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Posts Made By: dan hilts

March 12, 2013 07:18 PM Forum: Mounts

clock-drive eq mount with 30 pound payload?

Posted By dan hilts

The early EQ6 was not goto. If you find one of those it will carry 30 pounds. That mount was rated by the manufacturer at 25kgs.

dan

March 29, 2013 05:52 AM Forum: Telescope Making

12.5in mirror - Ronchigram after 5hr polishing

Posted By dan hilts

Very nice! And a good photo too.

I suspect there are many others like myself who have been watching your progress reports from the side lines. I am impressed with what you have accomplished so far. There are some very knowledgeable folks here who will be able to help you through the final figuring stages when the time comes. Congratulations on a fine job so far.

dan

April 15, 2013 05:54 PM Forum: Off Topic Discussions

Nice Utah Star Scene

Posted By dan hilts

If you pause the playback, it shows for a lot longer. Nice sky.

dan

May 28, 2013 04:04 AM Forum: Equipment Talk

2" diagonal internal restriction issue

Posted By dan hilts

The true restriction is the inside of the nosepiece on the diagonal. In all cases, the light cone tapers from the front edge of the nosepiece to the eyepiece field stop. This distance is about 4" so there is considerable amount of taper of the cone. The light cone also has to pass the length of the focuser tube as well before it gets into the diagonal so this too can be a real restriction. If the focuser tube is 4" long, there is a total path length inside the focuser/diagonal that is 8" long. A similar situation exists in SCTs with the baffle tube.

In a 4" f6 scope for example, the widest maximum fully illuminated field is only 20mm or so at the eyepiece field stop.

hope this helps,
dan

June 27, 2013 03:42 AM Forum: Eyepieces

a rather oddity

Posted By dan hilts

The magnification of a Barlow is defined by the formula M = 1 + (x/f) where x is the location of the final image behind the lens and f = Barlow focal length.

The final image must be at the eyepiece field stop when the everything is in focus so it seems you have two eyepieces with considerably different locations of the field stops, one towards the end of the eyepiece barrel, and one much further up inside the barrel. You can easily check this by using the eyepieces without the Barlow and noting the difference in the focuser position with each eyepiece.

Variable Barlows do so by changing the distance where the final image is formed, similar to what you have done using extensions. It is also common to change a Barlow's magnification in a refractor by placing the Barlow in front of the diagonal instead of after the diagonal.

Hope this helps,
dan


September 4, 2013 09:31 AM Forum: Home Observatories

Indirect lightning damage

Posted By dan hilts

Yep, sure looks like something let the smoke outta that chip.

Often surge damage will simply cause a transistor or other device in an IC to become near dead short. Once that happens, the unit's power supply will provide enough juice to create the heat that causes the volcano. Either way, it won't work any more.

dan

October 3, 2013 09:05 AM Forum: AstroMart FAQ

Rate someone with no deal

Posted By dan hilts

That has been my understanding. If goods/money do not change hands, no rating is to be given.

dan

December 12, 2013 07:13 AM Forum: Astro-Physics

Visit to Chile

Posted By dan hilts

Nice report. Thanks for sharing. I have yet to get to the southern hemisphere but it is on my bucket list. Maybe I need to move it up in my priorities.

dan

January 12, 2014 06:13 AM Forum: Eyepieces

Paul Rini

Posted By dan hilts

Mr. Rini has posted some items for sale on CN as recently as two months ago. As far as I know he has not been in the eyepiece business for a number of years.

dan

March 11, 2014 07:14 AM Forum: Off Topic Discussions

Calif Gas Prices To Go Ballistic

Posted By dan hilts

That's a bit of doom and gloom speculation. Other parts of the world already deal with significantly higher gas prices than the US. Here in Canada a US gallon is about $5.50 and for services like deliveries, freight, and postal service, it is a lot further between markets than it is in the US.

The article states, "will lead to price increases of at least 12 cents a gallon immediately." I see that kind of price variation everyday, often more. Last night gas was $1.25/L, this morning $1.32/L. That's about $.28/gallon fluctuation, everyday, and even more on holidays.

You need to be more concerned about the rising cost of food. You do have to eat.

dan