ollypenrice

Olly will need a larger scope to use the Gaia CCD, it has a total of 106 CCD's with a size of 6cm x 4.7cm each, resolution is 4500x1966 pixels.

Total size of the array is around 0.5m x 1m with a total of 938 MP.

Total area of the array is 2.8m2

Damn!

If you are going to use that GAIA CCD, maybe you could get computing time on Zeus, my nifty little compute server (nothing too fancy, just a 2U rack server with 64 cores and 512 GB RAM (and 6 TB disk). Chews through a 870 Mpixel image in 11 seconds for multi-scale processing)

I might need you to hold my hand through some of this, Michael! My IT skills are at the level of an abacus user. In fact that is pretty unfair on abacus users, thinking about it...

Olly

Olly I have found a new CCD for you !!!

http://www.bbc.co.uk/news/science-environment-25450068

Very decent of you Earl, dear boy, and a happy Christmas to you too! You've got my address, I take it? Think I'll need to update the netbook for processing? 

Olly

The clutches (at least on mine) wil barely hold the mouht in RA. Tighten the clutch and then lift the lever and reposition it to allow further tightening. Rinse and repeat.

Mine needs a couple of goes like this to get it fully cinched up. This might cure your backlash issue

Thanks for that. I'll give it a go, but I don't quite follow the 'reposition it' bit. What do you reposition? We need to persuade SW to give us the clutch adjusting information.

As for more Taks on the rig, it really wouldn't be impossible. Used FSQ 106N scopes do come up second hand, but sooner or later someone will realize how good they are, talk too loudly on the forums, and the price will soar.       Mine ended up costing under £2K by the time Parcel Farce had refunded the price of a new flight case. And I can promise you that it won't be flying anywhere in a hurry so no need for a case!

Olly

never really been one to suffer from envy of other peoples kit but with all this eq8 malarky going on, i'm definitely getting to look like the Hulks puny brother

just out of curiosity, are you imaging the same object with both scopes and stacking them all?

Yes, we'll double shoot the same object. We'll need to experiment with regard to how to organize the filters, though. On the one hand shooting, say, L in one and RGB in the other reduces the stacking/calibrating workload which is quite significant when you have such volumes of data. On the other hand the older camera has some columns which take time in Ps to clean up. The noise reduction when combining two cameras' data from a given filter seems to be very perceptible when compared with a stack of the same length from only one of them. So we'll probably do LRGB in both. At a thousand dollars a pop, though, we have an Astrodon 3Nm Ha in only one of them and that won't be changing!! Maybe we'll put an Astrodon 0111 in the other one day.

Thanks for all the encoragement, folks! I'm removing the smaller Tak mount from the intended observatory at the moment.

Olly

Hi olly, great post, but I thought you said you were banned from puting it together in the livig room.... I suppose a new pair of shoes or even a handbag are on order.

what sort of battery life do you expect to get with that sort of setup as theres a lot to move if driven all night and I suppose the backlash indicates that there is some resistance in the design anyway. Do you feel a 7ah pack would last a night or is 17 with daily charging needed?

cheers

Yes, I was pushing my luck but she saw the look on my little face when it arrived in the rain and she let me set up for test purposes!

I don't know about battery life because we have fixed onservatories here and run on the mains. Our guest sites are also mains fed for those who prefer it. I gather there's a mount (not handset) firmware upgrade which reduces current consumption but this is second hand info. 

Olly

Well ahead of schedule following the unexpected release of three more mounts already in the UK, our EQ8 arrived here in south east France yesterday. Thanks to FLO on all counts. Speedy service, a link to a thread on the tripod and a general air of pleasant goodwill! Two of our guests were here working on another project so we set to and had the whole thing sorted out in a couple of hours, the mount itself taking about half an hour.

I've been doing lots of astro DIY recently so went for the easy and flexiblle solution of the standard tripod. I think this is a brilliant design, with a bevel drive to hold down the mount's centre bolt and a system whereby the weight pressing down on the centre column tends to force apart and stiffen the legs. This is really a tri-pier since the upper part is pier and doesn't collide with the scopes after the meridian, which is important. Assembly was dead easy.

The mount was much as I expected it to be, big and beefy and well up to the job. It must have Gemini origins at some level because the resemblance is clear. I'd consider this good news.

Once assembled we found quite a lot of backlash in both axes. Initial scrutiny and internet homework suggests that this may not be at the mesh of the worm and wheel but at the clutches. I hope that Skywatcher will be open and professional in advising on the adjustment of this backash from whatever source since sending EQ8s back and forth is a silly option. Besides, one never knows how this will play out in practice so before touching anything I'll wait till we've tried it under the stars. It may be fine.

Next came the mounting of the dual rig, Tom's and our Takahashi FSQ106/Atik 11000s which are the intended payload of the EQ8. I'd bought an ADM max guider as the tilt-pan adjuster to put under one of the scopes in order to facilitate alignment. Unfortunately this proved far from capable of carrying the FSQ, rather to my surprise. Maybe ADM will be able to advise before we send it back. (As ever, Steve at FLO was utterly no-nonsense and offered immediate collection and refund.) I'd like to check out that it wasn't us, though, or something we could tinker into behaving itself. Imagine looking through the scope. If you then held to top of the scope you could rock it as if to move the eyepiece from one eye to the other. It didn't move anything like that far but it did move and wouldn't resist flexure as it was.

Fortunately Yves was here working on his resident instruments and kindly offered the loan of his Robin Cassady equivalent. This is a very expensive bit of kit and no longer available since Robin Cassady retired. It works by having two thick plates separated by two large metal balls which ride in conical indentations in the plates. Tilt and pan is contrived by push-pull bolts, as you'd expect. It works very well. Somebody needs to come up with something like this because dual rigs are gaining popularity and guide rings don't cut it with larger scopes, especially short fat ones like the FSQ! Since not much movement is required I don't see this as much of a design challenge. 

I also borrowed Yves' wide side by side bar but will order a short one today.

Two Taks with heavy CCD rigs, Cassady device and a guidescope make for quite a lump. Bolted onto the EQ8, it was instantly clear that this mount would carry a third one without batting an eyelid. (Actually Yves happened to have an FSQ106 about him but we let this megalomaniac idea go past!!!!)  The whole lot felt very solid and well within its comfort zone, though the Dec baclash was easier to feel in the long side by side plate. I have a strong feeling that this is going to work.

The EQ8 has absolute encoders and at present there seems to be no way of telling it to offset the Dec position by 90 degrees in software for the use of a side by side plate. However, some net homework revealed the obvious solution of rotating the puck by 90 degrees. I felt I should have thought of that myself! I'll do it when we are set up outside and I can be sure to turn it through the right 90 degrees once I see where the mount thinks it's orientated.

Balancing this rather unweildy payload proved remakably easy though it is a two man job. It will now sit happily in any position without moving.

Here we are in the sitting room. I now need to take it to bits with the positions all marked up and put it in the observatory. Madame is showing signs of telescope intolerance and must be placated! Personally I think it makes a nice Christmas tree but there we go...

Lower left is Cachou, who was badly hurt recently by getting herself under a tractor, we think. Those SGLers who know her will be pleased to hear that, though she's hobbling, she's doing well and is just as nice as ever. Her hip is peramanently damaged but she's not in pain and can still trot around and get in the way!

Olly

This business of 'flying off the screen' doesn't sound like the usual stuff that afflicts guiding. I don't use a Synguider but I've seen the guide star fly off the screen often enough with all the systems I've used. There are two causes;

1) Bird brain that I am, I have failed to switch the Takahashi handset for the EM200 mount to guide speed and away from high speed.  OK, you are not using a Tak mount but maybe the mount is not really set to 0.5x siderreal. Maybe it just says it is, but you know what IT gadgets are like. Have you tried a lower guide speed? Are you dead sure that you've applied the 0.5x speed by whatever means the handset requires? I can't remember what that is off hand.

2) The guide commands are inverted so instead of getting a command for Dec positive it gets one for Dec negative, then another, and another and off the screen it goes. PHD (does the Synguider use this as its in-house programme?) detects the direction reliably for me. Astro Art, which I actually prefer, does not and needs the guide direction manually converting.

However it's arising, I strongly suspect that you have a problem either with guide speed or guide direction and this may be a bug in your electronics and no fault of your own. It might also explain why the standalones get such a mixed press, working for some and not for others. Just a thought, but the 'ST4 cables' (in parenthesis because the original ST4 cable from SBIG was nothing like the ones now called ST4) are not phone cables, though they look like them. I believe the plugs are reverse wired.

To my mind there are too many of these Synguider failures being reported for there not to be a problem somewhere. Surely it's reasonable to say, some work and some don't? I remain convinced that most of the 'convenience products' in astronomy are more trouble than they're worth. I've found I do best when I go for the slightly more complex solution and get slightly more control along with more flexibility in terms of the software or hardware. I'll stick to a netbook (very small), a good guide camera and a choice of software, Asto Art or PHD. The bit of genius in AA is the scattergraph which builds up a picture of the guide hit positions over the whole night. You can see at a glance if you've so much as one bad hit in the night. If you haven't you know all your subs will be guide error free. All guide software should have this.

Hope you sort it.

Olly

I agree Filter wheels have various but I have not seen a CCD with anything other than a T thread by default.

Our Atik 11000s are M54. Big chips!

Olly

Very nice! Thanks for the info.

Olly

Thanks guys for all your comments what would you recommend as a good fast scope to complement the dslr. Just building a picture of future purchases I will go the dslr route thanks to the positive comments.

Sent from my HTC One using Tapatalk

The problem with good fast scopes is that they're darned expensive. A cheaper scope with a CCD might end up at a similar cost and, in my view, a long way ahead. However, if you aim for F5 to F6 after the FF/FR you would be in affordable territory with the small refractors.

Olly

A few questions pop up in my mind.

How will you find your targets? Can the mount start up from cold, so to speak? ie can it make its first slew accurately enough to find an alignment star?

Does it have a reliable Park position?

Will you use some kind of fully robotic focus or will you use FWHM and an electric motor driven focuser operated at a distance?

Can you set slew limits somehow to prevent mount collisions?

Olly

Good decision. Still thinking aloud, what about defective edge blackening of the lenses? Like you I like to get to the bottom of these things.

Olly

I think that a very small stopping down will do it. That's my hunch anyway. I don't think the flattener will help.

Olly

You just need a strip of wood with a pinhole in one end, cut to the length of circle you need. Just pin this to a piece of card via the pinhole and use the outer end as a guide for a Stanley Knife or whatever.

Olly

Elegant refinement;

You don't need two lengths of wood for the inner and outer radius.

You don't????   

No! You just need two pinholes!!

Bu-bum.

It's the reflections!!!

Olly

Exactly right.  At fast F-ratios, unless the sky is pristine, the only real difference in quality between a DSLR and a cooled one-shot-colour camera is down to the quantum efficiency of the sensor.  At slower F-ratios the OSC has a clear advantage unless the DSLR sensor is cooled. So it makes me very interested to see how the JTW performs - though I think the cooling has been taken to the extreme!  For narrow band imaging the choice is obvious - it has to be a cooled mono CCD.

Mark

There is also the matter of bit depth, which is why decent star colour from DSLRs is rarely seen, though it is sometimes seen. Whatever you do to a DSLR it cannot match a CCD other than on price.

Olly

Sorry - don't know what happened when I edited my post - it was just a reminder that 3 objects in the light path could cause a 6-point pattern, as with a 3 vane spider on a newtonian.

Gina, the first photo shows some reflective areas around the edge - it couldn't be this I suppose 

Or did you leave the focus mask on (I'll get my coat  )

Dead right, those bright points in the top two images have 'guilty' written all over them.

Olly

I am a great fan of DSLRs - a Canon 350D (with the internal filter removed )is still my main imager.  If budget is your main limiting issue then a DSLR is no-brainer.

However, from my experience I should point out the following couple of points.

The C9.25 is still a slow optical system even with a focal reducer.  This means that without cooling, you will probably find that thermal noise becomes the limiting factor in your images in the Summer and mild Spring/Autumn evenings.  I think an uncooled DSLR is ideally paired with a fast scope.

I also think you will quickly find you want to mod the camera for H-alpha sensitivity.

Mark

You have an Epsilon and, at F2.8, DSLRs really can perform close to CCD levels on many targets. At more mundane F ratios I'm firmly of the CCD persuasion. But they cost.

Olly

The C9.25, even reduced, has a long focal length so you do need a biggish chip for many targets. It will maybe not cover the Canon chip perfectly but you should get a large clean area.

DSLRs are noisy so they thrive on fast F ratios and low temperatures. Still, I think you're going down the right road with a Canon.

It will be good to read what Alveprinsen has to say about the highly modified camera when he's had it under the sky. 

Olly

The aperture mask test would be indicative if it cured the effect. I've had a good hunt around on the web without finding anything like this aberration. The nearest to it, which wasn't all that near but was a generally spikey look, came from a turned down mirror. I don't know if a refractor lens can mimick such an effect.

Olly

This is one of those things for which a clear explanation will be found. The effects are clear and that's the main thing.

Olly

The stars are a million miles away from being acceptable. Dammit, something is creating those spikes. Hey, well done for the overall image but, no, the stars are not right. I'll stick my neck out and say that something is intruding into the the lightpath. If I'm wrong (I'm used to this  ) then I'll take it on the chin.

But how can 'random bad optics' create a neat set of  unwanted diffraction spikes? I don't believe it.

Olly

Let's just look at these stars. They have six evenly distributed spikes. This doesn't smack of pinching (triangular stars) or any other randomly generated effect because the effect is too regular. It smacks to me of six regularly spaced intrusions into the light path. So, first question, does the Esprit 80 have six lens clips? Are there any other possibilities for incursions into the lighpath? Dewsheild, OAG, F/W, filters, adapters? I'd advise Gina to pull the whole rig apart (again! I know, I know, I've been doing it all day myself sorting a new F/W) and peer through the components of the lightpath. What is odd is that you'd expect this to affect all scopes as it did with the WO132 (was it?) rather than just Gina's. (I don't want Gina's SW kit to be atypical because I want our EQ8 to track like hers!!)

Or (belated brainwave) just make a quick mask for the outer part of the objective. See if that loses the spikes. Just stop it down slightly to block the outermost part of the incident beam.

Before deciding on what alternatives to go for (though I wouldn't throw out the baby with the bathwater on first bathnight) I'd be sure to look at broadband images from the candidates on the shortlist. Any old apo can take a good NB image. It beats me why Optique Underlinden (Tak Europe) only show narrowband FSQ images on their website. All they show is the size of the field.

Olly

I'd buy a stainlees steel bolt, two nuts to fit it and a bottle of wine. I'd lock the two nuts together on the bolt to make a permanent stop at the right depth then give the bolttle of wine to the astro neighbour in exchange for another moulding! That would be better than the stadard system and you'll never break a SS M6 by hand.

If anybody does this and can't get the bolt out the solution is easy. You buy a stud extractor from Halfords etc and a drill bit of the right size for it. You drill down into the top of the sheared bolt and then the extractor threads into it with a L/H thread by using a spanner on it. It is tapered and soon binds in the drilled hole, so winding out the RH threaded bolt. Anyone brought up on old British motorbikes has done this dozens of times. 

Olly

Thank you Olly   You raise some interesting points   With the proposed 4 scope setup there will always be one free that I could put the guide camera on.  And I still have the ST80 I could bung on somewhere if I find I can use all 4 scopes for imaging   Also, many DSOs can be imaged without extended exposures and may prove OK without guiding with the EQ8.  Or I can have the OAG on the MN190 and guide that way, as I have in the past.  What I really need now are some clear nights

I shall be getting a mini lathe and plan to make my own adapters etc.  I also have uses besides astro for a lathe.

Heresy!!  

Moderators, Inquisitors, quick! This must be nipped in the bud.

 lly