Hello all, these are the first attempts with my home modified 450D. I am Ok with the Eta one, but the M42 has these strange blobs on it. I used the same set up-camera, field flattener, scope etc. I took darks at almost the same temperature. I used new flats with the same set up. Only difference was I cleaned the objective on my refractor between the images but I would have though if it was smudges then they would have been compensated for in the calibration frames (I didn't do dark flats though).
Was a pretty bright Moon nearby in the M42 shots so maybe reflections. But those would be taken out with darks as well wouldn't they?
Help please,as beginning to regret taking screw driver to 450D!
Graham
I just stretched your image to buggery......you do have blobs. They're dust bunnies. Means you're going to have to clean your camera and also take better flats to compensate for any that might be left. You've also got a lot more detail there in your piccie. Just by raising the black point a bit and lowering the midtones in your levels, the neb starts to pop out. And so do the dust bunnies. I've attached a copy of your image I had a play around with, to show you.
I would not be at all surprised to find out these are reflections on something in your imaging train. The brightness of the M42 core is well and truely bright enough to cause these. Eta being not so bright doesn't show uo like M42.
Yep - I see them now - thanks Carl. Although I think they are still there in the Eta image - just camouflaged by the nebulosity. I would be leaning towards reflections also Doug - isn't dust usually a dark blob?? Although you might have left something behind on the objective when you cleaned it - especially if you did your flats before the subs as the flats would then not have picked it up.
Also Graham - it looks like you might have some issues with your sensor being not quite square - look at the Eta image - the stars in the middle on the right side are tightly focused with a progressive blurring and elongation towards the left.
Graham. The shims might need repositioning to square off the sensor, and possibly a good clean with some isopropyl alcohol. If the bunnies are deep, you'll have to dig them out and give the sensor and low pass filter, if installed a good alcohol clean as well.
Trying to be helpful, and if you don't have pro cleaning equipment, wash out a good quality microfibre cloth in alcohol and let it dry. Grab a soft plastic square ended (a soft plastic ruler cut to size) blade, the same width as the sensor area and wrap the cloth tight and flat around it just damp with alcohol. Clean in single sweeps use one edge then turn over, rewrap at different points on the cloth to avoid spreading what you have already removed. Use a magnifying glass and good light to inspect the surface from different incidents. Get the low pass filter on asap. Keep the bits in glad bags once clean and remove and fit with pointy nose tweezers.
If that doesn't fix it then I have been of no help at all...
Hi. While stacking images and trying to improve on my basic skill set, i have found when i zoom in around 400% i find these red marks and sometimes blue marks in the picture. When viewing normally they can not be seen. Could someone please tell me what they are? Here is an attached example. Also is attached the origional image.
these are hotpixels. They almost always show up in long exposure images.
the easiest way to counteract them is either in- camera noise reduction or to take dark frames manually.
Holy **** guys, not only have I assaulted my 450d, it seems now that i have twisted the sensor as well. And ****ed the shims up.
Man oh man this is turning to one heck of a DIY project.
I think I will take it all down and clean everything then try again.
With the sensor being not square, these are the first pics with the flattener, so maybe I didn't crop as much in the post processing.
Post processing, you know for me, is - after DSS, some StarTools and pretty much that's it.
In fact, I am the Luddite of astro processing. Or the recidivist -take your pick.
Will take everything apart and try again I think.
Graham
What they mean by being square on is that when you've attached you camera to the scope, you may have not quite attached it straight on. The sensor itself hasn't been twisted out of alignment!!!!. It may only be microns out, but if your camera isn't dead straight, it can affect how your piccies turn out. It's just a matter of trial and error to get everything working smoothly.
If you're going to be taking piccies, you're going to have to get comfortable with processing your piccies. You don't necessarily have to become expert with all the ins and outs of processing an image, but just so long as you know enough to be able to produce results that you're happy with.
Graham. My comments are entirely what-if, just a thought. Having modified a DSLR the issues mentioned are only possibilities. The link to cleaning sensors relates to cleaning the front of the low pass filter, whereas, the mod involves exposing the face of the sensor. I found it particularly difficult to keep the sensor face dust free during installation of the new filter assembly until I got the cleaning technique under control.
The shims, well... the horse has bolted. If indeed they are part of the problem and most likely it's focus tube attachment. Realigning the sensor can be done with basic tools, so it's not the end of the world and a slim possibility. If as I noticed, the very thi shims, 0.1mm become dislodged during disassembly they are easy to miss. Particularly as they stick to the sensor frame and may go unnoticed - there, I'm worrying for you. Perhaps needlessly.
Also Graham - it looks like you might have some issues with your sensor being not quite square
yep the most likely issue is that the whole camera is not square in the focuser (it will only have to be a mm or two out) - sometimes the nosepieces have that little undercut that doesn't gel with the compression ring, or any one of various other reasons for stuff not connecting cleanly. I found that to be an issue with the compression ring on the lipstick on the pig and the nosepiece I was using on my DSLR
By the way when are you going to post some images from the pig...??
Thanks geezers-Adam- have been wanting to use the pig for a while but the clear sky has been so rare of late that I didn't want to dissasemble my 80mm set up and then start again. This is in fact what I am going to do now anyway so I can re-square the sensor, take better flats then see how these come out.
Will let you know.
By the way how do you think I would go guiding the 8" with a modified guide scope, or should I be trying to attach my old orion 80mm guide scope?
Clouds again and rain this wek so not much hope of any further images.
Cheers
Graham
