WO Reducer Flattener IV spacing

[zicklurky]

I'm getting a bit confused with the spacing requirement for WO Reducer Flattener IV and an FLT 98 and my Atik One with OAG. WO state the spacing should be 76.8mm. I've read that you should have about 55mm from chip to reducer, and then set the reducer setting to 76.8mm. Is this correct? Atik One with OAG has about 47mm backfocus, so would I just need an 8mm extension?

[Davey-T]

I had the same problem pity they don't supply any instructions with it, hopefully Steve Richards will spot this and advise as he has got his head round the settings.

There is a thread somewhere that explains it.

Dave

[wuthton]

Sorry, sorry... The below is regarding the Flattener 6, I don't know if it's the same situation.

It's the included spacer that causes the confusion.

With the spacer screwed on the spacing is the usual 55-56mm, without the spacer it is 76.8mm. It took me two nights to notice that there was a spacer and then the penny dropped.

[steppenwolf]

I've read that you should have about 55mm from chip to reducer, and then set the reducer setting to 76.8mm. Is this correct?

This is absolutely correct. For reasons that drive me NUTS, astro equipment manufacturers produce equipment assuming that we all use DSLR cameras so with a nominal 45mm DSLR lens mounting face to sensor distance on a typical DSLR camera and a 'T' adaptor with a nominal depth of 10mm, the magic figure that they work to is 45 + 10 = 55mm.

Atik One with OAG has about 47mm backfocus, so would I just need an 8mm extension?

When WO tested the FR IV with the FLT 98, they determined that its internal lens system worked best when set to a position of 76.8mm assuming that a DSLR camera was in use. If you have an Atik One CCD camera which has a mounting face to sensor depth of 27.0mm plus an OAG with a depth of 20.0mm then you will require an extension spacer of 55 - (27 + 20) = 8.0mm thus proving that you didn't need any help at all! :grin:

[zicklurky]

Thanks! Spacing is enough to give me a headache! 

[Dave In Vermont]

This article, though written with a MallinCam in mind, nonetheless throws some light on the situation:

http://www.mallincam.net/uploads/2/6/9/1/26913006/focal_reduction_for_dummies.pdf

Clear Skies & Reduced Vignetting,

Dave