Hi all, I picked up an ac adapter for the canon 350D and tried it out.
I noticed that I have dark lines in images now. I'm not sure at this stage if they are in all subs and in the same place, though I think they will be.
The image below has been stretched to plainly show them.
I think they are maybe a 50hz noise, and wondering if anyone else using the adapter has found this problem?
Image is 3 mins @ ISO800 x 6, average combined (unaligned)
The problem is also visible in 300 sec images.
I'm not above placing a bypass filter cap in the line, but I'd be interested in the experience and thoughts of others first.
Whoa, (nice shot bar the banding, was it on an ED80?)
I have the 400D on a power adapter, but I run mine through a UPS. I have once or twice seen banding - but nowhere like that. Can I suggest you try borrowing a friends UPS and see if the problem goes away - else its a contact Canon.
One other thing I noticed (with horror) when I first plugged my DC adapter in, I felt tingling in my arm when I picked up the Camera - like 240V about to be earthed tingling. Not a nice feeling - Canon where quite concerned when I told them - then never rang back!
Since the third use I haven't noticed the tingling any more...
G'day g__day, gbeal,
Yes, ED80, I'm surprised to get vignetting, will need to enlist the aid of a flat field, but one problem at a time.
On checking back, yes the lines were present in earlier captures. The milk splask image (eta carina) was downloaded with a 90deg rotate and only ISO 100 so the lines were less prominent, and more or less vertical. That rules out the power supply and points the finger at the usb cable.
I have the main camera and the guide camera cables loomed together to avoide guide error issues; maybe I need to use some ferrite clamps or bobbins to suppress noise radiations.
The power cable is not all that close to the usb cable (opposite ends of camera body from mmemory) but it is incorporated into the same cable loom as the signal cables. But the lines are there pre power supply kit days, so........
Doug,
well at least you are narrowing it down. Try another cable, and also try the cables apart, although as you suggest it is also present on the pre-power supply shots.
Gary
not sure if this applies to USB cable, but the DC cable on my JVC camcorder has a core filter. It's used to stop interference from outside sources infiltrating the signal in the A/V cable (I think). If the AC Adapter on the Canon doesn't have one on the DC cable, then this might do the trick. you can get it for $4 at Dick Smith Electronics. Linky
Marc, thanks for your input. The Canon usb and also the dc cable both have ferrite suppression. Also on cheching earlier subs I found that those lines are present when just using the battery instead of the power supply.
My current thinking is a timing issue with the usb. I had been downloading the frames as colour processed tricolour fits instead of CR2 files. This takes longer to download than the native CR2 and might be the source of timing issues??
When the sky clears I will take some 5min subs and download as CR2 files and see if that clears the lines. There is surprisingly little info on the web that I could find...one post on one forum that remains un answered since 2005....not good.
If all else fails I think I can work around the issue by shifting the guide position slightly from frame to frame, align and median combine to remove the outlier pixels from ther final stack result. But not much is giong to happen by way of testing with cloudy skies.
cheers,
Doug
G'day Baz, you also need a long exposure cable if you want exposures longer than 30seconds. You can run for a fair time on battery, try this before investing in the power kit etc.
Quote:
Originally Posted by bloodhound31
guys, I am just about to buy a 400d from harvey normals.....
What do I need to buy with it to get going on the telescope?
If that is the remote manual switch; yes it will work I believe. I don't have one myself, I made up a shutter release cable that goes into the puter, but there is no reason why you could not use a manual cable and just work with a cf card.
G'dat g__day and gbeal ++,
Preliminary results are somewhat discouraging re the banding.
So far I have:
1. isolated the camera side earth from the puter side earth with no better result.
2. provided extra ferrite suppression to the usb cable. with no better result.
3. changed from tricolor file saves to CR2 saves, with no better result. Interestingly the lines are more evident after RGB conversion though.
4. used bias frame with dark, and also tried scaleing. This seems to have reduced the lines significantly, but with o/cast skies, I'm waiting to give it a good test under actual imaging conditions.
3) Suspect your powersupply outside is poor quality - run it into a small UPS to get line quality up and run the adapter into the UPS
Any remaining problem is wierd - check it with Canon and/or more your viewing site in case you have background noise or radiation!
else its a crappy adapter (transformer or cable) - return it for a swap.
Well g__day, I did try a long shot on battery, however I was also uploading the image 'direct' as a tricolour fits. What this really means is the camera raw is auto colour converted and saved as an RGB fits file.
I have tried a new set and though the lines are still there, they are not as obvious. The attached image is again a 300sec x 6 but this time it was uploaded as a raw CR2, calibrated and colour converted then combined using a median stack. Again the image is overstretched and I suppose normal processing will not suffer from the lines.
I have run out of time with it I think and am about to pull the EQ6 out of service for a while and remount the LX200 Classic and expect to use a monochrome imager. I suspect the problem is a slow PC. I will try the camera inside the house as you suggest, or at least I will try it without the computer and see if I still get lines. If so I'll talk to canon.
cheers,
Doug
