Ultra Wide Field Setup for late 2020

[TerryMcK]

I'm just pulling together an ultra wide field setup that I can use starting late 2020.

Camera and Lens

This will utilise my old goto standby of Canon EOS400D DSLR camera that is astro modded. Not the newest kid on the block but it works fine, is built like a (plastic!) tank and has always produced good results from its APS-C sized 10.1M pixel sensor.

I have just ordered a second hand Canon EF 50mm f1.8 STM prime lens. When it arrives this will fit on the camera albeit with a more handy 80mm focal distance.

The lens has an M49 filter thread. So I have bought a cheap M49 to M48 step down ring off Fleabay to fit my 2" light pollution filters - I made sure it was the right way around. This might produce some vignetting but hey ho. Crop it out or gradient adjust in Photoshop.

Mount

I already have a short SkyWatcher vixen rail and a look through my bits of photography equipment found a ball head mount with quick release to screw onto the bottom of the camera.

This little setup can go onto any mount and I'm thinking either my HEQ5Pro (maybe even dual mounted with a bigger scope) or a separate little mount like the SW Star Adventurer or one of the IOPTron mini mounts. Put this onto one of my photographic tripods.

Control

Also to control the shutter I can use my Shoestring Astronomy DSUSB box that can be velcroed onto the top of the vixen rail.  The shutter release on the 400D via USB can only hold the shutter open for 30 seconds under USB control. This is a limitation of the electronics within the camera. However the DSUSB box works by holding the shutter open via the mini jack socket and can hold it open as long as you want. An alternative shutter controller is of course an intervalometer. No computer required for that.

I'm not sure if Astroberry on the Raspberry PI recognises the DSUSB box. I shall have to have a play with that. Otherwise it's back to a Winders lappy running windoze drivers.

When/if this Covid19 crisis is over it can just be a portable rig to take out into the field.

 

Edited May 5, 2020 by TerryMcK

[petevasey]

Neat setup Terry.  That will give you a field of view of 25 x 17 degrees - just enough to enclose the Plough, or Cygnus Cross or the main body of Orion among others. Nice!  Don't forget a dew heater if you plan on long exposures.  Unless you're using mains, how long will your batteries last?    You can certainly buy or make 'dummy' batteries for the camera reducing 12 volts to 7, so you can use a 12 volt  lead-acid or similar power pack to run everything including the dew heater .

There are tiny 'buck voltage regulator' units which will comfortably fit inside a battery case - if you are handy with a soldering iron and have a dying battery, carefully open the casing, use a test meter make sure you know which are the output terminals, remove the actual battery and fit  a regulator with the 12 volt input lead matching the slot in the camera case.  Again use a test meter to set the output voltage to 7, then glue the case back together.  These regulators are so cheap I suggest you buy two, and test before using on your camera!  I have a similar unit which I made for my 700D and it runs for hours without getting hot.  Photo below - as you can see I used a piece of 'veroboard' to mount it, but that's not strictly necessary.

An intervalometer might be a better solution for control - then definitely no computer needed.  They are very cheap for example this one.

Best of lukc

Peter

Edited May 5, 2020 by petevasey

[TerryMcK]

6 minutes ago, petevasey said:

Neat setup Terry.  That will give you a field of view of 25 x 17 degrees - just enough to enclose the Plough, or Cygnus Cross or the main body of Orion among others. Nice!  Don't forget a dew heater if you plan on long exposures.  Unless you're using mains, how long will your batteries last?    You can certainly buy or make 'dummy' batteries for the camera reducing 12 volts to 7, so you can use a 12 volt  lead-acid or similar power pack to run everything including the dew heater .

There are tiny 'buck voltage regulator' units which will comfortably fit inside a battery case - if you are handy with a soldering iron and have a dying battery, carefully open the casing, make sure you know which are the output terminals, remove the actual battery and fit  a regulator with the 12 volt input lead matching the slot in the camera case.  You need a test meter to set the output voltage to 7, then glue the case back together.  These regulators are so cheap I suggest you buy two, and test before using on your camera!  I have a similar unit which I made for my 700D and it runs for hours without getting hot.  Photo below - as you can see I used a piece of 'veroboard' to mount it, but that's not strictly necessary.

An intervalometer might be a better solution for control - then definitely no computer needed.  They are very cheap for example this one.

Best of lukc

Peter

Nice tip Pete. Yes I will incorporate a dew strap and may ultimately power the rig with a battery.

I power the imaging rigs off the mains at the moment with a 12V ham radio supply housed in a protective plastic box. I have a dummy battery and 8 volt supply for the DSLR. But when Covid-19 disappears and I get out into the field a battery beckons.