Need some advice

[Dindsy]

hi Guys,
I've not looked into my scope for a year I think (about the time i went to a sky party and looked through someones $3000 Meade GOTO thingy that had crystal clear images) but am keen to get back into it. I think my problem is that i get disheartened with my expectations and i what i end up seeing. I read about the great things people see with 6 inch scopes and how on earth did that 17 year old see Saturns rings with a home made 3 inch in the latest AS&T?

I have a 6 inch newt Sywatcher 150 on an EQ6 GEM.

I took it out last night, despite the huffing and lugging and had a look at Jupiter. OK I could see it quite well, i saw the bands around it. Two distinct bands. But it was small. There was no way i was going to see the spot and I'm sure i read about people seeing this with a 6 inch. It was a clear night but don't ask me about seeing because i don't think i could tell the difference.

My scope probably does need collimating but it was collimated by someone who knows how to when i last used it at the sky party. And i still wasn't overly impressed with my images

I used a 10mm Televue plossl that i just bought because i only had the generic ones that came with it and i was hoping to be more impressed.

So the questions:
1. Am i going to see more/bigger/better images if i get say a 4mm EP and give me 250x image?

2. If i followed common advice and got an 8in or 10in dob would i see a better image? i'm guessing from the ones i've seen that the size of the image would be about the same as they have similar Focal lengths (1200 - 1500mm) Mine is 1000mm?

My real passion would be to take some photos but i know i enter a whole new world of pain here. I'd like to be able to at leat get some ordinary looking shots before delving into DSO's etc.

Anyway, enough for one post?

cheers

[Dennis]

Hi Martin

Assuming your 6” optical tube and components are of at least average quality, that is, the optics are not too rough, poorly corrected, etc. then I would persevere with the 6”.

You are probably suffering the symptoms of poor seeing, lack of experience and sky high expectations, and perhaps poor collimation?

Poor seeing:
Even with my Celestron C9.25 and Takahashi Mewlon 180, I can easily relate to your descriptions of Jupiter. Small disc, a few indistinct bands and what Red Spot!

When the seeing is really good, with Jupiter high in the sky (over 70 degrees altitude) and a thermally stable mirror (scope cooled to ambient) then with practice, you will be able to see more detail on Jupiter and even see the (pale) GRS.

Lack of experience:
It takes time and practice to learn how to “see” at the eyepiece. At public field nights, I am often astonished at the range of experiences reported by members of the public looking through the same ‘scope at the same object. Some have the ability to see most of the detail that is present whilst others report seeing a fuzzy blob.

As you gain more experience, you will be more relaxed and begin to see ‘what is actually there” rather than cloud your mind with what should be there, from looking at the world class images available on the web these days. These images will invariably show text book perfect renditions of Jupiter because they combine several 100 short exposure images stacked together, under ideal conditions, taken with large telescopes and skilfully processed.

High expectations:
If you base your expectations on Hubble images, space mission fly by’s and images captured through mega metre professional scopes the you will be disappointed with the views through your 6”.

Poor collimation:
This can make a big difference to the quality of the image seen at the eyepiece. Even if the image is small, with a properly collimated ‘scope and good seeing, you will be able to see a lot of detail through a good 6” ‘scope.

The big danger (and expense) for you is that if you purchase a 12” ‘scope and suffer poor collimation, poor seeing and have little experience, the views of Jupiter may not be that much better that your current 6”.

Cheers

Dennis

[xelasnave]

I have such a scope and had it on such a mount..

I found it to give sharp images and minimal color flare.

You may question this but I found the addition of 11 kgs weight from a weight set to the tray of the tripod made viewing and particularly focusing markedly better.

When first starting go for low magnifications I think you will find this more satisfying.

good luck ..you just have to spend time behind the wheel.

alex

[rmcpb]

I would agree, more practice especially with Jupiter and check the collimation. It only takes one serious bump between now the the star party to put it out.

The 6" is a real beauty, especially with that mount.

[Dindsy]

Yeah i will be checking the collimation. I'm sure my 4 and 2 yr olds are the "seriuos bump" in question.

I need to read up the howto for collimating. Anyone got a good reference for this?

[erick]

Martin, Search the threads here - there will be enough to enlighten and confuse!

Find the references to the collimation video at "Andysshotglass" or just Google this!



"...and what's more, he knew how to treat a female impersonator"

[jungle11]

Hmmm....:whistle:

If you don't want to scare the wife, google the first one me thinks...:lol:

[erick]

Wooops! :ashamed::rofl:

I was talking about Dinsdale! ;)

[Dindsy]

Thanks for the feedback.

First take away (to use a wanky management term :sadeyes:) is more practice. I get that and concur.

Second thing is this collimation. I've had a crack at this before with the andyshot glass video. I went through this many times again this morning and some things are starting to click. The sceondary mirror circle and the grey part being the secondary mirror holder. I finally get that. I think i have been distracted with too many things being seen further down the OTA to actually be looking closer at the secondary mirror... cool.

I think the key was to abandon all fear and really get into it and start turning screws and figuring out what was actually happening to the bits and pieces. I figured what's the worst that can happen, the secondary mirror comes off completely. So long as the OTA was horizontal it would be OK.

Anyway, my excitement at getting this far is making me rant.

So i think i've got the secondary mirror lined up and tilted so that i can see the primary. I move on the primary to get the spider vane aligned.

After all this the laser collimater is pointing straight out the top. I loosen off the locking screws and withdraw the hex adjusting screws all the way and the mirror shifts visibly and now at least the laser is all internal.

I adjust the hex screws until the laser is centred on the collimator. Lock the screws. All should be OK. However, looking back through my (homemade) collimating cap, the spider vane is not centred. :shrug:

I thought the rear adjustments should have fixed this. What now.

:help:

Actually, rereading i just had a thought. I'll still leave this for feedback but i may need to collimate my collimator.

thanks

[acropolite]

Martin, in case you didn't take in Dennis's comment on mirror cooling, it's important for the mirror to be at or close to ambient telmperature. This can take a couple of hours, often in condions were the day has been hot and the temperature is dropping rapidly, the primary mirror will have difficulty in reaching equalibrium. If your OTA doesn't have cooling fan/s it may be worth fitting them. Also FWIW the best seeing conditions often occur in the wee small hours just before dawn twilight.

[astro_nutt]

Hi Martin
If you can find a small fan from an old PC..fit it about 30mm from the rear of the Primary and power it with a 9 volt battery..works for me!!
Cheers!