JamesF

Are you sure they're 55mm, GIna? I was fairly sure they were all 45mm. Obviously they all have to be the same otherwise the lenses wouldn't be interchangeable.

James

I had at one point considered the viability of a "scraper" or cleaning arm driven across the sensor by a screw thread (or a pair, working at right angles to each other. Such an arrangement might be quite a faff to rig up, but could well help with keeping the connection wires safe.

James

The Hyperstar rig on a large SCT is an interesting illustration of some of the points above regarding f-ratio. The characteristics of the OTA are massively altered when swapping between the standard configuration and the Hyperstar setup, without changing the aperture at all. It also shows up some of the difficulties with having exceptionally fast f-ratios, such as razor-edge focusing

James

I will be working on this. As it stands this would be feasible only on refractor telescopes where the extra optical path can be accommodated. On Newtonians there is generally insufficient back focus for this and I think this applies to other scope designs too. Even refractors that use focal reducers don't have enough back focus behind the reducer.

SCTs and Maks would probably be ok too, because focusing them involves moving the focal plane, not the eyepiece or camera.

James

As they're apparently the same as for the 450D I've just checked mine and the terminals are in the same orientation as the picture linked above. That is, contacts uppermost and on the left the terminals read - T + from top to bottom.

James

Does the large image on this page help, GIna?

http://www.ebay.co.uk/itm/2-Lot-Battery-Canon-LP-E5-EOS-450D-500D-1000D-Rebel-T1i-Xsi-Kiss-X3-X2-UK-/281004305104

James

£185+£11 carriage seems a bit extreme to me for a 1000D and nifty fifty. Perhaps the weekend isn't the best time to be bidding on these things.

James

You don't think a heated nichrome wire would work? It wouldn't have to cross the face of the sensor at all, just the area where the glass is bonded.

James

- Time to go down the local shop and buy a Magnum

I thought a hammer and chisel was a bit heavy-handed, but shooting it is just going too far...

James

I tried knitting some time ago got it out of my system Found it too boring... Just feeling rather frustrated ATM!

Trying making a machine that knits instead

I understand your frustration though. Does the first 1100D sensor you modded still work in the other body, or is that the one that fails if it gets too cold?

James

So it looks like some other part of the camera that may be at fault?

James

The 30s exposure completes (can hear the shutter) and then I get err70. Now cooled down and I'm getting err70 immediately on starting time exposure.

That seems a very odd failure mode. If the exposure completes then presumably it's not a problem with the exposure per se. But if shorter exposures work ok then presumably there's no issue with getting data off the sensor either. Might be interesting to try at different ISO settings too? Perhaps there's some different execution path in the firmware for exposures greater than some limit at some ISO setting and the longer one finds a problem that the shorter one doesn't.

James

I now have the test camera in the fridge with power and USB cables brought out past thr door seal. It hasn't had much time to cool down yet but a time exposure of 10s at ISO 800 is fine but with 20s I get the exposure then err70. 15s OK... 19s OK... strange. Camera power now off and letting camera cool down.

That's quite odd. If you set the exposure for 30s does it give the error after 30s, or terminate the exposure at 20s and throw the error?

James

OK I've only got to page 15 ATM but a wooden lolly stick cut from one side with a blade will give a 'soft' chisel edge - do not sand as abrasive grains will embed themselves in the wood.

The stuff about heating the glass to remove it and using epoxy to protect the connecting wires is definitely something you should read, too. And there's a post from "Rottweiler" explaining how they have done it on some sensors.

James

Does it fail again if you try to run an exposure with the lens cap on, or is the camera not in a suitable state for that?

James

"The Abridged Debayering a DSLR" doesn't exist I'm afraid. TBH, I think it is worth reading through the thread as there are lots of projects followed through with detailed pics and lots of examples of pitfalls to avoid.

I'm inclined to agree. There's a lot of information on what's worked and what hasn't, but it's quite haphazard. Until it's a successfully repeatable process I think it will probably remain that way. Just don't let your camera see the stuff that Gina has done to some of hers. It'll be running for the door before you have a chance to grab it

James

I tried scraping without covering the gold wires and was quite unable to avoid them. Why? you ask - because my muscle control is not what it was and I'm just not steady enough nowadays to do this job without having the gold wires protected.

I can't see that the epoxy is likely to be a problem. Electronic components are sometimes embedded in epoxy to protect them from moisture or vibration, for instance.

James

Let's hope the promised clear sky actually happens. It should be clear here now according to the Met Office, but we're currently under thick black cloud

Thinking about those extra sensors, Gina... I wonder if they continued to work through the epoxy because if it's thin it actually transmits light reasonably well. If you've scuffed the epoxy since or caused it to scatter light more perhaps they're now struggling to get enough light.

Perhaps the way forward is just to keep well away from the sides of the frame and leave the CFA intact there. Limit the scraper movement with a couple of "fences" if necessary. You might lose a few hundred pixels off the width of the images, but I wouldn't have said that was a major issue.

James

Just been going over the 1100D sensor very carefully removing the last few bits of CFA. Not easy but with lots of patience...

I have taken some more flats. Here's an example. Something has gone wrong Tried various exposures and I think this would be about right.

That's odd. Looking back at your previous image there's a definite darkening to that side of the image though. I wonder if the actual problem occurred earlier on?

It doesn't render the sensor entirely unusable, I guess. You'd just have to position the image on the working section and crop the rest off.

James.

No it doesn't - I've just run a search. I'm a bit loathe to download any of the "fixes" listed by Google as this is a known way of catching a nasty.

I quite agree. Give it a whirl on Linux instead.

James

Actually, there's probably no reason you couldn't run dcraw on Linux, Gina.

James

Does that DLL exist on your machine at all, GIna?

James

That really does look excellent. Well done.

James

That looks like it would fit rather neatly into an X-Acto handle

James

The Arduino solution has a certain appeal in terms of perhaps incorporating a guiding system rather more neatly, too.

James