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The Orion Nebula (M42) and Jupiter with a 5" (130mm) Reflector - Stock len issues


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I noticed the very good "What Will I see?" thread, but thought I'd share my experience of a second observing session.

For the first time since I got my scope, I braved the scarey outside world in order to use the EQ mount properly as I went to see Jupiter.

Very minor issues with getting it in the scope (I just need to remember to lower the tripod! Surprising how low you need it, even when you're a tall person) I managed to get a pretty good view of Jupiter's stripey Christmas jumper. There were at least 5 clear bands; two whiteish, two redish. And I could see two of the moons (Ganymede and Io), apparently I should have been able to just about see Europa, but I must admit I didn't notice anything. (Though part of me thinks I may have just been able to make out the Red Spot, but I'm pretty sure that's just my mind getting over zealous)

Later on I turned my scope to point to M42, and could see a good collection of stars, but for the life of me, I could not find the fuzzy smug of the nebula itself (could easily be viewing conditions I suppose). (That was with just the 25mm lens)

When viewing Jupiter I did notice 4 quite strong white smokey streaks coming out of it. I'm assuming this would be due to my telescope needing Collimation? Or is it due to the stock lenses?

Also, I noticed that when Jupiter was drifting towards the edge of the eye piece, it started to de-focus noticeably. Would this also be due to lack of collimation? Or "feature" of cheap eye pieces?

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Scope:

    Focal Length: 650mm

    Aperture: 130mm

    Lenses: 10mm (stock) 25mm (stock)

    Barlow: Baader Classic Q 2.25x Barlow

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If you could see 5 clear cloud bands on Jupiter, sounds good.

If Jupiter was that good, then M42 should easilly show some of the nebula.  Are you sure the scope was actually pointing at it ?   Perhaps a check that the finder is aligned would help, easiest to do during the day on as distant an object as you can, chimney etc.  Start with your lowest power eyepiece, find the distant object, then adjust the finder so it's pointing at the same object, switch to a higher power eyepiece, then fine tune the finder adjustments.

Simplest way to check collimation is to view a bright star at medium to high power, and defocus a bit until you can see tiny circles of light.  Keep the defocused star in the centre of your field of view, and the tiny circles of light should look concentric, not skewed to one side.

Maybe the "4 quite strong smokey streaks" are diffraction from the secondary supports (called the spider).   Were they cross shaped and centred on Jupiter ?  That's normal with a Newtonian telescope when viewing a bright object.

I'm not putting down entry level eyepieces, but it's common for the view to be less sharp away from the centre of field of view, even some expensive eyepieces may not be perfect in that respect.

HTH, Ed.

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I agree with the above. You have quite a fast scope at around F/5 so it will be quite fussy with EP. The views will get better with better eyepieces, but I wouldn't worry too much about that just yet.

The steaks area almost certainly from the spider, they should pretty much disappear when looking at anything else?

M42 should have been very obvious in the 25mm eyepiece, so like others I suspect your finder is of slightly.

Sounds like you had fun though - that's the best bit :)

Cheers

Ant

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I thought that by using averted vision you could detect a fuzzy smear around that part of orion.  Is this a fair comment compared to what others notice?  Similar if you avert you vision at pleiades it becomes a smear instead of distinct stars....

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Depends on what some would consider a smear I guess. 

I've only viewed M42 twice but both times I didn't have to guess at what it was. It was pretty apparent without using averted view.

My guess is the same as those above and maybe your alignment wasn't spot on.

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I guess you have the astromaster 130 is the stats are the same - the best advice is to get rid of the standard red dot finder and get a rigel or a telrad. It totally changed my experience with the scope as I could actually find things!

I found the orion nebula last week and was a very nice view in the 25mm ep. I expect it would be clearer with a better ep but you should know that it is possible with the kit you have before spending any money.

As for your view of Jupiter, were you seeing two dark bands and three lighter areas? That is all I see with the barlow and 10mm ep.

Michael

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Thanks for the comments guys!

Was a nice view of Jupiter, and diffraction from the spider makes sense; didn't notice it when looking at M42, and don't remember noticing it when viewing Saturn earlier in the year.

It is quite possible that I wasn't pointing quite the right direction, I think my problem was that I got distracted by Jupiter, and then clouds started to roll in, so didn't have long to correct my aiming.

As for Mrlangston's comment about what I saw on Jupiter; yes, that's roughly what I saw! Using a 10mm lens and a 2.5 barlow.

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I guess you have the astromaster 130 is the stats are the same - the best advice is to get rid of the standard red dot finder and get a rigel or a telrad. It totally changed my experience with the scope as I could actually find things!

Michael

Totally agree with Michael here. The standard finders are shockingly bad. I couldn't find zip with one.

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