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C8 HD hyperstar V3 wrong adapter?

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#1 msacco

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Posted 15 December 2019 - 03:24 AM

Hi, I've bought a C8 HD hyperstar from opt second hand and I've received a filter adapter with it which as far as I'm aware should be used for backfocus.

Yesterday I tried my first attempt but unfortunately I think I just didn't manage to reach the required backfocus, after checking this further I believe I might've received an adapter that doesn't fit for me?

 

Here is what the starizona C8 adapter should look like: https://starizona.co...mera-adapter-c8

But this is what I received: https://optcorp.com/...er-celestron-c8

 

Here are a few more pictures:

https://i.imgur.com/vS7tFXh.png

https://i.imgur.com/qw3WcVv.png

 

Sort of comparison: https://i.imgur.com/Kq2eZGL.png You can see that the bottom of the one on the right is bigger than the one on the left.

 

I've also found the same here: https://www.highpoin...c8-hsca-c8-cust

Is it possibly a custom adapter? Would love to know what you think. Thanks!



#2 GregsCNAccount

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Posted 18 December 2019 - 08:25 PM

The adapter you need is specific to the camera you are using.  I presume you have a version 3 Hyperstar.  The backfocus for the C8 Hyperstar V3 is 39.8 mm.  In my case I use my Hyperstar with a QHY10 camera that uses up 20 mm of backfocus.  So the correct adapter for me is 19.8 mm long.  If your camera uses up more than 39.8 mm of backfocus, you are out of luck.  That is why DSLRs with 55 mm cannot be used on the C8 V3 Hyperstar.


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#3 msacco

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Posted 21 December 2019 - 12:55 PM

The adapter you need is specific to the camera you are using.  I presume you have a version 3 Hyperstar.  The backfocus for the C8 Hyperstar V3 is 39.8 mm.  In my case I use my Hyperstar with a QHY10 camera that uses up 20 mm of backfocus.  So the correct adapter for me is 19.8 mm long.  If your camera uses up more than 39.8 mm of backfocus, you are out of luck.  That is why DSLRs with 55 mm cannot be used on the C8 V3 Hyperstar.

This is exactly what drives me crazy....Take a look at the image I've attached to the post.

 

As you can see the adapter is 22.3mm, I'm using the ASI071MC pro, so the backfocus from the thread to the sensor is 17.5mm, so......

22.3 + 17.5 = 39.8mm, it should be spot on as far as I understand! And yet, it's not...I did make sure that the pull/push screws are at 0 position, I have also tried using a 4mm extension and that actually seems like it helped a bit with the results(not that much though...).

 

I'm kinda lost, wondering what I can do. Thanks for the help.

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#4 pyrasanth

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Posted 21 December 2019 - 03:16 PM

You might be measuring from the wrong position on the attachment (can't really see on the picture)- your 22.3 mm is including the end of the thread that gets lost in the camera. You can probably chop a few mm off that reading. The only exception to this is if the thread extends a little from the camera but again the measurement would be shorter. If the camera sits nearly flush with the top of the adapter then that is where you should measure from. There could also be + or - 0.5 mm in the camera back focus tolerance.

 

The reason your extension is helping a bit is that it is extending the length of the back focus & getting you closer to where you need to be.


Edited by pyrasanth, 21 December 2019 - 03:35 PM.

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#5 msacco

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Posted 22 December 2019 - 01:30 AM

You might be measuring from the wrong position on the attachment (can't really see on the picture)- your 22.3 mm is including the end of the thread that gets lost in the camera. You can probably chop a few mm off that reading. The only exception to this is if the thread extends a little from the camera but again the measurement would be shorter. If the camera sits nearly flush with the top of the adapter then that is where you should measure from. There could also be + or - 0.5 mm in the camera back focus tolerance.

 

The reason your extension is helping a bit is that it is extending the length of the back focus & getting you closer to where you need to be.

According to what I've checked in a few places and friends, this is the correct way to measure this.

Since the adapter itself has a thread connected as well which is not measured here, the outer thread that connects to the camera should 'cancel each other' and eventually result in the correct measurement, but I might be wrong.

 

Still, if I'm missing even 1mm, 4mm extension sholdn't make it better I believe as it should take me 'too far'?



#6 pyrasanth

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Posted 22 December 2019 - 07:22 AM

According to what I've checked in a few places and friends, this is the correct way to measure this.

Since the adapter itself has a thread connected as well which is not measured here, the outer thread that connects to the camera should 'cancel each other' and eventually result in the correct measurement, but I might be wrong.

 

Still, if I'm missing even 1mm, 4mm extension sholdn't make it better I believe as it should take me 'too far'?

Hard to say. I would measure the entire assemble length and go from there because clearly some information is not being correctly applied.


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#7 elmiko

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Posted 22 December 2019 - 10:03 AM

Send the one that you ordered back and get the one from Starizona. It's obvious to me by comparing the two pictures you posted, that the one you bought places the filter in a different location or distance from the sensor. This could be the problem.

Remember at f/1.9 the slightest bit that backspace is off can effect the Hyperstar performance! The required backspace is 39.8 mm + - .5 mm so very sensitive to backspace error.



#8 msacco

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Posted 22 December 2019 - 10:20 AM

Hard to say. I would measure the entire assemble length and go from there because clearly some information is not being correctly applied.

What should I compare it to?

 

Send the one that you ordered back and get the one from Starizona. It's obvious to me by comparing the two pictures you posted, that the one you bought places the filter in a different location or distance from the sensor. This could be the problem.

Remember at f/1.9 the slightest bit that backspace is off can effect the Hyperstar performance! The required backspace is 39.8 mm + - .5 mm so very sensitive to backspace error.

You mean the whole unit, or the adapter only? I'm completely aware of the fact that with such high speed of f/2.1(this is the V3) the slighest backfocus difference could make a huge impact.

I'm just not totally sure how I could check that. I've tried to contact starizona, but they didn't answer me.



#9 elmiko

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Posted 22 December 2019 - 10:30 AM

Did you buy the whole Hyperstar system from opt? I thought you already had the Hyperstar but ordered the adapter separate.

Are you in the states?



#10 elmiko

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Posted 22 December 2019 - 10:34 AM

Either way you may have to spend the 100.00 dollars for the proper adapter from Starizona. Or better yet, make opt exchange the adapter for the proper one.



#11 msacco

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Posted 22 December 2019 - 10:46 AM

Did you buy the whole Hyperstar system from opt? I thought you already had the Hyperstar but ordered the adapter separate.

Are you in the states?

Yes I have bought the whole system from opt, when you buy a hyperstar you also get an adapter, so I guess this is what I got. They did ask me whether I have the correct scope and camera(c8 edge + ASI071), so they should've known what should work I guess, but I don't know..

 

Either way you may have to spend the 100.00 dollars for the proper adapter from Starizona. Or better yet, make opt exchange the adapter for the proper one.

I will try to contact them about this. Since it's sunday I'm waiting for tomorrow.


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#12 elmiko

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Posted 22 December 2019 - 10:47 AM

Good luck, ask for Dean or Steve. They know what they are doing!



#13 msacco

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Posted 22 December 2019 - 10:59 AM

Good luck, ask for Dean or Steve. They know what they are doing!

Thanks!! :)


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#14 GregsCNAccount

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Posted 22 December 2019 - 10:09 PM

The  39.8 mm backfocus in the actual physical path, so the male thread is not included in the length of the adapter.  The assumption is that the adapter screws completely into the female threads on the camera.  If that is not the case the gap between the adapter and the camera needs to be taken into account.


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#15 msacco

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Posted 23 December 2019 - 05:57 AM

The  39.8 mm backfocus in the actual physical path, so the male thread is not included in the length of the adapter.  The assumption is that the adapter screws completely into the female threads on the camera.  If that is not the case the gap between the adapter and the camera needs to be taken into account.

Just to make sure I understood correctly, can you please draw somehow how I should measure it?



#16 elmiko

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Posted 23 December 2019 - 08:16 AM

Measure where I painted the red marks. Don't include the threads. 

It should measure 22.3 mm. 22.3+ 17.5= 39.8

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Edited by elmiko, 23 December 2019 - 08:28 AM.

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#17 msacco

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Posted 23 December 2019 - 12:23 PM

Measure where I painted the red marks. Don't include the threads. 

It should measure 22.3 mm. 22.3+ 17.5= 39.8

I'm not home yet, but as far as I can see my adapter is obviously not 22.3mm, which means...I got the wrong adapter?

By the way, what is your equipment? Is it C8 edge with an atik camera? Does the backfocus of the camera is 17.5mm as well? Should this set up in theory work for my case as well?

 

Thanks!


Edited by msacco, 23 December 2019 - 01:01 PM.


#18 elmiko

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Posted 23 December 2019 - 01:01 PM

I thought the same thing. You have to realize though , my Atik camera has only 6.5 mm space between the sensor and camera front. So my Hyperstar spacer would be longer than yours. Just measure yours when you get home.

Hope you can get this fixed.



#19 msacco

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Posted 23 December 2019 - 01:11 PM

I thought the same thing. You have to realize though , my Atik camera has only 6.5 mm space between the sensor and camera front. So my Hyperstar spacer would be longer than yours. Just measure yours when you get home.

Hope you can get this fixed.

I will :)

I also just realized, I could print some M42 spacers with my 3D printer, something like this:

https://www.aliexpre....14354c4dDcUifV

 

Except I could print whatever thickness I need. Hope that might help.


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#20 elmiko

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Posted 23 December 2019 - 01:32 PM

Sounds like a great idea!



#21 msacco

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Posted 23 December 2019 - 03:11 PM

Sounds like a great idea!

So..........According to my measurements the length of the adapter is 16.7/16.8mm, pretty far from the needed 22.3mm smile.gif

Which means that I need around 5.5mm I believe, this is rather weird though, as I have tried using a 5mm extension and also a 4mm extension and it seems like the 4mm was much better than 5mm, I would expect it to be opposite?

 

Would love to hear what do you think. Also, the measurement for your adapter is 22.3mm?


Edited by msacco, 23 December 2019 - 03:19 PM.


#22 elmiko

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Posted 23 December 2019 - 03:20 PM

Try the best one! I had to bring my whole setup to Starizona a couple weeks ago to get my spacing correct. I just couldn't get good looking stars. No matter how I tried to collimate. They decided that my mirror is a bit under corrected. So, to compensate they reduced my spacing by .5 mm . Remember at f/2 spacing is more critical than at f/ 6 or f/ 10!

At f/2 everything shows, whether it is bad focus or spacing not exactly correct!

Good luck!



#23 msacco

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Posted 23 December 2019 - 04:20 PM

Try the best one! I had to bring my whole setup to Starizona a couple weeks ago to get my spacing correct. I just couldn't get good looking stars. No matter how I tried to collimate. They decided that my mirror is a bit under corrected. So, to compensate they reduced my spacing by .5 mm . Remember at f/2 spacing is more critical than at f/ 6 or f/ 10!

At f/2 everything shows, whether it is bad focus or spacing not exactly correct!

Good luck!

Yes I'm well aware of this! Unfortunately since I'm not from the US I don't think I'll be able to get such service :\

I've contact opt so I'll wait for them to get back to me.


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#24 msacco

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Posted 25 December 2019 - 01:44 AM

In anyone gives a ****, I've so far contact starizona and they confirmed that I didn't recieve the correct adapter.

 

I'm currently waiting for opt to reply to me.


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