Posts Made By: Tom Mengel

Errrrrie!

Thanks for the link!

TM

Love your device - I have an old pair of safety goggles and may try it out myself. I've also fooled around a bit to make eye shields for my binos and found my own "contraption".

I used a 8 X 4 X 3/4 inch chunk of generic black packing foam cut to look like a slightly over-sized "masked ball" kind of thing (just covers your eyes and over the bridge of the nose). By cutting the "eye holes" to stretch over my bino EPs a bit and spacing the holes the right distance apart it can be "contorted" to fit my face tightly and shield my eyes like the winged flaps sold for some EPs. Works great! It's very light-tight, light weight, rolls up and fits in the bino case when not in use, the foam breaths to dissipate stray moisture from my eyes, and it's REALLY cheap to make! The only down side is it has to be custom cut for the bino EP diameter and the user's inter-papillary distance so it can "stretch and warp" correctly to form the tight eye/face shield. It took me maybe three attempts to get it just right but the one I’ve made for my 12X60s has been used 3 to 4 times a week for a year and is still going strong (and I can replace it in 20 minutes if I have the foam and a craft knife).

Anyway – FWIW, Thanks for the look!

I used a "Big Honking Soft Luggage case" (LUCAS brand I think) from COSCO for my LX-10 (should be close in sixe to a LX-90). It's main compartment is about 12 X 12 X 24 inches with six big outer pockets and wheelie wheels and a collapsible handle to roll it with. I lined the inside of the main compartment with 1/8th inch hard-board. I then put some 3/8th inch camping ground-pad material between the outer Nylon luggage material and the hardboard to make sort of a soft lined hard case under the outer bag (but it still flexes some). I completed it with 2 inch thick hard-foam inserts to hold the OTA and forks snugly in place.

Works really well - good impact protection a regular soft case alone would not provide but still light weight and it has lots of storage room in those outer pockets. And it rolls pretty well even over grass (and the bag even has a "skid plate" for when you bottom out).

The bag itself was about 25 dollars, the rest of the stuff I scrounged up or paid a few bucks for (hardboard was 4 dollars I think, I had the foam) so the total was well under 40 dollars for the whole project. It also does not scream "$$ Telescope equipment!" if I leave it in my car and it happens to gets cased out by some lower form of bottom dweller ....

FWIW - TM

The rear "hole" in an 8 inch SCT is actually made to give a clear "total unobstructed illumination" image to a 35mm camera frame. That's because when these scopes were designed back in the '60s and '70s most astro photo types would use a 35mm camera to take photos, and that standard dictated that size as the maximum for the real field size for SCTs.

The figure many folks seem to use these days is that plus a little extra or about 45 to 48mm as the maximum usable size of the "real" illuminated field or about the maximum field stop on most 2 inch EPs. You may get some light cut off at the edge of a 48mm field but most folks don't notice it too much.

So, if you stick with 1 1/4 inch EPs you should not see any darkening at the field edges, but are limited by the maximum size of the field you can "cram into" the 1 1/4 inch EP barrel. On the other hand with a 2 inch EP you can cram more real field into the EP barrel (bigger field stops with very wide-field 2 inch EPs) but you might get dimming at the edges of the field as the SCT was not really designed to fully illuminate such a large real field.

Roughly translated (my understanding here) is that if you use EPs of 25mm to 32mm or less (depending on how WF they are) the field stops will always be able to fit into a 1 1/4 inch EP, so the cheaper 1 1/4 formats works just fine. But and if you want longer focal length (lower power) EPs with very wide apparent fields (for example a 40mm with a 70 degree apparent field of view) then you will need the 2 inch format to accommodate the bigger physical field stop size the EP requires. This means the EPs will be bigger, heavier, and cost a whole lot more money for that larger field stop a 2-inch EP format can give you.

So, (as an example) if you are content with about 60X with a 32mm Plossel (55 degree apparent field of view) then you can stay with the 1 ¼ inch format. If you want wider field views then you can go to 40X with a 50mm Plossel (same 55 degree apparent field of view). If you use EP with wider apparent field of views (like those nice but $$ TeleView Eps) you will have to reduce the EP focal lengths to get the same results.

You can also get a 6.3 reducer/field flattener here on AM for about 100 bucks that makes the SCT seem to have a shorter focal length. This will make a 1 1/4 inch 32mm EP act like a 50mm and give you the same apparent field of view but a wider real field of view at a lower power. Be aware, however, that such devices will not make the REAL field size (the illuminated spot in the back of the SCT) physically any bigger, so EPs that worked fine without the reducer may end up with a lot of dark edges with it.

This is my understanding - FWIW - TM

Does re-inventing the same scope count?

My “oldest scope” is an 8-inch F5.6 reflector I bought from a friend’s Dad back in 1965 when I was in high school. He had ground and polished the primary in 1936 from a 1 inch think plate glass WW-I military ship porthole (so rumored – he said he picked it up at a NY shipyard for scrap as a kid) and he then cobbled together two 24-inch long 9-inch in diameter stove-pipes screwed together to make the OTA with a wooden cradle mounted on a Sam-Brown style 2 ½ inch cast-iron pipe “EQ” mount all set on a “bird-bath” ornate pedestal. He even sawed a 2 ¼ inch hunk off a WW-II Sherman tank periscope to make the secondary (he kind of liked doing thing himself). He also silvered the mirror himself, too.

After using it as is for a while I proceeded to get a good mirror secondary make a “steel truss” tube with a 1 inch angle-iron fork with 1 inch pillow bearings as the DEC. axis and a ¾ ton truck axle as the RA axis. That was just too darn heavy (but I did use it and truck it through 3 moves and a marriage with two kids) so now I’m making a “lazy Susan” AZ/EL “DOB” style mount with built-in wheelie bars using the same steel fork which should make it much lighter and easier to use.

The mirror is a bit over-corrected but very good, maybe 1/8 or so wave. I will need to re-overcoat it soon (had it AL and SiO coated in 1968 so it’s about time).

TM

I got one 4 years ago and have been playing with it ever since. The first thing is BACK OFF THE LENS RETAINER! I think this is the source for 90% of the poor performance complaints and it sure imporved my viewing. I've "goosed it up" to about 230X (TV 7.5mm Plossl with stacked barlows) and have split the Eps. Lyra dbl/dbl and gotten 7 bands with cloud details on Jupiter and an easy cassinni's on Saturn. In short, it's no TV-85 but it does pretty darn well none the less (and low power is a joy). BTW - I got the MV-1 filter but stopped using it as the color is not as bad as the filter effects.

I just swapped in a 2 inch focuser from a Synta 100mm (yes, it fits but the holes have to be re-drilled and tapped as they ar 60* off, but not a biggie) that is much more HD and smooth than the original focuser. And it has the nice Orion "TV-style" AL knobs, too. I replace the stock lens cap with a lighter plastic one (took off about 10 ozs.) and I'm also making a really HD "foldable" but light fork AL/EL mount from 3/4 inch red oak and some big ball/roller bearings (on both axis - 3 inch ball on the AZ and two 1 inch rollers on the EL fork) that really will make this a nice smooth "Grab-'N-Go" scope. At 13 inches in length (the lens cap reverses) and about 3 lbs. for the total OTA weight this would be hard to beat for portability.

I may replace the ST-80 later with an ST-120 but the little guy will always be around for a my quicky rig.

TM

If you want to spend a bit more (and avoid Hamster fur on your optics) ...

Use a 12-volt "garden light" setup (to avoid some of the "stray electrons" problems) with two 12-volt lamps wired in series. That will give you 1/4 the wattage for each bulb (or 1/2 wattage for the total) and since the bulbs are running at half voltage they should last almost forever.

The GFI is still a good idea, however. (BTW – in many areas that’s a requirement for new Bathroom or Garage construction so you may already have it).

Looks like a varient of the Edmund Sci. 28mm RKE to me.

Interesting the longer focal length unti costs more - seems it would be easier to make . . .

I guess it's a SC so it has a "lens", and it's also well color corrected ... but the "Walks, sounds like, and looks like a duck" don't make it a REAL duck (otherwise all the Newt owners will be seeling their scopes as APOs and hiking up the price - smile).