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Sear's Discoverer 4-6333 A Not Able To Focus

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#1 AMStarGazer

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Posted 08 July 2024 - 03:24 PM

Last week I purchased a used Sear's Discoverer 4-6333 A telescope on Ebay.  Paid a fair amount of money for it, so I was really anticipating that it would work.  I've run into a problem.  I am unable to get it to focus.  The only thing I get is a blurry image through the eyepiece.  I'm using the 22mm eyepiece.  No matter what I'm looking at through the scope, as I'm turning the focus knob in the direction that brings the eyepiece inward towards the telescope body, the focus starts getting better, but just doesn't get focused and I can't turn the knob anymore.  The eyepiece tube is all the way in by that time.

 

Is there something I'm not doing correctly?  The scope didn't come with an owners/operators manual.  I looked it up online and see that the manufacturer instructs the user to use the 22mm eyepiece when starting out.  Pull the eyepiece tube about halfway out and then use the knob focuser to sharpen the image.  I get nothing but blur and it only starts getting better as I push the tube all the way in and turn the focus knob to where it brings the entire eyepiece assembly closer to the scope.

 

I think it's going to be a pain to try and return it to who I bought it from on ebay.  Cosmetically the telescope is very good.  I hope that it's something that I can solve/fix relatively easily.  Any ideas on what I'm doing wrong or what is wrong with the telescope?  Before I dig into the telescope and try and fix anything, can someone provide perhaps a diagram of how the eyepieces are assembled, how the objective lenses are assembled in the telescope?

 

Without an eyepiece in the scope, I look through the telescope and the image I'm seeing through the scope without an eyepiece installed looks blurry as well.  Is that they way it's supposed to be?  Is there a way to adjust anything inside the scope?  I have to wonder if anything has been removed inside of the scope. Is there anything like a lens between the objective lens(s) and the eyepiece?  Something just isn't right.  The seller stated that it worked the last time they had tried it.  I'm looking at terrestrial objects during daytime (light) at various ranges, quarter of a mile and up to one mile away.  All blurry.  The first night I had the scope, I took it out and couldn't focus a single star.  The next day I took it out during the daytime and still unable to focus on anything.  It's like if the focus knob could turn one more turn to bring the eyepiece assembly closer towards the telescope body, it might sharpen the  image.

 

Any help is greatly appreciated.

 

 



#2 SpikeFalcon

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Posted 08 July 2024 - 03:40 PM

Greetings, are you using a star diagonal or porro prism? The eyepiece goes into either one, then into the focuser tube. The star diagonal is for astronomy, the porro prism is for correct image terrestrial viewing. Also, does the big objective lens on the front end of the scope look cloudy or dirty? Good luck, hope you get it working. Should be good for the Moon and brighter planets.



#3 Kasmos

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Posted 08 July 2024 - 05:59 PM

Last week I purchased a used Sear's Discoverer 4-6333 A telescope on Ebay.  Paid a fair amount of money for it, so I was really anticipating that it would work.  I've run into a problem.  I am unable to get it to focus.  The only thing I get is a blurry image through the eyepiece.  I'm using the 22mm eyepiece.  No matter what I'm looking at through the scope, as I'm turning the focus knob in the direction that brings the eyepiece inward towards the telescope body, the focus starts getting better, but just doesn't get focused and I can't turn the knob anymore.  The eyepiece tube is all the way in by that time.

 

Is there something I'm not doing correctly?  The scope didn't come with an owners/operators manual.  I looked it up online and see that the manufacturer instructs the user to use the 22mm eyepiece when starting out.  Pull the eyepiece tube about halfway out and then use the knob focuser to sharpen the image.  I get nothing but blur and it only starts getting better as I push the tube all the way in and turn the focus knob to where it brings the entire eyepiece assembly closer to the scope.

 

I think it's going to be a pain to try and return it to who I bought it from on ebay.  Cosmetically the telescope is very good.  I hope that it's something that I can solve/fix relatively easily.  Any ideas on what I'm doing wrong or what is wrong with the telescope?  Before I dig into the telescope and try and fix anything, can someone provide perhaps a diagram of how the eyepieces are assembled, how the objective lenses are assembled in the telescope?

 

Without an eyepiece in the scope, I look through the telescope and the image I'm seeing through the scope without an eyepiece installed looks blurry as well.  Is that they way it's supposed to be?  Is there a way to adjust anything inside the scope?  I have to wonder if anything has been removed inside of the scope. Is there anything like a lens between the objective lens(s) and the eyepiece?  Something just isn't right.  The seller stated that it worked the last time they had tried it.  I'm looking at terrestrial objects during daytime (light) at various ranges, quarter of a mile and up to one mile away.  All blurry.  The first night I had the scope, I took it out and couldn't focus a single star.  The next day I took it out during the daytime and still unable to focus on anything.  It's like if the focus knob could turn one more turn to bring the eyepiece assembly closer towards the telescope body, it might sharpen the  image.

 

Any help is greatly appreciated.

Just to be sure, since they can be very stiff from non use, are you pulling it out by the inner pull tube?

 

To be more clear, the chrome focuser's tube is a two piece type with a smaller pull tube inside of a slightly larger one that moves via the focusing knobs.

As seen below

Penncrest focuser.jpg

The black arrows points to the larger tube that is controled by the knobs for fine focus. In this photo it is racked all the way in.

The white arrows are the smaller diameter pull tube that slides inside it and is pulled out for rough focus.

That's the one that should be pulled out some before trying to focus with the knobs.

 

More than once a newcomer has had this problem, so I'm very sure that rechecking what you are doing will solve your problem.


Edited by Kasmos, 08 July 2024 - 06:02 PM.

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#4 Kasmos

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Posted 08 July 2024 - 06:20 PM

BTW, when they are stiff I focus the outer tube out enough so I can grip it when I pull on the inner pull tube. That way I don't put stress on the pinion gear and the  rack teeth.



#5 DAVIDG

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Posted 08 July 2024 - 09:43 PM

 This sounds to me like a problem with the lens. Anytime you buy a used telescope you never know what has been done to it and with refractor it is quite common that someone in the past  took the lens out and got it back in either totally backwards or one of the elements  is flipped.

   Are the air gap spacers still in place ? Are there 3 of them and are they at a 120° centers ?  Does the slots in the retainer show signs that in has been unscrewed as in the slots are distorted and/or the finish has been worn off with metal exposed ? Any of these signs are strong indication that the lens has been tempered with. When you look into the lens from the front you should be able to see the edges of the two elements in the cell. The thinner edge should be in the front and the thicker edge in the back. If not the lens is in backwards. If the elements look in the correct order then  the front element  maybe flipped over which is very common mistake that is made in when a novice reassembles a lens.

 

           - Dave 


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#6 deSitter

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Posted 08 July 2024 - 10:33 PM

 This sounds to me like a problem with the lens. Anytime you buy a used telescope you never know what has been done to it and with refractor it is quite common that someone in the past  took the lens out and got it back in either totally backwards or one of the elements  is flipped.

   Are the air gap spacers still in place ? Are there 3 of them and are they at a 120° centers ?  Does the slots in the retainer show signs that in has been unscrewed as in the slots are distorted and/or the finish has been worn off with metal exposed ? Any of these signs are strong indication that the lens has been tempered with. When you look into the lens from the front you should be able to see the edges of the two elements in the cell. The thinner edge should be in the front and the thicker edge in the back. If not the lens is in backwards. If the elements look in the correct order then  the front element  maybe flipped over which is very common mistake that is made in when a novice reassembles a lens.

 

           - Dave 

I agree, first thought - the lens has been replaced with one that has too short a focal length. To the OP, tell us the specs on the badge.

 

-drl



#7 deSitter

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Posted 08 July 2024 - 11:12 PM

Try pointing it at something really close, like in your yard. Even in the house. Tell us what you see. As mentioned, the drawtube may be stuck all the way out. Looking at something close will allow it to come to focus no matter what the state of the drawtube.

 

-drl


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#8 DAVIDG

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Posted 09 July 2024 - 09:15 AM

 I believe the 6333 is  a 60mm with 900mm focal length.  The Moon is now visible in the evening sky so point the scope at the Moon and with no eyepiece or diagonal in the focuser hold a white card behind the focuser  and move  the card back and forth until the image of the Moon is sharply in focus on the card.   If the focal length is 900mm  the sharply focused Moon  on the card should be  about 900mm or 35.5"  behind the main objective lens.  That distance is were the end of the focuser should be to start  when your looking at  an object at infinity ie the stars. With the diagonal and eyepiece in place you'll need to rack the focuser inward around 2" to compensate for the light path through the diagonal to get a sharp focus in the eyepiece.

  If you can't get things to come to sharp focus close to the position you started from,  by focusing only few inches around the 900mm position  or if  the Moon comes to focus on the white card is off from the 900mm ( 35.5" )  by a good amount then something is wrong with the main objective lens.

 

                 - Dave 


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#9 AMStarGazer

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Posted 09 July 2024 - 12:54 PM

Great information.  Thank you all so much for this.  I greatly appreciate it.  Yes, the 6333 is the 60mm 900 focal length.  That inner tube that the white arrows point at, when that is fully extended, does it have play where it moves around a bit?  This is how it is on the scope that I have when that piece is extended outward.

 

In reference to the objective lens assembly, how many lenses are in this assembly?  Also mentioned are three air gap spacers.  Where exactly are these located in reference to each of the lens in the assembly?  

 

I did try and focus on something very close, but it's just as blurry as it is when trying to focus on something far away.  I've also tried using a combination of diagonal with the image correction component and without.  No difference at all.  Everything still blurry.

 

I've got to wonder if the objective lens assembly was at some point removed and then reinstalled incorrectly.

 

For the focus assembly, is there any type of lens' inside of it and/or an adjustment of any type?

 

The objective lens' are clean and crisp.  No dirt, dust, debris or discoloration/cloudiness at all.  When I have the eyepiece out of the scope, I can look through the opening where the eyepiece mounts, I can see a crystal clear/sharp image when looking through the scope at something a few feet from the telescope with the eyepiece out.

 

How about the eyepieces themselves?  Could there be something wrong with them besides cloudiness or discoloration?  Holding them at a distance away, I can see a clean, clear upside-down image through them.

 

Thanks again for all this great information.  Looking forward to any more info.


Edited by AMStarGazer, 09 July 2024 - 01:04 PM.


#10 deSitter

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Posted 09 July 2024 - 01:04 PM

Great information.  Thank you all so much for this.  I greatly appreciate it.  Yes, the 6333 is the 60mm 900 focal length.  That inner tube that the white arrows point at, when that is fully extended, does it have play where it moves around a bit?  This is how it is on the scope that I have when that piece is extended outward.

 

In reference to the objective lens assembly, how many lenses are in this assembly?  Also mentioned are three air gap spacers.  Where exactly are these located in reference to the lens assembly?  

 

I did try and focus on something very close, but it's just as blurry as it is when trying to focus on something far away.  I've also tried using a combination of diagonal with the image correction component and without.  No difference at all.  Everything still blurry.

 

I've got to wonder if the objective lens assembly was at some point removed and then reinstalled incorrectly.

 

For the focus assembly, is there any type of lens' inside of it and/or an adjustment of any type?

 

The objective lens' are clean and crisp.  No dirt, dust, debris or discoloration/cloudiness at all.  When I have the eyepiece out of the scope, I can look through the opening where the eyepiece mounts, I can see a crystal clear/sharp image when looking through the scope at something a few feet from the telescope with the eyepiece out.

 

How about the eyepieces themselves?  Could there be something wrong with them besides cloudiness or discoloration?  Holding them at a distance away, I can see a clean, clear upside-down image through them.

 

Thanks again for all this great information.  Looking forward to any more info.

Don't worry about any of this - push the inner tube all the way in and do as DAVIDG suggested. You can even do this during the day - point it at something distant with a lot of contrast like a tree line.

 

-drl



#11 AMStarGazer

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Posted 09 July 2024 - 02:52 PM

 I believe the 6333 is  a 60mm with 900mm focal length.  The Moon is now visible in the evening sky so point the scope at the Moon and with no eyepiece or diagonal in the focuser hold a white card behind the focuser  and move  the card back and forth until the image of the Moon is sharply in focus on the card.   If the focal length is 900mm  the sharply focused Moon  on the card should be  about 900mm or 35.5"  behind the main objective lens.  That distance is were the end of the focuser should be to start  when your looking at  an object at infinity ie the stars. With the diagonal and eyepiece in place you'll need to rack the focuser inward around 2" to compensate for the light path through the diagonal to get a sharp focus in the eyepiece.

  If you can't get things to come to sharp focus close to the position you started from,  by focusing only few inches around the 900mm position  or if  the Moon comes to focus on the white card is off from the 900mm ( 35.5" )  by a good amount then something is wrong with the main objective lens.

 

                 - Dave 

Great.  I'll try that tonight and report back with the results.  Thank you.



#12 Kasmos

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Posted 09 July 2024 - 02:54 PM

Great information.  Thank you all so much for this.  I greatly appreciate it.  Yes, the 6333 is the 60mm 900 focal length.  That inner tube that the white arrows point at, when that is fully extended, does it have play where it moves around a bit?  This is how it is on the scope that I have when that piece is extended outward.

 

In reference to the objective lens assembly, how many lenses are in this assembly?  Also mentioned are three air gap spacers.  Where exactly are these located in reference to each of the lens in the assembly?  

 

I did try and focus on something very close, but it's just as blurry as it is when trying to focus on something far away.  I've also tried using a combination of diagonal with the image correction component and without.  No difference at all.  Everything still blurry.

 

I've got to wonder if the objective lens assembly was at some point removed and then reinstalled incorrectly.

 

For the focus assembly, is there any type of lens' inside of it and/or an adjustment of any type?

 

The objective lens' are clean and crisp.  No dirt, dust, debris or discoloration/cloudiness at all.  When I have the eyepiece out of the scope, I can look through the opening where the eyepiece mounts, I can see a crystal clear/sharp image when looking through the scope at something a few feet from the telescope with the eyepiece out.

 

How about the eyepieces themselves?  Could there be something wrong with them besides cloudiness or discoloration?  Holding them at a distance away, I can see a clean, clear upside-down image through them.

 

Thanks again for all this great information.  Looking forward to any more info.

I'll answer those questions in order

 

There may be some play in the pull tube, less play as in no droop is better, but you really shouldn't have it extended all the way out when using the star diagonal for astro use. Also, even with some play it should come to focus.

 

There are two lenses inside the objective cell.

On your model of scope there will not be 3 spacers between them, but instead these scopes have a ring spacer between them.

Lens Crown-Flint.jpg

This is how they should be arranged, with the more convex side of the Crown facing the Flint.

And with a ring spacer between them.

spacer-rings.jpg

This is from a similar scope and shows the 2 lenses and 2 plastic spacer rings.

There should only be 1 ring between them and some (like mine) have another behind the flint.

Don't worry if yours has only one.

Also, older models have 1 metal spacer ring instead of plastic.

I wouldn't suggest taking it apart just yet as it's very easy to damage the lenses when removing them and putting them back in.

It's also very easy to get them in the wrong order.

 

The Star Diagonal and Image Erector are not designed to be used together.

 

There is not suppose to be any lens inside the focuser.

The only adjustments that can be made is the tension on the pinion gear , which doesn't affect the focus.

 

Yes it's possible that there's something wrong with the eyepiece, but it's hard to say what it might be without seeing it in person or trying another one in the scope.

 

Before tearing into the objective or an eyepiece I still kind of think you could be having some kind of problem with how you are going about focusing it.


Edited by Kasmos, 09 July 2024 - 02:57 PM.

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#13 tony_spina

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Posted 09 July 2024 - 07:06 PM

It would be helpful if you posted some pictures in the configuration that you are trying to use it. Back end by the focuser and diagonal 

Also a picture of the front showing  the lenses. If you can take the dew shield off so we can see the lenses better 



#14 AMStarGazer

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Posted 09 July 2024 - 07:49 PM

I'll answer those questions in order

 

There may be some play in the pull tube, less play as in no droop is better, but you really shouldn't have it extended all the way out when using the star diagonal for astro use. Also, even with some play it should come to focus.

 

There are two lenses inside the objective cell.

On your model of scope there will not be 3 spacers between them, but instead these scopes have a ring spacer between them.

attachicon.gif Lens Crown-Flint.jpg

This is how they should be arranged, with the more convex side of the Crown facing the Flint.

And with a ring spacer between them.

attachicon.gif spacer-rings.jpg

This is from a similar scope and shows the 2 lenses and 2 plastic spacer rings.

There should only be 1 ring between them and some (like mine) have another behind the flint.

Don't worry if yours has only one.

Also, older models have 1 metal spacer ring instead of plastic.

I wouldn't suggest taking it apart just yet as it's very easy to damage the lenses when removing them and putting them back in.

It's also very easy to get them in the wrong order.

 

The Star Diagonal and Image Erector are not designed to be used together.

 

There is not suppose to be any lens inside the focuser.

The only adjustments that can be made is the tension on the pinion gear , which doesn't affect the focus.

 

Yes it's possible that there's something wrong with the eyepiece, but it's hard to say what it might be without seeing it in person or trying another one in the scope.

 

Before tearing into the objective or an eyepiece I still kind of think you could be having some kind of problem with how you are going about focusing it.

Wow, that's some great information.  Greatly appreciate that dissassembled view of the components.    Very helpful.



#15 AMStarGazer

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Posted 09 July 2024 - 07:50 PM

It would be helpful if you posted some pictures in the configuration that you are trying to use it. Back end by the focuser and diagonal 

Also a picture of the front showing  the lenses. If you can take the dew shield off so we can see the lenses better 

I'll get some pix of these and post them tomorrow.  


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#16 Senex Bibax

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Posted 10 July 2024 - 08:05 AM

I hope you solve the mystery quickly. I had a 6333 and the views were sharp as a pin. The simplest mistake that a previous owner might have made is to remove the objective lens pair and reinstall them flipped upside down (without having separated the two halves).

 

Regarding the inner and outer tubes of the focuser, if they seem to have a loose fit  or excess play, there are three small felt or fibre pads that are spaced evenly around the inside of each end of the outer tube, which help to keep the inner tube centred. If any are worn or missing then you will bet some "slop". IIRC the 6333 focuser also has a small thumbscrew on the top rear edge of the outer tube which can be finger-tightened to lock or free the inner tube.

 

Also, if you look at the bottom of the focuser, there should be a covering with two screws over the pinion gear. Very slight adjustments to those screws will make a big difference to the smoothness and ease of the focus knobs.



#17 AMStarGazer

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Posted 10 July 2024 - 11:55 AM

Problem Solved!  This scope didn't come with a user manual, so I figured it worked basically just like my 14 Edge HD, meaning, I could use both the diagonal and the image erector component at the same time, even though on the 14 Edge, the diagonal and image erector is just one component providing both services.    Kasmos mentioned that little tidbit in his post and I remembered to try that.   I had tried using the scope the previous night without both of those together installed.  I guess I didn't try hard enough.  Glad I didn't have to try and take the telescope apart.    Thank you everyone for the help.  I greatly appreciate all of the suggestions/replies that everyone provided in a prompt and timely manner.

 

I was able to view the moon last night for an hour before it went down below the horizon.  Now I'm good with spending a fair amount for the scope, it works.  All good.

 

Thank you.


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#18 deSitter

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Posted 10 July 2024 - 12:02 PM

Problem Solved!  This scope didn't come with a user manual, so I figured it worked basically just like my 14 Edge HD, meaning, I could use both the diagonal and the image erector component at the same time, even though on the 14 Edge, the diagonal and image erector is just one component providing both services.    Kasmos mentioned that little tidbit in his post and I remembered to try that.   I had tried using the scope the previous night without both of those together installed.  I guess I didn't try hard enough.  Glad I didn't have to try and take the telescope apart.    Thank you everyone for the help.  I greatly appreciate all of the suggestions/replies that everyone provided in a prompt and timely manner.

 

I was able to view the moon last night for an hour before it went down below the horizon.  Now I'm good with spending a fair amount for the scope, it works.  All good.

 

Thank you.

Welcome to the club! These old instruments were made with precision and often perform far above their class.

 

-drl




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