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Eyepiece recommendations for f/4 scope?

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#26 Atlantic Devil

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Posted 01 December 2020 - 03:28 PM

You could also keep an eye on the classifieds for one of the vintage Japanese 3.8mm models (several brands). Quite sharp and available at bargain prices. They aren’t wide AFOV but they are sharp and have usable eye relief. 3.8mm would be a reasonable jump from 5mm.

Note the Xcel LX 5mm is really 4.5mm. I recently read a rather poor review of this eyepiece so the 5mm paradigm might be a safer bet.

Scott

thanks for that info!



#27 BDS316

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Posted 01 December 2020 - 03:56 PM

Stick with plossls for the two inexpensive scopes.  The f/4 will not be a problem with eyepieces with an apparent field of view of 50 degrees or less.  With larger apparent fields, all the good performing eyepieces would cost more than the telescopes, and would be heavy enough to cause balancing problems too.

 

A 25mm plossl would provide nice low power wide field, relatively speaking, views.  For high power views you will need a barlow most likely given the short focal lengths of the scopes.


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#28 hoof

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Posted 01 December 2020 - 04:03 PM

In my Starblast, I used a 3mm eyepiece for 150x magnification. Collimation had to be spot on, but I was able to observe the Cassini division, Titan, the Great Red Spot, and subtle hints of the maria on Mars with that combo.

It was pretty much just for the moon and planets, though. Everything else was pretty dim at that magnification.


Heh, I picked up my 3rd Starblast a few months ago just so I’d have a telescope that had a shot at being usable with my Vixen HR 1.6mm :)

Not many telescopes can use a 1.6mm eyepiece regularly on anything other than double stars, but the Starblast can. Now if only someone made an upgrade for the 1.25” plastic focuser...
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#29 Atlantic Devil

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Posted 02 December 2020 - 01:07 PM

Heh, I picked up my 3rd Starblast a few months ago just so I’d have a telescope that had a shot at being usable with my Vixen HR 1.6mm smile.gif

Not many telescopes can use a 1.6mm eyepiece regularly on anything other than double stars, but the Starblast can. Now if only someone made an upgrade for the 1.25” plastic focuser...

Any issues collimating your starblaster?



#30 SeattleScott

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Posted 02 December 2020 - 01:13 PM

Any issues collimating your starblaster?

The Starblast is collimatable. If there is a concern, it is with the weak plastic focuser’s ability to hold the laser steady enough for precise collimation.

Scott

#31 hoof

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Posted 02 December 2020 - 04:46 PM

The Starblast is collimatable. If there is a concern, it is with the weak plastic focuser’s ability to hold the laser steady enough for precise collimation.

Scott

Agree.  The biggest challenge is the sloppiness of the focuser throwing off the axis of the collimation tool.  After much trial and error, I got the secondary positioned and aligned well, which made the primary easy to align with a barlowed laser.  Fortunately it holds its collimation pretty well.

 

The biggest bummer is the focuser slop during use (thus my comment about wishing for a better focuser).  

 

So far it seems to work rather well (the StarBlast and my Vixen HR's).  Ironically, the usage issue that is most troublesome is that the 'scope is so small thus breath and body heat end up degrading the image quality unless you're careful.  Exhales go directly in front of the nearby tube opening! =)



#32 SeattleScott

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Posted 02 December 2020 - 07:26 PM

Agree. The biggest challenge is the sloppiness of the focuser throwing off the axis of the collimation tool. After much trial and error, I got the secondary positioned and aligned well, which made the primary easy to align with a barlowed laser. Fortunately it holds its collimation pretty well.

The biggest bummer is the focuser slop during use (thus my comment about wishing for a better focuser).

So far it seems to work rather well (the StarBlast and my Vixen HR's). Ironically, the usage issue that is most troublesome is that the 'scope is so small thus breath and body heat end up degrading the image quality unless you're careful. Exhales go directly in front of the nearby tube opening! =)

Oh yes this is kind of the reflector curse but especially with such a small one!

#33 isolli

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Posted 05 January 2021 - 08:13 AM

Stick with plossls for the two inexpensive scopes.  The f/4 will not be a problem with eyepieces with an apparent field of view of 50 degrees or less.  With larger apparent fields, all the good performing eyepieces would cost more than the telescopes, and would be heavy enough to cause balancing problems too.

 

A 25mm plossl would provide nice low power wide field, relatively speaking, views.  For high power views you will need a barlow most likely given the short focal lengths of the scopes.

Wouldn't something like the Orion Expanse 9mm be a worthy upgrade, considering the increase in eye relief and apparent field of view?

 

Since the true field of view would be rather narrow, the eyepiece would show a part of the image that does not have too much aberration. Or did I miss something else that makes short focal lengths difficult for eyepieces?



#34 barbie

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Posted 05 January 2021 - 10:06 PM

I use Plossls and Paradigms in my Starblast and have no problems with the views. The plastic focused is fine for me now that I am primarily using my Starblast 4.5 for short observing sessions using low to medium powers. I don't have any issues with mine nor did I have any issues with the one I had years ago when they first appeared on the market!! To each their own!!



#35 SeattleScott

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Posted 06 January 2021 - 12:28 AM

Wouldn't something like the Orion Expanse 9mm be a worthy upgrade, considering the increase in eye relief and apparent field of view?

Since the true field of view would be rather narrow, the eyepiece would show a part of the image that does not have too much aberration. Or did I miss something else that makes short focal lengths difficult for eyepieces?

An Orion Expanse in a F4? You are a braver man than I.

Idk I suppose it might work ok. I can think of a much better option but it costs $90.

Scott


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