Barlow lens

[shaft]

Has anyone used a bst starguider 2x Barlow?  Worth the £50?

[Zermelo]

This thread was opened not long ago:

 

[Louis D]

For the same money, keep an eye out for a used Celestron Ultima, Parks Gold Series or Orion Shorty Plus 2x Barlow.  They are still one of the best shorties I've ever used.

[Xgaze]

On 18/09/2021 at 13:37, shaft said:

starguider

Hi Shaft,

Had mine nearly a month now (as per my post above in the link) I have found it pretty underwhelming to be honest! I was expecting it to show planets slightly larger, which it does however, I was not expecting to lose so much detail. Perhaps this is to be expected? But I didn't read this anywhere or have any kind of idea it would, very noticeably, sacrifice definition and clarity for the extra magnification. 

I did find that DSO'S like, for example, the ring nebula and M13 were better viewing but certainly not the case with planets. I much prefer to view them without it.

Wish I'd only bought the Astro Essentials one for £25. I'm not really going to get enough use of the £50 BST shorty to justify double the price. 

Of course, this is just my opinion. 

I've been using the Barlow with a BST 8mm, Plossl 32mm and the two stock EP's with my SW Heritage 150.

Good luck with whatever you choose.

T

Edited September 19, 2021 by Xgaze

[John]

The only barlow that I own / use now (having owned lots in the past) is the Baader Q-Turret 2.25x. Simple external design but it seems to have good glass in it

https://www.firstlightoptics.com/barlows/baader-classic-q-225x-barlow.html

 

Edited September 19, 2021 by John

[Tiny Clanger]

31 minutes ago, Xgaze said:

Hi Shaft,

Had mine nearly a month now (as per my post above in the link) I have found it pretty underwhelming to be honest! I was expecting it to show planets slightly larger, which it does however, I was not expecting to loose so much detail. Perhaps this is to be expected? But I didn't read this anywhere or have any kind of idea it would, very noticeably, sacrifice definition and clarity for the extra magnification. 

I did find that DSO'S like, for example, the ring nebula and M13 were better viewing but certainly not the case with planets. I much prefer to view them without it.

Wish I'd only bought the Astro Essentials one for £25. I'm not really going to get enough use of the £50 BST shorty to justify double the price. 

Of course, this is just my opinion. 

I've been using the Barlow with a BST 8mm, Plossl 32mm and the two stock EP's with my SW Heritage 150.

Good luck with whatever you choose.

T

I'm not defending the BST barlow, , and have only used (and disliked) a skywatcher barlow (which appears identical to the astro essentials one) but if you have been looking at planets with the 8mm plus 2X barlow in the heritage it will be giving you 187.5x, and some of the lack of detail might be down to the seeing , i.e. atmospheric conditions rather than the optics.  It doesn't help if the planet you are looking at is at fairly low alt, so there is more of our atmosphere in the way .

I've no idea if the BST barlow allows you to remove the lens only , screw it on the eyepiece filter thread and use it to get 1.5 x magnification, but if it does that might be worth a try with your 8mm . I was able to use a 6mm eyepiece in my 150 heritage on the one clear night we had round here last week , but Jupiter was a bit low when it finally emerged from behind a neighbour's tree !

Barlowing the stock eyepieces will , I suspect not be ideal, you probably get reflections from their uncoated glass ...

Heather

[Xgaze]

36 minutes ago, Tiny Clanger said:

 but if you have been looking at planets with the 8mm plus 2X barlow in the heritage it will be giving you 187.5x

Hi Heather,

Is the above good or bad?

Apologies in advance, I absolutely hate maths and have not applied or forced myself to understand all the focal length, magnification sums and all the rest of it (I know I must at some point) so, I don't yet understand.

I know I will reach a limit on magnification in accordance with the scopes spec. Have I done this or not?

On seeing conditions, they are pretty good around here. I'm in Bortle 4 and have been out quite a few times so far. Will try again tonight...

I have resided myself to the idea that, anything magnified or "blown up" will loose definition. Just like a zoom on a camera phone or a pixelated picture that's been enlarged?

Thanks,

T

[Nyctimene]

37 minutes ago, Xgaze said:

I know I will reach a limit on magnification in accordance with the scopes spec. Have I done this or not?

Hi, Xgaze,

the magnification of 187x is well within the limits of your 150/750 mm scope. I'm using almost the same magnification with the smaller brother of your scope, the 130/650 Heritage Flextube, when observing moon and planets, or double stars, and can go up to 244x mag, when the seeing is good (Baader 2.25x turret Barlow and 6 mmf UWA eyepiece). The optical quality of the Heritages is really good; but you have to wait for these nights of really good seeing (= low atmospheric turbulence; the Bortle scale doesn't refer to this, but to sky brightness btw.), and the scope has to be properly cooled down (rule of thumb: 5 mins for each inch of aperture) and well collimated. Under such circumstances, you might reach 250x mag  (with an additional 6 mmf eyepiece). So, have patience, go out and enjoy your mighty Heritage. It's my most used grab-and-go scope for good reasons. Splitting Pi Aquilae with 1.4" distance is a real challenge, but this scope is mastering it!

Stephan

[Tiny Clanger]

Well, the generally used rule of thumb is that a telescope can manage 2x it's aperture in mm as a maximum good magnification. So in  theory our 150mm dobs could handle 300x. Bad news though much of the time, our unstable atmosphere in the UK means that 200x is a more practical maximum to expect . Just think that as you magnify the view of what you want to see more,  you inevitably magnify the wobbles introduced by the atmosphere at the same time.

There's more complication to atmospheric conditions than just light pollution (which is what the bortle scale deals with) , there's also transparency, which is how clear the sky is, and 'the seeing' which is to do with how stable the air is. A bit like the shimmering seen above a tarmac road on a hot day, turbulent air can make your view through the atmosphere unstable.

More information than you probably want : https://www.skyatnightmagazine.com/advice/what-is-astronomical-seeing/

and   https://skyandtelescope.org/astronomy-equipment/beating-the-seeing/

In short, let the 'scope cool a bit , try to stand it on grass not slabs, try to not view over house roofs (which radiate heat, especially if the insulation's  not up to standard !)  , you want the air as stable as possible. Not a lot you can do about the air higher up except keep observing and hope for good conditions. It will happen 🙂 .

Heather

Edited September 19, 2021 by Tiny Clanger

[Nyctimene]

Re.: seeing:

Meteoblue presents the values of astronomical seeing, cloud layers, jetstream velocity etc.:

https://www.meteoblue.com/de/wetter/outdoorsports/seeing/portishead_vereinigtes-königreich_2640037

Moreover, you can look up data of dust or pollen contamination, that may have influence on your observing:

https://www.meteoblue.com/en/weather/outdoorsports/airquality/portishead_united-kingdom_2640037

Stephan

Edited September 19, 2021 by Nyctimene

[Xgaze]

3 minutes ago, Tiny Clanger said:

Well, the generally used rule of thumb is that a telescope can manage 2x it's aperture in mm as a maximum good magnification. So in  theory our 150mm dobs could handle 300x. Bad news though much of the time, our unstable atmosphere in the UK means that 200x is a more practical maximum to expect . Just think that as you magnify the view of what you want to see more,  you inevitably magnify the wobbles introduced by the atmosphere at the same time.

There's more complication to atmospheric conditions than just light pollution (which is what the bortle scale deals with) , there's also transparency, which is how clear the sky is, and 'the seeing' which is to do with how stable the air is. A bit like the shimmering seen above a tarmac road on a hot day, turbulent air can make your view through the atmosphere unstable.

More information than you probably want : https://www.skyatnightmagazine.com/advice/what-is-astronomical-seeing/

and   https://skyandtelescope.org/astronomy-equipment/beating-the-seeing/

In short, let the 'scope cool a bit , try to stand it on grass not slabs, try to not view over house roofs (which radiate heat, especially if the insulation's  not up to standard !)  , you want the air as stable as possible. Not a lot you can do about the air higher up except keep observing and hope for good conditions. It will happen 🙂 .

Heather

12 minutes ago, Nyctimene said:

Hi, Xgaze,

the magnification of 187x is well within the limits of your 150/750 mm scope. I'm using almost the same magnification with the smaller brother of your scope, the 130/650 Heritage Flextube, when observing moon and planets, or double stars, and can go up to 244x mag, when the seeing is good (Baader 2.25x turret Barlow and 6 mmf UWA eyepiece). The optical quality of the Heritages is really good; but you have to wait for these nights of really good seeing (= low atmospheric turbulence; the Bortle scale doesn't refer to this, but to sky brightness btw.), and the scope has to be properly cooled down (rule of thumb: 5 mins for each inch of aperture) and well collimated. Under such circumstances, you might reach 250x mag  (with an additional 6 mmf eyepiece). So, have patience, go out and enjoy your mighty Heritage. It's my most used grab-and-go scope for good reasons. Splitting Pi Aquilae with 1.4" distance is a real challenge, but this scope is mastering it!

Stephan

Thank you both.

I find your your replies encouraging!

I appreciate I'm still very much at the beginning of my journey and still have much to learn.

The subject of turbulence now explains why, even after allowing plenty of time for cooling down the OTA and not viewing over rooftops, I'm still seeing that 'wobble' or as said, those kind of heat waves.

Stephen, what does "splitting" mean? Is this separating stars/objects that are close together?

Heather, thanks for the links, I will look them over.                                                          Is there any App. or forecast that will tell air conditions with things like turbulence or, is it just a case of trying? I'm just wondering how I would ever know what's good other than of course not seeing that shimmering?

Thanks again both of you, very kind to give me your time, much appreciated!                    I'm not put off in anyway yet, but perhaps ought to be a bit more patient, allow time to learn more and keep enjoying it!

Regards,

Tony

 

 

[Xgaze]

13 minutes ago, Nyctimene said:

Re.: seeing:

Meteoblue presents the values of astronomical seeing, cloud layers, jetstream velocity etc.:

https://www.meteoblue.com/de/wetter/outdoorsports/seeing/portishead_vereinigtes-königreich_2640037

Moreover, you can look up data of dust or pollen contamination, that may have influence on your observing:

https://www.meteoblue.com/de/wetter/outdoorsports/airquality/portishead_vereinigtes-königreich_2640037

Stephan

Brilliant, thanks!

Just answered my question above!

[Nyctimene]

Hello, Tony,

"splitting", as you guessed it correctly, means the separation of celestial bodies close together. There are several levels of "splitting" for double star observers; Sissy Haas' criteria are useful (Table 1):

http://fisherka.csolutionshosting.net/astronote/astromath/ueb/Unequalbinaries.html

Stephan

[Tiny Clanger]

1 hour ago, Xgaze said:

Heather, thanks for the links, I will look them over.                                                          Is there any App. or forecast that will tell air conditions with things like turbulence or, is it just a case of trying? I'm just wondering how I would ever know what's good other than of course not seeing that shimmering?

Thanks again both of you, very kind to give me your time, much appreciated!                    I'm not put off in anyway yet, but perhaps ought to be a bit more patient, allow time to learn more and keep enjoying it!

Regards,

Tony

You are welcome Tony, I'm a relative beginner, still plenty to learn myself, and happy to pass on what I've managed to learn so far.

I don't bother with detailed forecasts much to be honest, English weather being what it is , I just use the met office or BBC general forecast for my area to get a rough idea of how settled conditions are likely to be, then stick my head out of the door and look for myself.

If the sky is reasonably clear, I park a 'scope out to cool. If a look through the 'scope suggests that the 'seeing' is poor, sometimes the transparency is OK, in which case forget planets, look at DSOs. If transparency is poor, maybe the seeing is good ... have a look at any available planets.  If the Moon is up, spoiling faint fuzzy hunting, look at the Moon ! I just go with the flow.

Patience is certainly a help, you can look at a planet for an hour, and get a handful of glimpses of better detail at random moments, your brain starts to build a better picture using them .  I've also found it really helpful to be able to sit down to observe, much easier to keep my eye steady over the eyepiece.

Heather

[Louis D]

20 hours ago, Xgaze said:

Had mine nearly a month now (as per my post above in the link) I have found it pretty underwhelming to be honest! I was expecting it to show planets slightly larger, which it does however, I was not expecting to lose so much detail. Perhaps this is to be expected? But I didn't read this anywhere or have any kind of idea it would, very noticeably, sacrifice definition and clarity for the extra magnification.

Contrast seems to go way down at higher powers without increasing aperture.  That's one reason going with a large Dob with a very well figured mirror can reveal lots of additional planetary detail.  Of course, steady seeing conditions as we have most of the summer here in Texas really help as well.