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Discovery 150i & eyepieces on order - what else do I need?

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Hello all

I have a Sky-Watcher Star Discovery 150i WiFi https://www.firstlightoptics.com/az-goto/sky-watcher-star-discovery-150i.html on order from FLO, which I hope to get in the next week or so (fingers crossed). I have also ordered a 2x Barlow and a BST StarGuider 18mm eyepiece, a Baader Hyperion 24mm and a Baader Hyperion 8mm.

I was wondering what else I need to get to hit the ground running? I'm interested in observation only (both planets and DSOs if possible), and live in north west London.

My thoughts at the moment are a BST StarGuider 5mm eyepiece and a Celestron Lithium Powertank https://www.firstlightoptics.com/batteries-powerpacks/celestron-6-1-ah-powertank-lithium-lt.html

Anything else I should get? Any recommended filters to cope with light pollution? Dew hood?

Thanks for your advice.

Old Clive

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Hi , i don't think you need to worry about a dew shield ... as for filters , i would try the scope without them first . It's a really nice scope and a good size too , plus the mount is a nice solid platform . a powertank is a good idea . It's tempting to buy everything and anything ( been there done that ) . 


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Get a good guide to start with. Turn left at Orion is often recommended, but there are others, such as Nightwatch: https://www.abebooks.co.uk/Nightwatch-Dickinson-Terence-Firefly-Books/30442906126/bd?cm_mmc=ggl-_-UK_Shopp_Tradestandard-_-product_id=COUK9781554071470NEW-_-keyword=&gclid=Cj0KCQjwsqmEBhDiARIsANV8H3ZVC0VNWFhVuzJBp5-_vcvLCtAZYr20VIfwiRDwv5QkEYEAmgE_PVAaAhCWEALw_wcB

You don't have to rush in to quickly. Get used to what you have, then you can see where you might want to make improvements. It's easy to end up with loads of stuff you don't use!

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I'm a little under a year ahead of you with the 150i.

With the eyepieces you have already ordered (including barlow combinations), you will get 31x, 42x, 63x, 83x, 94x and 188x (leaving aside the 10mm and 25mm EPs that came with the scope). You have a gap between 94 and 188 that you might want to fill, for planets and double stars. The 5mm would give you 150x and 300x barlowed. I bought a BST 5mm recently and I thought it performed better than a similar power obtained with the barlow. As you may know, 300x is about the theoretical maximum for the 150i when seeing is very good. Since I've had my scope, there has been one night when I've used 300x very successfully, and two or three others when it wasn't so good, but didn't blow up. The rest of the time the limit was between 150x to 200x. Zooms can be very handy, but you may want to hold off on that as you have a few fixed EPs.

A power supply (other than AA batteries) is a must. I made my own from a lead-acid battery. You will find several threads elsewhere discussing various choices from car starters to leisure batteries. The one you mention isn't the cheapest option, but it looks well-designed and will be light. 6Ah should be fine for a session unless you try to run a lot of other stuff from it. 3A peak load is more than enough for the Star Discovery mount. Did you check that the Celestron cable will also fit the SW mount?

The scope doesn't suffer much from dew. I did make my own guard for the top end (to protect the secondary) but I'm not sure how much of a difference it's making. On rare nights when it's been very bad, my eyepieces and finder are misting up first, and when my books start to get damp I call it a night.

Turn Left has already been mentioned, and has proved very useful. I use Stellarium on a laptop when planning, and SkySafari Plus on my phone for planning, controlling the scope and recording observations. I have found that the tech has really contributed a lot to the experience, but I know that's very subjective. I made a physical red filter for my phone, as I found night modes unreliable.

I dispensed with the red dot finder and stuck a Telrad on the back end of the OTA. I used the vacant finder shoe for a 6x30 RACI, and I find the combination of Telrad+RACI+SkySafari to be very effective. Combined with a heavier EP, I'm pushing at the limit for the mount, but it doesn't seem to be a problem.

As others have said, filters can probably wait a bit. Planetary filters won't be needed urgently. You can think about a UHC or OIII for emission nebulae, though you're looking at close to three figures for a good one. It helps a lot on the right object (e.g. the veil) but in most cases I've found the views with and without a filter are both worthwhile, though different. Possibly six inches isn't enough aperture to make the most of them. Sky pollution filters I've avoided, being persuaded that ubiquitous LED lighting has reduced their effectiveness. I believe IDAS types give some success, but they are not cheap. The only filter I would get straight away is a moon filter. I got a 25% ND type, which is a reasonable compromise for a 6" scope, but sometimes you want more and sometimes less. With hindsight I'd go for a variable polarizing type, they're not expensive.

Clothes - be ready for next winter. You can never have too many layers. I eventually found a combination that did the job, but after many iterations. Hands are the worst - have a read about what people have tried with gloves. I've never managed to operate successfully with both hands gloved, so pocket handwarmers are worth considering.

Think about any annoying neighbour lights that are going to impinge on your viewing area, and whether you need to set up screening. I don't bother on moonlit nights, but on the darkest ones it can ruin your night vision.

I suspect you have lighter skies than me (if you'll be observing from home), so finding objects will be more challenging. The goto can be a real help (especially used with a RACI) but it has some quirks and it has taken me a while to get the most out of it - I suspect it's down to me settling into a regular mode of operation and refining the setup.

You should get a lot out of the 150i.  At F/5 it will give you decent views of larger DSOs (up to about 2 degrees TFOV) but you can still push it a bit the other way for doubles when the conditions allow (I've managed down to 2.2" so far). You won't see much of planets at the moment of course, it will be a while until Jupiter and Saturn are better placed, but I did get some good views of Mars last year when it was close.




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