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Mattwaters

Small upgrade!

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When I got my scope I brought the basic powerseeker kit from Celestron. It had a x2 barlow, 6mm and a 15mm eye piece with some filters. I overall felt quite flat about them, the Barlow and 6mm produced very blurry images. I was more shocked with the 6mm eye piece considering it should've only delivered around x160 magnification which is 3/4 What the scope can apparently use.

The 15mm was fine, but found the stock 10mm that came with the scope to still be the best eye piece I owned..... kinda felt like I wasted my money.

So Thought it was time I upgraded! 

I brought a x2 OMNI Barlow and a 6mm OMNI eyepiece!

Will be good to see the difference between the Kellner lenses and the plossl lenses! Will try and photo the differences in the coming weeks

Let me know your thoughts and experiences with either!!!!!

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Edited by Mattwaters
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I was reading a series of reviews on the Celestron Omni EP's earlier today. People were very pleased with these. I'm quite tempted by the impressions on the 32mm & 40mm for my purposes.

I hope to read your thoughts on the 6mm soon. A Plössl should be a marked improvement over a Kellner easily. And the Omni's seem to be a winner!

Enjoy!

Dave

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They look good. It will be interesting to hear about how they compare.

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I've used a few Omni plossls and they worked pretty well. The one that did not was the 4mm - uncomfortable to use and poor optically. I dismantled it and found that the cemented lens elements were not properly aligned - they must have moved during manufacture, before the cement hardened. I got a bad one there ! :rolleyes2:

The others seemed OK though.

Those 2 barlows look very similar in some ways - might be the same optical elements in a nicer body with the Omni perhaps ?

Hope you get a performance boost over the basic kit eyepieces :smiley:

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5 hours ago, Mattwaters said:

When I got my scope I brought the basic powerseeker kit from Celestron. It had a x2 barlow, 6mm eye piece and a 15mm with some filters. I overall felt quite flat about them, the Barlow and 6mm produced a very blurry image. I was shocked with the 6mm eye piece considering it should give around x160 magnification which is 3/4 What my scope can apparently use. The 15mm was fine, but found the stock 10mm that came with my scope was my best eye piece..... kinda felt like I wasted my money.

 

Looking at your previous posts it appears your scope is a Celestron Astromaster 90EQ. There is an industry standard of quoting 50-60x aperture (in inches) as the maximum magnification that a telescope is capable of and so to get the maximum of 213x Celestron have optimistically picked the 60x limit. However, this is the limit for the separation of double stars and the limit for planetary observation, which is what most people really want, is half that at 25-30x aperture.

Personally, I tend to remember an exit pupil of between 0.85 and 1mm as a guide because you can simply multiply these numbers by the focal ratio of your scope to get the focal length of the required eyepiece. For your scope (FR=11.11) this means your ideal eyepiece for planetary observation will have a focal length approximately between 9.5 and 11mm. No wonder that the 6mm and barlow (together?!?) produced a blurry image and that the 10mm supplied with the scope turned out to be the best choice.

Unfortunately, given that you have now bought another barlow and 6mm I doubt that you will see much of an improvement as the focal length is still too small.

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1 hour ago, John said:

I've used a few Omni plossls and they worked pretty well. The one that did not was the 4mm - uncomfortable to use and poor optically. I dismantled it and found that the cemented lens elements were not properly aligned - they must have moved during manufacture, before the cement hardened. I got a bad one there ! :rolleyes2:

The others seemed OK though.

Those 2 barlows look very similar in some ways - might be the same optical elements in a nicer body with the Omni perhaps ?

Hope you get a performance boost over the basic kit eyepieces :smiley:

I've had a look and the Barlows do appear different.  In the sunlight the lenses reflect different colours, ones more blue and the other is more green, also the OMNI has a white ring around part of the lenses, which at first I thought was just the light but it does appear noticeably different...... made me feel slightly better that they are odviously constructed differently considering they cost roughly the same. 

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I'm not sure what that white ring is in the Omni :icon_scratch:

The lens edges are suppose to be blackened according to the spec.

Anyway, see how they perform - what you see will be the real test.

I tend to agree with Ricochet regarding the max useful magnification with a 90mm scope. 160x is probably around the top (useful) whack.

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30 minutes ago, Ricochet said:

Looking at your previous posts it appears your scope is a Celestron Astromaster 90EQ. There is an industry standard of quoting 50-60x aperture (in inches) as the maximum magnification that a telescope is capable of and so to get the maximum of 213x Celestron have optimistically picked the 60x limit. However, this is the limit for the separation of double stars and the limit for planetary observation, which is what most people really want, is half that at 25-30x aperture.

Personally, I tend to remember an exit pupil of between 0.85 and 1mm as a guide because you can simply multiply these numbers by the focal ratio of your scope to get the focal length of the required eyepiece. For your scope (FR=11.11) this means your ideal eyepiece for planetary observation will have a focal length approximately between 9.5 and 11mm. No wonder that the 6mm and barlow (together?!?) produced a blurry image and that the 10mm supplied with the scope turned out to be the best choice.

Unfortunately, given that you have now bought another barlow and 6mm I doubt that you will see much of an improvement as the focal length is still too small.

Cheers, would a Barlow and say my 10mm be a better option then? 

I am still learning with all this lol

Edited by Mattwaters

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37 minutes ago, Mattwaters said:

Cheers, would a Barlow and say my 10mm be a better option then? 

I am still learning with all this lol

If you add a 2x Barlow to an eyepiece you effectively halve the focal length of your eyepiece so a 10mm eyepiece acts like a 5mm. Based on my calculation above there will be a rapid degradation of image quality once you go past 9.5mm so I suspect the 10mm by itself might still give the best image. Test the 10mm by itself against the 15mm + Barlow (~7.5mm) and two 6mm eyepieces on their own and see how you get on. 

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Seriously, stop all the playing around at absurdly small exit pupils and get a 32mm plossl to maximize your field of view for larger objects.  It will barlow to 16mm or so quite well, possibly with a bit of eye relief extension thrown in by the barlow.

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I have the 6mm Omni which is useable (just) but to be honest it's quite uncomfortable.  I'd imagine that it's way overpowered with a Barlow it's just not a good enough eyepiece to support x2.

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So since I brought these 2 eye pieces the weather has been unbearable! Constant cloud coverage, rain, or just to much light to see anything!

Although! Last night my wife asked me to take the rubbish out, and to my surprise there was a huge patch of clear sky! Ive never been so happy to take the rubbish out! So out came the telescope :)

I Compared my 2 x2 Barlows at first using my 15mm eyepiece with my scope aimed at the moon. The omni seemed to provide more clarity and sharpness and had a much better 'sweet spot' than the compareable cheaper Celestron Barlow. Although the differences were minor not rendering either unusable. 

So then I decided to use the 6mm eye piece vs the kellner 6mm. Automatically notice the kellners eye relife is slightly worse than the omni, and the omni was still pretty bad lol although for observing the moon I dont think it was to bad, the kellner might aswell go into the bin but the omni was a huge increase and I was able to make out detail in craters which was a blurry struggle with the kellner. 

So then the real test...... Saturn! Spotted it using my 20mm and switched to my 10mm to get it linned up near the centre of my view. Then i switched out the Eyepiece for my omni barlow with my 15mm. It wasnt as clear as the 10mm although you could still see the rings clearly and the image wasnt as bad as you would think. I switched out to the cheaper barlow, I did need to adjust but results were the same as the moon, it produced a slightly worse image. 

Now it was time for the 6mm! This wasnt bad, nor good, I could still make out the rings but viewing just wasnt as enjoyable as the larger eye pieces. The x2 barlow with the 15mm definatly out preformed it.

Overall I am quite happy, the 6mm probably wont see much use but the barlow was definatly a good buy, the eye relief and ability to have larger eye pieces was amazing and will be using it again. Was definatly a good combination! Here are some screens shots of the moon, the image with a blue squiggle is the Omni, see what you think :)

Need to get a better camera ratger than using my phone.

 

 

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Glad to hear you could finally get out under the stars.  Finding what works best for yourself is half the fun with astro equipment.  You're never quite satisfied that you've found the best.

Those are really good first efforts at what's known as afocal photography (pointing one lens into another lens).  Getting axial alignment without a camera holder is difficult.  Keeping the image centered without a drive is also difficult.

Keep at it and enjoy your new hobby.

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