I'm still on the fence about the zoom. I think I'd only use it for the planets, moon and maybe double stars. 8x to 24x sounds a little too low power for that, but 4x to 12x might be a little better. Less hassle swapping eyepieces at high power I suppose. Is it easy enough to make adjustments without causing too many wiggles?
Zooms are not for everyone. And some people don't like Barlows.
I didn't have access to this info when I made the earlier posts. Let me share it now.
It is easy to match a zoom, any zoom, to your telescope's best working range to enhance your observing experience. This is about the approach and process rather than the specific eyepieces or barlows.
I am going to use the 8" XT8i as the example here but this applies in exactly the same way for my ETX 80, GSkyer 80 and Orion 100 mm scopes and to my ETX 125. You can do this using a 2X, 2.25 2.5 or 3X barlow, depending on the FL of your scope. And some barlows have removable elements to provide 1.5X.
I am taking advantage of the removeable nature of the barlow element from the this particular Barlow to expand my options to match my zoom to my XT8.
The XT8i is a 1200 mm FL Dob. With the below set-up the Baader Hyperion zoom was my primary eyepiece for this scope. And, BTW, this applies equally to the Celestron Zoom as it works in the same range.
Start with 38 mm/70, go to a 20 mm/82, then to the zoom.
8-24 mm - 50 to 150X
16-5.3 mm - 75 to 225X (1.5X barlow)
12-4 mm - 100 to 300X (2X barlow)
Using this 2" GSO 2X ED barlow, I get 2X. But I can remove the barlow element and use it as 1.5X by directly attaching it to a 2" eyepiece or the 2" adapter that comes with the BHZ.
These 1.5X/2X barlows provide the same capability in the 1.25” format.
With the 1.5X element the BHZ operates as a 16 to 5.33 zoom. For me that results in 75X to 225X which is a perfect range for this scope as I can rarely get over 225X. Even my single FL 82 degree eyepieces stop at 5.5 mm as I can rarely go above that so I would barlow above that either way.
If I want to use the BHZ in the low range, 50 to 150X, or in one of my 1.25" scopes, I just take it out of the BHZ 2" adapter. If I want it in the mid range in the XT8 I put the BHZ into its 2" adapter. If I want to use it in the high range, 100 to 300X, I put the element back on the GSO barlow for 2X, or I use my 1.25" 2X barlow.
Comparing the BHZ image with the 2" GSO element to my ES 82 8.8 and 6.7 and my Meade 82 5.5, I find the image comparable, but of course not as wide. I am no eyepiece expert but, but most of the time I stay with the BHZ + 1.5X. I love those 82 degree eyepieces but in the XT8k I rarely used them unless I need that wide view, which is not often.
Part of the reason for this great image might be that this is a 2" barlow element and I am only using the center 1.25" portion of the lens so I may be working in the sweet spot. But this 2" GSO does get excellent reviews. And, yes, I have used it with my 2" eyepieces.
Naturally this barlow allows me to barlow my 2" eyepieces at 1.5X or 2X, which is why I purchased this barlow in the first place. But the BHZ 2” adapter +1.5X element gives me a 1.5X barlow for my 1.25" eyepieces too for a bit more flexibility.
I now store the BHZ with the 1.5X element attached to the 2" adapter. I open each session with my 2" 38 mm 70 degree /31.5X and/or my 20 mm 82 degree 60X eyepieces. Then I go to the zoom for anything 75X and above. Works really well.
I could use a similar techniques with my three 400 mm FL scopes. For these scopes 2X or the 2.5X barlows that I have seem to be better matches.
ETX 80 F5 Goto refractor - 400 mm FL
GSkyer 80 F5, manual refractor - 400 mm FL
SkyScanner 100 F4 manual tabletop Dob Newtonian– 400 mm FL
In these I tend to use the Celestron zoom because it is smaller and lighter and with these the 2X or 2.5X or 3X barlow is a better tool to match the zoom to the targets I am working that night. The zoom goes in the barlow and tends to stay there all night. Here I start the session with a 32 mm Plossl for low power wide view.
Celestron 32 mm/50 12.6X and 4 degrees FOV EP 8
Then I go to the zoom most of the time using the barlow that matches the zoom to the task
Celestron 8-24 zoom 16.6X to 50X ( sweeping, exploring, open clusters, large low power DSOs)
Celestron 8-24 +2XB 33X to 100X (general observing, globulars, double stars)
Celestron 8-24 +2.5B 40X to 125X (Planets, doubles, globulars, galaxies) The swee spot for these scopes
Celestron 8-24 +3X B 50X to 150X Seeing needs to be really good for me to push these scopes this high.
This mag range matching also tends to put you into the wider part of the AFOV range of the zoom most of the time.
Again, this is not about the eyepieces but how to use the appropriate barlow to match the tool to the task. I don't think people really understand how your can take advantage of a barlow to optimize their eyepieces to the task. You can do the same thing with single FL eyepieces, creating ranges for them so you are not popping the barlow in and out, but we all use our tools differently.
I am not suggesting everyone has to do this. Just offering up how I have learned to leverage barlows to optimize my observing experience.
Hope this was useful information.
Understanding and using a Barlow Lens
Edited by aeajr, 20 September 2019 - 10:35 AM.