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Celestron HD Wedge Measurements?

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#1 barbarosa

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Posted 13 April 2013 - 02:55 PM

I want to buy a Celestron HD Pro Wedge (the current model) but before I do it would help to know how much the wedge adds to the mount/pier stack. I plan to move from a tripod to a pier in a small RoR observatory and want to specify a pier height. I am at ~38°, I did not find anything helpful on the Celestron site. I know that I can email them and perhaps even get back a precise measurement, but typically, they do not respond rapidly if someone has to go and check the actual item.

My best hope is that someone with an HD Wedge can give me a good measurement of the distance from the center of the mount’s base to the horizontal plate of the wedge (and their latitude). It will help even if you are further north or south. Alternatively the length of the pivot arm from the hinge to the center of the mount’s base and the distance from the hinge to the center of the top of the tripod/pier should revive my trig skills.

Thanks.

#2 Koen Dierckens

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Posted 16 April 2013 - 06:05 AM

David,

I would be glad to help you, but as I'm not a native English speaker, could you clarify which measurements you are interested in? I'll attach some pictures of the wedge, marked with letters. Just refer to the letters for the distances you're interested in. PM me, so I am attended to the fact that you replied. Lately I don't have much time to scan the forum for new posts.

Edit: feel free to add extra markers if your reference points are not present.

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#3 Koen Dierckens

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Posted 16 April 2013 - 06:07 AM

Second pic

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#4 Koen Dierckens

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Posted 16 April 2013 - 06:08 AM

third pic

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#5 dragonslayer1

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Posted 16 April 2013 - 08:47 PM

Koren, what is the power supply with the cigarette lighter plugs in it? Is that homemade? Looks like is a multi plug in power bank of some kind.. Thank you, Kasey

#6 Koen Dierckens

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Posted 17 April 2013 - 02:04 AM

It just is an 12V splitter with extra 5V USB outlet. On the first pic, you can see the small adapter that comes with it that can be mounted on one of the threaded holes in the wedge, so you can detach/attach it rather easily.

On top of that, I strapped the power convertor for my IMG0H CCD.

#7 dragonslayer1

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Posted 17 April 2013 - 08:47 AM

nice set-up. thank you, kasey

#8 barbarosa

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Posted 18 April 2013 - 01:37 PM

Sorry, I think that I assumed that the wedge was simply a triangle, hinged at the one vertex. I think the old wedges were like that. I see now that the HD wedge is a bit harder to measure.

Before we talk about measurements, do you have an problem with shake or vibration because of the wedge? I know that you have a 925 but the mount is identical.

In the end, I want to know how much the wedge increases the stack height. Take the measurements (top of arm, bottom of handle or vertically down from point A’ or A to the top of pier/bottom of wedge) indicated by any of the three arrows and your latitude should get me close. If point A is a stand off from the back of the wedge plate could you estimate or measure the distance from the plate or to A'?

Also, let me know if the tube is pointing along the 0°-180° or if you rotated the mount to put the handle at 180°.

Dank u Koen en Koen uw Engels is oneindig veel beter dan mijn Nederlands. Si vous parlez français comme un Parisien, il serait mieux que mon pauvre effort. Engels spreken als een native is niet altijd een goede zaak (Any error, offense, or lost meaning is entirely the fault of the web translator).

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#9 Koen Dierckens

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Posted 19 April 2013 - 08:32 AM

David,

About vibrations: the setup vibrates more than when placing the OTA directly on the tripod, there is no doubt about that. The effect is mostly noticeable when you touch the scope during focusing or other manipulations. However, if you do not touch the scope, I never saw it vibrating just by itself or by wind. I also read on this forum comments from other users that they are very satisfied with the sturdiness of the wedge.

For the measuring, I quickly set up the wedge on the tripod, without mounting the scope on top of it. This means the numbers refer to the most right arrow in the picture modified by you, close to markers A and D.
As a matter of fact, all my measurements were made from the bottom of the wedge till marker A', which is the top of the plate where the scope mounts.

I measured 3 distances: The first where the plate is complete level with the ground (scope has equal position as mounted on tripod without wedge, just higher), indicated on the orange scale on the left of the wedge as 90°. (not visible on any of the pics)
The second measurement indicates the height of A' on the position I normally use (My latitude is about 51,25°, but on the scale of the wedge this rather is 53 degrees)
The last measurement is an attempt to be as close as possible to your position of 38°.
You should know that when it comes out of the box, the wedge can be mounted in two different ways: one for higher latitudes, the other one for lower. The way I assembled the wedge allows me to go for a minimum of 40 degrees of latitude, not lower.

Original measurements were made in centimeters. Converted into inches by dividing by 2.54 and rounded to two decimals.

height	inch
90°		19cm	7.48"
53°		30cm	11.81"
40°		35cm	13.78"

Could you clarify your 3rd question? As the scope can rotate freely on its AZ-axis when unlocked, once placed on the wedge you can position it freely as on the picture. The setup indeed shows that the fork/handles of the scope were oriented in an E-W direction while the scope was pointed at the south. I guess this is not very important, as I measured without the scope on the wedge...

FYI: my native language is Dutch. French officially is my second language and I occasionally happen to be in the neighborhood of Paris, but I prefer English over the language of Molière. The web translator did a flawless job ;-)

#10 barbarosa

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Posted 19 April 2013 - 01:50 PM

Koen,

Thank you very much, this is exactly what I need. :bow:

I like your ingenious rooftop pier and the modification of the fork arm for connections.

Petje af voor Google Vertalen voor een goede vertaling. Maar je Engels is zeer goed. Het heeft slechts een voorproefje van wat ik Germaanse syntax zou noemen, maar is verder uitstekend. We kunnen Googel sparen voor taalkundige noodgevallen.

I have used two CPC on tripods, the 925 and now the 1100 and in terms of shaking during focusing both are a big improvement compared to the 8 SE. If a wedge moderately increases shaking during focusing, but is otherwise stable, I can live with it. I will order from a retailer with a good return policy.

The odd question was because I was uncertain as to whether the side plates would obstruct a measurement from near point B to the handle or arm and if it would be easier to measure with the arm rotated 90 degrees to the rear. From your other posts, I should have known that you would do a careful job of measuring from a good base point.

In high school and college chemistry and physics, it was all MKS (or CGS) and later SI. I remember the apathetic and foolish response in 1975 when the government tried to plan and encourage a very gradual switch to metric (highway signs in mph and kph). I think it lasted about five years. Until we come to our senses, decimal fractions become 64ths 32nds or 16ths. In this case close is good enough.I admit to owning at least one metric ruler, I keep it hidden to so as not to alarm the neighbors. :bigshock:

#11 Koen Dierckens

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Posted 20 April 2013 - 05:06 AM

:thanx:
Always glad to help.

#12 katie

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Posted 20 April 2013 - 07:10 AM

I see you have replies to your question. Coincidently, I was asked the same question via email 5 days ago. So, I provide my answer as more data for you to crunch.

NOTE: This is for the CPC1100 and I am at 38*

From the bottom of the wedge(or top of any mounting plate) to the top of the OTA (the OTA in a level position pointing toward the horizon), I measure 31.5 inches.

With the OTA in the upright position (pointed toward my zenith), I measure 41.25 inches.

If you want to do some trig, the fulcrum point on the wedge is 7 inches above the tripod mount (junction of wedge plate and tripod plate - same plate you would use on your pier). The arm (radius) from the fulcrum point to the center pin of the scope base is 7.5 inches.

An interesting point. My OTA in the horizontal position, mounted in the alt/az, is 28 inches above the mounting plate. Mounted on the wedge only raise it an additional 3.5 inches using the same horizontal position. Seems odd, but that is how the geometry works out.

#13 barbarosa

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Posted 22 April 2013 - 12:09 PM

My calculated number was 32.8, using Koen’s measurements, one estimate, one erroneous measurement (mine), nine small diagrams, and 82,300 former brain cells. Who knew that my Junior High geometry teacher was right when he told me to pay attention, because geometry was useful?

Katie I appreciate you taking the time to post your data. I’m at 37.84°N, making your numbers good enough. :)

By the by, do find that the wedge increased image shaking, and if it does is how would you describe it compared to any shaking without the wedge?

#14 katie

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Posted 02 May 2013 - 06:57 AM

...By the by, do find that the wedge increased image shaking, and if it does is how would you describe it compared to any shaking without the wedge?


David, I apologize for the delayed reply; did not notice the question. :foreheadslap:

Since putting the scope on the wedge I have used it primarily for imaging because some of the eye positions for visual objects when using the wedge are a bit out of my reach or uncomfortable.

However, when using a diagonal and eyepiece I do not notice any extraneous shake. Meaning, no more/less than alt/az (sans wedge). Also, I use an e-focuser.

For imaging I operate it remotely (pointing and e-focusing) 10 feet away.

I can tell you that when I have the guide scope running on-screen and I do something on the scope that would cause shaking, by the time I walk back to the laptop the running image of the guide scope has settled. Another contributing factor (maybe) - I use the Celestron anti-vibration pads.

#15 barbarosa

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Posted 03 May 2013 - 03:30 PM

Thanks Katie.

I think the vibration/shake issue is off my list now.

I owned an 8 SE and the amount of shaking during focusing was irritating. I bought the pads and they helped. The CPC is such an improvement that I no longer use the pads, but I still have them.

#16 aamilo

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Posted 16 May 2013 - 07:32 PM

I owned an 8 SE and the amount of shaking during focusing was irritating. I bought the pads and they helped. The CPC is such an improvement that I no longer use the pads, but I still have them.


I found the exact same thing. The 8SE was a good scope but the mount on the CPC is so much better.






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