Louis D

How about we try to debug what is going on with your current scope? I've gotten decent images even from "crap" scopes at low powers and on axis (in the center). It's usually the mounts they come with that are abhorrent. What is it? Can you post some images of it on here? Can you describe the views through it during the daytime at distant targets?

Can you loosen all of the secondary mirror's screws, and then see if it tips enough to point straight at the primary mirror? You also need to ensure it is rotated such that it looks like a circle in the sight tube. That part is fairly straight forward. Once you have the secondary square on with the focuser (round circle) and tipped properly, tighten up all the screws little bit by little bit, readjusting at each step as needed. Once that is done, you shouldn't need to touch your secondary again. They generally don't shift between uses.

I just discovered that Ernest in Russia tested this eyepiece back in late September. My report was even mentioned up above. Ernest panned my report as being methodically flawed, though he didn't expound on this point very much other than mention unknown distances from ruler to exit pupil. The distance from ruler to focal plane is fixed, though, as the tripod and ruler never moved. Regardless, my numbers for the field stop, apparent field of view, effective field of view, and eye relief if you use my value to see the field stop are all pretty close to his. He didn't even bother trying to quantify as I did the usable field that is mostly SAEP free. I do disagree with his assessment that SAEP is not an issue at night. Under my light polluted skies, my pupils will not dilate far enough to cope with the extreme SAEP (largest he has ever measured!). Maybe at a dark sky site, but not in my backyard. He also fails to mention that the 25mm ES-100 has a 94 degree eAFOV as well due to rectilinear distortion, so neither is a "true" 100 degree eyepiece. Each eyepiece comes at the same eAFOV from two different directions distortion wise (angular vs rectilinear). He also arrives at the 90 degree eAFOV value by plugging the claimed 26mm FL rather than the measured 25mm FL. Since both are the same for FL and field stop diameter, they have the same eAFOV. I was surprised that he measured the MWA to have a 25mm focal length instead of 26mm. I did a pixel count of the center section where distortion is lowest and did a comparative analysis against known good eyepieces to arrive at a measured FL value of 25mm as well. I don't know how Ernest measures it, but I'm glad he does because I don't normally check this. I'll have to amend my value for eAFOV as a result to 94 degrees now.

I've used a black nickel plated ball bearing at one end my darkened house lit by a tactical LED flashlight (torch) next to the scope at the other of the house. That produced a very fine specular highlight. The black nickel plating reduced other reflections a bit by being darker than chrome plating, but has little effect on direct, specular reflections. It makes it easier to see the shape of the reflection when analyzing aberrations or collimation.

110F=43C, which we hit many summers here in Texas, and 118F=48C, which is fairly common in Phoenix. Imagine spending 90 days at or above 38C with high humidity. Basically, mid-June through mid-September is spent entirely indoors in the A/C here. Phoenix spent 144 days above 100F=43C this past summer, which was a new record for them. Of course, it's a dry heat there. 😉

I've been in 110F humid heat in St. Louis and 118F dry heat in Phoenix. I'll take the dry heat any day. If you drink lots of water, the dry heat is tolerable. There's just no way to stay cool in humid heat that high. I was starting to suffer heat exhaustion until I retreated to air conditioning that day. That despite drinking 1.5 liters of water in 2 hours. My favorite vulture cartoon is the following Far Side:

You do realize that setup weighs about 36kg or 79 pounds when all set up? It has to be assembled in parts and can't be easily moved around once assembled. This can be an issue if you have trees or buildings to dodge to see certain areas of the sky.

We hit 91F on February 15, 2019. That's 33C I guess. Of course, it's a dry heat that time of the year. It's nice having mostly warm winters, though, to make up for our excessively hot summers. For instance, we had 90 days above 100F (38C) in 2011. It was pretty miserable that year. Y'all would probably melt if that happened in Ireland.

The RDF base may need shimming to get it better aligned with the main optical tube so the adjustment screws can do their job.

Orion did try to purchase Meade, but as this media quote below says, they were outbid by two Chinese companies. I think Meade would have been better off under Orion ownership. Orion had tried to acquire the then financially ailing Meade but was outbid first by another Asian manufacturer and finally by Ningbo Sunny. Orion alleges that after the Meade merger with its Chinese buyer, Orion’s ability to buy products from the combined entities ended.

Viganella, Italy and Rjukan, Norway both use mirrors on nearby ridges to reflect light into their town squares during the winter since they're also in perpetual shade at that time. I wonder if you could work up a similar solution. 😉

We learned the hard way that it is still easy to get sunburned in Texas in the winter. My niece was visiting in early February one year. We went for a hike in a state park in an area with little tree cover. Because it was in the 80s, she just wore a sleeveless top to stay cool. She got the worst sunburn on the tops of her exposed shoulders. Lesson learned, we're pretty far south, so even in winter, the sun can still be intense.

I guess you've rarely trekked across a snow covered field in winter under a noon sun. It is still blinding bright. I had wear reflective sunglasses back in the 80s to make it bearable to walk between classes during my college days in the upper Midwest.

If I may ask, why is a super high power eyepiece your primary focus when reentering amateur astronomy when it will rarely be useful due to sky conditions on a select few categories of objects? Are you big into splitting tight doubles?

I think what they're really hoping for is for the antitrust court ordered settlement to be discharged as a debt and then they can emerge from bankruptcy without having to pay it. My hope is that the bankruptcy court will strip them of the Meade brand and award it to Orion as partial compensation since Meade illegally transferred all their liquid assets out of the US prior to filing for bankruptcy. If not, it will completely gut the US's antitrust laws.

I was wondering that myself. I can't recall ever reading it anywhere. His numbers do match up pretty closely with mine on eyepieces we've tested in common. Here's Jon Isaacs's method, which I've duplicated myself. It is slightly more accurate than sending the light unfocused through the eyepiece. The relative photographic method combined with the above technique allowed me to calculate the numbers below by counting pixels and extrapolating the tangential relationships from known good values: Given magnification distortion in the camera lens, it's probably wise to only apply this technique within a fairly narrow range of apparent fields of view and then cross correlate them with the projection measurements as a double-check on their accuracy. It's also obvious from the image that it's difficult to determine where the edge of field lies when it gets fuzzy due to a lack of a distinct field stop or has chromatic smearing.

For widest field at 40mm, yes. If you are willing to give up a bit of true field for higher magnification, you can move up to a 30/31mm 82 degree eyepiece or 20/21mm 100 degree eyepiece. If you want a larger exit pupil for nebula filter observing, you could drop down to a 55/56mm 50 degree Plossl. You may end up with all of them after a time as you experiment with what works best for your observing style.

It's not accurate for measuring apparent field of view. It doesn't take into account magnification distortion across the field which can vary widely. The 26mm Meade MWA is an extreme example of this. This method only gives you the true field of view which can be converted into the effective field stop size once the true focal length is known (probably from exit pupil diameter). There are several methods to determine the apparent field of view based on projecting light through the eyepiece and measuring the projected circle or cone of light coming out of the eye lens. The more accurate method is to split the exiting light cone across a sheet of paper and measure the angle with a protractor after tracing the edges onto the paper. I use the more involved method that requires measuring the eye relief distance from the top of the eyepiece, the distance from the top of the eyepiece to the wall, and the diameter of the projected circle. Then there's a trigonometric calculation. I've found it a bit less accurate because it can be difficult to determine the exact eye relief distance and the diameter of the projected circle for certain eyepiece designs. The formula is AFOV=2*arctan([circle_diameter/2]/[wall_distance-eye_relief_distance]) if you want to go this route. The best method to project a circle is to put the eyepiece in a telescope and project light into the front of the scope. Barring that, project light directly into the field end of the eyepiece after blocking it in a miter box to keep it from moving and to keep everything aligned. Make sure to back the light away from the eyepiece until you get a sharp edged circle projection. At first, I had the light too close and was getting fuzzy edged image circles as a result. The exit pupil is where the cone of light exiting the eyepiece is at its narrowest. Move a card back and forth until the projected circle is minimized and measure that distance to the eyepiece. This can be difficult for some eyepieces that have a poorly defined exit pupil due to aberrations.

I take my CC out of my Dob and my field flattener out of my fracs for planets because each contributes a bit of spherical aberration at high magnifications. They stay in place the rest of the time.

So glad I moved to Texas 27 years ago. I haven't had a spot of rust on any vehicle since. It's really odd to see immaculate cars and trucks from the 60s and 70s in daily use around here. Interior upholstery rots away in the sun here after 10 to 20 years, though.

Fertan MSDS:

Yes, much better to have a dedicated Dob for observing and an EQ mounted ED refractor for DSO imaging. If you want to get into planetary imaging, an SCT or Mak would probably be the way to go.

Mold and mildew are big issues as well for optical surfaces stored outside in humid environments without adequate ventilation. If you live in a desert climate, this is simply not an issue, though. First surface reflective mirror coatings are also prone to corrosion in humid environments. Even professional observatories have to have their big mirrors realuminized every so often. My 20+ year old mirrors in my Dob look and perform fine after having been stored in a climate controlled house between uses, though.

As long as the central obstruction doesn't become so large as to cause a distracting shadow, you'll be okay. You'll just have part of the light from the primary truncated by your pupil, so you won't make full use of your aperture. You'll also have a more washed-out background making it more difficult to locate faint fuzzies. If you're just taking in bright star fields, it shouldn't be an issue.

It's pretty miserable when using much above a 25mm eyepiece due to loads of spherical aberration. I have it in the PICO-6 livery. There have been too many reports of this defect to think it's just manufacturing variation.