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Red dot finder wobble


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Hi, I’m using the red dot finder that came with my Celestron Nexstar 8 se and I’ve been having trouble getting it aligned properly. I just noticed today that the finder isn’t tight, it has some play between it and the bit that connects to the scope, about 2-3 mm. Is this enough to affect the alignment or am I just a bad workman blaming his tools?

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That amount of movement will make it virtually impossible to align your RDF with your scope. You need to check the RDF and ensure that the movement isn’t originating from it itself. Then check the the mounting bracket on the telescope, that it’s secure and no movement. Once you have ensured all that is free from movement, fit the RDF into the shoe and tighten the holding screw(s)

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2 hours ago, bosun21 said:

That amount of movement will make it virtually impossible to align your RDF with your scope. You need to check the RDF and ensure that the movement isn’t originating from it itself. Then check the the mounting bracket on the telescope, that it’s secure and no movement. Once you have ensured all that is free from movement, fit the RDF into the shoe and tighten the holding screw(s)

Hi Bosun, I tightened every screw I could see and it still wobbles. The problem appears to be with the finder itself, I took it off and found that there’s play between the bit that screws onto the scope and the body of the finder; the two halves aren’t stable. I can’t figure out if it’s possible to tighten this as I can’t see any screws etc. I’m wondering if it’s worth getting a replacement sent out from Amazon (it’s only a few months old) or to cut my losses and buy an upgrade, I don’t want to end up with a replacement that has the same problem. The scope itself is great, I would just like to be able to point it at stuff without having to fish around for 15 minutes!

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Hi, here’s a couple of photos of my finder. The top down photo shows the direction of the wobble and in the side view I’ve pointed to the joint that seems to be loose. I can’t see any way to tighten this but I’m not very experienced! I had earmarked a Celestron dew ring as my next purchase but maybe I’ll upgrade the finder instead, what do you think?

Geo

67EB3D2A-402B-44DB-AD4F-20BFCD356F9C.jpeg

9D0ABBD3-8A2A-4D7B-91E5-CABD99549EEA.jpeg

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16 hours ago, Sunshine said:

Is this the star pointer pro? if so I had it before and gave it up as it would shake like a tuning fork and the slightest touch would sent it out of alignment.

Hi Sunshine, it’s listed as the star pointer, no pro. It does seem a bit flimsy and cheaply made so I might be ditching it as well,

Geo

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6 hours ago, Seoras said:

Hi, here’s a couple of photos of my finder. The top down photo shows the direction of the wobble and in the side view I’ve pointed to the joint that seems to be loose.

I have a C8 SE with the same style of finder.   Sorry I can't offer any further advice. I assume you have tightened the two long bolts that pass through the 2 inch long clamp under the finder body?   My finder is fairly rigid for what it is. 

Is there any way you can get someone familiar with these finders to take a look at it?

If you want to replace the whole thing, I recommend the Baader SkySurfer III finder.  I have had three of the basic red dot finders like the one in your photo and they all started acting up after a while and refusing to light up the red dot.

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2 hours ago, Cosmic Geoff said:

I have a C8 SE with the same style of finder.   Sorry I can't offer any further advice. I assume you have tightened the two long bolts that pass through the 2 inch long clamp under the finder body?   My finder is fairly rigid for what it is. 

Is there any way you can get someone familiar with these finders to take a look at it?

If you want to replace the whole thing, I recommend the Baader SkySurfer III finder.  I have had three of the basic red dot finders like the one in your photo and they all started acting up after a while and refusing to light up the red dot.

Hi Geoff, thanks for the advice. I went back to the scope and checked the two bolts but it’s still the same unfortunately, I think this one is a Friday afternoon job! I’ll have a look at the Badder finders but I’m starting to lean towards a right angled scope. I use a wheelchair and I struggle to get down far enough to use the red dot finder, I was hoping to put off getting an upgrade but I think it’s time now. If anyone on this thread can recommend one for less than £80 I would be very grateful,

 

Geo

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This one looks a bit different but I couldn't find any like yours- it's probably similar in how it clamps to the stalk. Could it be that one of the 2 clamping plates is upside down? They seem to be asymmetrical and if it was then I don't think it would clamp properly. Otherwise you could shim whichever is the loose side with a sliver of plastic material or thin card?

Mark

Celestron Starfinder 2.jpg

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1 hour ago, Seoras said:

Hi Geoff, thanks for the advice. I went back to the scope and checked the two bolts but it’s still the same unfortunately, I think this one is a Friday afternoon job! I’ll have a look at the Badder finders but I’m starting to lean towards a right angled scope. I use a wheelchair and I struggle to get down far enough to use the red dot finder, I was hoping to put off getting an upgrade but I think it’s time now. If anyone on this thread can recommend one for less than £80 I would be very grateful,

 

Geo

There you go, Seoras. This is the one I use:

https://www.firstlightoptics.com/finders/stellalyra-8x50-right-angled-correct-image-raci-finder-scope-with-bracket.html

 

Edited by cajen2
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33 minutes ago, markse68 said:

This one looks a bit different but I couldn't find any like yours- it's probably similar in how it clamps to the stalk. Could it be that one of the 2 clamping plates is upside down? They seem to be asymmetrical and if it was then I don't think it would clamp properly. Otherwise you could shim whichever is the loose side with a sliver of plastic material or thin card?

Mark

Celestron Starfinder 2.jpg

 

8 minutes ago, cajen2 said:

BTW, Mark is right. The side plates are specific as to which way up they are. Worth checking.

Thanks I’ll check that out tomorrow 😊

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14 minutes ago, cajen2 said:

This looks just the job, hopefully the suggestions of Mark and yourself will allow me to use the red dot finder until FLO send me the Stellalyra. I suppose having both couldn’t hurt, I noticed some people have both types on their scope

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34 minutes ago, Seoras said:

This looks just the job, hopefully the suggestions of Mark and yourself will allow me to use the red dot finder until FLO send me the Stellalyra. I suppose having both couldn’t hurt, I noticed some people have both types on their scope

You need to keep the RDF so that you can tell where the right angled scope is pointing, else you won't know which stars you are looking at in your finder. 

With regards to the RDF, I had a similar issue with a Bresser one. The problem was not in the connection of the finder to the stalk, but backlash in the horizontal adjustment mechanism of the finder. I solved the problem by adding a small spring and a couple of tiny washers I had lying around over the screw that forms the adjustment rod, as shown in the photo below. In my mind I thought the spring came out of a pen, but it looks a bit short for that, perhaps I cut it down to size. 

DSC_3462.thumb.JPG.898a4b83c5e211a4818101726a690cec.JPG

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13 hours ago, Ricochet said:

You need to keep the RDF so that you can tell where the right angled scope is pointing, else you won't know which stars you are looking at in your finder. 

With regards to the RDF, I had a similar issue with a Bresser one. The problem was not in the connection of the finder to the stalk, but backlash in the horizontal adjustment mechanism of the finder. I solved the problem by adding a small spring and a couple of tiny washers I had lying around over the screw that forms the adjustment rod, as shown in the photo below. In my mind I thought the spring came out of a pen, but it looks a bit short for that, perhaps I cut it down to size. 

DSC_3462.thumb.JPG.898a4b83c5e211a4818101726a690cec.JPG

Thanks Ricochet, you’re spot on! This is the problem with my one, I’ll root around in my garage for some washers and springs and see if I can do anything with it. 

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Many thanks to everyone for your help with this, it’s good to know I have somewhere to go if I’m not sure about something, on some forums I use the people can be a bit condescending or even nasty but everyone here has been so helpful and friendly, thanks again 

 

Geo

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14 hours ago, Ricochet said:

You need to keep the RDF so that you can tell where the right angled scope is pointing, else you won't know which stars you are looking at in your finder. 

With regards to the RDF, I had a similar issue with a Bresser one. The problem was not in the connection of the finder to the stalk, but backlash in the horizontal adjustment mechanism of the finder. I solved the problem by adding a small spring and a couple of tiny washers I had lying around over the screw that forms the adjustment rod, as shown in the photo below. In my mind I thought the spring came out of a pen, but it looks a bit short for that, perhaps I cut it down to size. 

DSC_3462.thumb.JPG.898a4b83c5e211a4818101726a690cec.JPG

I did wonder about that after looking at some images of one taken apart on CN. It's astonishing that they don't fit springs as standard on a part that needs to be accurate to work and is made so cheaply!

Mark

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1 hour ago, markse68 said:

I did wonder about that after looking at some images of one taken apart on CN. It's astonishing that they don't fit springs as standard on a part that needs to be accurate to work and is made so cheaply!

Mark

Yes, it seems to be poorly made, maybe I’ve been unlucky with this one as everything else from Celestron seems to be reasonable quality, to me at least. I’m going to follow cajen2’s recommendation and get the Stellalyra Finder scope, hopefully that’ll make life a bit easier!

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20 minutes ago, Seoras said:

Yes, it seems to be poorly made, maybe I’ve been unlucky with this one as everything else from Celestron seems to be reasonable quality, to me at least. I’m going to follow cajen2’s recommendation and get the Stellalyra Finder scope, hopefully that’ll make life a bit easier!

Raci finders are nice for starhopping and fine targeting but like Ricochet mentioned they’re not very good for initial pointing- there a red dot or Rigel finder excel so worth getting this one going or there’s some for sale in the classifieds. 

Mark

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2 hours ago, cajen2 said:

Yes. I use an RDF AND a RACI - best of both worlds. To keep things tidy, you can buy a double mount which accommodates both. Here's mine:

IMG_20221101_162829.thumb.jpg.500d1b9688b43b3d6f5b4e9d51db6fa6.jpg

 

 

The three-way versions are sold for around £14 - £16 posted, by various Chinese suppliers on the Bay (and I see a couple from Belgium at the moment). For some reason the two-way versions don't seem to come up nearly as often. There's a used one there at the moment, but he wants as much as a new 3-way.

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5 hours ago, Seoras said:

Thanks Ricochet, you’re spot on! This is the problem with my one, I’ll root around in my garage for some washers and springs and see if I can do anything with it. 

Glad I could help. Good luck with your spring hunt. 

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