Which barlow for Skywatcher Heritage 130p

[inertia8]

Hi All,

I've acquired a Skywatcher Heritage 130p second hand and would like to get a barlow that can be used with this scope as well as my future purchase, which is most likely to be a 10" Dob, probably of the Skywatcher FlexTube variety.

I understand that the little dob doesn't have much in-focus travel and hence probably need a shorty barlow for this one, which may not necessarily work in the 10" dob. For using the 15mm Bintel/GSO SuperView eyepiece I have had to shorten the focal length of the scope by about 1cm using the storage rods to allow me to focus on astronomical objects.. Interestingly it can focus just fine on terrestrial objects that are several hundred meters away without requiring adjustment to the storage rods.

I am having to return the Bintel/GSO 15mm to Bintel this week due to particles trapped inside the eyepiece, so would appreciate if anyone knows if the standard TeleVue 1.25" Barlow or the Bintel/GSO 1.25" Barlow in either 2x or approximate 1.5x mode will work with the little SW 130?

Eyepieces I currently have are:
25mm Super (inc with 130p)
10mm Super (inc with 130p)
15mm Bintel/GSO SuperView
6.7mm Explore Scientific 82deg

Thanks in advance

[barx1963]

Personally, and I know others have the exact opposite view, I have never had any joy using Barlows. The ones I have used have been good quality Televue ones, but never liked the view through them compared to a stand alone eyepiece.
Sorry to hear that you have an issue with the 15mm Superview. I have one and I think it is a little ripper for the price, it is my main ep in my 8" f4 dob. Little bit of barely noticeable field curvature but coma that one would expect in an f4 is not noticeable and the stars are pinpoints in the middle.
If buying eyepieces in person, I always (even with inexpensive ones) ask to see the eyepiece and check it for dust or particles before handing over my hard earned. Never had a problem yet, but always worth doing.
So your existing eyepieces will give
25mm - 26x with exit pupil of 5mm
10mm - 65x with exit pupil of 2mm
6.7mm - 97x with exit pupil of 1.34mm
If you barlow them you get
52x
130x
194x
To be honest, 97x is pushing this little scope to its limits, so the only useable power you will gain is 52x and you already have 65x, so I don't think it will be worth while IMHO.
I was not aware that either Televue or GSO made a 1.5x barlow?

Malcolm

[inertia8]

Hi Malcolm,

I appreciate the input and I have found that with the 6.7mm and the 6mm tmb before it the scope was feeling close to the limit, difficult to get a sharp snap-to focus.

The stars seem much more vibrant/brighter in the longer focal length eyepieces and the GSO SV was superb to my crummy eyes.

I will certainly be inspecting the eyepieces in future, I've learnt my lesson twice now!

Any recommendations for perhaps a wider field eyepiece or have I got it about right with the 15mm?

I was hoping for something in the 30mm region with a wider FOV to give good immersion but alas only a 1.25" focuser and typically when looking at eyepieces, I'm wanting them to be suitable for my larger dob so I don't wish to re-purchase.

[OzStarGazer]

I have your scope too, but prefer not to use a Barlow. Eyepieces are certainly better. I do have two. One is an average Celestron 2X Barlow, the other one is an extremely cheap 3X Barlow. It is super light and when it arrived I thought it would be junk, but it works better than I expected if you just want a detail and the weather conditions are favourable of course.

[inertia8]

I could see the bands on jupiter with the 10mm and then the 6mm TMB. Assuming they will be fine with the 6.7 ES 82deg as well.

I just wanted to see if I could get it to be a little bigger is all for more comfortable viewing.

ta

[CJ]

Hi, I used to use one of these budget barlow's.
http://www.ozscopes.com.au/skywatcher-2x-1-25-single-barlow-lens.html
It was very cheap when I bagged it. It worked, and with the T-thread it allowed me to experiment, mostly unsuccessfully, with my dslr, but with your collection of EP's I wouldn't bother.
Cheers

[inertia8]

Thanks for the advice, I skipped on getting the barlow and instead got a 25% ND96 1.25" filter and a blower for de-dusting/de-dandruffing eyepieces..

FYI Malcolm the Bintel/GSO 1.25" 2x barlow can have part unscrewed and then when it is screwed onto the eyepiece it will give approx 1.5x.

[OzStarGazer]

I know. I could see the bands too, even with the 25mm eyepiece! Not these days though; it was last year when the weather conditions were better.
Details don't only depend on magnification of course; they also depend on aperture because if your scope doesn't have enough aperture the images will be dark at high magnifications. Last year I managed to take a couple of pics with our scope where even the great red spot was visible, although not very clear. I mean, it is a nice scope to get started.

[barx1963]

There you go! Learn something new everyday.

Thanks for the info:thumbsup:

Malcolm

[inertia8]

An Orion 2x Shorty Barlow (japanese version) appeared in the classifieds. I've picked this up to try with the little skywatcher and it will come in handy with the 10" dob when I procure it.

[barx1963]

Will be very interested to hear what you think of a barlow in that scope. Personally I am not a big fan of barlows (as I have mentioned before) but always interested to hear others opinions!!

Malcolm

[inertia8]

My only experience with Barlows is the 2.5x GSO/Bintel that was provided with the loan scope. This seemed to make the view through the eyepiece much darker and only useful when looking at bright subjects.

I wanted to try something else and this little fella gets a good rap, worse case if I end up not liking barlows he can go back up on the classifieds.

[barx1963]

Higher power does make things darker, the light from the object you are viewing is spread over a larger area, so it dims it. But higher power also darkens the sky background so makes some dim objects start to stand out from the background. The end result is that for various objects there is an ideal magnification in many cases.

Malcolm

[brian nordstrom]

:) I have one of he older Celestron ultima 2x 1 1/4 inch ( with the orange writing) and it is the best barlow I have ever looked thru , I hear these are the same as the Telvue 2x one's , very , very good .
Brian.

[inertia8]

Shorty Plus worked a treat in the 130p. Now to await for the moon to wane.

Malcolm, I'm not yet convinced by barlows myself. This one seems a goodun but the focuser is screwed almost all the way in. Being collapsible I can simply shorten the focal length by 10mm or so if need be, like I have to when using the GSO 15mm Superview.

[shutterhigh]

Personally, i'm also not a fans of using a barlow lens. If you using the eyepiece come together with telescope, it will only magnify the poor quality of the eyepiece. However, getting this cheap barlow lens from ozscopes is still an option for those with limited budget and perhaps good enough for this small dob.