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New Focusing Aid

George

By George
in Imaging - Discussion

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Psychobilly

Psychobilly

Posted
Posted

Hi Billy

I have one of the new William Optics Flt98's (F6.3) being delivered tommorow , any chance of ......... :hello2:

When you get it post the measurement here and I'll do you a template...

No on second thoughts send it to me for a few weeks and i'll try it out for yah... :D

Billy...

Come to the Spring Star Party and you are welcome to use it :p

Its on my wish list of things to do next year...

I can see why TJ like the laser cut first order mask for the Megrez 72 that i sent him ... I have just had the first chance to use mine and... to quote the man himself WOW!!!

Billy...

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RichieJarvis

RichieJarvis

Posted
Posted

Hi Peter,

Finally got around to posting my dimensions:

GSO 6" Newt

Focal length: 750mm

Focal Ratio: F/5

Mirror Diameter: 150mm

Obstruction Diameter: 42mm

Tube inner diameter: 172mm

Tube outer diameter: 182mm

Astro Professional 102ED

Focal length: 714mm

Focal Ratio: F/7

Tube inner diameter: 120mm

Tube outer diameter: 124mm

Williams Optics ZS66

Focal length: 388mm

Focal Ratio: F/5.9

Tube inner diameter: 66mm

Tube outer diameter: 85mm

Thanks Matey!

Richie

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Psychobilly

Psychobilly

Posted
Posted

Cheers Richie

Thansk for posting the infor in sucha clear and concise manner...

66 is already done will do the rest once i have checked the list - I really should have kept better notes as i was going along...

and then post the links to the pdf's

Billy...

Third order masks here...

GSO

http://www.btinternet.com/~psmithuk/Focus_Masks/GSO_6Inch_F5/PS_GSO_6Inch_f5_TO.pdf

AP102

http://www.btinternet.com/~psmithuk/Focus_Masks/AP_102_F7/PS_AP_102_f7_TO.pdf

the 66 is an old one...and is a first order design...

http://www.btinternet.com/~psmithuk/Focus_Masks/Skywatcher_Equinoxe_66/PS_SWE66_Fullsize.pdf

Billy...

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Kai

Kai

Posted
Posted

Hi Billy

If you would be so kind

William Optics FLT 98

Focal Length : 618mm.

Focal Ratio : F/6.3

Tube Inner :115

Tube Outer :125mm

And one for the same but with a 6.3 reducer in place

Focal Length : 391 mm.

Focal Ratio : F 4

Tube Inner :115

Tube Outer :125mm

Cheers in advance

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Psychobilly

Psychobilly

Posted
Posted

Hi Billy

If you would be so kind

William Optics FLT 98

Focal Length : 618mm.

Focal Ratio : F/6.3

Tube Inner :115

Tube Outer :125mm

And one for the same but with a 6.3 reducer in place

Focal Length : 391 mm.

Focal Ratio : F 4

Tube Inner :115

Tube Outer :125mm

Cheers in advance

got to pop out for a few hours will do them when i get back

Here you go... sorry it took a bit longer than normal... Third order "easy cut" designs as usual...

http://www.btinternet.com/~psmithuk/Focus_Masks/WO_FLT98/WO_FLT98_F4_TO.pdf

http://www.btinternet.com/~psmithuk/Focus_Masks/WO_FLT98/WO_FLT98_F6-3_TO.pdf

Billy...

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michaelmorris

michaelmorris

Posted
Posted

Over the last two days I've read this thread and the related thread on Cloudynights (longer than the Bible!) with great interest. These discussions have raised a couple of questions in my mind which I don't recall have been fully explored in these threads.

1) My 8"LX200 has a very long dew sheild. Does it make any significant difference how far in front of the scope mirror/lens the mask is placed.

2) I have an Orion 80ED and an 8" LX200. The LX200 can have anything from a f3.3 focal reducer to a 4x barlow shoved on the end meaning the focal length can vary from 660cm to 8000cm. The formulae for designing these masks includes the focal length of the system, yet the one of the commercial retailers for these masks (http://www.spike-a.com/) just sells them by OTA diameter. So is it really necessary for me to have 5 different masks for my LX200 (f3.3 focal reducer, f6.5 focal reducer, normal, 2x barlow and 4 x barlow) or is a single mask adequate?

3) In relation to question 2 ,are the sensitive of masks to different focal lengths more, less or insensitive to whether the mask is a first order or a third order mask?

4) What are the advantages of a 1st order mask over a 3rd order mask?

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Psychobilly

Psychobilly

Posted
Posted

Hi Mike,

As an example the megrez dewshield extends a few inches infront of the ota and i clip my mask on there without any probs, on the 8" sct with a flexi dewshield i remove it and fit the mask directly to the front of the OTA and repalce the dewshield after focusing...

The formula gives a range of slot widths ... and only has a focal length term in it... for short focal lengths the same mask covers the scope native and with a 0.8X reducer fitted....

The same mask will work native and with an F3.3 reducer as it will be first order in one configuration and third order in the other...

The third order masks with their wider slots are easier to cut by hand and appear to be less sensitive to errors in the cutting... The first order laser cut ones seem to be extremely sensitive to the perfect focus position...

I haven't got a complete range of reducers and barlows so i cant comment on how well a single mask would perform over such a large focal range...

Hopefully someone who has will test some of the prototype masks that are currently being produced for evaluation...

I havent doen a comaprison of a laser cut third order mask over a laser cut first order mask the cost of production would be slightly higher on the first oreder masks as there are more slots to cut so this will take longer ont he machine and use more gas...

I will continue to draw 3rd order masks based on my interpretation of the formula and post them for people to use in any form they so wish...

There is a possibility that Laser cut first order mask may be made available for sale ... if they are they will "sold" to forum members by "billysbits" I am replying to this post as "psychobilly" as i cant post in this thread as "billysbits"...

Regards,

Billy...

For those who are interested...

Heres the solution of the formulae for an 8" F10 SCT (CPC800) with various reducers and barlows

X Fact 1 0.63 0.5 0.33 2 4

FL 2032 1280.16 1016 670.56 4064 8128

150 FO 13.55 8.53 6.77 4.47 27.09 54.19

200 FO 10.16 6.40 5.08 3.35 20.32 40.64

150 TO 40.64 25.60 20.32 13.41 81.28 162.56

200 TO 30.48 19.20 15.24 10.06 60.96 121.92

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michaelmorris

michaelmorris

Posted
Posted

Has anyone tried using a Bahtinov mask for focussing on the Moon? I realise that focussing masks are designed to work on points of light rather than extended objects such a planet and the Moon. However, it struck me that if one used a bright reflective point on the Moon (Proclus for example) and delibrately overexposed it one might be able to induce similar fiffraction patterns as one gets for stars.

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imagefan

imagefan

Posted
Posted

Has anyone tried using a Bahtinov mask for focussing on the Moon? I realise that focussing masks are designed to work on points of light rather than extended objects such a planet and the Moon. However, it struck me that if one used a bright reflective point on the Moon (Proclus for example) and delibrately overexposed it one might be able to induce similar fiffraction patterns as one gets for stars.

why try to focus on moon?, focus on a star, moon is for all intent and purposes at infinity so once u've got ur star spikes there you go - moon/planet focused too!!

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Psychobilly

Psychobilly

Posted
Posted

Its unlikely these are going to be available for quite some time... I won't be doing any new templates for a while either going to have a break form it all...rushed to get the CAD done but cant get the "agreed" manufacturing done in a timely fashion... cant even get a reliable quote :D

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Psychobilly

Psychobilly

Posted
Posted

ok... too later fro pre-crimbo shipping but had the first half of the sheet run over night - 2nd half will run monday which has the bigger masks on ... Billysbits might end up beign a goer after all in the new year...got the goods but still no firm idea of prices...

11086_normal.jpeg

(click to enlarge)

11087_normal.jpeg

(click to enlarge)

Billy...

Admins & Mods... this is a transitional post once (if) they are a commercial prodcut i'll post in retailers section using the Billysbits Account...

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Psychobilly

Psychobilly

Posted
Posted

Thanks Helen,

Just trying to work out whats here at the moment ... the 10,12 and 14" will hopefully be with me monday night...

I have (spare) in addition to those already allocated...

1 x Celestron 6SE

1 x ETX 105

1 x SW 190 Mak Newt

8 x SW ED80

12 x SW 66 also WO 66

10 x WO Meg 72

1 x SW EQ120

5 x SW EQ80

The 8" GSO , 10" LX, 12" LX, SW250, and 14" LX masks should be ready Moday evening

Cant get anywhere near the parcel office at the moment so I'll leave getting shipping prices till the new year...

Merry Xmas Alll...

Billy...

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