Tony PS: I'm told that these units very, very rarely fail – one more reason why the diagnosis took a little longer. So my wish for all those Mesu owners out there is that this never happens to you. PPS: Just to be clear, the wish is that your servo controller never fails, NOT that you never get a bigger telescope.

Chris Thanks for that. I did post on that forum back in January and got some helpful advice. In particular, to check the cables, but these turned out to be OK. Most recently I have been in direct contact with Sidereal Technologies who actually logged in remotely to my machine to help diagnose the problem. It now seems certain that it’s the controller itself and we’re trying to narrow it down to a single component. I’m in the UK so will have shipping costs and delays to deal with, but even so, I expect you’re right about the cost, although a new controller pales into relative insignificance, since when the mount is fixed I hope to get a bigger and better scope to put on it! I’ll certainly post the resolution of this saga, when it happens. Thanks again Tony

Gav Thanks so much for the offer. No indeed, yours is a SciTech II and mine is a I. (The e200 Mesu doesn’t have the extra encoders, just the motor ones.) Otherwise, Wiltshire would have been handy… my best offer yet is Dorset! Thanks anyway. Tony

Appreciate the help so far. Apparently my post here was forwarded to Lucas Mesu by someone asking if he could help further. I'd like to say that Lucas has been very responsive, both now and back in January when the problem arose. I know that he tries his level best to help everyone with a Mesu-Mount no matter how old or if second hand or not. The issue in this case is, alas, the barriers which now exist between GB and Europe: shipment between UK and the EU more complicated at the moment with customs and import duties. Once convinced that the issue is indeed the controller, I'll be getting it fixed, or buying a new one, direct from Siderial Technologies in the US. Tony.

Two great offers there – thanks so much! Would appreciate Dan’s email as a first step, and thanks for the heads-up on forthcoming price rises… no surprise there, I suppose. Much appreciated. Tony

Nothing beats actually trying it out…

It's a while ago, now. This particular configuration was a planetary imaging setup, of course, so tracking wasn't really an issue. I mostly used it with an 8" F4 Netwtonian for deep sky stuff,which was certainly lighter, but I recall it was good enough at the time. Not sure you'd do much better at that price point.

Hi Tooth! I had an HEQ-5 with a belt mod and it carried a C9.25 (9kg OTA) plus guide scope, heavy focuser, flip mirror and small camera. Must have been at least 11kg… Tony

Help! Still struggling with the non-working Mesu mount that failed in January! After much testing, and discussions with all and sundry, including Lucas Mesu, I've come to the conclusion that my SciTech I servo-controller has a failed RA channel. I can swap all the cabling and the issue swaps axis, so I'm pretty sure that the servos / encoders / cables are all OK It turns out (AFAIK) that getting a new one is (a) expensive, and (b) quite difficult (have to go via the States.) As a final check before I bite this particular bullet, I was wondering if there's anyone in or around the Oxford area who might have a Mesu e200 mount who would be willing to provide a definitive check: either or both plugging my controller to their mount, and their controller to my mount. This would only take a minute or so of time each way. Of course, any other solutions welcome, but this looks like the simplest approach if anyone nearby is available to help in this way. It seems such a waste to have an otherwise fine piece of kit sitting around unable to work. Thanks in advance. Tony