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Posts Made By: dan hilts

June 29, 2005 08:11 AM Forum: Beginning Astronomy?

Baader full aperture 10" dob or not?

Posted By dan hilts


The sun is plenty bright enough that you don't require a large aperature to view. The off axis mask allows a smaller filter that is less likely to be damaged and is easier and cheaper to replace when it becomes necessary.

Also note that unless you have extremely good circumstances, the heat of the sun causes localized atmospheric conditions that destroy seeing. The effect of this is typically much worse than the loss of contrast due to the spider and seconday obstruction. There is little to be gained by using a full 10" aperature.

clear skies,
dan

July 6, 2005 07:53 AM Forum: Eyepieces

50mm x 1 1/4"

Posted By dan hilts

Hi Chet,

The 50mm in a 1.25 barrel is not used because it does not provide a pleasant view. The 1.25 barrel restricts the field of view so much that the view is like looking down a tunnel (some say like looking through a soda straw!) Even a 40mm will suffer from this. Also, in daytime use you would probably see the shadow of the secondary.

IMHO, you would prefer a spotting scope.

regards,
dan

July 22, 2005 09:31 AM Forum: Equipment Talk

AZ3 modification for altitude lock

Posted By dan hilts

Tim,

I had the exact same issues with the AZ3. After a couple of unsuccessful attempts to fix it I had made some ugly wrench marks on the lock nuts and I gave up on it. Easiest solutions I came up with were:
1) add a counterweight system to the AZ3 to correctly balance the scope or
2) get a small EQ and use it in the AZ mode by realigning the polar axis to a vertical position.

The EQ solution proved to be the best because slo-mo cables can be in a fixed position for use. For terrestial viewing it was way easier to use than the AZ3 ever was. I never did put a counterweight to the AZ3.

have fun,

dan

August 3, 2005 09:44 AM Forum: Telescope Making

In-line finders?

Posted By dan hilts

<>

I recall seeing a design like this in some ads somewhere. There was an objective lens mounted in front of the secondary. The secondary could be rotated to divert either the primary mirror image or the finder image to the focuser. I remember thinking it would be a mechanical nightmare to get it properly aligned and keep it that way. I also didn't like the idea of having to swap eyepieces anytime I wanted a low power finder view.

The ad was not for a premium scope. I got the impression it was a marketing thing more than a really good idea.

I like an optical finder. You simply have to determine the best place and method to mount it that suits you. It shouldn't be so flimsy and in the way that it is constantly bumped out of alignment. I can't recall the last time I tweeked the finder on my 8" Newt. It stays put pretty good. If you can build a flip mirror with the needed precision to return to decent collimation everytime it gets turned, then you can mount a finder and keep it aligned (and probably do it a lot cheaper than the flippin' mirror.)

have fun,

dan hilts

August 16, 2005 06:24 AM Forum: Refractors

How to test focuser collimation?

Posted By dan hilts

The easiest way that I have found is to use an alignment tool such as a Cheshire eyepiece or a laser collimator.

Remove the diagonal and insert the aligment tool. It should be aimed at the exact centre of the objective. The centre can be identified by using crossed threads or tape on the outside of the objective cell (not touching the lens) or if the lens cap is perforated in the centre it may be installed to indicate the centre. It is not necessary to have the lens installed to check the focuser alignment.

Rotate the alignment tool in the eyepiece holder to check the fit and alignment of the tool. If the centre wanders as the tool is rotated then there will be errors in the final alignment.

Rack the focuser all the way out and check the alignment, then rack it all the way in and see if the aligment has changed. If the focuser is well aligned, there should be no change from one position to the other.

clear skies,
dan

August 20, 2005 07:59 PM Forum: Telescope Making

Good Telescope Making book?

Posted By dan hilts

This is one of the best. You may find a copy at your local library.

Build Your Own Telescope.

by Richard Berry
Hardcover - 286 Pages, Second English Edition (1985, revised 1994) Willmann-Bell; ISBN: 0943396425
Dimensions (in inches): 11 x 8.44 x 0.91


have fun,
dan

August 21, 2005 07:02 AM Forum: Telescope Making

Good Telescope Making book?

Posted By dan hilts

Zack,

Also worth mentioning is the Sidewalk Astronomers web site. They have a lot of online plans with detail for building scopes and lots of pictures. Well worth a visit.

http://www.sidewalkastronomers.com/telescope.html

dan

October 21, 2005 08:58 AM Forum: Refractors

Orion ED100 fix

Posted By dan hilts

If the spacers are not where they are supposed to be I would have two concerns:

1) The spacers are not all equal distant from the centre of the lens and are creating a wedge in the airspace. A wedge is not good in any lens, particularily bad in an APO.

2) If the spacers aren't where they are supposed to be the lens never rec'd proper QA or the spacers have moved since assembly. If the spacers have moved, they will move again.

Either way, I would want the scope properly serviced to ensure continued reliable performance.

good luck,
dan

October 26, 2005 05:46 PM Forum: Eyepieces

Planetary Eyepiece Info Needed

Posted By dan hilts

When I think of planetary viewing, I think of higher powers. A 12mm in your scope will provide in the neighborhood of 100X. That's not very high on the scale. 10mm is not that much more, maybe 120X. I would think you're going to need something in the range of 7-5mm for better planetary views.

Personally I detest tiny little eyepieces with really tight eye relief so when it comes to the shorter focal lengths I tend to use a barlow on my 15mm and 12mm. I have also just ordered and not yet received one of the 66 degree WE9mm which I beleive is a Synta product. Also available from Orion as the Expanse line I believe. Folks here have spoke highly of it so I thought I'd give it a try. Price was also very right.

I also have one of the now discontinued Apogee 7-21mm zooms which performs respectably enough for the $50 it cost. These might be hard to come by now.

dan

October 27, 2005 01:47 PM Forum: Reflectors

Mars

Posted By dan hilts

Philip,

You have my pity, (and understanding)

I know seeing conditions vary depending on the area but from what I have seen in the last couple of months, and in particular, the last couple of weeks, seeing here in the NE of the continent has been very lousy. On clear nights, turbulence has been quite destructive and the few clear nights I have seen have not been good for anything but the lowest of low power viewing. October has been anything but good. (at least there are no bugs!) Check the clear sky clock in advance, wait for Mars to get high up in the sky, and do a simple star test to check seeing. Then if conditions are right, look at Mars again.

have fun
dan