ollypenrice

Ah, I misread the chip dimensions. My apologies. Olly

27x34mm is pretty big. I wonder if the FSQ85 will give distortion free stars at this size? Both Yves Van den Broek and I found that it was nowhere near covering the 11000 chip without distortion. I know Tak claim it will cover 35mm format but - well - I think it may be a rather wild claim. Are your filters 2 inch mounted or unmounted? We use both in our dual rig. The vignetting is certainly more severe with the mounted set but both are workable on the full frame Kodaks and FSQ106. Olly

For an imager the H beta line traces pretty much the same gasses and structures as the H alpha but with a fraction of the signal. Is it worth it? Why not add a touch of Ha to the blue channel as surrogate H beta? Many do. But for visual hunters of the Horse then our eyes can see H beta and so this filter can pass just enough of the emission to render the dusty HH visible by contrast. Yes well - I reckon I've 'seen' it three times in our 20 inch Dob but I'm using the word 'seen' in a rather optimistic way!! Olly

Ah yes, you'd mentioned the FLO devices but I'd forgotten. It's too hot to think at the moment!!! Olly

That, my dear fellow, is the definitive multiple rig. Even the cables have been persuaded to curve like synchronized swimmers. The style is a tantalizing blend of the military and the surgical. I'm rarely of a religious turn of mind but I do believe I could worship that... How do you get the scopes parallel? Olly

Quite surprizing, really. However, I've seen enough of very fast optics to know that they are not for me. I prefer two slower ones! I'm not asserting anything, here, other than a purely personal preference. Olly

Ours is all about speed. The two Taks are aligned using a Cassady T Gad under one and carried on a Mesu 200 which could easily handle another two... Five hours become ten hours. Or maybe, in terms if residual noise, it's better than that because the noise which calibration fails to remove is partially neutralized when combined. Note that doubling the scopes is only the equivalent of coming down one F stop. However - and here's the key bit - these F5 refractors work. Always. Every single time. They have a workable depth of field. If you go, instead, for a single faster astrograph you have to be ready for what that entails in terms of making it work. Good luck! Olly

It seems as if it's well worth the extra bit. Olly

Totally mad! 'Mad as the sea and wind when both contend which shall be mightier.'

F7? That's not.... Olly

I think that in this case and in many others there is an interaction between the buyer and the seller in which the seller anticipates what the buyer wants (in this case small fast refractors at less than half Tak price) and tries to deliver it. Inevitably competition between manufacturers means that they don't want to be the ones to say they can't do it, they all want to be the ones who say they can do it. So they push to the very limits of what they can do, they get some prototypes to work, and they go into production. This interaction is 'policed' by the laws of consumer protection. If they say the scope can do it, it must do it or the sale can be recinded under the law. This system is working, but it strikes me that it is creaking as a system since customers like you are being put through endless faffing about which, in the end, will not be recompensed. Nobody will pay you for your time. My contention is that it would be better all round for the consumer to demand a little less and the manufacturer to promise a little less by either charging a little more or easing off on the spec or both. If this were a defence procurement contract and you were dealing with the manufacturer to decide price and spec I strongly suspect that you'd pitch in for a slightly slower F ratio and - quite possibly - a slightly higher price. The free market is not a procurement contract, it's an environment in which manufacturers are tempted to promise the impossible. I've said this before but I think the purchasing community should start to make it a bit clearer to manufacturers that we only want products which work. I can guess that they might come back with, 'Yes, but you won't buy them if we make them, you'll buy the ones our rivals fail to make reliably...' Olly

I always feel it's sad to think that the cheap Chinese import might put a guy like David Lukehurst into difficulty but it seems it's very much the other way round. Great review, very honest. For all its faults, and even though I'd go for a Lukehurst myself, I expect you'll get some great nights out with this when you've sorted it out. The dust lanes in M31 are, as Peter said, off centre and are very distinctive from a dark site and with the galaxy near the zenith. The elevation makes a big difference. Olly

Shoot me down in flames by all means but I see no reason to believe that the manufacturers know how to mass produce these small fast refractors with an acceptable probability of their working to spec. We have moved from the consistent successes of the stalwart ED80 (F7.5/F6) to thread after thread of dodgy corners and distorted stars. Is it not time to ease up on the flashy numbers and settle for something more like F6? I'm not a fan of extreme optics because I like optics to work. Lord knows, the IT side of the imaging business gives plenty of opportunity for random failure. At least optics can in principle be perfectly reliable, night after night, if you don't ask for more than the makers are competent to deliver. I could live with F6 and I believe the mid-price manufacturers know how to do that. It's a bit like houses. The developers want to be able to put '4 bedrooms and garage' on the description so you end up with garages in which you can't open your car door and bedrooms in which you can't fit a bed. I counsel F6! Olly

This is a beautiful job. Are you a professional in the machine shop? Welding stainless isn't for everyone. It does give the whole thing some real class. (I am probably the worst amateur welder in Europe. ) We have a 20 inch F4. It's such a nice size, big but not ridiculous and not too terrifying at the zenith. Olly

This seems like a good idea. It arises from an honest look at the reality of the present situation. The manufacturers are underpricing and failing to achieve the QC their designs deserve. We can argue about whether that's their fault or our fault or we can give FLO's idea a chance. If I were in the market for one of the scopes in question I would, without any hesitation, give this deal a try. Olly

That is a good and thorough review. I'd call F4.4 more than 'reasonably fast' for a refractor, I'd call it screamingly fast! Not many refractors go inside F5, after all, and doing so is never going to be easy for a maufacturer either optically or mechanically. I hope the fine tuning of tilt and chip distance go well and that you'll be back with more. Olly

I'm slightly wary of asking this - but what's 'insertion rubber?' How about having one plywood sheet with layers of rubber on both sides and one with a handle as per Shan's suggestion. Place the double sided one on a worktop, lay the offending rings on it and press the other one down turning with the handle. Come on FLO, this is right up your street! Olly

Floor matting of some kind? It will just be a matter of seeing what's around in the hardware stores/supermarkets. It needs not to be too heavily ribbed. Olly

"Ah, Mr Einstein, I wish to sublmt a patent for a piece of rubber glued to a piece of wood." Olly

I think I'll try a refinement of the trainer soles technique which has the virtue of not distorting the rings at all. I'll try to find some kind of strong rubber mat and cut out two squares which I'll bond onto plywood sheets. These will replace the trainers. The stuck adapter menace strikes visiting astronomers very regularly and the resident one from time to time as well! A definitive solution would be nice to find. Olly

But then what would I do? Hold a normal bubble level next to them? I can do this by holding a normal level against the Atik sitcker which is aligned with the chip but it's a fiddle and only fairly accurate. I'm hoping this will be easier, and won't require me to find my bubble level each time. I mean, I'm a bloke. I can never find anything!! Marking the FW against the draw tube won't work because you sometimes take the camera off it and it won't necessarily go back in the same orientation. Sure, I'm not expecting perfection, just a hand to get close. If the target needs perfect alignment (because it nearly fills the chips) then I'll refine it the usual way. If one or both of these cheapo levels is not at right angles to the other then either the idea won't work or I'll get to remember how far off centre a particular bubble needs to be, and in which direction. I might even write it down on a piece of paper and lose it... It does occur to me that a classic engineering track rod could be used between cameras to oblige them to rotate together but you'd need to pull out all the cables for it to work. An idea too far, perhaps! Olly

That has some great numbers going for it, particularly the possible FOV which would make it a cracker for things like the Veil, Rosette, etc. The price strikes me as more than reasonable, too. Very nice indeed and with that excellent red colour thrown in as a bonus! Olly

I've just this minute ordered some mini 2 way self adhesive bubble levels intended for caravans and camping cars. I'm going to get my cameras perfectly orientated either in landscape or portrait using the star trail method, then set the counterweight arm and OTAs to horizontal and stick them on the backs of the CCDs. I use a dual scope fast imaging rig and this should allow me to switch between landscape and portrait on both very quickly and fairly accurately. I'll report back on how well this works. Olly

Here's where you are, courtesy of Registar. I always think it best to have a camera orientated along RA and Dec, either in portrait or landscape, unless there is a good reason not to do so. It makes life easier in many ways. It is easy to do so. Just take a short exposure while slewing slowly. The camera angle is shown by the angle of the star trails. Olly

Can you tell us something about autoguiding in de-rotated alt-az mode? The only professional scope I know from experience is direct drive and so 'encoder guided.' This is hardly the thrust of the thread but I'm interested. I know that there are still plenty of professional EQs but are many being built these days? I thought alt az and de-rotator had become the norm. Olly