Posts Made By: Tom Masterson

Eddie:

First, the 1-1/4" diameter of the eyepiece barrel is going to be your limiting factor. To keep it simple, we'll ignore any influence the binoviewer may have. The choke point in 1-1/4" eyepieces is around 32mm focal length. Beyond this the apparent field starts to narrow as you'll see in examples below.

The best way to get you an answer is with some math. I'll use my scope and a few eyepieces as examples.

My scope is a 4" f/6 refractor with a 600mm focal length. To get your real field divide your eyepiece's apparent field by the magnification it give in your scope. Do the same math with your scope's data for your personal results.

EXAMPLES:

32mm plossl w/52d apparent field 52d / 19X = 2.7d

25mm W70 w/70d apparent field 70d / 24X = 2.9d

40mm plossl w/44d apparent field 44d / 15X = 2.9d

32mm Konig w/52d apparent field 52d / 19X = 2.7d

As you can see the two eyepieces with the same apparent field - the Konig and the plossl, give the same real field, the design has no impact on the results.

You can also see the lower power 40mm eyepiece gives a wider true field but the 44d apparent field can look restricted to your eye.

Suprisingly, the higher powered 25mm eyepiece, because of its wider apparent field, offers the same real field as the 40mm, yet does so at a higher power and with a more pleasing, spacious apparent field.

Hope this helps.

Tom M

Michael:

What is important about the refractor lens is correction in red light. It doesn't need to be well color corrected, just corrected well in color (red). I have two similar scopes an Orion Astroview 100 achromat, and a Brandon 94 APO. I actually feel the achromat does a better job with my h-alpha set-up. I think that while the APO too has good correction, there's more glass in the way. Some glass types aren't as efficient in transmitting in the red, and in standard designs, I feel less glass is better.

As I understand it (and I could be wrong) one of the reasons the Maxscopes have higher contrast - they are not only corrected for red light, but also use glass that is selected for better red transmission and reduced scattering.

For my 2 cents worth of opinion (note the word OPINION, not FACT)a doublet is all that's needed for h-alpha work. If you already own an APO, don't sell it just because I say a doublet would be better! Use it, I'm talking side by side comarisions with only two specific scopes. You mileage may vary...

As to the advantages of larger filters. Think of the h-alpha scope/filter combination just as you would any other scope - a solar scope in this case. Increase aperture, and resolution goes up, cost goes up, and to a lesser extent portability goes down and mount size become more of an issue.

The narrowing, or squaring of the filter bandpass increases contrast, aperture increases resolution. The narrower the bandpass the darker the surface features such as filaments and the brighter active region appears compared to the surrounding surface. Of course increasing aperture increases one's "top end" power wise and reveals smaller details. HOWEVER - I say most people would "prefer" a one-size-smaller doublestacked view to a larger single filter view dispite higher resolution in the larger filter. This is because the jump in contrast with the additional filter is MUCH higher than the increase in resolution of going to the next size. Untechnically speaking, there's more WOW-factor in the next-size-smaller doublestacked system. Also, resolution is seeing limited more than contrast.

Hope this helps answer your questions.

Please remember, this is opinion that's worth evey penny you paid for it =;^)

Clear, sunny, NARROWBAND skies!
Tom M

WE ARE ALL DOOMED!!!! THE END IS NEAR!!!!

Fortunately, I happen to sell End-of-the-universe insurance.

Its only $99.95!

Make checks payable to:

The Tom Masterson Solar Observing Accessory Fund....

Great shot Barry! You unknowingly got a RARE astronomical compliment this morning. To set the stage for the compliment , please understand the following: My wife doesn't have ANY astronomical "imagination". I've shown her auroras and she doesn't see them move. I've shown her Albereo, and she deosn't see the colors. I've pointed out constellations, and she doen't see the figures. I show her M51 in my big dob and she deosn't see spiral arms. BUT! I showed her your photo and she says: "WOW! it DOES look like a skull!"

Getting an astro-based WOW out of her is no small feat. congratulations. =;^)

Tom M

PS - Now if you could keep your eye out for a heart shaped prominence I could use in our anniversary card....

Floyd:

What do you mean arguments? I'd like to disagree with you on that one, every word on your post is wrong wrong wrong, and emotional!!??? Whyyyyyy, that's a bunch of astro-B-essence, and if you ever post that kind of... we'll have to step outside and settle this mano to mano... (or is it bino to bino?) Oops, if you don't own a binoviewer and I do, then its mano to bino, or is it...

=;^)

Yeah, it get old sometimes, but there IS good info here. Sometimes I catch on after a few messages and skip on to others, sometimes I read for "head-shaking-entertainment". I HAVE seen worse and left that forum long ago because just about every second thread was an astro-pissing match.

Eurvin is right in his posting in this thread. Harry seems to be quite the lightning rod. I know just being a vendor attracts some of the hits, but in the couple months I've been here, he seems to handle himself well. I even lurked here before that and haven't noticed any "line crossing" when it comes to blatant self advertising. Infact I find him mentioning OTHER brands more than his own. I know he rarely mentions one brand and that's a sore point with some. But geeze, NO ONE EVER mentions the brand I own which really gets my plossls in a knot... NOT!

I for one appreciate his input and knowledge on the bino-subject (and many of the other people who post here!).

As a newbie to the forum and bino-world I offer the following advice for the times when emotions seem to be ready to boil over. Once postings exceed a certain level of "firmness" the argument is lost because the "Facts" of the argument have evaporated taking with them the credibility of the person posting. I respect differences in opinions and even a good argument or disagreement. That's how those of us on the sidelines learn things. Debates are good and can be educational, bar-fights are not. I've found wanting to know the answer to a question posted, because it was a good question at its core. Unfortunately, the question when posted more as a challenge, makes the answer more defensive and the good information is thrown out with the bathwater.

Ok, I'm stepping down off my soapbox now. Sorry I pontificated a bit, but even I get sucked in now and then ;^)

Tom M

PS - Hey, thanks again to ALL who post good stuff here! DON'T STOP!!!

Floyd:

NO! Don't go!!!

We CAN follow you where-ever you go, bring bickering to ALL corners of the forum-universe!

Seriously. It is getting better. The emotions flare up every now and then, but good info is here. The more that come and participate in good spirit, the better. Just learn to skip and scoff.

Now everyone.... Let's all join hands as Bino-brothers and Bino-sisters, to chant while projecting good bino-vibes: Bino-love... Bino-peace... Bino-... whaa?? am I going NUTS!!?? Oh, NOOOOO I must be BINO-POLAR!!!! That explains why there's so many ups and downs.

=;^)

Clear and two-eyed-monster skies.
Tom M

Brian:

Great report - THANKS!

I must admit that reading reports of binoviewing had me thinking about getting one. However, what got me NEEDING one was when I had a chance to use one for a couple days. After that, I knew I had to have one. It has offered a whole new kick-in-the-pants to my hobby. I can't imagine viewing the moon or planets without one. Shortly my OCA should arrive and low"er" power viewing should open up the rest of the sky to my two eyes.

I must admit binos aren't for everyone. I had a friend who tried opserving through the ones I had for a trial and he did NOT like them. Had great trouble merging and seeing much. To me it was so natural. They've also been a Godsend for a person like myself, plagued with floaters. Jupiter has ALWAYS had some burring junk drifting by its globe for me, and now that is mostly gone thanks to redundant information going to my brain.

Thanks for the positive report. Send some more.

Clear and two-eye'd skies

Tom M

John:

I've had one of these great little mounts for about 6 years now. It holds my Brandon 94 APO and makes for a great grab-n-go package.

I don't know WHY this these drives do this because mine did too. I discovered simply mounting the motor on the opposite side solved the issue, otherwise I left my drive controller switch in the "S" position.

FYI- If you are handy with simple tools, and want to experiement with making your mount a GO-TO, check out Gary Russell's website. He has a couple kits consisting of Meade Starfinder controllers and motors. I recently bought the kit with motor mounts and adaptors, and modified it to fit my mount. I haven't tried the GO-TO part yet, but even without it, its handy to have dual drives with selectible slew speeds. It does take some changing of the drive ratios in the controller's set-up menu, but it tracks great! The only warning is the drive's motor uses plastic gears which cannot take much in the way of unbalanced loads. Shear a tooth and you must replace the whole motor albiet at only $10. Telescope Warehouse has the replacements.

Clear and nicely tracking skies.
Tom M

I really like the idea too - either zoom or switch. I think one important factor would be EASY zooming or switching, whatever the mechanical means. Anything that required too much force would be frustrating at higher powers. While it would save the hassle of switching eyepieces, if the object leaves the field when you switch, it would nuetralize much of the advantage.

As this bino-technology marches foward WE benefit! (Ok, so my wallet doesn't benefit, but my eyes do!)

Tom M

PS But what happens to all those purdy pairs of eyepieces in my box??!!

Dave:

Don't worry too much about the flourite element. I've not heard of a single report of a flourite element breaking in normal use. Flourite is soft and care should be taken if you need to clean the element to prevent scratching. Most manufacturers put the flourite element as the rear element or in the case of a triplet, the inside element. Flourite is also more easily damaged by moisture so be sure not to close the scope up tight on a dewy night.

Really, if you treat this scope with reasonable care, you shouldn't have any problems.

As for oil spaced triplets leaking. Mine's nearly 20 years old and hasn't lost a drop!

Tom M

Holey optical illusion Batman!

Ok, I see this thread, click on the message and see a couple guys standing in what looks like a room with wood paneling - a picture on the wall. One guy has his arm leaning on the railing of the stairs with a bookcase and doodads infront....

Hey wait!!! Thems ain't stairs!!!!

My gawd - if Jules Verne was alive to see this, he'd think this is the canon used in his book - From the Earth to the Moon, and these are the two astro-explorers preparing for flight!!!

Tom M