Second Time Around

Louis, I agree that the APM zoom isn't small, but it's not huge either.  However, I don't add a complete Barlow when I want to increase magnification, just the cell containing the lens.  So it's barely bigger than the zoom itself. This is because, as mentioned above, adding a Barlow to the APM zoom increases the magnification more than normal.

In fact I now have 5 different Barlows that I can use with just their cells, although I've yet to try the 2 newest.

Found my receipt too.  The Omegon Redline was £116 including postage on 2nd Jan 2020.  So a big increase since.

I also use sat24 that's the same as netweather.  Both use infrared satellite pictures so, unlike visual pics, show cloud at night.

Another similar but different site I find useful is https://zoom.earth/maps/satellite/ This also shows low cloud/fog.

38 minutes ago, Don Pensack said:

It's the same eyepiece as the Astromania 22mm for $128.99 (£103.54).  Even with VAT, it'll be cheaper than the Redline.

https://astromaniaoptics.com/products/astromania-2quot-22mm-70-degree-super-wide-angle-swa-mean-you-always-enjoy-a-huge-field-of-view?VariantsId=10092

Also sold as Arcturus Ebony, and Omegon Redline.  You might find a used one sold as an Astrotech AF70 or Olivon 70.

Thanks, Don!  Good spot!  I see that Astromania is having it shipped direct from China, that hopefully will mean that postage is also low. 

Has anyone found it even cheaper?

I said to my wife that the current Omegon price is a lot higher than I paid, that if I recall correctly was about £110 including VAT.  However, that was just before Brexit.

On 13/04/2024 at 15:42, groberts said:

If I may, a couple of questions:

1. What's the eye relief of the APM?

2.  Looking around, I see that using the AMP as 1.25" can be a problem - any thoughts?

1.  Ernest in his bench tests measured the eye relief at a constant 17mm, i.e. about the same as a 25mm Plossl.  For comparison he measured the Baader Mk IV to be 10-15mm, and the Svbony 3-8mm to be 6.5-9.5mm, both depending on the focal length.

Incidentally, I didn't buy the Svbony 3-8mm because of the short eye relief.  I prefer to Barlow my APM zoom, especially as  Barlows somewhat increase the eye relief.  

2.  Whether it's a problem will depend on the amount of infocus of a given scope.  There's no such problem with either my 72mm ED refractor nor my 10in OOUK Newtonian.  I haven't tried it on my 4 inch achro yet.

One thing to note is the amplification factor of Barlows varies from eyepiece to eyepiece according to the position of the field stop.  With the APM zoom it's particularly increased.

I have several Barlows including the Revelation in your signature.  Here are the amplification factors I measured:

As 1.25 inch cell only 1.97x

As 2 inch cell only 1.77x

I couldn't test the complete Barlow as the set screw was too long.  I haven't got round to replacing it as I have other Barlows I can use when I want greater amplification.

19 hours ago, Second Time Around said:

We repeatedly have comments on the forum dissing the cloud forecasts.  However, some of you will remember that I recorded the accuracy of 6 (later 😎later eight such  forecasts every night for 17 months.  See https://stargazerslounge.com/topic/376745-a-record-of-the-accuracy-of-my-local-cloud-forecasts/#comment-4081235) These showed 2 things:

1) the forecasts were correct roughly 2 nights out of 3

2) only 4% were completely wrong

3 there was no significant difference between any of the sites (including Clear Outside)

So how do we account for the criticism not tying in with the data? I commented in that thread that it's human nature to remember the wrong forecasts more.  In fact, there's a scientific term for this;  it's called Von Restorff Effect.

 

 

Can't get rid of the sunglasses in the above thread.  

Any suggestions?

We repeatedly have comments on the forum dissing the cloud forecasts.  However, some of you will remember that I recorded the accuracy of 6 (😎later eight) such forecasts every night for 17 months.  See https://stargazerslounge.com/topic/376745-a-record-of-the-accuracy-of-my-local-cloud-forecasts/#comment-4081235)

These showed 2 things:

1) the forecasts were correct roughly 2 nights out of 3

2) only 4% were completely wrong

3) there was no significant difference between any of the sites (including Clear Outside)

So how do we account for the criticism not tying in with the data? I commented in that thread that it's human nature to remember the wrong forecasts more.  In fact, there's a scientific term for this;  it's called the Von Restorff Effect.

I bought the 22mm/70 Deg Omegon Redline.  Everyone's different but I preferred it to the much more expensive 22mm Nagler.  It's supposed to be not quite as sharp as the Nagler at the extreme edge, but the shape of my eye sockets means that I can't see the very edge of many wide angle eyepieces anyway.  I also found the Redline very comfortable as well.  A further advantage is, as Louis kindly pointed out to me some years ago, it can take a Dioptrx astigmatism corrector that I prefer to wearing glasses.

It's currently £162 including VAT plus shipping from £6.90.  Go to https://www.omegon.eu/eyepieces/omegon-redline-sw-22mm-eyepiece-2-/p,33239

I'm a great fan of zooms and have used 5.

The best is the APM Super Zoom, that I found even better than the Baader.  It has a constant 66 degree field of view.

I haven't tried the very expensive Leica though.  This is because it doesn't accept a Televue Dioptrx astigmatism corrector that I prefer to wearing glasses.  Both the Baader and the APM accept a Dioptrx, although the eyecup of the Baader revolves when you zoom, making it fiddly.

Neither have I tried the Svbony 3-8mm as there would be insufficient eye relief for me.  Instead I prefer the APM plus a Barlow.

Another site with seeing forecasts: https://www.metcheck.com/HOBBIES/astronomy.asp

It also shows transparency forecasts.

I mentioned tourism, that of course affects locals and the local economy.

Done.

1 hour ago, Flame Nebula said:

Hi John, 

Yes, you're right. I actually have the Barlow. I should have said use the 2.25, but I'd still fall a bit short of 290 mag, especially if I have a 0.95xcoma corrector in place. Having said that, might be able to avoid the corrector for planets. 

I'm wondering if something like the explore scientific 52° 3mm might be better than barlowing a 6mm.

Mark 

You can add an inexpensive extension tube(s) between the eyepiece and Barlow.   For instance Baader do an 18mm one, and each of these will add approximately 0.25x extra amplification. 

Go to https://www.firstlightoptics.com/adapters/baader-dt-4-1-31-8mm-nosepiece-extension-18mm-long.html

One thought is to combine an OOUK Dob base with another make of OTA.  This is what I posted recently about the OOUK bases.

"The bases are the best part of the OOUK Dobs.  They're made of aluminium so are lighter than steel or plywood let alone particleboard.  They also have a smaller footprint that enables them to be carried close to your body. 

Both of these features make them much easier to carry.  Indeed, I can go up to a 10 inch OOUK Dob, but only an 8 inch with Chinese makes.

The only mod I've done is adding a pair of kitchen door handles.

OOUK make these bases to order to fit any Dob, not just their own.  Expensive yes, but well worth it."

A second idea is to buy the cheapest Starsense Explorer in the range that costs £189 and retrofit it to whatever scope(s) you end up with.  I believe Ratlet here can provide a 3D printed adapter.

The only solar I'm doing at the moment is with my Quark at a final f/26, so at that focal ratio there won't be many aberrations.

However, it's often said that prominences are a stiff test of eyepieces because of scatter.  One data point here is that I found my Baader 8-24mm zoom markedly better than my Svbony 7-21mm, although there was less difference on other objects.

Usually I'm using 25-32mm Plossls and I did other head to heads between the following:

Televue

GSO clone

Baader

Vixen NPL

I found no discernable difference between any of them.  The ones I kept were the NPLs because they were the easiest to acquire and retain the image (awkward with a Quark) due to the adjustable eyecup.  I need it in an intermediate position but if I rest my eye on the top it slips.  This is easily solved with a doubled-up hairgrip or an elastic band in the desired position.

The 6inch Bresser Messier Dobsonian looks particularly good value at £234.90 down from £345!  An excellent mounting plus a 2 inch focuser.

Wow! Those last few minutes from 2023 were spectacular!

My wife is hopefully having a knee replacement shortly, although the date has already been changed 3 times.

Because of this we plan to go on a cruise to see the aurora as she won't be fully mobile after the op.

Depending on the date of the op we plan to go late autumn or early Spring.

Wow!

17 hours ago, Flame Nebula said:

Thanks. Point3 is very useful. But I'm intrigued on point 5. Please tell me more about your night vision eyepiece? 🤔

I ought really have said night vision device, although mine can also be used as an eyepiece.

They hugely amplify the light coming in but, unlike EAA where the image builds up over time, the effect is immediate and so it's just like looking through a normal eyepiece.  

They'll show much fainter stars and nebulae, plus with an h-alpha filter most nebulae will really pop!

However, they're extremely expensive, especially outside the US (their military doesn't allow exports).

Mine cost me over £6000.  I could only afford it because I had a lump sum on retiring.  Go to https://www.ovni-nightvision.com/en/content/11--ovni-m-

Anything further is really off topic, but Cloudy Nights has a specialised night vision forum.

My 10 inch Dob is easily my most used scope.  However, it wouldn't be the one I'd choose as a sole scope.

That would be my 72mm f/6 ED for the following reasons:

1) It's grab'n go, not needing any cool down time.

2) It's lightweight so easy to carry outside.

3) It's easy to move round the garden to different positions to avoid trees.

4) It's sharp on the moon and planets, although I'm mainly interested in DSOs.

5) It's great on DSOs with my night vision eyepiece, and equivalent to a much larger scope without night vision - especially on globulars and nebulae.

6) It's great for wide field views.

7) It's just about the longest focal length to get whole disc views of the sun including prominences with my Quark.

😎It's great for terrestrial use.

9) It's compact enough to go as cabin baggage in an aircraft.

10) It would be easy and relatively inexpensive to replace if it got lost or damaged.

Having said all that, I'd not like to be restricted to just 1 scope.  However, I'd happily be restricted to 2, and would add my 10 inch f/4.8 OOUK Dob.  This is the biggest I can take in and out the house.

I have 12x36 Canons where the switch has to be held down continuously.  However, despite having badly disabled hands I have no problem holding the button.  This is because my finger naturally falls into place on the button.

If I have no problem others shouldn't either.  So don't let this put you off buying such a model.

One point that the video mentioned was that planes often wouldn't have to change course, merely change their height.

It was made by a Lufthansa pilot and referred to the same AI research done by Google that the article referred to.

I remember the lack of contrails during the first part of lockdown.  IIRC it was here, or possibly on Cloudy Nights, where it was observed that both transparency and seeing were better then

Fascinating video, Dave!

It's long, but it's basically saying the same as the article I quoted but goes into more detail.

Steve, if you read the entire article you'll see that:

".....reducing contrails by 73% would raise fuel costs by just 0.11% and overall operating costs by just 0.08%. They also noted that rerouting aircraft under such a scenario would only involve 14% of all flights."

Yes, it does of course depend on atmospheric conditions.

I didn't quote the entire article but this extract is relevant:

".......used weather and satellite data to create software models and AI prediction tools to determine whether it was feasible to divert planes from airspace that would lead to contrail formation. They found that it appeared possible to reduce contrail formation by approximately 54%."