Posts Made By: Alan French

Chris Brown's question about a Moon filter reminded me of an interesting comment Harold Hill made in his "A Portfolio of Lunar Drawings."

Mr. Hill started out using a 6.5" reflector, moved up to a 12", and then moved to a 10". Later, he had a chance to use his old 6.5". He writes on page xx '..., I felt positively handicapped by the apparent dimness of the image in the smaller instrument although using magnifications strictly proportionate to those in my present telescope. In fact, I saw nothing like the same amount of detail I had previously been able to record with the 6.5" when it was in my possession. Advancing years may provide some explanation for this, but I have a feeling that, with continued exclusive use of the 6.5", the brightness adaptation which would eventually take place might lead to the recovery, in part, of my previous success with this instrument...it would be an interesting experiment."

Amateurs know that experience increases our ability to see. If we do indeed become used to the brightness level of the instrument we use, it may mean our evaluation of instruments of different sizes is somewhat handicapped. It may also mean that frequent switching between instruments of differing apertures is not the best way to hone our skills. Interesting things to think about during this cloudy spell.

Awaiting clear skies, Alan

Originally announced Febuary, 2003,....

We have been busily working in our shop since returning from WSP this year (2003). As many of your know, the dew was unusually heavy this year. There was a big demand for dew control equipment, and the sound of hair driers often drowned out the steady roar of traffic on US 1. The many hair driers exacted a toll on the site's electrical system, and circuit breakers popped with regularity. Those of us at Flurry Astro-Innovations thought, "there has to be a better way."

After weeks of development, we have come up with a better dew control
solution - the propane powered "Dew Slayer!" Slip the Dew Slayer onto your lens cell or around your primary mirror, push the igniter switch, and you'll never worry about dew again! You're off the grid and ready to fight dew anywhere, any time! (Replacement tanks are readily available on any
hardware store or store that carries camping equipment.)

The Dew Slayer puts out enough heat to handle the wettest nights. Our test department was able to fry eggs on an 18" Newtonian primary with the Dew Slayer set to maximum (naturally, such extreme settings are unnecessary for simple dew prevention).

I suspect some of you have concerns about stray light from the gas fired Dew Slayer, but rest assured it has been fully baffled to prevent any stray light from detracting from your view. Careful testing has shown that the baffles function perfectly.

The Dew Slayer is now available to fit all AP and TMB APOs, all Meade and
Celestron SCTs, and all standard sized Newtonian primary mirrors. Dew
Slayers will soon be available to fit the 10" AP Mak and all TEC Maks.
Custom sizes can be tailored to any existing telescope at an additional
cost.

For those of you who camp, we will also offer an accessory kit that will
allow you to use you Dew Slayer for cooking.

We will be announcing prices and availability soon.

Clear skies, Alan, for Flurry Astro-Innovations (makers of Astro-Stilts and Chromagalore)

Was there anything of note displayed at RTMC this year?

Thanks.

Clear skies, Alan

Noted on one of our flower boxes this morning.

Clear skies, Alan

What, if anything, does "APM" stand for?

Clear skies, Alan

Someday I'd like to treat myself to a nice digital SLR, so I was reading the piece on the Canon EOS 20Da in the July Astronomy with some interest. Then I noticed a "Product Note" saying Canon had annouced the camera was being discontinued as of April 21. Anyone know why? Not enough interest?

The enhanced H-alpha pass sounded very nice.

Clear skies, Alan

Aside from the obvious increase in cost for wider field, better corrected eyepieces, due to their increased complexity....

1) higher quality glass
2) better, more thorough polish
3) coatings carefully matched to the glass types
4) more care in assembly to insure clean surfaces
5) better quality control (involves time, rejected parts)
6) higher quality and tighter tolerances on mechanics
7) adjustable eyecup

A quality eyepiece provides years of service with many telescopes, and seems a worthwhile investment. I think a lot of us spend more than we need to, not because we buy more eyepiece than we need, but because we buy more eyepieces than we really need. In most cases, we don't really need "the complete set."

Clear skies, Alan (one more eyepiece and I'll need a new case)

Greg,

I can provide a 7mm XW for comparison purposes.

Here is one oddity I've noticed with the Pentax eyepieces. If the Moon is just outside the field there is a pretty severe glow in the eyepiece. It seems to be eyepiece related, as I don't see it in other eyepieces and it is visible in a variety of telescopes.

Clear skies, Alan

[Quoting Dr. Hillig, Herbert wrote, in part] .... though at f/30 it's not a wide field of view! Also, the focal plane tilt is closer to 7 degrees, so this demands a very good eyepiece to handle an effectively f/3.5 light cone!"

Herbert,

That has me really confused. I understand the tilted focal plane, but how does an f/30 light cone become an f/3.5 light cone?

Clear skies, Alan

I am making some repairs to an older Dob for a friend of mine. The upper cage is line with aluminum flashing, which is pretty beat up and coming away from the inside of the rings.

I believe a lot of folks use Kydex here. I checked a few ATM suppliers and didn't find anyone selling it, so the first question is: Where do I get Kydex (need 10.5" x 48" minimum)?

The second question: Is there something better? I do want it lightweight, as the OTA is a bit front heavy now.

Clear skies, Alan