Steve 1962

Quote

Is it still OK to apply the first coat with a brush?

Yes - that's what I did!

@JeremyS

I'm very pleased with the way that my dome has come out with Polytrol

The two lessons I've learned are:

Don't try to apply too thicky - mine worked best in the places where it was a bit thinner and "soaked into" the surface. It went a bit matt, but I've applied a second wipe over and it's now got a nice sheen all over.

Make sure you allow enough time for it to dry before the dew comes down - I found that it goes milky if gets damp before it's dry.  This wipes off with white spirit and can be resealed with another coat.

Hope you're pleased with it

Steve

Haha @hughgilhespie!

Thanks for that Hugh.

It was actually easier than Photoshop - although something I've learned is to make sure that it's done in the morning so that it has time to dry / soak in before the dew comes down. The last panels that I did on Thursday didn't have long enough to dry and were a bit milky in the morning - but I found yesterday that a wipe of the milky bits with white spirit followed by a wipe of Polytrol restores the shine.

I (and more importantly Mrs L) am very happy with the way it looks.

Did you get your USB woes sorted??

Hi @JeremyS

I just washed the dome off then brushed the Polytrol on and wiped it off as per the instructions.

It’ll be interesting to see how it looks in the morning.

I've had my dark green Pulsar dome for nearly seven years and I've washed / polished it most years, but recently it's started to look very faded and dejected.

I've tried various polishes and waxes but after a few weeks it always goes back to worse than before.

Now I've found some colour restorer called Owatrol Polytrol that says it's good for bringing gel coat back to life.

This stuff has good reviews and the best price I could find was on Amazon (about £25 per litre delivered). One coat took about a quarter of a litre. I'm going to wait for this coat to dry, then give it another wipe over, so I reckon it'll be about half a litre for the whole job.

https://www.amazon.co.uk/gp/product/B00E3VACQE/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

Here are some before and after pics of my efforts today...it was really easy to apply and looks fantastic, but the true test will be to see how it looks in a couple of month time. Watch this space.

By the way -Polytrol is a yellowy brown colour, so isn't suitable for white fibreglass.

Hope someone finds this useful.

Steve

That is simply jaw dropping Sara. I really like the palette. It gets a definite thumbs up from me.

Steve

So, much more likley to be flexure than any optical issue then?

Edit: Poor PA wouldn't look like this would it?

I would have thought poor PA would give rise to field rotation rather than a "tilt" effect.

Bear in mind that we're looking at micron scale pixels here. A human hair is about 100microns across - or 20 pixels to put this into perspective.

Looking at the problem from that perspective makes it obvious (to me at least) that the slightest flex or slop can show up - so I only use big, solid, bolted or threaded fittings and an OAG. The OAG takes a whole raft of "risks" out of the equation - and in my opinion doesn't have a down side - providing you've got the spacing available.

Hi Steve....another Steve here!

I agree with the other Steves (what sort of name is Olly for goodness sake?) - the spikes look like micro lensing. I get the same with my Atik 460.

The stars look bit odd to me, but given you're working at the native focal length of the scope and spacing isn't an issue I'd be inclined to live with it. I found that any egginess from my Tak 106 "stacked out" during processing.

I agree with Only about pixel peeking. Your camera (and mine) has small pixels and therefore has a high sampling rate. When you see perfectly flat images from a Tak they're gemerally paired with something like an 11000 chipped camera. These have 9um pixels which cover 4 x the area of our pixels. They therefore are more tolerant of tilt, curvature and all the others things we worry about. We've got higher resolution of the target..and field defects. So just process down the stars and enjoy the signal!

I've been away this weekend - that's why last night's conditions were so good.  

Anyway, when I saw this come up on my iPhone with "400 hours", "Olly", "Tom" etc. one of my first tasks tonight on getting home was to power up the home PC and have a look at the image on a decent monitor.

Although I was expecting something special - I was completely unprepared for the sheer scale, detail and beauty of this. Congratulations to both of you and curses to you both too for raising the bar so @#£%^ high that us mere mortals who need some sleep occassionally and / or live in the UK can only ever dream of.

Thanks for sharing. I would imagine that your next big challenge will be to find a display medium to do the image justice - do they have iMax theatres down there??

Steve

Martin

I have a 2.2m Pulsar dome which I've managed to motorise with an DIY Arduino, M542 Stepper Motor Controller and a Stepper motor  - it slaves to the mount and allows for auto flips. I'm just in the process of motorising the shutter.

If you want any details, PM me and I'll let you know the details.

Steve

Thank you Steve - I found this by chance yesterday and had a play with it last night. I think it's great! 

Sorry Neil - I'm quite chuffed - that's a first - it's always me who gets beaten to the post normally! 

My question is why is an 80T belt used since it doesn't correctly mesh with the pulley teeth?

 

80/48= 1.666

80/12= 6.666

Hi Frank 

The belt does mesh with the pulleys because they're the same pitch.

The "gear ratio" of the belt and pulley is always one to one (i.e. one tooth movement on the pulley will give tooth movement of the belt). It's the ratio of the two pulleys that sets the gear ratio i.e 48:12 or 4:1.

The number of teeth on the belt has nothing to do with it - the mod just needs a belt 80 teeth long because of the spacing between the pulleys.

Does that help?

Steve

John's just made me an adapter which allows the SCT thread of my William Optic RFIV to be directly screwed to the rear 92mm thread of my Feathertouch focuser and keep my 2" IDAS LP filter in the train. 

John is a really nice guy and his workshop has to be seen to be believed - just amazing!

The adapter is exactly what I needed, very nice quality, well priced and delivered earlier than promised.

I'd highly recommend John - he deserves to be very successful.

Steve

PS - I must also thank Buzz (who has also ordered a similar adapter) for producing the adapter drawing and providing the thread info!

 I got Astrophad to make me a feather touch to SCT adaptor

Ah ha! I see - thanks Chris

You have a PM

Steve

 the only problem I have run into is how to mount a P2 in front of my flattener. I have the WO FF68 and WO FFIV.  I'm going to have to make some kind a SCT- T mount adaptor that accepts a 2" filter. The 2" noisepiece of the FFIV has an SCT thread, as does the alternative FF68 rear adaptor.

Chris - my IDAS is screwed straight into the 2" nose piece of my WO RFIV.

Steve

Just found this....

here: http://icas.to/space/optical-filter/LPS-d1.htm

According to Hutech here: http://www.sciencecenter.net/hutech/idas/filtdata.htm it looks to me as though the P2 allows more Sii through than the D1 .... so my earlier post about Sii transmission was wrong - it also looks as though the curve shown on FLO's website for the P2 is more like the D1 curve.

I'm sticking with the P2.

Steve

My IDAS filter stays in place in front of LRGB, Ha and Oiii filters all of the time too. I've not had any problems with it either.

Looking at the transmission graph for the IDAS, it would degrade Sii by c. 50-60% though.

I had the same problem and managed to thread them on after warming them in hot water .... But I know that I'll struggle to get them off again.

Great tutorial - thanks for taking the time and trouble to write it.

Just one point that had me scratching my head for a while is that I cut and pasted the -r and -objs 50 text into my Custom Setting and kept getting a "Cannot find file "50"" error. This went away when there was no space between the -r and the -objs as follows "-r-objs 50"

Thanks again

Steve

A year or so ago I bought a second hand SX USB filter wheel from someone on the old SGL Buy and Sell section. The kit turned up in beautiful condition and has provided stirling service since then.

However, one evening last week when I powered the obsy up, the wheel was completely dead - nothing, bereft of life it rested in peace, it had gone to meet its maker (sorry John Cleese!).

So, at 2am I emailed SX support and went to bed.

When I got up to go to work, there was a response email from Terry Platt with some very helpful suggestions about leads and hubs etc. none of which worked, so when I rang him, he told me to put it in the post, which I did.

Three days later DHL arrived back with a perfectly functioning wheel...no covering note, bill or anything. So I rang SX and was told that the wheel had needed a new circuit board because the USB chip had failed..and that there would be no charge! ...for a three year old wheel which had been bought second hand!!!

Now that, in my book, is exceptional customer care.

Well done and thanks SX - keep up the great work.

Steve

Hi Alistair

Have you tried loosening off the single brass nurled bolt on the top of the focusser??

Steve

Just ordered and received a Celestron f6.3 reducer flattener from 365 Astronomy - great price (£96) and quick delivery. I'm very pleased with the deal.

Stunning Olly - please excuse my ignorance - how did you get 8 point diffraction spikes??

Just wanted to say "thanks" to Martin and Steve at FLO.

They've never been too busy to chat to me while I ummed and ahhed about a new mount. Martin has been monitoring the importers so we knew when they came into the UK.

I ordered the mount and couple of other bits on Wednesday - the bits turned up direct from FLO on Thursday and the mount arrived direct from the importers on Friday.

On Friday Martin even emailed me to check that the mount had arrived.

Top class service, great prices, fast delivery and friendly people - what more could you ask for?

Steve