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Messages - frenafverbi

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16
I use a lot more CeOx than most people  and for an 18" mirror 1/4 lb is more than enough. Besides, it's expensive unless you buy 20 kg pails from Salem Distributing ($670 currently).

17
aeajr, your post is most informative and helpful! You hit it spot on with the goscope. I am looking for it to be used by my eldest daughter to have her get into astronomy.

My garage is ambient temperature; I'll just have to make a spot. My light situation is that mostly the northern section of my viewing has bad light pollution as it is over Toronto but the south is alright - I can make out Virgo and Leo major but to the west only the heads of Gemini are visible.

I am on board with the Dob (bang for buck wins all the time) and I was hoping that this one would be good - http://www.canadiant...scope-8974.html. I like the website for the free shipping which is always a plus and I am in Canada. It has 1.25" eyepiece adapter, Eyepiece rack, 2x Barlow 1.25", Collimation cap, Safety film solar filter, 8" and the eyepieces are Sirius Plossl 10.0mm (1.25"),DeepView 28.0mm (2"). I know it is not computerized but I do not mind doing things the 'old fashion way.'

To collimate the Dob I was thinking of http://www.canadiant...mator-5959.html.

How does that sound?

18
ATM, Optics and DIY Forum / Re: ST-80 secondary spectrum reduction
« on: January 23, 2018, 04:12:17 PM »
"Do you have any designs or technical publications along this line of thinking you could offer?"
***************
 Replace the relatively fast stock doublet with a long singlet???????
M.

19
Beginners Forum / Re: Eyepiece Question,
« on: January 23, 2018, 02:43:59 AM »
Quote
Quote
Contrast is the ratio of two brightnesses.
Sez who? To quote the Wikipedia article on Contrast (vision), "There are many possible definitions of contrast."
Your definition has the virtue of being simple, and it's certain useful for some purposes. However, it definitely does not match the subjective experience of contrast.
Quite aside from the effect of increasing scale (magnification), another important factor in the perception of contrast is how sharp the boundary between two regions is. The human eye is first and foremost an edge detector. A region that's 25% brighter than the background is trivial to detect when the boundary is sharp (as at the edge of many dark clouds in the Milky Way) and very hard to detect when the brightness changes smoothly (as at the outer edge of the Milky Way).
Yes, but that definition would imply that lower magnifications will have higher "contrast", because magnifying a diffuse edge (and all astronomical edges are diffuse to one degree or another). So, I don't think that's the type of contrast under discussion so far in the thread. (And it's completely unrelated to AFOV).

The type of contrast under discussion appears to be ratio of brightness of object to background. That's at least been strongly implied (e.g. ,when filters are introduced into the discussion).

20
Beginners Forum / Re: First Telescope: ETX125, LX200 or Nexstar 8SE
« on: January 22, 2018, 09:38:25 PM »
Quote
I'm sure Turkey must also have hardware stores. A couple of small 'line levels' will work really well for leveling your mount. Set them at 90° angles to one another, and you'll level in two directions at once.

I've also downloaded a small app for my Android smartphone that gives me a level inside of it, which has two line levels and a bubble level, all displayed on the screen. I'm not sure how accurate it is, but it seems to work well so far.

Gary


Gary, thank you for your contribution. No problem with leveling it, I just surprised Celestron didn't thought of a bulit-in bubble level. Forum member Thomas just explained that levellin is not that important.

21
The mirror box on my Lightbridge 16 (metal) weighs 65 lbs. At 64 years old, that's also the max I dare carry.The mirror box on my homemade 16 (wood) weighs 50...still a lot, but doable. Both mirrors are the same weight.
Andy

22
ATM, Optics and DIY Forum / Re: Modifying 24mm Panoptic for wider fov
« on: January 21, 2018, 09:31:42 AM »
I'll mess with a lot of things- EP design is not one of those things...

23
Beginners Forum / Re: What does a telrad do?
« on: January 21, 2018, 06:33:02 AM »
Quote
What does a telrad do and do i need it?


HitshotPlayZ,

Have we answered your questions? Was this helpful?

24
General Astronomy & Observing / Re: ** 2018 Mars opposition **
« on: January 21, 2018, 03:08:40 AM »
Yes, we need good weather on both planets please.

25
Reflectors Telescopes Forum / Re: Walter D150/F750 6" Newtonian Reflector
« on: January 20, 2018, 11:29:57 PM »
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I am not sure about the prices in your area but if a 6" is what you want this is a very good telescope and you can upgrade it:

https://www.optcorp....cope-31057.html:

Exactly what I was going to recommend. I have the OTA and really like it, for a small scope.

26
BT is nice, you could make an app on your phone to control focus. Interface is like a UART.

27
I dislike the "kits" because they usually include several eyepieces that aren't useful.

For most telescopes, two eyepieces is a good way to start. That particular scope would have included just one... a Meade 26mm Plossl (Meade includes that same eyepiece with every telescope they sell... whether you pay $100, or 10,000 ... it comes with the same 26mm eyepiece). Anyway the 26mm on that scope is sort of a "middle of the road" eyepiece... not particularly high magnification and not particularly low either.

For your scope a "low" magnification (wide field) eyepiece would be something in the 35-40mm range (I own a 41mm with my scope).
A "high" power eyepiece would be something in the 10-15mm range (I use a 13mm).

You can see how the 26mm is basically about half-way in between low and high.

You can use any eyepiece that fits... but if the eyepiece is less than 10mm then you'll likely think things are just a bit too much on the fuzzy side to be enjoyable.

Eyepieces for your scope will either have 1.25" diameter barrels or 2" diameter. I'd probably nudge you toward a 2" diagonal since it opens up so many more options for low-power (long focal length) eyepieces. Most eyepieces in the 30-40mm and greater range are probably going to have 2" barrels. Eyepieces with shorter focal lengths (25mm and below) generally only need 1.25" barrels (they make them with 2" barrels as a convenience for people with 2" diagonals... so they don't have to reach for their 1.25" to 2" adapters.)

28
Does anyone know if new (2017+) Losmandy G11GFT mounts come already with the one piece worm upgrade that everyone seems to be buying for older G11's, or is the OPW upgrade still necessary to buy even for new G11GFT mounts? Thanks!

This is the specific mount i'm asking about: https://www.bhphotov...rial_mount.html

29
I'm interpolating a bit. If you zoom in, the vernier isn't *quite* at 25, so maybe 23 plus or minus one.

The tricky one, of course, is the RA scale. Because it moves, I use two gauge points, also with verniers - one for sidereal time (once set I just push the ring around to keep up with the sidereal time on my dual-time wrist watch) and one for the RA of the object I'm looking for. That'll be my next picture when I get around to it.

30
M54 is part of Sagittarius Dwarf Spheroidal Galaxy and pretty easy to see. Most of the other Milky War globular are not that hard to see. Omega Centauri is so easy that you can see it with the naked eye.

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