People are asking the connect methods of ASI2600MM Pro: How to use it with the new 36mm EFW? How to reach the 55mm back focus distance? What accessories I need and can I add the original OAG or OAG-L into my imaging train?

To get all of the answers of these questions, you need to read this instruction.

 

1. The Basic Connection Solution:

No filter wheel or filter drawer in this solution, only adapters or the original OAG.

Suitable for telescope up to f/4.8

APS-C format cooled camera - 55mm back focus length solution

 

You can change the T2-M48 16.5mm into the original OAG. But please note that the OAG will block the sensor in a bit if the thread of the end side of your telescope is M42.

 

2. Using 36mm EFW:

This solution can be divided into 3 cases: with the original OAG and adapters, or with the OAG-L, or with adapter only.

1) With the original OAG or adapters:

Suitable for telescopes up to f/5.4

APS-C format camera + 36mm EFW + OAG

 

In this case, the connection method can be very convenient with the use of threads. You can take the full advantage of the accessories you have. A few notes:

– The original OAG can be replaced to T2-M48 16.5mm extender;

– The original 36mm EFW and new 36mm EFW will both work;

– T2-T2 2mm adapter can be found in the package of 36mm EFW;

– The back focus distance in this case is 56mm;

– Like we mentioned above, the original OAG will block the sensor in a bit if the thread of the end side of your telescope is M42.

 

2)With OAG-L:

Suitable for telescopes up to f/4.2

 

连接OAG-L和新36mm-EFW-英文

You can leave the adapters aside and directly connect the new 36mm EFW to the camera via screws in this case, the distance from the sensor and the filter will also be much closer. A few notes:

– The M42 sensor tilt adapter attached to the camera need to be taken off;

– The original OAG can not be replace to OAG-L, but if you have the M68 OAG, you can also use the M68 OAG instead;

– This method does not support the telescopes with M42 threads at the end side.

– M48/54/68 sensor tilt adapter can be bought separately.

 

3)No OAG, with adapter only:

连接M42M-M48F-22.5L和36mm EFW-英文

This method only supports the telescopes with M42 or M48 threads at the end side。 The M42M-M48F 22.5mm extender needs to be bought separately.

 

3. Using 2” EFW:

Being the same as Solution #2, this solution can be divided into 2 cases: with the original OAG and adapters, or with the OAG-L.

1) With the original OAG or adapters:

APS-C format cooled camera + 2inch EFW

– The back focus distance in this case is 56mm;
APS-C format cooled camera + 2inch EFW + OAG

– The back focus distance in this case is 56mm;

 

2)With OAG-L:

连接OAG-L和2寸EFW-英文

This method is quite similar to Solution #2 → 2), so we do not go into details here.

 

4. Using 2” Filter Drawer:

APS-C format cooled camera + OAG

APS-C format cooled camera + M42 filter drawer

APS-C format cooled camera + M42 filter drawer + OAG

Above the 4 solutions for the ASI2600MM Pro APS-C camera to reach the 55mm back focus length. Indeed there are more than 4 solutions in total, but these are what we most recommend. If you have any questions about this guide, please do contact us, we are glad to help!

77 Responses to [ASI2600 Guide] 4 Connection methods to get 55mm back focus length
  1. Avatar

    Hello,

    What size is the screw to connect the new 36mm filter wheel to the camera body directly? I need more than I received in the box to finish. Thanks.




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  2. Avatar

    Hi,
    I already have 2600 Color and standard oag.
    Will it work with my new f/4 Newtonian telescope or I must buy the M68 oag?




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  3. Avatar

    I have the solution 3.1, EWF + OAG. I’m having a problem connecting directly the OAG and the EWF with the mentioned adapter, as the OAG when rotating will hit EWF case and cannot be connected completely. What other solutions beside adding M48 spacers?




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  4. Avatar

    Hello,

    If i understood correctly, i can use the wheel a filtre New 36mm EFW if i have a telescope open to f/5,6 with M48 OAG. But with its focal reducer at f/3,9, i can’t.
    Do i need to go 2 inches for it to work ? ( solution 3.2 ? )

    Thanks




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  5. Avatar

    Is there a way to attach the 2600mm to the two inch filter wheel without removing the tilt plate adapter and bolting it directly to the filter wheel? I would like to be able to thread the camera on to the wheel so I can remove it and attach it to a different setup without taking the filter wheel apart and unbolting it every time.




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  6. Avatar

    Hello! I have a 2600mm on the way and the new 36mm filter wheel. In some cases, I would like to use my Canon lens which requires 44mm of back focus. So, there is 12.5mm for the camera (minus the plate) plus 20mm for the filter wheel. So, what is needed is a EOS – M42 adapter that is 11.5 mm thick to connect the lens to the filter wheel. You have the EOS – M54 adapter that is 11.5 mm thick for the 2 inch filter wheel, but not one to work with the new 36mm filter wheel. Are there plans of making the EOS – M42 11.5 mm adapter? Thank you!




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  7. Avatar

    I want to connect my newton f4.5 with OAG and asi 2600 OSC. How should I do it – 1 solution has limit of f4,8 and i dont want to buy EFW for this. This limit of f4,8 is bit strange given in account that OAG will be taking light from shorter edge of sensor could You elaborate bit on this?




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  8. Avatar

    I have scope f4.5. how should connect scope with oag and camera not to have vignetting? Solution 1 is limited to f4.8




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  9. Avatar

    Hi
    I have the exact setup as described above with the M68 OAG. That is the 2600, the 2″ filter wheel, the M68 OAG fitted with the standard tilt/tip adaptor and a screw-in 2″ nosepiece. I find that when inserted into the focuser of my ED80 (f/7.5) or my RC10 (f/8), in both cases my 290 mm mini cannot come to focus when the main camera is in focus. It needs to be be inserted into the focuser further than it is able. If I push the guide camera as far in as it goes and screw the focuser all the way down and adjust the OTA draw tube to achieve guide cam focus, then the OTA draw tube needs to be wound out up to 11 mm further to achieve focus of the main camera. I cannot reduce the length of the OAG prism stalk as it will then be in the shadow of the 2″ nosepiece.
    Do I need the larger tilt/tip adaptor?
    Thanks
    John




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    • Avatar

      Could you confirm what adapter did you use to connect the tilt and scope? And which size of the thread on scope

      We don’t recommend M42 thread works with the M68 OAG. Because the prism should be moved up, but if it is M42, it will cover the prism.




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  10. Avatar

    I am trying to understand the f-ratio suitability values. What determines these and what specifically happens when you have a scope with lower values?




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    • Avatar

      f-ratio = Focal Length/Aperture




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      • Avatar

        I understand the definition of the f-ratio. I just wasn’t aware that there is suitability rating for different connection methods. It’s the first time I have seen this stated for cameras.

        To be clearer… what happens if a scope is at f/3.9 in case where the recommended limit is at f/4.2 for (2) with the M68 OAG? Are there going to be artifacts (vignetting, aberrations, etc.)?




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  11. Avatar

    I am trying to understand if the original OAG and original 36mm EFW will work with a 102mm F/7 telescope when used with a 0.74 reducer. With the reducer, this would be F/5.2, which is a slightly larger ratio than your stated F/5.4. Is this an acceptable setup, or would this configuration of telescope and reducer require the M68 OAG and new 36mm EFW?




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  12. Avatar

    Hi,

    Where we can find the M48 sensor tilt adaptor ?

    My dealer has not this item and i did not find it on your web site.

    Thanks.




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  13. Avatar

    Hello,
    Nice article, thank you.
    Question. I possess the ASI 2600 mc pro. Regarding the back focus, if I use a 0.8 focal reducer for ma ES 102 refactor, is the “the Basic Connection Solution” enough ? Or do I care about something else ?
    Thank you for your feedback.
    Best regards,
    A.




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  14. Avatar

    What’s the maximum distance the prism can adjust from the top of the M68 thread?

    My telescope thread is M48. When using with M68 OAG and M48 sensor tilt adaptor, I worry that, the prism may not be able to collect light from scope (block by M48 sensor tilt adaptor)!?

    Thanks.




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  15. Avatar

    I have the EFW mini with Astrodon 1.25″ NB filters…will this setup work with the ASI2600MM or do I need 2″ filters?




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  16. Avatar

    Why does ASI2600MM come with very small M42 sensor tilt adapter? And when using ASI2600MM with the M68 OAG, I have to buy bigger sensor tilt adapter for very high price (near 30$ if I’m not mistaken)!!! It’s a waste of money.




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  17. Avatar

    Where can I find the M48 sensor tilt adapter (shown above in the diagram)? I cannot find it in your shop.




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  18. Avatar

    Hi, I want to purchase the ASI2600MM special kit with the 36mm filters and M68 OAG.
    How do I select the above configuration (APS-C, 36mm New EFW and M68 OAG) ?

    Thanks
    Uri




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  19. Avatar

    Hi, I want to purchase the ASI2600MM package deal, when will you update the ASI2600MM page to show the above configurations ?
    Do you confirm the above configuration is final ?

    Thanks
    Uri




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  20. Avatar

    Hi, have just purchAsed the 2600 with m68 OAG and 2 inch 7×2 filter wheel. I also have a Celestron 0.7 reducer. Will I have to compensate for anything regusrfing back focus.?
    Will it still be 55mm?

    Thanks for your time.

    Neil.




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