ollypenrice

1 hour ago, kirkster501 said:

Holy thread revival......

Following the issues encountered by the Steve's in this thread, here is yet another Steve's contribution.

Here is my Ha NA Nebula 30 mins with FSQ85 and reducer stretched to within an inch of its life to make it easier to see for the purpose of this thread.  This is on a NEQ6 which has "good enough" PA because I am not spending an age getting it perfect with drift alignment as I am awaiting my MESU.

My results look pretty good I'd say?

Steve

Yes. Sigh of relief!

Olly

Would switching from side by side to piggyback be an option?

As for concrete, I don't think heat is an issue. We have a six tonne concrete base for our 4-scope remote hosting shed and daytime temperatures reaching the high thirties in summer. I think the effect on seeing is negligible. Likewise in one of our own 'in house' roll offs we imaged at 0.66"PP with a 14 inch deep sky rig and had no issues.

Olly

When you cannot be sure of the distance you cannot be sure of the real speed of movement. If your brain has convinced itself that the object is distant then it will be very hard to dislodge that notion and you will therefore greatly overestimate its speed. If you are intentionally out looking at the stars you may well be predisposed to think in terms of long distances. Something much, much closer moving much more slowly would be my guess. A drone seems highly possible.

I don't offer this as an explanation but just as an example of how our eyes deceive us. I'm out all night regularly since I run an astronomy guest house and recently I noticed a slowly moving light near to where I would have expected to see Capella. My view was limited by the house and a tree at this point. The light was moving randomly and quite slowly but I was sure it was moving about. I kept my eye on it and moved to more open ground. As I did so the movement diminished and finally stopped altogether and I was simply looking at Capella. Why the impression of movement? I don't know, but the limited field of view and possibly motion in the tree branches had created it.

Olly

9 minutes ago, gnomus said:

Let me expand.  I am no expert but the stars in your sample images are all heading off in different directions - that is they are radiating outwards from the centre (except perhaps in the bottom left corner).  To my mind, that cannot be 'Tilt' and it must point to an optical defect.  As such, I don't see how a new focuser is going to help.

Nor do I.

I host a robotic FSQ85 which did a recent first light and, with an 8300 chip, the corner stars were not perfect, they were elongated radially from the centre a tiny bit. A pixel peeper would have been disgruntled (and in view of the price one can understand that!) but I'm a pragmatic imager and I'd have bought that scope and camera for my own use. It wasn't far from perfect and I think you'd be taking a risk in swapping it for something else in its class. Yours is far worse and I would not accept it. I do think Takahashi have a problem with the Baby Q.

As an aside, I now use a couple of old FSQ106N fluorites, mine and Tom's, worth about £2K a pop and they have no trouble at all with full frame sensors. Quite a bit cheaper than a new Baby Q....

Olly

6 minutes ago, gnomus said:

My view is that if this expensive scope is not performing as you expected (and as Takahshi promised), you should return it.  

Without doubt.

Olly

Just a further comment on two posters above. Pieter was too modest to say that he is an expert mechanical engineer and Steve was too modest to say that he wrote yet another bible, this time on how to live happily with SiTech!

Olly

It's the multi rig that really does the business for us. That's the dual Tak. The TEC is a luxury on the side but the multi rig is fast...  Now, sure, I personally have lots of clear skies here but the guests who come for just a week have just a week. The tandem is the thing. I counsel... multi-scoping! 

Olly

Hyperstar. The numbers look great. The pictures are not always that good...

As I said above, I think Takahashi are overly optimistic in the flat field claims they make for the FSQ85. There does seem to variability from instrument to instrument, too. I used mine with a 15mm sqyuare chip and had excellent results but I think Takahshi should be brought to book over their field size claims. This has been much discussed on here.

Olly

You cannot ignore the pixel scale when thining about an imaging rig. If your pixel scale is too small for your local seeing and your guiding to support then your long focal length is simply not going to bring in more detail. You will reduce the FOV without increasing the resolution, which is clearly a waste of time. (You might just as well resample a shorter FL image upwards in software.)

It might also be worth remembering that, within the backfocus of an SCT, you really need room for an off axis guider. Using a separate guidescope with an SCT is not a good idea.

Accurate guiding is not just about round stars. Random errors produce round stars but resolution is still lost.

Olly

One of my guests uses a Berelebach wooden tripod for his mobile Mesu. It seems to work superbly but I'm not sure which model it is.  https://www.berlebach.de/?bereich=firma&sprache=english

His website is here: https://pietervandevelde.smugmug.com/

In terms of quality of construction and performance the Mesu is in an entirely different class to the EQ8. Have you seen this video? (Sorry, the quotation system on the new forum still won't play nicely for me so you'll need to scroll up from here to the top of the thread.)

It gives a good insight into the EQ8. 

At the risk of repeating myself, the Mesu I share with Tom O'Donoghue has still to drop a sub to guiding error of its own. We have dropped a few due to faulty guide camera cables but you can't blame the mount for that. In terms of its fit and finish it looks like new, being made of first class materials throughout. I'm one of the few astrophotographers who can say that his mount is the most reliable bit of kit in his observatory.

Olly

2 hours ago, andrewluck said:

Only some images of the sky will confirm, one way or the other. I'll post here as soon as I have some.

Sensor size is 27 x 21.6 so the diagonal is 34.6mm rather than the KAI-11000's 43.6 so it's considerably smaller.

Filters are mounted.

Andrew

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

3 hours ago, Jessun said:

Three OK too?

/Jesper

 

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

2 hours ago, RobertI said:

 

Interesting information about the two scopes being equivalent to one F stop, I'd never thought about about it like that. 

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

19 minutes ago, Paul73 said:

 

Speaking personally. It brings the likes of Mr Luckhust's creations into reach. When you read comments such as "for only a little bit more ....." I get to thinking.... 

These scopes were mentally out of my league, but now I have a buch of proper observers telling me that it is worth the little bit extra!

Paul

 

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

Olly

2 hours ago, gnomus said:

No it isn't.  Are you mad?

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

11 hours ago, gnomus said:

I must say that I salute your patience.  I have had to return 3 scopes because I couldn't get decent stars in the corners.  I think I was lulled into a false sense of security by my ED80, which just 'worked'.  But I wonder if Olly might be on to somethng with his idea that we should demand a little less and pay a little more.  My next purchase is f/7.  I have fingers and toes crossed.....

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