Telescope and Camera image size test

I was doing some visual observing with my Meade LX70 refractor. I then tried connecting my Canon T3i and was disappointed with the results. I was looking at Jupiter and could make out some of the bands and the moon with the different eyepieces but the image was way too small on the image with the Canon. So, I did a test some tests. I tested all three of my telescopes (Meade ETX90EC, Meade LX70 refractor, Meade Lightbridge 10”) with my two cameras (Canon T3i and ZWO AS103MC).

The results are in this wiki article called “Image Size Test”.

The first thing that is interesting is of course the difference between the image with the 55 MM camera lens and any of the telescope images. But, the more critical comparison is between the telescopes themselves using the different cameras.

The ZWO camera results is significantly closer image than the Canon regardless of which telescope is used.

When comparing the ZWO images, I was surprised the ETX had a larger image even though it is a small diameter. I will need to do more research. The Lightbridge image is very puzzling. It is a significantly larger diameter and the image isn’t a similar order of magnitude bigger. In fact, the Lightbridge doesn’t look much bigger than the ETX.

Related to the Barlow, the image size is noticeably larger.

Though not related to this test, the blurry images are a problem but again the test was during the day going through a window.

To summarize, interesting results and will need another test using a night time object like the moon.

daylight test 55mmimage size test Capture_00005

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Purchased Meade LX70 Refractor

I purchased a Meade LX70 mount to use with my Lunt solar telescope for the solar eclipse.  I was thinking about my next plans on the telescope models since I now have a reflector in the from of the Light Bridge 10” and a small compound in the ETX 90EC.  I had read before that small refractor is the best for astrophotography but feel that is a long way off.   But, I did some other reading that refractors are better for planetary viewing because they give sharper images then reflectors.  So, I thought it might be a good idea to get a small, cheap refractor to experiment with that type of telescope model.

I had planned to wait until Christmas for a sale but I looked at Meade’s website for the LX70 telescope and noticed the 5” LX Refractor was being discontinued.  So, I checked around on the telescope store website and found one still in stock and purchased it.

It arrived and of course mounted easily on the LX70 mount.  Definitely needed the counterweight unlike the Lunt.


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First Light – Meade ETX-90EC – Sept 8, 2013

I had finally decided to take my ETX-90EC out to look at the sky in August.  We had a few weeks of perfect summer clear nights.  The kids were visiting my parents so no excuse not to stay up late.  I had re-read all the manuals and got everything prepared.  Then fate stuck.  The weather turned bad and the entire weekend was cloudy.  We had a vacation the following week so I resigned myself to just waiting for the next opportunity.

That opportunity came quicker than I could have imagined.  The weather forecast was for an entire week of hot days and clear nights in September.  The sun was setting earlier and the moon was also setting early in the evening.  So, I re-prepared to head out on Sunday evening, September 8, 2013.

The home position for polar alignment for the Meade ETX-90EC turned out to be very straightforward.  The Meade tripod helped with this situation.  I had also purchased a power adapter so I didn’t have to worry about batteries.  I also took out my eyepieces and red flashlight.  I add everything ready and then started the alignment using the Meade AutoStar.

The Meade AutoStar easy alignment was more straightforward than I thought.  It kind of made me wonder I didn’t try earlier.  The telescope slew to the first star, Arcturus.  I wasn’t sure if it was the correct one but there was only one bright star in the distance.  I used an app on my iPhone called Star Walk.  I was able to confirm I was in the right area.  I used the finderscope to get it closer to center and then looked through the eyepiece for finally centering.  I hit Enter of the AutoStar and it moved to the second star.  I did the same process.  However, this task was much harder because the telescope was pointed straight up and I could easily see through the finderscope.  The finderscope is a straight through type.  I had to get on the ground.  It was also made even more difficult because I hadn’t extended the tripod legs.  I figured it would be easier to be sitting in a patio chair.  Nevertheless, I got it aligned.

Then, I was at a loss.  What to a look at now?  I wasn’t prepared for the next step.  I used the AutoStar to search for a planet but none were visible at this time.  Uranus was but it was in the eastern sky which was blocked by my house.  I was out of time but remembered in the back of mind that there was a binary start in the Big Dipper so I usedg Star Walk to figure out which one and GoTo it.  I had to move the telescope to get close but there it was.

To summarize, I had finally aligned my ETX and saw something.  Not bad for my first light and first night.

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Meade tripod

For my Meade ETX90, I originally purchased the tabletop tripod legs.  As I was thinking about getting into astronomy as a serious hobby, I was thinking that a full tripod would be nice addition to my equipment.  This was a situation were eBay is so helpful.  I was able to find the Deluxe Field Tripod that was reasonably priced and won an auction.

The tripod was a great addition.  The tripod has a tilt-plate which allows for a equatorial mounting.

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Meade ETX-90EC

I purchased my Meade ETX-90EC in the summer of 1999.  My wife and I were joining my parents for a few days on their vacation to Bend, Oregon.  I can’t remember why I went into the store but I did and noticed the ETX.  I was amazed that it was automatic and could point at an object in the sky.  I hadn’t followed astronomy or telescopes at all so this seemed unbelievable to me.  I thought this might let me do the things I wished a could do as a kid.  So, I went back to the store and purchased it.  I even have the original receipt that I kept with the manuals.

I recall trying it out a few times but never finding the time to really use it.  I never even learned to align it.  I did purchase a carrying care, a few eyepieces, a Barrow and an adapter for my Nikon SLR.  But, I never used it and it moved from apartment to apartment as we moved.

A couple of years ago I restarted some of my hobbies including astronomy.  With eBay’s help, I was able to get a full tripod and a Meade camera called the LPI Imager.  I was thinking astrophotography sounded interesting and figure an old camera would be a good thing to take a look at.  I even found a book written by Mike Weasner called “Using the Meade ETX”.  He has a website called Weasner’s Might ETX Site.  I found and re-found this website over the years and it is an incredible site for ETX owners.

I did get the ETX out a few times in the last years to let the kid’s look through it for a major astrological event.  I even setup the camera but never found the time to set it up to start some test astro-photographs.  But, that is now the goal and I will update my progress in this blog.

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