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Topics - frenafverbi

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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

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I'm actually going back and forth between getting a 17 or 22mm T4. Which do people consider the best?

I am thinking of the 17 myself.

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Eyepieces Questions & Recommendations / Dakin 1.25x barlow
« on: December 30, 2017, 12:43:03 PM »
This barlow arrived about 2 weeks ago but last night was my first opportunity to use it. I purchased it specifically to use with my 5mm Pentax XO, which then becomes a 4mm. But I also wanted to test it on a 10mm, which becomes an 8mm. It arrived in a nice little red box with two soft plastic caps.

It is nicely made and compact at 1" (26mm) long and has standard filter threads to screw into the barrel of an eyepiece. Vernonscope makes two models, a 1.5x and the 1.25x, and each of them is produced with either Brandon specific filter threads or standard filter threads... I chose standard threads for use on more of my eyepieces. Ironically, I cannot use it on my Chester Brandons which are very old and have no threads at all. The attached photo includes a UO HD 6mm for size comparison.

Using a TEC 140 and a Zeiss Prism Baader diagonal with the 5mm Pentax and Dakin 1.25x seemed quite satisfactory. Targets were Luna, Jupiter, the F-star in the Trapezium and double stars Zeta (2.5" sep), 32 (1.1"), and 52 (1.2") in Orion. Seeing was not the best and atmospheric moisture was obvious, but the image through the Pentax with the Dakin attached held up quite well and appeared to be at least equal to a UO 4mm Ortho. I'll have to wait for steadier seeing to give it a fair test though.

Attaching the Dakin to a 7mm RG ortho, UO 9mm ortho, and a UO 18mm ortho, provided satisfactory results. The field appeared very sharp on axis with little softening at the very edge.

Wide field eyepiece performance was good on axis, but dropped as the EOF approached. With a 20mm RG (Erfle), stars in focus on axis soften at about 70-75% from center, and the edge was obviously distorted. No seagulls... but bloated stars

I then attached it to a 10mm Ethos (making it an 8mm) and found that on axis was fine, sharp and clear, but softening started about 50% out from center and increased significantly to the edge. I don't think the Dakin was really made for a wide field eyepiece, since it is a barlow... light rays exiting it's lens are divergent. BUT on axis it was fine. So next time there is a clear, steady sky, I'll attach it to a 4.7 Ethos making it 3.7mm and look for a good target to put in the center of field.

I'll keep this little barlow for now, specifically for the Pentax XO, making the eyepiece serve double duty at 5mm and 4mm. I'd be interested to hear results from anyone else who has used one of these compact Dakin Barlows.
Attached Thumbnails


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OK, sorry for all the questions about eyepieces but I am really on a plan to renew some of my old eyepieces now. I have been considering hyperions, the hyperion Zoom and the ES82. The ES82 are great from what I heard here, but the ER is a little bit short some people say. Long story short, I am considering again the Baader Zoom Mk III.  Please could you tell me how good is this zoom, optically?
I would appreciate your help.
Thanks!

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Reflectors Telescopes Forum / Question on CF tube Newtonian's
« on: December 28, 2017, 10:34:22 PM »
So while I am researching Newtonian's, which CF scopes would you recommend? I have been looking at the Teleskop-Express offerings in 10" and 12" and the Sky-Watcher Quattro 10 CF and I am interested in the ONTC1216.

http://www.teleskop-...stomizable.html

Also in their line-up UNC30515 is interesting.

http://www.teleskop-...in-Germany.html

I am leaning more towards the 10" due to mobility of it and not not having to get a monster mount for the TS 12", as the weights are running in the neighborhood of 40 pounds and the 12" Quattro is 57 pounds.

Do you have any recommendations other than these than won't break the bank? I am trying to narrow down in each scope type the "One" and then weight the pro's and con's of each scope type and make a decision from there for the final one.

Oh the scopes will be used for visual and AP work.

Thanks for your imput

Shotgun

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Hello,

I’m new to astronomy and recently bought a SkyWatcher 10” (the full length tube). It came with what appears to be their standard eyepieces; Super 25mm wide angle LER and Super 10mm. I also purchased an Orion Shorty 2x Barlow lens. I was viewing Jupiter a few days ago and I was pretty pleased with the performance (crisp images.) That is, with one exception; the 10mm with the Barlow was really poor. The best way to describe it is “fuzzy.” Now, the 25mm with the Barlow was good. And without the Barlow both 10 and 25 were good. So I guess I’m trying to understand why the difference in the 10mm when used in combination with the Barlow? I’ve read enough so far to know that others are not pleased with the S/W Super 10mm performance, so I’m not hoping to find a fix (other than replacing it.) I’m just trying to learn the reasons behind the poor performance and why it seems to be much worse with a 2x Barlow (i.e. the degradation is not linear.) I have read the excellent thread "Identifying eyepiece aberrations" but I'm still very much a novice and am trying to decipher its information. I'd appreciate any thoughts.

Thank you!!

Sonoran

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Hi folks.

I need a little advice.

I have a doublet optical group in a cell. The OG is mounted in the cell with an o-ring spacer between elements, and the rear element is snugged against the o-ring spacer from the rear with a retaining ring (I.D. ~70mm; a half millimeter or so deep, with two thing notches in it 180-degrees apart for installation/removal of the ring.

On smaller optics like eyepieces, I generally "caveman" removal of small retaining rings using a couple of jeweller's screwdrivers or similar held like chopsticks, but the notches on this baby are too far apart for this technique, and the ring is adhesed to the threads on one side with a tiny bit of lock-tite I can see.

What tool should I use to loosen the ring? Where might I buy one (today) at a hardware store?

Lemme know. I would like to pull the glass, scour it with acetone to see if the fungal infestation has etched the coatings or the glass and then put it back together after cleaning, today.

Thanks!

Jim

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Beginners Forum / Alt Az Directions in Stellarium
« on: December 27, 2017, 07:44:03 PM »
I can't find a reference in Stellarium documentation, though it might be there, that tells me the reference point for Az readings that Stellarium presents.I have been using Stellarium with a digital angle gauge on my Dob to locate targets but have only approximated the Alt based on compass coordinates, then hunt around. However if I click on Polaris it appears to be near zero but it does change.

I would think Stellarium would be based on Polaris being North as 0 degrees but have not been able to confirm it.

What is the reference point used in Stellarium?

9
Hi,
 I recently bought a new Ioptron CEM60 mount on a black/red Tri-Pier. The first night out I spent testing my new mounts PE expecting to get some wonderful results. The graph that came with the mount looked odd. More like close to 10 arc/sec but Ioptron told me it read 5 arc/sec and that most users get less than what their graph shows. And they told me the graph was made from off the worm.

I have had the mount a couple of weeks and every night that has been clear I have been testing my PE over and over. I had used Phd log viewer but since my results were so high I decided to use the trial version of Pempro. I have been getting close to the same results with both. I have tried different configurations with my 9.25 Edge, my C-11 and with a new 60mm guidescope with a focal length of 240mm. I also tried with a barlow in the guidescope once. I used a Qhy5LIIcolor camera with Phd log viewer and I used a meade DSI Pro and a DSI II color cameras with Pempro. I have used guide settings of 0.90, 0.80, and 0.50 and still got the same results. I used an image scale calculator to figure my image scale but then I used the Calibration wizard in Pempro each time to get a more accurate image scale. The mounts worm period is 299.18 and it has 288 teeth. I made sure the mount was Polar aligned with the Ioptron Polar scope then with PoleMaster each night. The mount was balanced East heavy and I also tried evenly balanced several times but East heavy worked best.

Here is an example of a Pempro graph made with my 9.25 Edge with the mirror locks tightened and a Meade DSI Pro with a Pixel size of 9.6 x 7.5 microns. Pempro measured the image scale at 0.802 arc-sec/pixel. taken close to zero declination at Declination -1.08 This run was from 6 worm cycles.
Thank you,
NeilsonI am wanting to know if with this information can I find out what the problem is with the mount causing the PE of 18.79 arc/sec . And/Or am I doing something wrong in my testing.Attached Thumbnails

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Reflectors Telescopes Forum / 10 inch go to or 14 inch push to?
« on: December 25, 2017, 10:29:56 AM »
Hello. I would like any input from members of the forum.  I have a pretty dark sky (about mag.  5) and watch in my back porch.  I've got a 10 inch go-to Dob.  My query is this: I am contemplating buying a 14 inch Skywatcher Dob, the one that has no electronics.  My budget won't allow for a go-to 14 inch.  I really do have a Lumicon Sky Vector using 3500 objects and also the encoders that I believe I could fit on the 14 inch Skywatcher.  In terms of deep sky observing, which is my main interest, would it be best to market the 10 go to and get the 14 inch?  I would not have monitoring since I do using all the 10, but I would have more aperture.  The 14 inch has nearly twice the light-gathering.  I am able to put rollers around the 14 inch and just roll it out and out of my house.  I wouldn't have to take it apart each time that I observe.  Which would you prefer?   Thanks for any input that you all offer.

Richard

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I see pictures of those huge newtonians, mostly dobs, where the observer has to use a ladder to get to the eyepiece.   Why can't the eyepiece be next to the base?

I would think a mirror or some thing could catch the light in the secondary and direct it to the eyepiece in a more comfortable place.  The reflector could be out the tube, I guess, to prevent interference inside the gathered light flow.   I don't know if this could alter the focal length as we are speaking a direct mirror to mirror rebound into the eyepiece down below.

Granted there may be some minor light loss but I would think it could be minimal when compared to what is being gathered.

Is there any limitation that prevents this?

12
Beautiful new postage coming out in a month in the USA.  Reveals the moon's cratered face surrounded by the corona.  When you touch the postage, your body heat makes the moon move pitch black.  I am not a stamp collector and I do not do much mailing but I'm going to catch some as soon as they are readily available.

Why service the USPS?  They can use the cash and they are undoubtedly the best deal for transport small-to-medium size astro stuff, IMO.

13
I only got my Explore Scientific 68-degree 24mm eyepiece - the one I ordered back on the previous day (April 30) of the NEAF sale for $99.  Seven months wait.

But I digress! 

This can be a honey of an eyepiece.  A spreadsheet I use to calculate all my telescope details says that the field of view should be only a little bigger with the ES 24 than the 32mm Plossl I always use as my finder eyepiece, so I chose to take it out to get a field evaluation in my 127mm Celestron Mak about the Pleiades and see for myself.  The spreadsheet calculates the field of view simply by dividing the apparent field of view of the eyepiece by the magnification.  So, the 32mm = 49/48 = 1.02 degrees, and the ES 24 = 68/64 = 1.06 degrees.

Individuals around the boards have said that the focal length of those 5-inch Synta Maks has been that the 1540mm listed on the Orion version as opposed to the 1500mm listed on the Celestron flavor, the one I have.  I always thought the 1540 figure made sense, that Celestron probably piled the numbers down to whatever reason, so I've always gone with this.

But, I know this formula for field of view calculation isn't accurate - there is some more complicated method to do this involving using radians and eyepiece field ceases and such.

Taking out the scope for a field evaluation on the Pleiades, I was able to see from Atlas directly through to Electra and a little beyond, into a subdued 9.1 magnitude star that Stellarium states is situated at RA(j2000) 3h44m23.6s and Dec 24d7m56.8s, which I'll refer to as 9.1.  Both Atlas and 9.1 were at the edge of opposite surfaces of the field of view from the ES 24; and indeed, this was only a smidge bigger than I could view at exactly the exact same perspective (swapping the EPs forth and back) with the 32mm.  Together with the 32mm, I could get one or the other in the field, but not both, and definitely with a noticeable smidge.

With Stellarium's Angle Step feature, I measured the distance from the center-to-center between Atlas and 9.1 as being 1d5m33s.  (Center to centre because Stellarium introduces a photo of the Pleiades where the brighter stars are nice big round balls.)  Transforming that dimension to decimal units, I receive <strong>1.09 degrees</strong>.  In my dictionary, this is more than the maximum real field of view than the 1540mm focal length of my range would allow.  But when I change the focal length in my spreadsheet to 1500mm, voila, the numbers come out perfectly.  The spreadsheet calculates the ES must - and does - provide me with a 1.09 degree true field of view.

Does this imply that I'm using the incorrect focal length (1540mm) for most of my range calculations?   I know this is almost splitting hairs here, but does this show that Celestron is actually right when they state that the focal length is really 1500mm?  Or maybe the Stellarium dimension is wrong?  Or the photo that Stellarium is using is twisted and does not match the true field?  Help! 

Just curious.  Thanks.

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General Astronomy & Observing / An Eclipse prayer
« on: December 23, 2017, 11:20:04 PM »
This past year I was deeply moved when Sandy Koufax disclosed that before every World Series, long time Dodger announcer Vin Scully went to church and prayed.  But he did not pray for the Dodgers to win, '' he prayed there would be:

"Only heroes, no goats."

For Monday's eclipse:

May everyone find a location.

May the traffic jams become minimal.

May the clouds and smoke clean for the length.

May all gear perform admirably.

May all eclipse viewers come together in a mass grasp of the one moment. .

Please include your own. .

Jon

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