Collimation success viewing failure

10 years 6 months ago #83596 by Crescent
Collimation success viewing failure was created by Crescent
Hi everyone,

I have spent hours trying to collimate the new scope over the last few days and I think I’ve cracked it. I was going to buy a Cheshire tool online but I couldn’t be bothered waiting so I got one from Astronomy Ireland’s shop instead. I found a good tutorial on line www.propermotion.com/jwreed/ATM/Collimate/Chesire.htm its colour coded and easy to follow.

I set up the scope on Mars last night and finally had some successes. I could see some of the darkened areas of the planet (kind of looked like Africa) and I was chuffed.

Another setback however. When I turned the scope on some of the objects I was familiar with (wile using the 15*70 binoculars) I couldn’t find them. In fact the binoculars were brighter. I gave up on the scope and ended up only using the binoculars.

I was using a Skywatcher explorer 150p and a 6mm eyepiece with 2* Barlow for Mars and a 25mm eyepiece for m36 and m38

Any taughts would be appreciated.

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10 years 6 months ago #83597 by mjc
Replied by mjc on topic Re:Collimation success viewing failure
Crescent

Well done on the collimation - it can be a daunting prospect for a beginner.

The skywatcher 150P has a focal length of 750mm so gives a magnification of of 750/6 = 125x with a 6m eyepiece (and twice that if using the 2x Barlow).

Your 15x70 binos will let in about a quarter of the light (proportional to area of aperture) as the 150P but you are only magnifying 15x with the binos.

I think that that is at the root of your disapointment.
For faint fuzzies and the like reduce the magnification.
Avoid the Barlow and go for a longer focal length eyepiece. I'm sure others will recommend some decent eyepieces for the job (I have a poor set but consider my chinese 40mm Plossel good and I'm happy with it on my 8" Skywatcher reflector).

There is a certain comfort viewing with both eyes (as in binoculars) and this may also be affecting your judgement.
It also reinforces the message that binos are not to be underestimated for anyone starting out or as an auxillary resource for the more seasoned observer.

Mark

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10 years 6 months ago - 10 years 6 months ago #83599 by dave_lillis
Replied by dave_lillis on topic Re:Collimation success viewing failure
Like Mark says, its all down to expectation.
If the stars are fairly pinpoint, then collimation is probabily ok, that's important for sharp details.
On objects like galaxies, slight miscollimation isnt going to suddenly make them invisible.

If you want to see faint fuzzies clearer or at all, then you eather need to reduce the magnification or get a bigger scope.

Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go. :)
+ 12"LX200, MK67, Meade2045, 4"refractor

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10 years 6 months ago #83601 by johnomahony
Replied by johnomahony on topic Re:Collimation success viewing failure
Getting good planetary views is the toughest test of any telescope optics. From what you mention, it seems like you are getting good views of Mars, which is a tough object, so your optics are probably quite good. As the previous post mentions, you may be applying too much magnification on the deep sky objects (diming them and reducing the field of view). Always start with your longest focal length eyepiece and then put up the magnification if the viewing permits. It might be worth investing in say a 35-40mm eyepiece for lower power and wider field views or a 2 inch wide field eyepiece (such as a Baader Hyperion)

The Lord giveth, the Revenue taketh away. (John 1:16)

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10 years 6 months ago #83625 by Crescent
Replied by Crescent on topic Re:Collimation success viewing failure
Thanks for the advice. I was looking at a 40mm 1.25" eye piece and a 40mm 2" on astronomy irelands site. They are discontinued celestron e-lux eye pieces for €30 and €69. What do you think? Is there really a big difference between the 2 and 1.25" in this range.

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