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3x barlow


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Sorry if this is already on here i couldnt find it? If i add a 3x barlow to my setup will it be a little more distorted no matter what or is that showing the quality of my EPs. If i buy better EPs will the viewing quality increase?


Thanks for your help!!



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Hello Chad. All telescope have a maximum magnification depending on their aperture and focal length , quality of mirror/lens. But the maximum magnification in theory is not always born out in reality due to atmosphere/seeing conditions ect.

A great barlow/powermate will not make a poor quality eyepiece better, but will just magnify that eyepieces ability. And a poor barlow can hold back a great eye.A telescope set up is only as good as the weakest link in the optical chain 

Do not make the mistake of getting into the thought of the more magnification then the better (we have all been there and tried it though?). To much magnification will just leave you with a larger image, but a poor quality blurry image. You are better off going for a quality defined smaller quality image, through less magnification.

If you are going down the barlow/powermate route then buy the best you can afford IMO as it will usually be a one off purchase as a good one will last you years and that way you also know a quality barlow/powermate will be adding to the quality of views with the eyepieces instead of possibly holding it back, again the telescope is only as good as the weakest link in the optical chain.


I hope the  above helps☺

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40 minutes ago, Chadnich13 said:

The starblast 4.5 from orion and the two eyepieces that came with it 6mm and 15mm expanse

If you add your x3 barlow you increase the FL by 3x times the amount..so you are effectivley using the 15mm at 5mm..and the 6mm at 2mm..with seeing conditions my scope couldnt handle that..a wider fov will give a sharper image a smaller one will give more mag but your lose the sharpness and clarity...a better barlow(powermate) will perform better but you still lose some  clarity and sharpness..to get a bigger brighter image aperture rules..

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The max theoretical magnification for your scope is 228x. With a 3x Barlow this would give your two EPs (15mm & 6mm) a magnification of 90x & 225x respectively. As stated before get the best 3x Barlow you can afford, and try to avoid the cheap ones (or the terrible 3x Barlows given away with some scopes) to get the best from the optics. Whilst you may not be able to push the viewing every night to this level due to seeing, you should be able to get good views on quite a lot none the less, especially on brighter objects like the Moon, Venus, Jupiter etc. 

Edited by Knighty2112
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Ok I got the televue 3x barlow used and it was decently clear last night. The moon seemed to focus well but got noticeably darker. Would a televue 5,6, or 7mm Ep give a brighter more clear view, compared to my stocl 5mm EP 

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5 minutes ago, Chadnich13 said:

Ok I got the televue 3x barlow used and it was decently clear last night. The moon seemed to focus well but got noticeably darker. Would a televue 5,6, or 7mm Ep give a brighter more clear view, compared to my stocl 5mm EP 

This dimming of the view always occurs when using higher magnifications, either via an EP or in your case a Barlow lens. Another EP of the same size may give a brighter view over your stock EPs (most likely plossl EPs),  but it will still suffer from been darker still than when using a 15 or 20mm EP. Nothing to be done about this as you are looking at a smaller area of the sky with the magnification, so also loosing some of the light too than when viewing a larger field of view with a 20mm EP.

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33 minutes ago, Chadnich13 said:

So in turn on the orion starblast 4.5 came a rack and pinion focuser. I was looking to upgrade to a jmi mini but scared of the alignment and doing it right. Any experience with that?

No. I've changed the focuser on one of my refractor scopes,  but never changed one on a reflector. 

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Hi Chadnich,

Your current magnifications are a bit "all or nothing" because you are using the x3 barlow.

The spec for your scope has focal length 450

The manfacturer has supplied 15mm (divide the focal length 450 by the eyepiece size 15) gives x30 magnification and the supplied 6mm gives x75 magnification.

Both of these are good magnifications for your scope.


By using a x3 barlow you are making them x3 times more, so x30 becomes x90 & x75 becomes x225

You have a range of available magnification of x30, x75, x90, x225

I always say that a good set of magnifications is one where the GAPS are around x50. Under x50 and there is little noticable difference at the eyepiece (as you may have found out with the x75 and x90 - too close together)

In my opinion the best magnifications are in the x100 to x150 range and there is a hole in your line up there.


Lets just consider a couple of points:

1. The maximum useful magnifcation from the earths surface is usually around x230. Above this the atmosphere will usually get in the way and the view will deteriorate.

2. magnification factor of x50 per inch is applied to be the max for the scope, you have a 4.5 inch so x225 is the theoretical maximum. I would say that over x175 is pushing it in a 4.5 inch scope unless you are looking at the moon.


Therefore the x225 is probably too much for your scope and you may find focusing impossible (this may be why you want to change the focuser?)

A 3mm eyepiece (450/3=150) would give you x150 magnification and I would say consider getting one of these rather than change the focuser.

And that is the only change I would make. Get out there any enjoy what you have and hopefully get hooked on it!


If you get into the hobby then you will soon out grow this scope, therefore only spend on things like eyepieces that you can take on to the next scope. Save your money for the next scope :)

Hope all this helps, but please ask any other questions??





Edited by alanjgreen
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