Additional eyepieces for Sky-Watcher Heritage 150P

[Patrick Bateman]

Just got this as my first scope recently and managed to use it properly for the first time on Sunday night. Just before packing up I released Jupiter and Saturn were visible, albeit very low on the horizon, so that was a nice surprise. Could barely make out Saturn's rings but Jupiter's moons were bright.

Looking for additional eyepieces and I'm thinking along the lines of this for planetary stuff but open to suggestions-

https://www.firstlightoptics.com/bst-starguider-eyepieces/bst-starguider-60-5mm-ed-eyepiece.html

Any other suggestions for a barlow and maybe another eyepiece to go with the 10mm and 25mm that come with the scope?

 

[Kyle Allen]

BST StarGuiders will certainly be an upgrade over the stock eyepieces. In your scope, the 5mm will be 150x so very useful for planetary observing. With the current position of the planets, it is unlikely you will be able to use much more magnification than that. 

The 12 and 8mm BST StarGuiders are also very good so you may want to look at replacing the stock 10mm at some point.

[ronl]

That answer from Kyle is a very good choice, I have been using Starguiders for quite some time, I find

them very comfortable to use, and they are really good value for money.

[Patrick Bateman]

Cheers, what about Barlows, any ones to recommend in particular?

[Kyle Allen]

A lot of people have mixed opinions about Barlows and some prefer not to use them. I use the BST StarGuider 2x Barlow and I'm happy with it. I use it with two eyepieces to get a good range of magnification in my telescope but if you don't choose your eyepiece focal lengths carefully, you can just end up duplicating magnifications. They are commonly used to turn a medium power eyepiece into a high power eyepiece. 

[Patrick Bateman]

7 hours ago, Kyle Allen said:

BST StarGuiders will certainly be an upgrade over the stock eyepieces. In your scope, the 5mm will be 150x so very useful for planetary observing. With the current position of the planets, it is unlikely you will be able to use much more magnification than that. 

The 12 and 8mm BST StarGuiders are also very good so you may want to look at replacing the stock 10mm at some point.

To a layman, what real difference am I going to notice size for size between BST eyepieces and ones that came with the scope? Just an all round clearer image?

 

Will need to have a think about what sizes to go for. My thinking was a 5mm BST with a Barlow would take my scope to its magnification limit. 

[Kyle Allen]

The BST StarGuiders have a slightly wider field of view and more eye relief so they are more comfortable to use than the stock eyepieces, particularly the 10mm. Also, they should be slightly sharper and have more contrast.

I would ignore the magnification limit - in reality you are limited by the stability of the atmosphere and a smaller, sharper image is more pleasing to the eye than a bigger, blurrier image. 150-200x will show you plenty of detail on the moon and planets and be useable on nights of less than perfect seeing. 

[John]

Magnification limits are theoretical assuming perfect optics and perfect seeing conditions. Real world conditions mean that somewhat lower magnificiations are much more useful.

Much astronomical observing is actually done at low or medium magnifications.

 

[Patrick Bateman]

Now thinking of going with the 8mm and a Barlow for now and maybe go for the 5mm later in the year.

 

 

Edited June 29, 2020 by Patrick Bateman

[Guest]

57 minutes ago, Patrick Bateman said:

Now thinking of going with the 8mm and a Barlow for now and maybe go for the 5mm later in the year.

 

 

I'm sure whatever ones you choose, you'll enjoy the views they give (weather permitting, etc).

[Patrick Bateman]

Well didn't think long on it as I bought them within half an hour of posting that. 😁

[GavinC]

As another 'layman' I am in a similar situation in that I have owned the Heritage 130p for about 18months and, on the basis that the scope has been outside on pretty much every decent night we've had and my children are still engaged with peering through it, I am in the process  of just starting to upgrade the 10/25mm eyepeices it came with to BST Starguiders after reading round the various forums for advice and reviews.

The main thing that I noticed is that the wider field of view allows you to see more of the sky for a similar magnification.  Websites like http://www.12dstring.me.uk/fovcalc.php demonstrate this nicely.  What websites don't tell you, and you only find out by using different EPs, is that having a longer eye relief makes peering through them more relaxing to use, or at least that is my experience.

As the BSTs are all similar in terms of their focusing it should also be possible to swap EPs with little refocusing, something that isn't possible with the stock 10/25mm EPs.

I have been mixing my EPs with a cheap Barlow I got at the time of the scope purchase and will keep using that until I get good enough that I think a more expensive (more elements) barlow will give an appreciable difference to my viewing.

Slight OT, however, the 150p is a new scope, but it's construction is very similar to the 130p and I found that of the two common modifcations often described for the 130p a bit of PTFE tape round the focuser really did help take the play out of it.  I have also recently made a light shroud from a bit of foam/sticky velcro that does seem to block some of the stray light I have round me.  I've only been able to try it on these long lighter summer nights, so not been able to evaluate exactly how much difference it's making to my observing but I think it has helped.

Gavin

 

 

[Dannomiss]

On 29/06/2020 at 17:35, Patrick Bateman said:

Now thinking of going with the 8mm and a Barlow for now and maybe go for the 5mm later in the year.

 

 

I can say myself the 8mm BST starguider is really nice and works well with a barlow as well 🙂  The eye relief is great and is such a nice full view in the eye piece

Edited July 7, 2020 by Dannomiss

[Dannomiss]

@Patrick Bateman I hope you don't mind me askign a question on your thread? Just seems silly of me posting a new topic when you are asking the questions on here...

So all those in the know... what really is the difference here. if I have a focal length of 750mm and I use a 5mm EP which gives me a Magnification of 150x - But then if I use a 10mm EP and a 2x barlow it gives me Mag of 150x? Will there be a difference? Will the view change? Will the quality change?

[Ricochet]

40 minutes ago, Dannomiss said:

So all those in the know... what really is the difference here. if I have a focal length of 750mm and I use a 5mm EP which gives me a Magnification of 150x - But then if I use a 10mm EP and a 2x barlow it gives me Mag of 150x? Will there be a difference? Will the view change? Will the quality change?

You are correct, the magnification given by a 5mm eyepiece and a 10mm eyepiece with a 2X barlow will be roughly the same. Technically, there may be a slight difference because your eyepiece focal lengths wont be exactly 5 and 10mm, and your barlow is unlikely to be exactly 2X, but the numbers are close enough that you probably won't notice the difference through the eyepiece. What will make a difference is the quality of your 5mm, 10mm and barlow. If you have a poor 10mm or barlow, then the combination will also be poor and worse than a decent 5mm eyepiece. However, if you have a poor 5mm eyepiece then the image will be worse than the combination of a good 10mm and 2X barlow. A top quality barlow will be unnoticable in the optical chain and looking through a barlowed 10mm will be just like looking through the 5mm from the same series. In fact this is exactly what I do for my high power DSO eyepieces. I have 10 and 14mm eyepieces, which then become 5 and 7mm eyepieces when combined with my 2X TeleXtender.

Generally:

1. If the eyepiece type has an eye relief that scales with focal length, using a barlow allows you to use an eyepiece with a longer, more comfortable eye relief.
2. The eye relief of a specific eyepiece is actually slightly extended when used with a barlow.
3. If the field stop of the eyepiece is close to the diameter of the barrel, the barlow may cause slight vignetting.
4. The magnification factor of a barlow depends on the distance between the barlow lenses and the eyepiece lenses.
5. If the eyepiece is poorly corrected at fast focal ratios, the barlow decrease the beam angle, simulating a slower focal ratio telescope, and the eyepiece may perform better than it does without the barlow in the optical chain.

2, 3, and 4 apply only to barlows, not to telextenders/powermates.

As an aside, eyepiece designs that are not scaled tend to have a barlow type lens set built into the nose of the eyepiece. The Starguider series under discussion here are an example of such eyepieces. They have a common set of four lenses at the top of the eyepiece, and the different focal lengths are produced by varying the strength and distance of the "barlow" housed in the nose. For instance if you look at the 8, 5 and 3.2mm variants then the 8mm is very short, the 5mm is a bit taller and the 3.2mm taller again. All the designers have really done here is taken advantage of point 3 above to create three different focal lengths. The 18, 15 and 12mm show a similar progression, but presumably with a lower power "barlow" in the nose. Point 5 shows why the shorter Starguiders tend to be the better ones.

If you specifically want a comparison between the 5mm Starguider and barlowing the 10mm MA that came with the scope, then my vote would be for the Starguider, which really is a very nice eyepiece for £50, whilst the 10mm MA is reportedly quite poor. The Starguider will have better eye relief, a wider apparent field of view (60° vs 50°), be sharper in the middle and be better corrected at the edge. 

[Dannomiss]

30 minutes ago, Ricochet said:

You are correct, the magnification given by a 5mm eyepiece and a 10mm eyepiece with a 2X barlow will be roughly the same. Technically, there may be a slight difference because your eyepiece focal lengths wont be exactly 5 and 10mm, and your barlow is unlikely to be exactly 2X, but the numbers are close enough that you probably won't notice the difference through the eyepiece. What will make a difference is the quality of your 5mm, 10mm and barlow. If you have a poor 10mm or barlow, then the combination will also be poor and worse than a decent 5mm eyepiece. However, if you have a poor 5mm eyepiece then the image will be worse than the combination of a good 10mm and 2X barlow. A top quality barlow will be unnoticable in the optical chain and looking through a barlowed 10mm will be just like looking through the 5mm from the same series. In fact this is exactly what I do for my high power DSO eyepieces. I have 10 and 14mm eyepieces, which then become 5 and 7mm eyepieces when combined with my 2X TeleXtender.

Thanks so much for a thorough explanation. That makes total sense 😁 I'm sure others will benefit from your reply... Thank you so much

[Xgaze]

@Dannomiss

Hi there,

Just wondering, now it's 14 months on, how have you found the BST lenses and their use with the X2 Barlow?

Was it the StarGuider X2 short Barlow with three elements you have?  I have this and the BST 8mm as upgrades for the Heritage 150 (also a Plossl 32mm) only tested the Barlow once so far but enough to conclude I lose noticeable detail on Jupiter and Saturn. In contrast, DSO'S are much better including; M13 Globular Cluster in Hercules and M57 Ring Nebula.

If anyone else reading this has any views, I'd appreciate hearing them.

Thanks,

T