EQ3-2 guided wide field rig......

[stan26]

A bit more DIY from cloudy suffolkshire.

Although i'm happy with how my tuned/guided EQ3-2 will handle my ST102 for DSO AP my main goal is to use it as a wide field platform. I prefer the wider field format and also its a lot less demanding on the whole setup in terms of weight and guiding accuracy.

I will start by introducing my weapon of choice for widefield AP, The Canon 200mm f2.8 USM II L series prime lens. For those who don't know, this is a very highly regarded high quality telephoto lens which is part of the Canon "L" series range of pro lenses. This lens offers a very flat field and very little false colour if at all when stopped down to F3.5 +. Its performance is said to match or even exceed that of simular priced small APO telescopes. At 200mm FL it should make a great WF lens. Canons RRP for this lens is £960, but in reality these can be had for around £600 new. I got this one for £400 second hand in absolute mint condition. After being immensely impressed when I used it at an airshow last year I can't wait to use it on the heavens for the first time........

[stan26]

Now for the DIY part.....

I needed to find away to attach the camera/lens/guide scope to the EQ3-2 mount, So I got a length of square aluminium tube and made a mounting rig to hold both the guide scope and the camera by way of a tripod ring mount. The ring mount I got of amazon for £15. I used the dovetail bar of the ST102 and used the original leveling pinch screws on the dovetail bar to fix the the alu tube to it. Its a very simple ladder style frame just drilled and bolted together. Its not finished yet, needs some smoothing around the edges and I may add a red dot finder for the camera side....

Total cost of wide field bracket......£15, and that was for the tripod mount. Alu tube was free scrap metal. I love cheapness

(sorry image quality poor, taken on mobile phone cam)

Stan

[steelfixer]

Looks good Stan.

That is one hell of a lens you've got there.

I would love to see some images you get from that set up.

Graham

[stan26]

Made a few modifications to the WF rig. The utensil pot guide rings worked OK but I wasn't happy with the flex and one of the nuts snapped off. I have made my ST102 OTA rings into guide scope rings, by simply drilling/tapping holes in them to take the adjustment bolts. This is a much more sturdy configuration. I have made a custom holder for the finder scope. The standard 3 plastic screw version was **** and wouldn't hold its position between imaging sessions. This new sturdy 6 bolt holder will make it much easier to find and align guide stars. I have also added a "quick on/off" mask holder to the platform using a simple office bull dog clip. This way I can use my home made bahtinov mask which simply clips into place in seconds. The clip will also be used to help secure an extended dew sheild (work in progress). The DIY mask is made from plastic/foam board and card. It has been coated in serveral layers of silver paint and then lacquered.

Stan

WF rig 1 by James stannard, on Flickr

WF rig 2 by James stannard, on Flickr

WF rig 3 by James stannard, on Flickr

WF rig 4 by James stannard, on Flickr

WF rig 5 by James stannard, on Flickr