John

8 minutes ago, RobertI said:

Informative thread. 🙂 I have a question and hope it’s ok to put it here rather than starting a new thread. 

I am looking to get an OIII filter, primarily for the Veil, but also any other nebs which may benefit from OIII. I had settled on the Astronomik OIII. I’m now wondering if the Astronomik UHC might be a better bet, not quite so good on Veil but possibly a better all rounder. I’d be using it with a C8 (+0.63 reducer), 150PL and possibly 130P. The lowest power eyepiece I have a present is the Hyperion 21mm. 

What do folks think - Astronomik OIII or Astronomik UHC? 

Thanks. 👍

In due course you will want to have both but a UHC is useful on a wider range of targets. The "kick" that the O-III gives to the Veil, Owl and others is highly addictive as well though !

Maybe get the UHC now and start saving for an O-III ?

1 minute ago, MarkAR said:

If you want to shoot narrowband on nebula then the Oiii is what you want. Do you have an Astronomic Ha to match with the Oiii ?

I think Rob is primarily a visual astronomer.

I've been observing the binary stars in Lyra this evening with my Tak FC100-DL. Rather an impromptu session because the forecast was not for clear skies.

Lots to choose from in this small but lovely constellation.

A first for me, as far as I recall, is Beta 648 which is close to Gamma Lyrae. I got a definite split of this close uneven brightness pair at 281x and 300x. The 8th magnitude secondary lies at a position angle of 251 degrees from the magnitude 5.3 primary and the separation is currently 1.2 arc seconds according to the Cambridge Double Star Atlas. I confirmed these details after getting the split and the PA seems to match where I could see the dim secondary star, just ahead and a wee bit south of the primary as the pair drifted from east to west across the field of view. The primary appeared to be pale yellow and the secondary star greyish.

A nice one to get in 100mm of aperture and I can't recall getting it before

7 minutes ago, markse68 said:

I’m not a chemist John but I’m pretty sure aluminium is fairly safe in alcohol too. But if it was contaminated with some caustic chemicals then that would be bad!

I'm not a chemist either but I believe that isopropyl does react with aluminum. Which is why I wondered if this mirror did not have overcoating, or had poor quality overcoating.

3 minutes ago, markse68 said:

i very much doubt the op’s green film was the mirror coating- it’s a mineral coating similar to that used on lenses etc -silicon dioxide (quartz) usually I think, and won’t be dissolved by alcohol...

I agree - my point was that some mirrors don't have an overcoating (quartz or otherwise) I was wondering if those would be affected by the isopropanol.

This thread has moved on from eyepieces I see !

As I understand it, mirrors are usually overcoated ie: have a protective coating applied over the reflective coatings.

It has been known for certain brands not to apply overcoats to their mirrors. The mirror works fine but the reflective coatings degrade faster than they normally would had the overcoating been applied.

It is possible that a mirror that is not overcoated could react differently to a coated one when something like isopropyl is applied.

Unfortunately it is not possible to tell an overcoated mirror from a non-overcoated one just by it's appearance.

Great - I'll replace the original link with that one. Thanks for the feedback

Some interesting developments in the pipeline for the AZ100 by the look of this

https://www.cloudynights.com/topic/708353-rowan-astronomy-az100-arrived/?p=10275688

I think this might be a working link to the original article:

https://www2.wwnorton.com/college/astronomy/astro21/sandt/startright.html

11 hours ago, Captain Rex said:

Hi, very new to this site and following all the advice I tried the link to this resource. Only it takes me here

https://digital.wwnorton.com/astro6

Which looks like a paid tutorial site. What am I missing ?

Thanks.

You are right. It seems as if the original piece has been taken down now. Shame because it was a good one but I guess 11 years have gone by.

I'll see if I can find something to replace it.

I think you would need a refractor of around 10 inches / 250mm in aperture to equal a 12 inch dobsonian on deep sky objects.

The budgets would not be comparable for such instruments

The refractor you are think of must be 140mm in aperture ?

1 hour ago, JeremyS said:

You've got me thinking now @Alan White. I've recently been using the Nagler 20mm in my Tak TSA-120, with superb results. I've got longer FL eyepieces, but this one does seem to perform particularly well. I've been using it, for example, to observe a variable star and the combination of FOV, magnification and dark background it yields does seem to help in making the observations.

Also, whilst it's a 2-inch barrel, it's not as bulky or heavy as many.

The Nagler T520mm was one of my favourite 2 inch eyepieces for quite a time. It was a wrench to let it go but I had to fund the 21mm Ethos somehow

1 minute ago, Robindonne said:

Really interesting indeed.  It basically says nobody will ever fully benefits its newton without a very active cooling?   Wow and almost 2 decades later we still think about solutions😬

Making the best of the imperfect is what we are about I think

5 minutes ago, Mihai said:

I'm just curious how I should go about separate the wheat from the chaff when it comes to pre-owned ones. Do you look for anything specific?

 

Ask on this forum - somebody on here will have used / owned the item in question and you should get opinions quickly.

UK Astro Buy & Sell is much better than buying from e.bay in my experience - it's run by astronomers for astronomers.

My observing site is just a few paces from my dining room so the eyepiece case / cases and other stuff go on the table and I step outside to the scope with what I want to use. It works well for me because I can pop in to warm up / have a brew, consult the star atlas, change eyepieces etc, and then pop out again for the next targets.

This is probably a rather unusual approach - I expect most people are observing further away from the house than I do. I'm not a very hardy astronomer I'm afraid - I don't like getting too cold !

Keeping the eyepieces and filters above the outside temperature works well for keeping them from misting up though.

I hope this is not a case of "if it seems to good to be true, it probably is" but even a budget half decent pair of 20x80's is usually £120 or so

If they turn out to be decent then they are an absolute bargain

There is a classified section on this forum:

https://stargazerslounge.com/forum/217-for-sale-swap/

And the UK Astro Buy & Sell website which is very popular:

https://www.astrobuysell.com/uk/

3 hours ago, Mihai said:

.... I've never actually considered them. Please let me know if you've had the pleasure of looking through one and let me know how your experince was....

I've owned this one for about 6, maybe 7 years now. Orion Optics 12 inch F/5.3 optical tube purchased pre-owned on a mount made by a forum buddy. My most used and best scope (I've owned around 30 scopes over the years):

Pre-owned is the way to go with Orion Optics in my view. They depreciate quite quickly in value if you buy them new.

14 minutes ago, markse68 said:

Doesn’t it depend what you’re looking at though?...

And the scope. In a 14 inch SCT the 20mm is a medium power eyepiece. In an ST80 it's a rather low power sweeper.

Best policy is to have lots of favourite eyepieces

1 minute ago, Stardaze said:

I'm just a bit particular with keeping lenses clean, always have been with my photography...

Same here. Everything capped or in it's case when it's not being used.

I wonder what the original owner of the filter has been doing with it

Mine stay in their cases for the majority of their lives - the most I've had on them has been a few specs of dust.

The ring that holds the objective in place is shown below - the one with two holes in it. You can make a tool to tighten it slightly with a piece of wood with two slim nails though it.

It only needs to be touching the objective enough to stop the rattle though. It should not be tight at all.

If you can keep a 6 inch F/10 hidden away you must have quite a lot of space available !

or is it just the objective and cell ?

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