Ultra Wide Field Camera and DSO Finder

[Gina]

I have attached a second Canon EOS 1100D DSLR camera (with lens) to my mount dovetail with a bracket. This will complement my ED80 and no. 1 1100D with full spectrum mod and cooling. The other scope in view is an ST80 with QHY5 camera for guiding. The second DSLR is intended to provide a very wide field of view using my old film days lenses with an adapter to convert the M42 Pentax thread to Canon bayonet fitting.

In additiuon to imaging very wide field star systems, this camera will also provide a super wide angle finder with long exposure facilities that will enable me to find faint DSOs that don't show in a normal finder.

Here are some photos.

Edited to remove latin word from title which the board software removed.

[Black Knight]

I like it. It's always fun to see what you're up to next Gina!

[Gina]

Thank you

[astrovirus]

Hi Gina,

That will probably work like a charm. Your photos do give me a sense of worry when I see that jar that serves as the water reservoir for the cooling. What will happen if it where to spring a leak? Your precious NEQ6 is right beneath it, kinda scarry don't you think?

Regards Tim

[Gina]

Hi Gina,

That will probably work like a charm. Your photos do give me a sense of worry when I see that jar that serves as the water reservoir for the cooling. What will happen if it where to spring a leak? Your precious NEQ6 is right beneath it, kinda scarry don't you think?

Regards Tim

I don't think any water would get in even in the unlikely event that there is a leak but I could add a cover for extra protection. I was thinking though that I might move the reservoir to the side of the mount.

[Gina]

Here are two images, one from each camera both scaled to 1024 pixels wide. First on the ED80 with 0.85x focal reducer (FL 510mm) and the second with 135mm f2.8 lens. So the calculated ratio of FOVs is 3.78 ie. nearly 4 times.

Note that the first 1100D has a full spectrum mod with CLS-CCD clip filter whilst the second is unmodified.

[Gina]

I'm expecting to mod the second 1100D for AP exclusive use. I shall strip it down to the sensor assembly then remove the two filters and replace the outer UV/IR block one to save needing a new IR filter.

[Gina]

Had a clear sky last night until just after 2am so was able to test out the wide-field and finder camera. It didn't get dark enough for long exposures on faint objects until well after midnight so I tried out the finder function first. Checked with M13, M51 and then I saw that M31, the Great Andromeda Galaxy, was in view using CdC so slewed to that, adjusted the pointing to centre it in the finder and then switched to the scope. M31 was well in frame so I further adjusted the pointing to get it near the middle and started imaging. The cooling wasn't working very well (as mentioned in the cooling thread) and I only managed to cool down to +4C. So I used ISO 800 and 60s exposures - 90s was too much.

Having got nearly an hours worth of data on Andromeda I switched back to the wide-field camera and slewed to Cygnus. The Veil Nebula was just visible and adequately positioned so I started imaging the Cygnus Loop. I think I could just about make out the Broom too. Managed nearly an hour on that before cloud came in at around 2:15. The EXIF T on that rose during the imaging run from 15C to 20C so I'm considering cooling on that camera too. Also, I need to do the filter removal mod to increase to sensitivity.

[sologuitarist61]

Blimey Gina, you certainly know your stuff don't you. I keep thinking about modding one of my cameras but then think of my big hands and all the small screws there must be - then I think, perhaps not :embarrassed:

[Gina]

You do need a fairly steady hand and also unless your eyesight is perfect, a magnifying lamp is helpful. The main thing is to take things slowly and steadily. Also, be well prepared with the right size screwdriver at hand, plenty of clean working space and plenty of time available - you don't want any pressure. As recommended by Gary Honis in his excellent step by step guide, I prepared a sheet of paper with all the steps and what size screws were involved at each stage. I used double sided sticky tape to which to attach the screws as each one was removed. I still managed to drop one or two though, sprang out of tweezers etc. and a strong magnet is useful to sweep carefully over the carpet to pick up tiny screws which love to hide in the pile Probably better to do it in the bathroom with a piece of board across the bath (don't forget to put the plug in!). A bathroom tends to be clearer of airborne dust too - helps with dust dropping on the sensor when you've carefully prised the filters out.

[Gina]

I did the filter mod this afternoon so I'm ready with a nice red sensitive camera for imaging tonight - which so far is clear I put the IR/UV filter back so I don't need an external IR filter.

I'm planning to add cooling too when I get the parts.

[Gina]

That apparently clear night sufferred from thin high cloud so didn't get anything usable The bad weather continues...

A little bit of progress this morning though - the first of the parts I ordered for the cooling mod has arrived - the box Now waiting for the Peltier TECs and copper sheet. I already have the electronics bits.

[Gina]

Got fed up waiting for bits so have been attacking the box and camera this afternoon. Ground down a couple of the PCB ribs in the box to allow for the battery cover and been measuring up for the holes for the camera. In order to make sure I got these right I had to see what I could remove from the camera body to mke it fit in as I want it. No puss.y-footing this time I'm going for the "Full Monty" in modifying the camera - making it fit so that the box front comes level with the lens mount as I need to be able to change lenses. No virtually permanently fitted adapter on this one. So it was out with the wire cutters (didn't use Dremmel so as to avoid tons of ABS dust in the camera). Firstly I butchered the flash unit so that doesn't stick out but leaving the flash unit itself connected (a camera I modified before had the flash unit removed entirely and then didn't work). Then I found the projection on the camera top that contains the shutter release stuck out too far and so I took that back a bit.

Photos to follow.

[The Sailor]

Thoroughly interesting, now as I have almost the same setup should I copy you , no, that would be cheating, will be nice to learn though .

Well done!!

Jim

[Gina]

Thoroughly interesting, now as I have almost the same setup should I copy you , no, that would be cheating, will be nice to learn though .

Well done!!

Jim

Thank you Copy me if you like but take care and be careful what and where you cut. If you accidentally cut through a ribbon cable you could stop the camera working.

[Gina]

For the flash unit, I firstly removed the cover by removing two screws and releasing two little clips through tiny holes. Then I cut through the sides of the flash frame with wire cutters being careful not to cut through the wires or optical cable. I carefully checked for switch levers etc. and then removed the spring and that side of the frame by undoing the screw at the side. There is a little pin that controls the flash on the other side where the wires are. I'll probably stick that side down to hold the switch pin in so that the flash doesn't fire. In between doing all these things I checked that the camera still worked by putting a battery in and holding the battery cover in place to close the cover switch, then switching on and taking a photo.

[Gina]

I've put the flash unit back together (mostly) to show how to take it apart etc. The cover was attached with two screws and two clips as shown by arrows in the first photo. The second photo shows the spring which pops it open when the catch is released which was held by a shouldered screw. The spring may be unhooked to prevent any parts flying across the room when the screw is released. The next two photo shows how I butchered the area around the shutter release button to make it fit in the box - I didn't want to cut a hole in the box that would be difficult to seal (others may prefer to do that rather than butcher the camera - I have no such scruples ). Finally, the box with flattened area for the battery compartment door.

[Gina]

Copper sheet and DC Coupler came this morning so I'm expectiing to make the cold finger this afternoon.

[yesyes]

I'm a bit lost, Gina. Are you now doing the same mod to your 2nd 1100D?

[Gina]

I'm a bit lost, Gina. Are you now doing the same mod to your 2nd 1100D?

Yep! Well, near enough. I need to get access to the bayonet to change lenses so this one is going further into the box so I've been chewing off the bits that stick out too far at the front. I can no longer find a supplier of the ThermalTake North Bridge water block so there will need to be a change there. But since this camera is going on the mount rather than the focuser of a scope it can be a bit heavier and I might go for air cooling or possibly the Zalman water block that I have already but is much heavier.

I have the same model of TECs on order that I used in the first cooling mod but I also have some lower power TECs on order from Hong Kong that I plan to try later. I want to find the optimum size of TECs for this purpose.

[Gina]

Cold finger made and put in place I took two shots at it - got it too short first time so made a second which then needed trimming down, but no problem with a Dremmel (or rather the Draper equivalent). I kept it well away from the camera etc. which I had covered.

Before putting the cold finger in I had to do a couple of alterations to parts of the camera. I decided to keep the screen that covers part of the imaging board so that needed trimming back a bit to let the coldfinger in. A peg on the image sensor frame also needed grinding down a bit. This turned out to be very soft metal so I was able to simply carve a bit off the top. These mods are shown in photo 2. A T shaped piece of thin plastic sheet was cut to provide insulation between cold finger and pins of the image processing chip. The stem of the T was inserted into the gap between sensor and PCB and then the cold finger between sensor and plastic insulator. The top of the T stopped the plastic being dragged too far down the gap. This can (just) be seen in photo 4.

Here are the photos :-

1. The image sensor assembly out of the camera
   
2. Showing the trimmed screen and peg
   
3. Copper strip bent for old finger
   
4. Plastic insulator plus trimmed and shaped coldfinger inserted into imaging assembly
   
5. Imaging assembly back in camera
   
6. Maind board back and connectors back in place in camera.
   

[Gina]

Photo of camera with cold finger in box plus diagrams of the cold finger position and insulator plastic piece.

[Gina]

Now have some TECs I can add to the cold finger so having fixed up the scope camera I'm now back to the wide-field/finder camera.

[Gina]

In view of the quite extreme cooling I have achieved with the scope camera and this being rather more than would seem necessary plus the dreadful weather, I have decided to delay any further cooling experiments until I get the much lower power Peltier TECs from Hong Kong. I have the wide-field/finder camera fixed in it's box and mounted on the Manfrotto ball and socket head, which in turn is attached to the NEQ6 dovetail with a strong galvanised steel bracket. It is also lined up with the scope to use as a finder so I'm all set up ready for any clear night we might get sometime.

[Gina]

Some of the low power Peltier TECs have arrived so I expect to be experimenting with cooling again before long. With this weather I don't feel any great hurry and I'm catching up on other things as a higher priority.

We did get some breaks in the clouds last and I was able to get a small amount of imaging done. I ran the wide-field setup beside the scope and made double use of the imaging time. I mainly concentrated on the Sagittarius area. Here are two single frames of the set, taken with my Super Takumar 55mm f1.8 lens stopped down to f4. Exposure was 30 secs at ISO 3200. The first taken early on, shows the full frame while the second, from when I gave up shows the cloud has rolled in. I cropped the dead area of sky from the top of the second (ie. this picture is the bottom half of the image). Terrestrial lights have been stretched by the sidereal tracking.

Looking at the first image, I think I need to sort out the focus. Must make a Y mask