Telekit Dobsonian

[jetstream]

I didn't offset my secondary either and we use the same size secondaries. Your 16" runs just under 20% central obstruction and with a nice fully illuminated field- this will be an excellent scope on the moon and planets... and DSO...

Congrats for the great work Simon.

[Singlin]

Thanks 

[Peter Drew]

I would normally go along with the offset being unnecessary approach provided that the secondary dimensions were adequate. However, we were recently bequeathed a 20" F3.5 Dob and try as I might with the collimation I couldn't get better than an OK image. I took this to be par for the course for such a large fast mirror but being as the test report indicated better than 1/8 wave I felt it should have more to offer. I noticed that there was no offset so I made a new holder that could be offset, recollimated and the telescope now gives outstanding Lunar and planetary images at high powers at least equal to our 16" SCT completely quashing any previous reservations I had about the high res capabilities of very fast large optics. 

[jetstream]

5 hours ago, Peter Drew said:

I would normally go along with the offset being unnecessary approach provided that the secondary dimensions were adequate. However, we were recently bequeathed a 20" F3.5 Dob and try as I might with the collimation I couldn't get better than an OK image. I took this to be par for the course for such a large fast mirror but being as the test report indicated better than 1/8 wave I felt it should have more to offer. I noticed that there was no offset so I made a new holder that could be offset, recollimated and the telescope now gives outstanding Lunar and planetary images at high powers at least equal to our 16" SCT completely quashing any previous reservations I had about the high res capabilities of very fast large optics. 

Great info Peter, one I'll remember. With the 20" f3.5 what size secondary is being used? I use a program to calculate the fully illuminated field for my scopes, just out of curiousity, how far is the secondary from the focal plane? My 15" is about 78% illuminated out to 26mm off axis. We chose a secondary just a hair bigger than optimum to leave a bit of wiggle room.

Thanks, Gerry

[Singlin]

I have now modified my wheel barrow handle attachment points by placing a stainless steel u shaped bar.

putting the handles on and off in the tight space of my little shed is now very easy and quick.

[Singlin]

I have just ordered the power kit from Astrosystems that enables  power from an external battery to reach a power hub inside the rocker box without hindering the capability to move the scope in Az. Below is the link:

https://www.astrosystems.biz/ASPFTinst.pdf

 

 

[mapstar]

13 hours ago, Singlin said:

I have just ordered the power kit from Astrosystems that enables  power from an external battery to reach a power hub inside the rocker box without hindering the capability to move the scope in Az. Below is the link:

https://www.astrosystems.biz/ASPFTinst.pdf

 

 

I plan something similar. Looking at the pic I can see the slip rings (parts 1 and 2) and a set of springs (part 13) but what does it use for the brushes? (Parts 11 and 12?) 

 

[Singlin]

Look at the pdf above.

[mapstar]

15 minutes ago, Singlin said:

Look at the pdf above.

Sorry didn't spot that will do 

[Singlin]

If anyone has some wires going from their rocker box to mirror box could you show me a picture of how you routed these.

Thxs,

Simon

[Singlin]

I have oredere the Servocat system to make my dob fully goto and motorized.

I have also ordered the new SkyFi 3 wireless controller that works with window,Android and IOS.

The SkyFi 3 plugs into the Servocat via a USB port.

This way I can do go tos from my pc or tablet wirelessly using Skysafari or cart du ciel etc.

Here is a link to the new SkyFi 3 that works with both IOS and Android and Windows:

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p975_SouthernStars-SkyFi-3---kabellose-Teleskopsteuerung-ueber-USB-und-RS-232.html

[mapstar]

On Thu Sep 01 2016 at 11:55, Peter Drew said:

I would normally go along with the offset being unnecessary approach provided that the secondary dimensions were adequate. However, we were recently bequeathed a 20" F3.5 Dob and try as I might with the collimation I couldn't get better than an OK image. I took this to be par for the course for such a large fast mirror but being as the test report indicated better than 1/8 wave I felt it should have more to offer. I noticed that there was no offset so I made a new holder that could be offset, recollimated and the telescope now gives outstanding Lunar and planetary images at high powers at least equal to our 16" SCT completely quashing any previous reservations I had about the high res capabilities of very fast large optics. 

Mines fine Peter at 22" F3.4 it has an offset of 9mm which seems huge but there again the 130mm MA secondary is 

[Singlin]

I finished the installation of the servocat.

I now command the telescope wirelessly via SkySafari on my 8" tablet.

 

[Singlin]

Here is a short clip of it working wirelessly, In Italian I am afraid.

 

[niallk]

Lovely setup!