Modification of 14 inch telescope equatorial platform - 1

[Chanlunlun]

Dear ATMs,

Inspire by Mr. Raymond Tse we decided to retrofit the old 14 inch Newtonian so that it could be used for planet and lunar shooting. The main job is to modify the equatorial platform so that it has a dual axis slow motion control.

Originally the equatorial platform has only one polar axis slow motion. I have used one week』s time to add another axis onto the platform so that it could slowly move around two axis. While shooting we can target could be continuously targeted at center via electrical remote control.

The modification has just been finished tonight and we cannot wait to test it on field. Hopefully clear weather will come very soon.

Best regards
Chan Yuk Lun

[Subaru]

鏡神又再次發威, 睇怕都又會係全港第一個用輕便大口逕自製鏡拍高解像行星影像嘅先鋒! 拭目以待, 好有機會會係全港解像力最高的行星影像.

[HK.Raymond.Tse]

You may try dual axis DSO photos using a visual guidescope.

Good work !

Raymond

[david_kmng]

Great!!!
Perhaps we need to do some test on the limit of exposure of DSO since there is no field rotation counteract measure. I think Mr.Chanlunlun is trying to add this, too. Probably a series of short exposure is required.

[HK.Raymond.Tse]

EQ platform by definition will eliminate any field rotation if accurately polared aligned. The length of exposure depends on the width of the EQ platform, usually an hour. My EQ platform can run up to 80 minutes before reset.

By constract, Alz-Altitude plaform (ie horizontal and vertical movements only) will suffer from field rotation.

Chan Sir's platform appears to fall within the 1st type, but the vertical tilting mechanism (ie Dec axis) is not clearly seen from the picture.

[Chanlunlun]

EQ platform by definition will eliminate any field rotation if accurately polared aligned. The length of exposure depends on the width of the EQ platform, usually an hour. My EQ platform can run up to 80 minutes before reset.

By constract, Alz-Altitude plaform (ie horizontal and vertical movements only) will suffer from field rotation.

Chan Sir's platform appears to fall within the 1st type, but the vertical tilting mechanism (ie Dec axis) is not clearly seen from the picture.

Dear Mr. Raymond Tse,

Yes you are correct. Our equatorial platform has a virtual polar axis and thus suffers from no field rotation.

I agree with you that it's not easy to see the second axis becuse the structure looks a little bit complicated. It consists of an intermediate wooden plate A that resting on the plaform . A tangent arm C with driving motors D drives the craddle B to rotate around an axis perpendicular to intermediate plate A. Theorectically this second axis is not a Declination axis because instead of 90 degrees it makes only an angle of 67.5 degrees with the polar axis. The polar axis is driven by tangent arm E.

One disadvantage of this design is that the second axis fails to move the telescope while transiting through the Meridian with the telescope tube vertical. However in most position of sky except the meridian it works fine. Yet this design is the simplest one that could be possibly implemented by us.

For deep sky shooting, with this equatorial platform, the 14 inch telescope is too long for the purpose. If we are serious we have to make another specified telescope with aperture about 12 inch of f/3.3 to f/3.5 to reduce exposure time not to exceed 3 minutes. (ISO800, EOS10D)

At the moment we would like to to see how this modified platform perform on planet shooting first.

Best regards
Chan Yuk Lun

[Chanlunlun]

鏡神又再次發威, 睇怕都又會係全港第一個用輕便大口逕自製鏡拍高解像行星影像嘅先鋒! 拭目以待, 好有機會會係全港解像力最高的行星影像.

Dear Mr. Subaru,

You know that I'm no expert like you in star shooting.

However I would like to see how home made stuff performs under a field ( astrophotograhy ) where premium telescope dominates.

Our telescope including optics and mechinical parts, however, are wholly fabricated by our students ( and me ).

Perhaps you may notice that we routinely use junk material ( especially wood timber ) to accomplish our dream. We do this because within the same limited cash available we think we may run faster and jump higher, while on the other hand we have help to save our environment.

Best regards
Chan Yuk Lun

[david_kmng]

眼大睇過籠, sorry, 我未訓醒...