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Thread: To Barlow or Not to Barlow That is the Question

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    Default To Barlow or Not to Barlow That is the Question



    I'm looking to upgrade eyepieces for my Zhumell Z10. I was thinking of buying a Zhumell 2" 2x Barlow and maybe a 18-20mm eyepiece then use barlow so I would have same mag as 9-10mm. Or do you think it would just be better to forget the barlow for now and buy a 8-10mm eyepiece along with a 18-20mm? I'm not trying to break the bank but want to upgrade since all I have are the eyepieces that came with my 2 scopes and the Zhumell eyepiece and filter kit. I have been thinking the Explore Scientific or Meade 5000 HD-60 for the upgrades?? Thanks!

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    Default Re: To Barlow or Not to Barlow That is the Question

    I love my HD-60's. I am upgrading my kit pieces to HD-60's now, So far I have the 18 and 6.5mm. I use my barlow on both which is awesome since it retains the eye relief of the EP. I think I may purchase the 32 next. I personally think you are better off with the 1 EP and a barlow, then picking up a different EP later that will give you 2 additional mag values, not a value that you already have i.e. 18mm which will equal a 9 when barlowed and a 6.5 that gets me 3.25 when barlowed. Good luck!
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    Default Re: To Barlow or Not to Barlow That is the Question

    One bad thing that happens when you use a barlow is that it dims the view considerably. With a larger scope it might not be too much of a problem, but with small scopes it would be a issue.
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    Default Re: To Barlow or Not to Barlow That is the Question

    To make you decision, you need to compare the price of the barlow versus the equivalent eyepiece you would buy. And then consider any differences in quality. The Meade HD-60 eyepieces only cost about $20 more than the barlow, so would likely be a better choice.

    But...
    One of the best uses of a barlow is to extend the range of your whole collection into the sizes between your eyepieces. Then you can buy fewer overall EP's. For instance a collection of 25mm, 17mm, 10mm EP's would be expanded to include 12.5mm, 8.5mm, and 5mm focal lengths with a 2x barlow.
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    Default Re: To Barlow or Not to Barlow That is the Question

    I don't have any issue with my image dimming when I use a Barlow. I think a Barlow is a critical piece of any Amateur Astronomer's kit so I recommend you get the Barlow.
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    Default

    Neal, I agree with you. A good barlow adds so many more options. I find it kinda fun swapping diff barlows with diff ep,s. But you gotta have good ep,s to go with them.

    Steve

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    Default Re: To Barlow or Not to Barlow That is the Question

    If you take a 24mm and 12mm (or 13mm in my case) of exactly the same design (Orion Stratus in my case) and flip between the two, then take the 24mm and barlow it (in my case a 2" APO barlow) you can clearly see the barlowed image is dimmer, and not as sharp. Now maybe it isn't too much for *you*, and heck, maybe *you* won't even notice. But more glass always dims (assuming you start at the same point) and degrades the image, there is just no way around it.

    That being said, give it a shot and see what you think. In the end, *your* view is what matters. For me personally, I only use barlows when imaging and I have no choice, otherwise it is single EPs for each focal length I want (and the same with my photography).

    Allan

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    Well, i do notice a slight darkening when i use a barlow but what,s the difference in in a high quality ep that has many diff. pieces of glass in it? If more glass degrades the image then why is there ep,s with several lenses in them?

    Steve

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    Default Re: To Barlow or Not to Barlow That is the Question

    Quote Originally Posted by Galileo3269 View Post
    Well, i do notice a slight darkening when i use a barlow but what,s the difference in in a high quality ep that has many diff. pieces of glass in it? If more glass degrades the image then why is there ep,s with several lenses in them?

    Steve
    On dimming: Note that I said "But more glass always dims (assuming you start at the same point)". More glass when it is all designed together as a single unit, and coated for that unit, does not necessarily dim the image any noticeable amount. But when you take that 5, 6, 7, or 8 element EP and slap a barlow on there that dims and degrades it. The same happens with photography when you add a teleconverter on it (which is why you almost never see a pro using a TC, and most pros don't use filters either except when the shot requires it for an effect).

    On degrades: Same rule applies. You can have 100 pieces of glass if the optical design calls for it with no degradation (although that would probably be difficult). The EPs are designed to focus all points of light into a very specific plane where your eye goes, any addition or subtraction from that formula and the light no longer focuses in all or in part where the designer intended.

    Allan

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    To: Allan, I understand now what you,re talking about. Thanks for clearing that up for me.

    Steve

 

 
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