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Evostar 80ED and Altair x0.8 reducer


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I'm about to order the evostar 80ed, and have decided to pair it with the altair x0.8 reducer.

I already own a unmodified Canon 600d along with a t ring. 

This will be my first ap rig, and I'm a bit lost with what I will need to connect everything together and be able to reach focus.

Will I need any other adapters/spacer etc, or will the above be enough to connect everything and reach focus?

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Unless you already own an Altair 0.8x reducer why don't you just order the 80ED with the dedicated SW 0.85x reducer?

The Altair Lightwave 0.8x reducer is a generic unit, so you will have to work out the optimal spacing on your own through trial & error. Because of that you will need to buy some T2 extensions with various lengths and a couple of 0.5/1mm T2 spacer rings. All these will soon add up in cost and you won't be saving much compared to buying the SW dedicated unit.

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The main reason for picking the altair reducer is cost, but also because it's in stock! I thought the altair reducer was basically made for the evostar 80ed?

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Assuming this is the one you plan to get:

https://www.altairastro.com/lightwave-08x-reducer-290-p.asp

It's a generic reducer for refractors between f/5.5 and f/8, so it will work on the 80ED. But unlike a dedicated unit for which the manufacturer tells you the optimal spacing (usually 55mm) between the reducer and the camera, you will have to work this out yourself for a generic one like the Altair. The rule of thumb is that the spacing is usually shorter (usually about 55mm) near the slower end of the reducer working range (f/8) and longer towards the faster end (f/5.5).

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3 minutes ago, KP82 said:

Assuming this is the one you plan to get:

https://www.altairastro.com/lightwave-08x-reducer-290-p.asp

It's a generic reducer for refractors between f/5.5 and f/8, so it will work on the 80ED. But unlike a dedicated unit for which the manufacturer tells you the optimal spacing (usually 55mm) between the reducer and the camera, you will have to work this out yourself for a generic one like the Altair. The rule of thumb is that the spacing is usually shorter (usually about 55mm) near the slower end of the reducer working range (f/8) and longer towards the faster end (f/5.5).

Great, that makes much more sense now. Hopefully someone who has used the same combo can give their insight, so that I have an idea of the optimal spacing.

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15 minutes ago, Daf1983 said:

Great, that makes much more sense now. Hopefully someone who has used the same combo can give their insight, so that I have an idea of the optimal spacing.

You could always email Nick at Altair to find out if he knows. Considering the high popularity of the 80ED and the compatibility with the Evostars are specifically mentioned in the product description, maybe people at Altair have already got the answers for you.

You could also start the trial & error from 55mm on your own. Being f/7.5 (so close to the upper end of the working range) I believe you won't be too far off with the 80ED.

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1 hour ago, KP82 said:

You could always email Nick at Altair to find out if he knows. Considering the high popularity of the 80ED and the compatibility with the Evostars are specifically mentioned in the product description, maybe people at Altair have already got the answers for you.

You could also start the trial & error from 55mm on your own. Being f/7.5 (so close to the upper end of the working range) I believe you won't be too far off with the 80ED.

It says on the altair website that you need approx 10mm space for a dslr. Does the this mean that the reducer itself provides about 45mm(sorry if this is a stupid question)? 

 

If so, is it something like this I need?

Thanks again

Screenshot_20210131-182019.png

Screenshot_20210131-190828.png

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2 hours ago, Daf1983 said:

It says on the altair website that you need approx 10mm space for a dslr. Does the this mean that the reducer itself provides about 45mm(sorry if this is a stupid question)? 

 

If so, is it something like this I need?

Thanks again

Screenshot_20210131-182019.png

Screenshot_20210131-190828.png

That 10mm refers to the thickness of a standard T ring. In the case of Canon, the flange distance is 44mm, so with a 10mm thick T ring you will already be at 55mm (ie no extra extension required).

The 55mm quoted in the product description is most likely for the slower end of the working range. Since your 80ED is f/7.5 which is so close to that f/8 limit, my guess is that you will probably only need 1-2mm extension. Just to be safe I'd suggest a 3mm extension tube + a couple of 1mm and 0.5mm spacer rings to start your own trial & error. Make sure you get T2/M42x0.75mm extensions rather than M48 because the Lightwave 0.8x has a T thread at the camera end.

https://www.ebay.co.uk/itm/High-Quality-T-T2-M42X0-75mm-Extension-Tube-3mm-5mm-6mm-10mm-and-20mm-NEW/371113516507?hash=item566816dddb:g:ovEAAOSwDk5T231-

https://www.harrisontelescopes.co.uk/cgi-bin/bb000001.pl?ACTINIC_REFERRER=https://www.harrisontelescopes.co.uk/cgi-bin/bb000001.pl&PRODUCTPAGE=baader-t-2-adjustment-spacer-ring-set.html#SID=1664

 

 

Edited by KP82
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5 minutes ago, KP82 said:

That 10mm refers to the thickness of a standard T ring. In the case of Canon, the flange distance is 44mm, so with a 10mm thick T ring you will already be at 55mm (ie no extra extension required).

The 55mm quoted in the product description is most likely for the slower end of the working range. Since your 80ED is f/7.5 which is so close to that f/8 limit, my guess is that you will probably only need 1-2mm extension. Just to be safe I'd suggest a 3mm extension tube + a couple of 1mm and 0.5mm spacer rings. Make sure you get T2/M42x0.75mm extensions rather than M48 because the Lightwave 0.8x has a T thread at the camera end.

https://www.ebay.co.uk/itm/High-Quality-T-T2-M42X0-75mm-Extension-Tube-3mm-5mm-6mm-10mm-and-20mm-NEW/371113516507?hash=item566816dddb:g:ovEAAOSwDk5T231-

https://www.harrisontelescopes.co.uk/cgi-bin/bb000001.pl?ACTINIC_REFERRER=https://www.harrisontelescopes.co.uk/cgi-bin/bb000001.pl&PRODUCTPAGE=baader-t-2-adjustment-spacer-ring-set.html#SID=1664

 

 

Brilliant, I think I've got it now! Thank you👍

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