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Posts Made By: Karl Kirk

November 4, 2002 07:55 PM Forum: Telescope Making

Angled Secondary?

Posted By Karl Kirk

Please excuse my ignorance... I'm curious...

Is it feasible to have an angled secondary mirror on a newtonian, instead of the traditional perpendicular 90 degrees, with acceptable results at the eyepiece?

For example, a 20" mirror with a 77.5" distance to a secondary angled at 45 degrees, to an "offset" focuser also angled at 45 degrees, 4" off to the side of "middle" structure.. and 14" off the axis? ( Which, I think, comes out to an F/4.8 scope with the eyepiece at 5' 8" height at zenith above the mirror? And also would bring in the center of gravity towards the base? )

Since I've doodled this out, if it *is* feasible then someone's probably already done this... are there examples of such in existence, and I suppose there's a name for such a critter?

Thanks in advance!

June 5, 2003 04:23 PM Forum: Equipment Talk

Feathertouch Adjusting?

Posted By Karl Kirk

Hi!

I recently acquired a refractor with a feathertouch focuser. When pointed above 45 degrees or so, if I have a Nagler 17/20/26 in the critter, the feathertouch starts sliding back out on its own.

Does anyone know how to adjust the friction on the critter to handle heavier eyepieces better?

Thanks!
Karl

July 11, 2003 05:24 PM Forum: Equipment Talk

Bino scope long baseline?

Posted By Karl Kirk

Hmmm...

I was reading about CHARA and was wondering...

If you took two 4 inch refractors and separated them by, oh, 12 inches, and then vectored diagonals ( collimatiable, say, William Optics modified with thumb screws ) to make a binoscope...

Would that work and create a scope with the effective resolution of a 16" refractor? ( light gathering, of course, would only be that of a 5.5" or so )

October 7, 2003 09:20 PM Forum: Equipment Talk

Double stacking

Posted By Karl Kirk

Anyone have any thoughts/comments/notes on double stacking? What exactly is required to double stack?

Is there any benefit to stacking a Solarmax 40 on a a Maxscope 60?

Anyone have any comparison notes on a double 60 vs a single 90?

Thanks for any advice in this obscure area!

Karl

December 15, 2005 05:18 PM Forum: Digital SLR AstroPhotography

5D full frame question

Posted By Karl Kirk

Bear with me if this has been asked already ( and I couldn't find it in the search ) or if this is obvious to all the pros.

I don't have a good grasp on how DSLR's work with astrophotography yet, so I'm trying to get my head around it. I'm trying to figure out which way to go, 20da/5d/Sbig.

With the 5D's FULL frame sensor, does that mean that at any given magnification the image recorded by the sensor will be wider field ( 1:1 vs 1.5 or 1.6:1 on non full frame DSLRs ).. or will it be the same field with just more resolution?

Will vignetting aspects of the 5D/Scope or 5D/eyepiece/Scope be a bigger issue?

Thanks
Karl

June 6, 2002 02:46 AM Forum: Deep Sky Observing

Table Mountain Star Party

Posted By Karl Kirk

*grin*. Oh yeah... I'll be there with 5-8 buddies and 1000+ future acquantances. See you at the expresso stand. P.S. Remember to bring a deck of cards and an umbrella... Just in Case.

August 1, 2002 11:58 PM Forum: Equipment Talk

12-inch premium Dob

Posted By Karl Kirk

After a lot of thought, I went with the 12.5" Portaball with eq platform as well, after playing with various dobs and then a Portaball at a star party. Modern dobs are pretty slick and maneuverable... but the Portaball was a blast to work with ( as you know! ). I considered the 14.5, but opted for the 12.5".

Staying with zambuto mirrors...
The starmasters also look very nice..
and you might also look at the teleport. I demoed one last month and it's pretty darn nifty.

I'm sure that the Obsession would be nice as well.. but with a 15" wouldn't you be stepping up to a stepladder? ( Literally ... or have a very fast dob? )... and Inge seems to be concerned about portability and weight?

I may be asking to be flamed, but I've always been impressed with how well 12.5" zambutos/swayzes seem to image vs cheaper 15" and 16" mirrors. ( Collimation helps loads, though ). The half mag depth gained didn't seem to outweigh other performance factors, in my eye. ( again, literally ).

A signficant consideration may be delivery time! Last I looked, I think the starmasters and teleports are booked up through 2003?

Also, one of the reasons why I went with the Portaball is that there ARE so FEW of them for sale. That seemed to speak loads as to how much their owners value 'em.

August 17, 2002 05:35 PM Forum: Equipment Talk

veiwing Jupiter /Equipment

Posted By Karl Kirk

The first: A CCD camera setup and photo processing software? I've looked at Jupiter at 6000' in very good seeing with 22" Dob ( with a really good mirror that was well collimated) and it still doesn't look like the first photo, Sorry. I'm not sure any amateur scope can give you that sort of image, to the buck naked eye.

Anyone look through the big Zeiss refractor in LA? Does something like that come closer to the first photo? ( All that light pollution improve contrast, eh? )

The second photo is nearer to any medium aperture decent quality scope, however, to get Jupiter that "size" one would have to push the magnification beyond what I usually like to, because even though the image gets bigger, the image gets messier on the scopes I have access to. No pun intended. A much Smaller Jupiter actually shows more detail on the scopes I use.

Just my experiences... maybe someone with more experience can give you some other ideas.

August 21, 2002 04:55 PM Forum: Equipment Talk

nexstart8i vs 8gps

Posted By Karl Kirk

I've got a Nexstar 8 ( while I wait for a scope on order to be built ), so can give you some feedback.

I decided AGAINST the GPS version. The $$$'s just didn't seem to be worth it. I can do a manual 2 star alignment in a couple of minutes...it's pretty easy.

I *might* have went for a GPS if I were to go globetrotting with the scope.. OK, in blunt, I think GPS is more of a marketing gimick than anything else.

I'm also getting skeptical of "40,000" object database. How long would it take one to get through 18,000 objects? Many of those objects are in the wrong hemisphere, or are objects only a specialist would enjoy. I'm finding about 300-400 objects are plenty to keep me busy and interested!

STURDY? At a star party, I brought the Nexstar 8 in under cover when there were some hefty winds about 3 AM. While we were asleep, the "shelter" got blown over! The Nexstar was on the ground. I had to open it up and snap in a "C" clip that had popped, and that was it... recollimated, works fine.

The Single arm hasn't been a problem. Heck, it's metal on the inside. And my critter has a lot more to move around... Ray's brackets, a hefty rich field/2" diagonal.. and I regularly use a Panoptic 35 and Nagler 17 on it ( big 2" eyepieces ).

Of course, if you intend on repeatedly bashing the scope into the ground OTA first, the double arm support may be prove useful. : )

I've determined that ALL scopes have their ideosyncrasies. Each scope has strengths and weaknesses.

Recommend you go to y a h o o and join the appropriate groups and read what real users have to say. I found that helpful. Also, take a peek through 'em at a local astronomy group's meeting, if possible. ( Use the same eyepiece... they're 50% (or more) of the image quality, imo ).

Personally, I found that the Nexstar 8 creates an image better than a base Meade 8...given the same collimation and sky... but that may be a scope by scope thing. I haven't had a peek through an 8 UHTC yet, so don't have an opinion.

And yeah... if you can spring for a 10", go for it. DON'T go down to a 5"... In the 8" I can see the Whirlpool faintly, M81/82 very nicely, the Ring big and pretty, the Veil with an OIII...but in a Nexstar 5 or ETX125 all nearly impossible except with averted vision and moving your head back and forth for an "I see a faint smudge!". Not saying you can't get 'em... but the bigger the aperture, the easier it is to see detail and get a pleasing image.

Your mileage will vary.

Finally, check out the weight of the various options, particularly if your son is getting old enough to set it up himself. A couple of pounds can make a big difference for some people.

GOOD LUCK!

September 23, 2002 03:54 PM Forum: Equipment Talk

Buyer BEWARE!!!!

Posted By Karl Kirk

I've had a similar problem with UPS. ( They are notorious for out of hand rejecting claims...you should see some of the net forum postings on this issue!) It became clear the person in power had no intention of allowing the claim no matter how valid. Small claims court came to mind.... but then the shipper filed a claim... and just on the paper claim the UPS person at their end reviewed the case and admitted UPS was at fault and paid! ( You might try that approach ).

Makes one wonder about all these new arbitration clauses that are popping up in banking/credit card/brokerage accounts... indicating that by using their services you forfeit the right to use the legal system and MUST use their "neutral" arbitrators, which are final and binding. Hmmm... if the arbitration firm is paid for by them... and they can fire 'em at will... how "neutral" can the party be???
( Whoa... that's off topic... )