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Messages - caenalfosen

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And now we have the Nexstar 8" EvolutionHD to throw into the mix.


Reflectors Telescopes Forum / Re: Discovery 10" Dob for $200?
« on: February 08, 2018, 11:23:46 PM »
DHQ was f 5.6 , the PDHQ was f6

I'd seriously consider a Celestron 6-inch SCT on an AVX mount, or possibly a Nexstar of the same aperture. From a dark site a 6-inch will reveal 12th magnitude galaxies, and a good 6-inch will showa lot. It cannot compete with a 10 or 12-inch true in terms of resolution and light grasp,but it takes inpanoramic views of large objects such as the Pleiades and candeliver superb views of the moon and planets too. All of the Messier objects andhundreds of NGC and IC objects too are no problem for a 6-inch under good skies, and they are not bulky nor are they back breakers to set up and take down. You wouldn't want to try lifting the OTA of a 14-inch SCT chest high,not if you saw what I saw a guy once doing to get his onto his mounting. When buying a telescope, the state of your health and strength do matter because after observing for hours, that OTA and mounting will get heavier. Fortunately, the OTA of a 6-inch Celestron is light and the AVX mount separates into three sections, none of which weighs more than 20 lbs. The Nexstars are just as light, but they are also sturdy.

Another portable telescope that is a good all around option for visual observing is a 8-inch F/6 Dob if that is you are sure you'renot interested in imaging. I do not recommend messing with astronomical photography through a telescopeat this point if you're a complete beginner, but opting for the SCT will give you the means to pursue that later. It's both a very steep learning curve and you won't believe how many gadgets you'll need if you're going to do prime focus, negative or positive projection imaging through a telescope. You can get inexpensive video cameras and image the Sun, moon and planets with a 6-inch Celestron as I am doing now with an 8-inch EdgeHD on the same mounting. It may be possible to piggy back a camera on the OTA and use the telescope and mount as a guiding platform, the mount can handle up to 30 lbs., at least for visual observing. Since you indicated you're computer savvy and mechanically inclined, both you and your wife would find this telescope and mountingeasy to set up and master it's excellent capabilities, especially for the price of 900 dollars when an AVX mounting is bought separately.

You are not limited on what kind of telescope you could use on an AVX, or any other German equatorial mount as long as the telescope's weight is within it's design limits. You could get a 6 or 8-inch SCT now, and later if you really want to do long exposure imaging an 80 or 90mm apochromatic refractor, camera and auto guider can be used on the same mount to take your pictures of nebulae and galaxies. Most DSO's are small in apparent size, but a telescope of this aperture with the right camera will work well on many of the sky's showpieces such as the Andromeda and Triangulum galaxies. What you need to bear in mind about imaging are two realties. One is imaging is mostly all about the mounting. You need a steadier mounting and a smaller telescope for imaging than folks who are mainly or entirely visual observers. Generally, you don't want to put much more than about half of a mountingweight capacity on it while imaging because that demands much more of a mounting thanvisual observing does.Two is few telescopes excel at both imaging and visual observing, SCT's and many but not all refractors can do bothand do it well.Other kinds of telescopes are generally made with visual observingor imaging in mind and are unsuitable or at best so-so for the other application. SCT's are jacks of all trades, and masters of none. However SCT's of recent manufacture do compare well to Newtonians in terms of image contrast and light transmissions, due to vast improvements in coatings and optical quality in general since their introduction back in the 1960's by Celestron. I found that compared to my 10-inch F/4.5 Dob which has very good optics the 8-inch EdgeHD I recently bought shows the same features on Jupiter and Saturn almost as clearly, and that is due to the smaller aperture.

An SCT OTA is among the most compact of all telescopes in the 8-inch and under apertures, and can be kept in a hard shell case. Small apochromatic refractors are also compact, some can be taken aboard airplanes as carry on luggage in a hard or soft shell case. All others are larger, bulkier and heavier.

The best thing I can suggest you do is attend some star parties and check out, as well as look through as many telescopes as you can in person, before you buy. That is how I made every major purchase decision, and not just related to astronomy. If you're prepared to spend $2,000 or more as I had done recently buying an 8-inch Celestron EdgeHD, doing some test drives is an excellent idea. A 6-inch SCT can be bought for $900 on the Nexstar mount, or around $1,300 on the AVX mount, which is both a GOTO and a true equatorial mount. Nexstars track objects but are not true equatorially mounted telescopes. You can take short exposurephotos through them, but during a long exposure the field will rotate as it tracks, trailing your photos. They are however, more compact, the tube and the mount will fit together in a protective case. During set up, you merely set up the tripod, then place themount and tube on top ofit. With aGerman equatorial, you have to set up the tripod, attach the equatorial head, then thecounterweight, then the OTA. To take pictures you'll then have to do a thorough job of polar alignment, a process I am beginning to learn myself right now. In contrast, an 8-inch Dob sells for around $400, and all that's needed to set it up is put the base where you want it, place the tube on the base, then insert an eyepiece and you can start observing.

Regardless of what telescope you buy, you will need additional accessories such as a stool or observing chair with an adjustable height seat, a star atlas, a red LED light and other things. It's not necessary to run out and buy a bunch of eyepieces and other accessories, that can wait until you learn your way around the sky and your telescope first. Then over time you can acquire the accessories that are best for you.

What I am getting at here is it would be a good idea to think about how much time and effort you can devote to this hobby because all of us have families, careers and friends we also have to devote time and attention to.

Personally, when I started off in astronomy over 40 years ago, I wanted to take pictures rightoff the bat, but soon found that it was far harder than I ever dreamed. I developed entire rolls of film only to throw it in the garbage because every shot failed because of one gotcha or another. I shelved the idea and remained a visual observer until recently. I had to learn my way around the sky first, then saw that even with a 6-inch under good skies there was no shortage of objects to see. When I got a 10 then a 15-inch, it was like taking a drink from a fire hose. Once you get your bearings, you will then be ready to pursue imaging, if you have the time and patience required to master the fundamentals.Clear skies!


Does anyone know what's going on in the ortho market? Clicking on University Optics' website brings up the message: "Thank you for visiting, but this web site has been closed down at the request of its owner."

Going to Agena's website shows that AstroHutech orthos and Kasai Trading Co.'s eyepieces are on closeout - all sales final, no returns accepted.

My understanding is that basically all of these orthos and other Japanese eyepieces are all made in the same factory in Japan. Is it possible that there's something going on at that factory? Are orthos done? Does anyone know what's going on here?

ATM, Optics and DIY Forum / Re: Final eyepiece height for dobs
« on: February 03, 2018, 10:55:22 AM »
a chief for those long focal length mirrors to bring down the EPH and have an unobstructed primary. why have diffraction from the 2ndry and spider...?

Mounts Questions & Expirience / Re: Opinions on Celestron AVX mount.....
« on: February 02, 2018, 11:00:33 PM »

What are the major differences between the AVX and the CGEM? I know the load bearing capacity difference but is there anything else?

I ask because I have a CGEM and I like it but it is a beast. Heavy.

One thing I don't like about the CGEM is the arrangement of the power, HC, aux, and auto guide inputs. Kind of cluttered.

It looks like the AVX may be better designed in the regard.

FYI I have both an 8" Edge HD and an 80 mm refractor. I like both visual and AP.



Pretty much everything mechanical, the electronics may be similar. Beefier gears, shafts, and bearings. Bigger motors, almost certainly. The AVX has a simple bushing on the DEC axis, rather than a more sophisticated bearing. It all translates to better tracking.

The good thing about mounts is that you generally get what you pay for. The bad thing about mounts is that you generally get what you pay for. <smile> Not much magic out there.
Actually the motors and gears are pretty much identical. In fact, insome ways the VX is actually a better, more modern design. The VX, for example, doesn't suffer from the transfer gear situation that makes using PEC on the CGEM problematical for some mounts.

Lots of people go on about the declination axis of the VX, but when I look at my declination guiding graph in PHD it looks pretty much like the RA graph. There are challenges using the VX or any other mount for guided imaging, but not being able to guide the VX in declination to the tune of 1" or lower RMS errors is just not one of them, no matter what you've heard tell.

The CGEM will give you some more payload capacity for imaging, but, frankly, don't expect it to give you better tracking.

Mounts Questions & Expirience / Re: Upgrade Atlas EQ-G to Losmandy GM811G?
« on: February 02, 2018, 08:37:36 PM »
Nice summary, Jmd. Once it was clear that improvements in rms values translate to very minor improvements in image quality, the only questions are really about consistency and imaging window. For instance, what kind of weight the mount can handle, how much wind, tracking at lower altitudes, lost subs, etc.. I guess that is part of the question I have about Losmandy mounts. Are they sturdy and precise enough that they can be left alone over night with reasonable assurance that most, if not all, subs will be usable in the morning?
As it is, the EQ does really well within narrow parameters. I've learned to work within those parameters and avoid situations that would expose its flaws. But a typical imaging session involves a lot of time babysitting the mount and keeping it within those confines. I'm curious if a Losmandy mount would be more of a set it and forget it experience, or do you have to go to the $7K mounts for that result?
I really appreciate everyone's insights.

Eyepieces Questions & Recommendations / Re: Low power planetary viewing
« on: February 02, 2018, 01:39:08 PM »
Try a 5x Barlow/Powermate with the RKE to get to proper planetary magnifications with your 130. Now if using a Barlow this will extend the eye relief of the RKE even further, so you will find you can really stand off from the eyepiece and view (great for sketching). It is fun and the RKE takes the Barlowing very well. Otherwise get yourself a nice 5mm and 6mm Abbe for planetary with your 130.


Let me know when you are ready to move, we can split the rent.

3 ways.
4 ways. let's get a collection going, maybe we could buy a ghost town.

Eyepieces Questions & Recommendations / Re: Good Kellners
« on: January 31, 2018, 01:51:01 AM »
Anyone try a Levenhuk? I see they market a 6.3 and 40 Kellner.


I can see the Veil Nebula with 10X50 binoculars on a decent night from my house (Bottle 3 skies), and it is very impressive through the 4 and 8-inch scopes--especially with a UHC filter. The California Nebula, on the other hand, is just not that exciting to see. It is a subtle brightening of the sky through the 4-inch without a filter, but with the H-beta or UHC filter you can make out the entire shape, but it's still dim, featureless, and unimpressive.


And I mean 'Versus'. Will these three technologies work well together?

I have a world-class 12.5" Dob with Servo Cat and Nexus DSC's. The drive is not accurate enough for video imaging which is something I would like to do with this telescope. (Imagine - the ServoCat's Azimuth drive is a knurled knob running on a wooden circular base and the altitude drive is a brass knob with a thin steel cable wrapped around it 2 1/2 times - not exactly an AP 1200.....) I will say the GoTo's are very accurate and the tracking is quite good enough for visual. But with a 2x Barlow for binary star imaging (need to be 3000 - 4000 mm focal length for accurate binary star measurement...) the image moves around too much for the stacking software to work.

So, an Dob tracking platform might do the trick...  But there is much I do not understand.

If I have Servo cat do I turn it off when using a patform base?

Can I use the servo cat go to function while the platform is tracking?

How does my Nexus DSC know what the heck is going on if I'm using a platform (and therefore the scopes encoders are stationary)?

Also, how smooth are these platforms?


Hello Dave,

What is the resolution ofencoders installed on your scope?

Have you tried to tune the gear ratios for ServoCAT?

If you have low resolution encoders or if the gear ratios are not set precisely then the tracking can be inaccurate. charotaguy has 40K encoders installed on his scope if I am not mistaken.

Best Regards,
For clarity I should say the inaccuracy is not in the encoders (10 000 tic) nor the Nexus DSC's - the Go To accuracy is excellent. The problem, so far as I have experienced, is in the mechanical design of the bearing surfaces which drive the Altitude and Azimuth axes.

For the azimuth there is a knurled knob about 1" in diameter which bears, with the help of a strong spring, against the circular, wooden groundboard. Even though the groundboard is cut with CNC machinery it just can't be perfectly circular, nor is the wood equally dense or rigid around the perimeter. There is some 'wobble' and drift. The altitude movement is via a wire wrapped 2.5 times around a brass pulley about 1" in diameter. Again there is some 'wobble' and drift in the design.

Now this 'wobble' is of ZERO concern in visual observing, for which the telescope was designed. The tracking keeps targets well in view even at 600x or more.

I have been trying, unsuccessfully so far, to do video lucky imaging at f/13 (2x barlow), 4100mm where the field of view in the Canon's video crop mode is about 1.3 x 2 arc minutes. In this application the 'wobble' and drift are both too much.

And so I seek other methods of driving the telescope...

Hope this is clearer.


Beginners Forum / Re: Binos advice (first pair)
« on: January 30, 2018, 01:51:08 AM »
Aperture light grasp and magnification are all relative. Don't be focused on aperture alone or magnification alone.
Exit pupil and field of view need to be understood before making a choice based on others' opinions. Eye relief and type of eye cup, standard or twist up, are also considerations. Comfort is important. Do you wear glasses? Do you have oily skin and long eye lashes? If yes, then long eye relief with twist up eye cups or easy to flip down cups are a good idea. This is also nice for daytime viewing. I don't wear glasses, but I can see the whole field wearing sunglasses, with the cups down on long er binos, and with the cups up and no glasses, the cups also block stray light.
10x50,8x40,7x35,6x30 are all relatively the same, 5mm of exit pupil dictates the brightness of the issue, to be as bright as 8x40, a 10x binocular needs to be 50mm.
7x35 is as good as a 10x50 but at lower magnification. 7x50 is a really bright 7mm exit pupil, which is only effective if you can dark adapt to 7mm, and many are limited to 5mm or less pupil dilation after age 50. Having exit pupils wider than your eye dilates is "wasted light" in astronomy use. (Marine use is different, as it is easier to keep your 2-3mm daytime pupil centered in a larger pupil on a moving boat)
Also, in light polluted skies, larger exit pupils tend to amplify skyglow and reduce contrast. This is why many of us choose 4-5mm exit pupils as our main pair if we don't always have dark skies (here it is 100-200 mile drive).
Another issue with most 7mm pupil binoculars like the majority of 7x50s is a very narrow apparent field, 40-50deg (narrow, soda straw) as opposed to 60-70deg in most 7x35,8x40(42) and 10x50 models. There are higher end 7x50s with wider angles, but generally they are narrow, offering the same or less area of sky than their 10x50 counterparts. This is because the longer focal length eyepieces needed to achieve the lower power are limited to narrower fields due to the available field stop aperture and design limitations. Higher end widefield 7x50s tend to have shorter barrels and big eye lenses, which are more expensive to produce with good optical quality.
I think 7x35 is a good starter for you if you had trouble with 10x42s. 8x40 might be OK too. With 7x35, a $200 budget buys a much nicer pair than you can get at 50mm.  I had chosen 8x40 Nikon action extremes as my main pair.
Note that I had started with modest priced 15x70s on a tripod, and if I was to suggest a $200 package, it would be with a pair of $60-80 15x70s and a $120-140 pair of 7x35 or 8x40 assuming you already have a tripod. 15x70s don't need heavy duty tripods.
Buy the 15x70s from a brand with a good warranty (celestron skymaster for instance) and or a dealer with a good return/exchange policy, in case you get a pair that is misaligned, which is common at that price point. They can be user adjusted, but you shouldn't have to deal with that.  I started with Barska 15x70 which I bought at big 5 sporting goods for $59, and was able to look through them first. They are the same as the skymasters and oberwerks, but had simple "fully coated" optics rather than multi coated or fully multocoated. In practice it is a subtle difference at that size, and they were very enjoyable for many years (almost a decade) until the rubber started to get sticky and a slight haze built up inside and I passed them on to a friend for chump change (I lived 5 miles from the beach and the windows were always open, no AC). I bought waterproof celestron cavalry 15x70 fully multicoated to replace them. 
My main pair of 20x80 are the zhumell fully coated versions of the corresponding skymaster/oberwerk models (all versions of Kunming BA-1) and I fully enjoy them. 
Nothing wrong with a pair of cheap big binos as long as they are collimated, but for hand helds that will be used all the time, it is nice to have a nicer pair, $100-150 gets a nice 35-40mm pair. I spotted a school of porpoise approx 8miles away on a fishing trip, with the Nikon 8x40ex that were not visible in the west marine 7x50s that the boat had, and that led to a huge school of yellowfin tuna.
Decent binos are a good thing to have for many uses. I miss mine, they were stolen.

They accepted the charge...that is why there is $95 pending on my credit line. They say the "flag" had to have been on the merchant's end. Something about my CC must have set off TelescopePlus' software.

I was in banking for a lot of years (though I'm not an expert in payment processing), but that explanation just doesn't add up to me. Card data is fed from the merchant's terminal through a processor to an interchange (a payment intermediary, e.g. VISA, MasterCard) which has a live connection to the card issuer who responds back with an approval or denial - period, approved or denied only. Not only have I never heard of anyone but the issuer maintaining information on fraud alerts or anything else related to approval of the charge, I believe it would run afoul of a phalanx of federal financial privacy laws and regulations for that information to be shared with a merchant. But again, I'm not an expert here.

My guess is that they screwed up in an innocent and benign fashion, and for whatever reason don't want to own up to it. If I'm right, it's crazy, but far from the first time someone has done this. And I'm confident the charge won't go through. And even if it does, federal consumer credit protection laws will protect you, providing you make the right notifications (i.e., formally dispute the charge with the issuer within 60 days (? - I think that's the window, but don't hold me to that).

Hope it resolves with the minimum of hassle to you.

Today I placed the orders for the remaining items:
- Glatter tools + parallizer
- DGM NPB 1.25"
- Bobs Knobs

which cost me $150 above budget but I think getting everything in order from the get go should make for a happier experience.

Thanks again everyone

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