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Topics - sihealhdoggse

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I got my new 10" Dob yesterday and assembled it last night after getting the kiddos to bed. It came with a laser collimator, so I needed to collimate that before using it to line things up in the scope. I came up with a super-simple setup.
1. Drill a 2" hole in a 2x6 (I'm sure a 2x4 would work fine; I just had the 2x6 already laying around).
2. Place the lumber in a vise or build little legs on it. I like the vise because it doesn't move or slide around.
3. Place a 2" extender tube in the hole. Mine happened to fit nice and tight; but if it didn't, you could probably wrap a strip of paper or something around the tube to keep it tight in the hole.
4. Place a 1.25" adapter in the extender.
5. Place the collimator in the adapter.
6. Aim the laser at a piece of paper on a far wall (mine happened to be abut 25' away) and mark the spot. Turn the laser a quarter turn and mark the spot. Do this until you have four spots. Just be sure your parts are all flush and tight, especially each time you turn the collimator. Otherwise, accuracy will suffer.
7. Draw a spot equidistant to the four spots (I put some cross hairs on the new center spot to make it a little easier to see).
8. Adjust your collimator's screws until it's centered on the new spot.
Quick, easy, cheap, and effective!

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Eyepieces Questions & Recommendations / 10mm Eyepiece?
« on: January 01, 2018, 03:17:44 AM »
Why are there so few 10mm focal length eyepieces? A 10mm eyepiece would be great for calculating magnification on the fly. For example, a telescope with an 875mm focal length objective would have 87.5x magnification with this eyepiece. But not so simple with a 9mm or 11mm eyepiece.

So my quest is to find a 10mm eyepiece with a 55-60 degree AFOV more than 12mm eye relief, weighs 6 oz or less, and works well at f/4 or f/5. Any suggestions?

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Eyepieces Questions & Recommendations / 100x and above - AFOV Choice...
« on: December 29, 2017, 01:29:05 AM »
For observing deep sky at 100x and higher, which would you prefer, an apparent FOV of 62º or 82º and why?

Driven scope by the way.

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ATM, Optics and DIY Forum / Where to find self adhesive velvet
« on: December 28, 2017, 11:49:33 PM »
Need to buy some self adhesive velvet for a project. Where can you find such stuff. All I see everywhere is the felt but that won't work.

Thanks

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ATM, Optics and DIY Forum / 6" f/9.3 Bird-Jones kit
« on: December 28, 2017, 01:48:59 AM »
Telescope Warehouse on eBay sells a complete 6" f/9.3 Bird-Jones mirror set and corrector for $50, and I have a spare focuser and such. I was wondering if this would make a worthwhile project. I know these are the optics of the ubiquitous "eBay scopes" but wouldn't the problems be fixed by better mirror cells?

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I came home to a nice surprise today, an ES 30mm 100 degree eyepiece and 3" diagonal.   Apparently they're sending in limited quantities from the mill and you will find "many orders"   The eyepiece is quite massive at 4 lbs 15.5 oz, while the diagonal is relatively light, 1 pound 11.5 oz or 2 lbs 2.5 ounces with the 2" adapter.   Both are extremely well made.

The eyepiece looks exactly like the one on the site, except that the print on the production eyepiece states "100 Degree Series EMD Fully Coated" instead of "Fully Multicoated" such as in the photo.   I assume the EMD (enhanced multilayer deposition) means multicoated, but I don't know ES eyepieces really well.   The eye lens looks dim green/purple.

The diagonal is well made, with a 3 twist compression ring which retains this monster eyepiece closely.   This past year, there was a talk of a 2" barrel adapter (I don't know why this is useful) along with a 2.7" adapter however they aren't contained in the package.

Equipment such as this usually brings clouds, but I had a different cruel fate.   My roll off roof has a broken posture, so I can not place this monster on a proper scope.   I will attempt to mount it on a TEC 110 later but I need to locate my adapter.   Desperate to test the eyepiece, I decided to go for the largest field I could.   I got my 67mm Borg f/4.5 lens along with a few 80mm extensions.   The diagonal slipped in with only 2 mm or so clearance, allowing manual focusing.   It was hard to prevent a lot of coma due to misalignment however I did manage to acquire a bit of seeing in before my arms tired.   The combo gave almost exactly 10 degrees FOV in 10x but I am sure my pupil wasn't near the exit pupil size in my light polluted back yard.   The stars in the edge of field seemed sharp though a final assessment will require someone with a true focuser and dark heavens.

In one field I could see Antares and the 3 claw celebrities in Scorpius in addition to Spica and Mars (near 7 degrees separation).    I could not get all four stars of the bowl of Ursa Major from the field, but the same job with Ursa Minor was simple.   Saturn was detectable as an oval.   Eye relief is 19mm but I was surprised at how close I had to get to the eye lens to observe the whole field.

The visual effect of this eyepiece is just like other 100 degree eyepieces.   The biggest visual impact it has is when someone looks at the eyepiece, not through it!   It is a really neat eyepiece though I am not sure it is well worth the money for most people.   Other 3" eyepieces may be made.   A 40mm 100 degree version would be fantastic but is probably not possible due to size considerations.   A 50mm Nagler type eyepiece would be fantastic, but again maybe impossible.

I'll update once I am up and running with my other scopes.

Derek

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ATM, Optics and DIY Forum / VFP Variable frequency drive?
« on: December 24, 2017, 02:51:07 PM »
Is this the purpose that controls stepper motors?  And just how does it really work?

Rob

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Intense heat forecast for the upcoming few days prior to a cool change.  Temps could strike 48-49C on Thursday, maybe 50C in my dark site.  The weather maps reveal red when it is hot, maroon if it is HOT, they have me PURPLE from Wed to Saturday.  Staying home and will delight in the moon with some beer!

Those chilly winter nights are much more agreeable and hope for those chilly summer winter nights - if it is cold and cloudy that the stout is awesome, when it is clear the dark site is FTW

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