John

5 minutes ago, fozzybear said:

... Never seen the milk carton Mod

 

It works well

The cost is £0, assuming you can lay your hands on a used plastic milk carton.

I put a couple of washers made from a plastic milk carton between the collimation screw tips and the rear surface of the secondary holder on my 12" Orion Optics optical tube. That seems to have improved the functionality of the collimation adjustement quite a bit to the extent that it virtually never needs adjusting now.

This modification is explained here:

http://jaysastronomyobservingblog.blogspot.com/2010/09/milk-jug-washers-for-secondary.html

Here is mine, Bristol Astronomical Society:

1 minute ago, Piero said:

Final specifications sent off... waiting now! ?

Sent off to where Piero ?

Hving had some good sessions with my 12 inch F/5.3 dob this week I think I'm swaying towards it as a one-scope option, if I had to have just one. I have some great refractors but the 12 inch dob takes me deeper and further into the Universe than any of them and if one of my scopes is going to still show me new stuff after the years that I've been in the hobby, it's the dob. 

Setup and tear down time is as quick as any of my other scopes as well.

I'd advise trying them before buying if you can. I've tried a few pairs of binoviewers out over the years with different scopes and have a set of the William Optics ones on loan from FLO at the moment but I just don't get on with the things. I can see a merged image OK the the views look nice enough but for some reason I prefer viewing through a single eyepiece 

I know that for others these devices are really enjoyable so I think personal preference plays a big part in this.

17 minutes ago, Paul73 said:

As Stu (a dedicated visual chap) pointed out in his comprehensive NV observing report earlier this evening.

I really can’t understand why people get sniffy about NV as an observing tool. May as well cry foul that someone has got an Hbeta filter to view the, massively underwhelming, Horses Head.

Paul

An H-Beta filter doesn't provide amplification though - it just removes the wavelengths that are less relevent. As I understand it, NV is sensitive to a broader range of wavelengths than the unaided eye ?

I believe that the impact that NV can have is (easily) similar to doubling the aperture of a scope. No simple glass filter can achieve that, as far as I know.

Is the Questar much better, in terms of the views, than, say, a Meade 90mm mak though ?

I'm sure I read a very experienced user here had compared the views between the two and found very little difference.

I'm sure the build and overall quality of the Questar are superb though.

But NV is EAA isn't it ?

It involves electricity, provides an assist and, here, is used for astronomy.

It seems to me to be like racing push bikes vs powered bikes - both go around a track but the powered ones will have much faster lap times so the two forms can't be directly compared in terms of results. Both are enjoyable though

Thanks to this thread and the reports / charts posted I've been able to spot PG 1634+706 with my 12 dob tonight. Thanks very much folks

It's very, very faint indeed. I've found around 400x magnification and a combination of slightly averted vision and the "1000 yard stare" has helped this dim point of light show against the background sky. 8.6 billion light years - wow !!!

Those photons have been travelling for nearly 2/3rds of the age of the universe .....

Using high or very high power definitely helps to tease out faint point sources.

Of the scopes that I have got, I guess the ED120 refractor is a pretty good "all rounder". 3 true degrees with the 40mm Aero ED eyepiece and up to 300x when target / conditions allow at the other end. The showpiece DSO's look nice under dark skies with the aperture as well.

Nice Greg - both Synta products of course - the Meade LX70 is the Skywatcher EQ5 !

A 900mm focal length scope (of whatever aperture) will be too much for the AZ5 to hold stablily at anything more than medium magnifications. Even an AZ4 is struggling with such a scope and that is a somewhat more robust mount than the AZ5.

I've used a 30mm XW (long ago) and thought it very nice but I slightly preferred the Nagler 31 too.

I've passed on the 14mm and 20mm XW's in favour of the Delos equivilents mainly because of reports of noticable field curvature in the XW's. Maybe this is overblown though ? - I've not actually tried the 14 and 20 XW's myself to be fair to them.

1 hour ago, Waddensky said:

If you have an eyepiece that magnifies 50x or more, you should be able to discern Saturn's rings. Good luck!

I agree with this. I could see Saturns rings quite clearly when I used to use a 60mm refractor which was about as powerful as your 76mm newtonian. Saturn will look small in the eyepiece but you should be able to see it's rings unmistakably. It should look a bit like this:

Wow - a 5 year old thread !

I have the 3.5mm Pentax XW but I have not owned or used a Delos 3.5mm. All the reports I've read indicate that the two are likely to be very, very similar in performance so I guess the choice would be over the ergonomics (which are also similar) and the price - bought new the XW 3.5mm costs around £60 less than the Delos.

I did compare my XW 3.5mm with an Ethos SX 3.7mm over a few months and concluded that, despite the massive field of view of the Ethos, the XW was a touch sharper so I eventually let the Ethos SX go to a new home.

I have the XW's in 10, 7, and 5mm focal lengths so it makes sense to have the 3.5mm as well for high power observing. I have the Delos in 17.3 and 14mm focal lengths and like those a lot. The shorter focal length Delos's have a different focal point than the longer two which might be a little inconvenient if mixed with my XW's which reach focus close to where the 17.3 and 14mm Delos do.

I've only bought small items from outside the EU. With those I was notified by the handling agency in the UK (usually Parcelforce I think) that the item is at their depot and will be released when the relevent tax / duty / handling charges have been paid. You then have to roll up, show your ID and their advice note, pay the bill and take away the item.

There may be a way to pay these up front but I've not used that approach ?

55 minutes ago, Geoff White said:

 

 

I still have my 4 inch refractor made by Ron Irving.  I've had it for about 50 years and it's as good as the day I collected it from Ron's house [removed word] workshop [removed word] office. He always showed his customers into his front room which consisted of an enormous table covered in just about everything imaginable.  How he could ever find anything was beyond me but he must have had a system somewhere.  I believe the OG is by David Hinds, not Wildey.

 

Geoff White

I know that David Hinds was a good mirror maker but I did not realise that he also did refractor objectives ?

Lovely setup Gavin

Meanwhile, back with something that will fit happily on an AZ-4 - My Vixen ED102SS doing a little white light solar today. My reward was just one teeny, weeny sunspot. Nice afternoon to be out anyway 

1 hour ago, Piero said:

According to https://www.teleskop-express.de/shop/product_info.php/language/en/info/p1681_Orion-Optics-UK-primary---300-1600mm---f-5-4---1-8-Lambda.html

It should be 38mm or 1.5in for the 12 f5.3.

 

 

It's quite a while since I had the primary out so they maybe right.

4 hours ago, Piero said:

@John out of curiosity, how thick is your 12" OO mirror? Do you use a fan to cool it down? Thanks

As Iain says, OO mirrors are a little thinner than chinese equivalents at least (thats the only other ones I've owned to compare them too). I think my 12 inch (11.79 inch to be exact - it's 300mm in diameter) is around 25mm thick but I'd have to take it out of the scope to be sure.

The cell on mine is a simple open back design which seems to help air circulation and cooling. It is fitted with a small fan but I don't use it. The scope can be used at low to medium power almost straight away after being put out from house but for high powers I find that 30-45 minutes are needed to allow all the air currents in the tube to dissipate.

Although simple the mirror cell seems to keep collimation very well. I drove the scope out to an outreach session last weekend which was 30 minutes of country roads, some speed bumps and a rather rough track at the end but the scope was still collimated pretty much spot on when I set it up.

My scope is probably not a fully "optimised" design by todays standards. It was made in 2006 so uses the designs that OO employed back then. Its seems to work very well though

I think the 28 inch might still be at Greenwich Chris ?:

https://collections.rmg.co.uk/collections/objects/11094.html

I visited the site around 20 years ago and it was certainly there and in use - I have the photos somewhere to prove it !

Maybe it's mothballed currently ?

8 hours ago, astronomer2002 said:

Sounds like the ES works for you. I am glad it does as with my f4.3 Newt I find  low powers with widefield eyepieces have too large an exit pupil. There's no doubt the big Newts score when it comes to seeing faint galaxies and nebulae though.

 

Ian B

I tend to agree Ian. I find my 21mm Ethos (exit pupil with my 12 inch dob is 3.96mm) to be a noticeably more effecitve galaxy / faint target tool than my 31mm Nagler with it's 5.85mm exit pupil with the same scope. If I observed from a really dark site, the Nagler 31 might get more use ?

That looks great

My only question is, if they can double box that one, why not the 1st one ?