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StarSharp Bahtinov focus masks

FLO

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keithmrris

keithmrris

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I have a similar question. If I get one for my SW 80ED would its use be affected by the use of the SW focal reducer?

Cheers

Ian

Hi all. I have a Williams ED102 (f7) with a Type IV Field Flattener which actually makes the scope f5.95. The original f7 mask still works very good but it would indeed work a little better if I were to make one at f6 or f5.95 but I really, hand on heart, haven't felt the need to. A little trick which helps an awful lot is (and this works with or without live view) is get focused as best you can then take a 2 seconds exposure with the mask STILL in place. Zoom in on the saved photo and check the diffraction pattern, adjust focus, and you will need only very to slightly adjust to achieve the perfect focus.

Remember when happy with the focus take the mask off before doing your exposure run.

Keith

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FLO

FLO

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Yes, Keith is currently preparing our order ready for dispatch Monday so we should recieve them Tue/Wed. We shall process orders same-day so customers should recieve their focus masks Thu/Fri ;)

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ollypenrice

ollypenrice

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I'm a real quality fusspot and these masks leave me absolutely nothing to moan about, which is their only drawback...

Cracking product, I have two, one hundred percent endorsement and a big thanks to the kind guest who awarded them as a pressie. You know who you are, Barrie!

Olly

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redfox1971

redfox1971

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Good product,used mine lastweek in dark,oops put it down on deck chair then accidentally sat on it,hard plastic crackes easy shame not more flexible material,glued crack at edge back together all good again.

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FLO

FLO

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These look really nice! Any word on a mask for a 200mm f/4? newt?

Good point. I have been concentrating on covering the models we sell but there are a few owners of GSO 8" f4 out there and of course the Skywatcher Quattro Newtonians will be arriving sometime this summer. I'll phone Keith in the morning. The regular f5 mask will definitely work but it might be worth having one custom made to suit f4.

Thank-you ;)

Steve

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Revs

Revs

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Steve, you're probably aware, but I thought I'd point out that some of the TS/GSO versions of the F/4 newts (the ones that Bern sells) have a larger tube OD. Also, I believe the tube lengths vary, I don't know if that make a difference to the required mask.

;)

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FLO

FLO

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Thank-you Paul, I didn't know that. I guess this also applies to the Altair version. They are probably using a regular f5 tube that is longer than is required for an f4 mirror-set.

Fortunately the tube length doesn't affect the performance, the mask is designed around the focal ratio. You can even use it on an OTA fitted with a flexible dew shield without affecting performance.

Keith is producing masks for the 200mm f4 as I type ;)

Also, there are a number of 102mm f7 refractors out there (Megrez, Meade, Ikhauros, Altair, etc) so we have added that to our options list.

HTH,

Steve

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FLO

FLO

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Darn, none for 120mm f/5 refractors :o
I'd buy one of these!:D

Okay, Startravel 80, 102 and 120 have been added to the options list ;):o

I am not sure whether Keith will be able to add the masks to our order being dispatched Monday, it might be that they arrive a few days later.

HTH

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