M48 adapter for FW8G-Aluma

Discussion in 'Aluma Series' started by Robert Kilby, Oct 13, 2019.

  1. Robert Kilby

    Robert Kilby Cyanogen Customer

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    I would like to buy an Aluma 8300 with the GW8G to use with my Stellarvue svx-80T, which has a .74x reducer on it. The reducer allows for 55mm backfocus and has a 48mm thread. To make this setup work, I would need the 48mm adapter for the FW8G-Aluma. I need to know how wide this adapter is. I believe the Aluma 8300 with GW8G takes up 54mm of backfocus, in which case I need the adapter to be no more than a couple of mm wide. Secondly, I see that this adapter is out of stock. Will you have it back in stock? Thanks.
     
  2. Colin Haig

    Colin Haig Staff Member

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    Hi Robert, we're closed for Canadian Thanksgiving long weekend and will be back at work on Tuesday (UTC-4).
    I'll have to get back to you with dimensions then.
    The parts should be back in stock later this week.
     
  3. Robert Kilby

    Robert Kilby Cyanogen Customer

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    Thanks for getting back to me so quickly. Could you also check to see if I’m right that the Aluma 8300 with FW8G takes up 54mm of backfocus? Thanks.
     
  4. Colin Haig

    Colin Haig Staff Member

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    Hi Robert, it's been a long and busy day due to the holiday yesterday.
    I've put together a few diagrams for you, so you can see how it all goes together.
    Tomorrow I hope to get the sensor distance needed to narrow this down precisely for you.
    It's going to be pretty close. We think by threading the reducer into the ACC07 M48 adapter plate, that you can get a few more millimeters of working room.
    The standard filter wheel (non self-guiding) would be a no-brainer.

    We recently had a fellow with another StellarVue 80 model buy a similar Aluma package, and it worked out for him, with the exception that he found his focuser drooped a bit under the camera weight. I think he was going to see about adjusting it to be more precisely aligned.
     

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  5. Colin Haig

    Colin Haig Staff Member

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    Hi Robert, the sensor optical distance A is 14.31mm, plus the filter wheel distance as shown in the ppt, less 1mm for filters.
    We should have the adapter plates next week.
     
  6. Robert Kilby

    Robert Kilby Cyanogen Customer

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    Unfortunately, I don't think that will work. I've got a 3mm M69 to M48 adapter between my reducer and the filter wheel, so that brings the total back focus up to 58.6mm, and my reducer only allows for 55mm. Looks like I may have to go with the standard filter wheel.
     
  7. Colin Haig

    Colin Haig Staff Member

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    Hi Robert,
    We're agreed on 55.6 mm, assuming the reducer is threaded into the M48 adapter.
    You may have to go with the standard filter wheel.
    BUT... I'm trying to understand why you have have the 3mm M69 to M48 adapter.
    Is THIS the focal reducer you have?
    https://www.stellarvue.com/sffr-74-focal-reducer-flattener-for-svx80t-3sv/

    We have a customer with an Aluma 814 and FW8G on a SV (not sure which model - there are variations of the 80) + FR, and it reaches focus. The difference is his has 0.12mm more available back focus due to the Sony sensor instead of the ON Semiconductor 8300.
     
  8. Robert Kilby

    Robert Kilby Cyanogen Customer

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    You’re right. That is the reducer I have. I thought the 69 to 48 mm attachment on the reducer was a separate adapter, but it is part of the original reducer, which means we are at 55.6 mm of back focus. I’ll purchase the guided filter wheel and try it with this scope. If it doesn’t work, I think I can use it with another Stellarvue scope that I have, the SVQ100. I think I have more room to work with on this scope. What size thread does the guided filter wheel come with without the 48mm adapter plate?
     
  9. Doug

    Doug Staff Member

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  10. Colin Haig

    Colin Haig Staff Member

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    Hi Robert, the M48x0.75 adapter plates are in stock. You may proceed with your order any time.
     

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