# albedo0.39

Members

1,210

1. ## Hilux coatings

Doesn't explain anything new. And more importantly, doesn't answer the question. But hey, once I get my "hilux" coatings on my 16", then.... it'll be like an 18" mirror right ? Brilliant. 16/2 = 8. 8x8x3.142 = 201"sq x 0.94 (now with Hi Lux) = 189 "effective" sq inches. 18/2 = 9. 9x9x3.142 = 254"sq x 0.90 (std optics) = 229 "effective" sq inches. Now, whether I can detect that difference is another matter.... having spent hours and hours at the EP of an 18" scope (std optics), I can report that the differences are...... very subtle and that is an enormous jump in area. (+21% - and in point of fact, I do not have Hilux so its really +26%). So, an 18" mirror gathering +26% light than my 16", under dark skies was barely different. Now that, I can relate to. Rgds
2. ## Hilux coatings

That made me laugh ! !!! ---------------------------- So John, what part of my maths is wrong ? Best Regards Steve
3. ## Collimation Cap Hole size

Very pretty - like the engineering !
4. ## Hilux coatings

14/2 = 7. 7x7x3.142 = 153" sq. X0.94 = 143.82 "effective inches" 16/2 = 8. 8x8x3.142 = 201" sq x 0.90 (std reflectivity from Galvoptics) = 180.9 "effective inches" Let's be harsh... assume 2 mirror reflectivity is 0.85. 201"sq x 0.85 = 170.85 "effective inches" Say John, help me understand what's going on here ??
5. ## July 9/10 all-nighter

Hi Seb - good to see you are getting max use of those photons. Well done for the PK DSO - good spot (don't forget, at this time of year you are not getting total darkness) Have you ever used your scope from a truly dark sky ? The LB comes alive !
6. ## Crescent Nebula

Ooohhh, now that IS pretty. Really unusual subject and lovely cloud definition
7. ## Whats the biggest telescope you've ever used...

30" dob... my mind boggles.. I've "only" used a 22" dob and was impressed
8. ## Local Council seen the light (sic)

This is good news. Not only does my council do the same in the villages, but they are also dimming a lot of lights in the centre of cheltenham It's really exciting !
9. ## Wahooooo !!!

Fantastic news Talitha... clear and dark skies + a large Dob - all the elements for a superb place to while the hours away. Not sure about your climate, but you might like to consider a dew system on the secondary. I cobbled one together for mine and it works a peach. The LB needs some mid range and upwards EP's to drag the best performance out of it, but one tip all people realise is that the mirror clips might well be down onto the mirror too hard and cause you astrigmatism You might like to get your dealer (or if you feel brave, do it yourself) and ensure that the clips are about 1mm off the main surface and not touching Many's the story of a LB-16 owner suffering until they loosened these clips. All the best Steve
10. ## The Pilars of Creation

That is DEEPLY impressive and I feel a picture that really lives up to it's title. Brilliant
11. ## Reducing light pollution

When writing this letter Gavin, you might like to cite to the council, how much work is being done in other Parish's and bourough councils up and down the land to turn non-essential lights off at midnight or dim lights that are required (but not so bright) This might help your cause. I would start with your local Parish council. As a councillor myself, we are duty bound to look at local issues like this and raise them wherever we can to the Bourough / district council. We are very persuasive and get good support. Perhaps you will have good luck with your cause ? Rgds Steve
12. ## Rainbow like no other I've seen before

Really nice picture - I'll bet that looked something special in the sky
13. ## 8" f6 Newt, suitable wide angle ep

The Aero ED is great lens.. most impressive on fast scopes (and surprisingly good value)
14. ## Aperture fever is a strong force, isn't it?

I'm with Mick and all the others... why fight it - you know it makes sense !
15. ## Not vanished....just very busy!

Take it easy Rob. Keep that guitar practise up. !
16. ## Hello from Bournemouth

Welcome to the forum. You live in a cracking part of the UK.. Must be lovely when the sun is out. Enjoy your new hobby !
17. ## Whats your next project!

Depends if it's been on the Cod Liver Oil.
18. ## Lightbridge / truss dobsonians

Mine takes ~ 15mins to get set up..[once it's unloaded from the car] but I faff around ensuring it's very weill collimated, so that takes me a little longer as I use the quaint but very accurate Cheshire collimation system. Fact is, 10mins should cover it.
19. ## Whats your next project!

Only one projects on the cards right now, Build a new lightweight base for my Dob, with new bearings made from marine ply. Oh, and finish the light-o-matic aperture increaser system (as designed by Wallace)
20. ## does this look collimated ok ?

Hi there Greenkat. If I were you, Id be looking at my focuser draw tube mechanism to see if there isn't excessive "slop". You might have a couple of screws under the main focusing knob.. refer to the manual and ensure they are tightened correctly. The next thing to look at, is making sure you insert the Hotech in the same way every time to reduce any fitting errors to a minimum. Finally, have you got a cheshire collimator ? It might be worth doing a quick side by side comparison - and don't forget, the final test [if you are a visual observer] is a star test. Locate Polaris, put in a high maginifaction EP and defocus the image. You are looking for the shadow of the secondary to be perfectly centralised in the image of the defocused star. The Hotech is a very good laser - better than most - so you should get perfectly acceptable results with it.
21. ## Eyepieces after some wheeling and dealing!!

Really nice set up you have there... top choice. Now, my Q to you if I may ? You have to go out for a general purpose session - which EP do you grab first. ? Which one do you use the least ? Thanks
22. ## Reducing light pollution

I have been most encouraged by what my local council is doing. As a Parish councillor myself, I can vouch that positive action works... but it takes time. Best tact is to focus on the energy and maintenance costs. Certainly, where I live, the skies ARE getting better... See below:- GLOUCESTERSHIRE COUNTY COUNCIL’S NIGHT LIGHTING PROJECT Gloucestershire County Council is on target to save more than £200,000 and cut carbon by almost 1,400 tonnes in the first year of its night lighting project. In February 2009, the council launched a scheme to turn off some street lights in rural areas and market towns between midnight and 5.30am. This was followed in April 2009 by a street light dimming scheme where high wattage bulbs were dimmed by 35% between 10pm and 5.30am. Both schemes have been extremely successful with £202,760 savings and a carbon reduction of 1,392 tonnes – enough to boil 90 million kettles. In total 59 parish and town councils have already taken part in the night lighting project with 32 more signed up to start the scheme. So far 4,556 lights have been adapted for part night lighting with another 2,440 awaiting conversion. In addition 9,540 high wattage lamps have been converted to dim after peak traffic hours. The County Council has committed to reducing its carbon footprint and energy usage and these projects have done just that. Before starting the projects, the council invited Gloucestershire Police to comment on the proposals regarding safety for pedestrians and motorists and they have confirmed the schemes are safe.
23. ## Epsilon Lyrae - The double double

Splitting this one requires good seeing conditions and last night was not ideal (skies were not that steady depression over the UK). As many people have mentioned, collimation has to be spot on - even in larger scopes and whilst I've split it in my 16", it doesn't show itself without a fight. Good luck and well done to all those people splitting in smaller scopes.
24. ## The dobman cometh...

Good luck on first light... although at this time of year, to really see your 'scope perform, you might struggle.. we are now not seeing true astronomical darkness and that's when you can really slay the dragons in the sky ! Still, with more light, you can get around to tweaking (dobs are excellent for that !) Steve
25. ## The dobman cometh...

You're gonna have so much fun with the 300. But.. is this the early signs of aperture fever ? It's incurable you know
×
×
• Create New...