Ok, funnily enough I was just sorting through my M8 pics last night. This one is 1hr 30min's integration, 180sec subs @ iso 800 unmodded canon 1100d 10" newt, guided. Not sure about the colour though? Added another with the core a bit blown out I think it looks better.
There's a big difference between our cameras, you are picking up a lot more faint stuff and background stars and with a shorter integration time as well
well seems a lifetime ago that the weather was any good in perth for any sort of imaging
last year i think?
80 45s iso 1250 unguided
APM 107 / 0.79 reducer
canon 60da
Pat: M20 for an added bonus. Nice image. We have pretty much the same colour.
Rick: Your colours add to the effect. Every now and then I do the facebook thing, and the more vibrant and colourful the better :-)
And surely there has to be some more M8's in the closet??
This is a shot using a modded DSLR. I did a custom white balance post modding and also used a CLS-CCD LP filter due to my inner city location.
As you can see, it does pick up other colours.
Bo
O.K. Here is my first digital try at it, quite a few yeas ago. An unmodded
DSLR will pick up blue, it's not a wrong colour, it is picked up by the camera, not conjured up from nowhere. This was only treated to the ministrations of DSS. The RGB cones were synchronised, the colour saturation done, and
that was it.
raymo
A couple or great images there Bo and Raymo and love that wide field version Pat.
My guess is that the red part of the spectrum is just overwhelming the blues in the modded cameras? With my unmodded camera increased gain just increases noise and blows out the background but doesn't effect colour. White balance adjusts the colour (temperature) in the processing side of the image not capture, you can change that with raw files after capture.
Just a couple more comments,
Peter, have you tried comparing reflectors v refractors as well as modded v unmodded DLSR, plus with or without LP filter? There are quite a few variable there...
Rick, with a modded camera, there is tendency for the red to show up more, because you have increased the senor response in the red end of the spectrum. That's why a custom white balance is needed (to tone down the red). Adding an LP filter in the imaging train, such as my CLS-CCD filter increases the contrast and limits some of the sensor response, but the result is a punchier image.
So if you have a full spectrum mod camera, do a custom white balance, add a LP filter if you are shooting from a suburban location and you can get equal blue and reds show up.
This is an image of the Triffd (M20) I took with the same set up and the blue showed up as prominently as the red http://www.iceinspace.com.au/forum/s...d.php?t=157269
If you want to read up on the modding process and how it affects the sensor response, Gary Honis has a great write up here http://dslrmodifications.com/DSLRcomparison.html
cheers
Bo
For me, if using DSLRs you need both modded and unmodded. Some
DSOs are overwhelmingly red, and need a modded one to highlight this,
and some items such as M8 have other colours present that are almost
completely overwhelmed, as stated by an earlier poster.
Bo, your remedy, whilst well worth doing is only a partial "cure" for the
problem. It only "restores" strong blues which M20 has in abundance,
and if you compare your M20 with unmodded pics you'll see that only the strongest parts of the blue are fully rendered; the upper part is faint, and
the right part is almost completely absent.
raymo
Thought I would throw one into the mix... lots wrong with this image but I was quite satisfied with the result, given it is a single exposure, 30 secs, ISO 6400, Daylight WB, Canon 5D MKII, 127mm f/6 achromat refractor on an HEQ5 Pro, unguided.
Coma is atrocious, focus is out just slightly, need a field flattener. All the things a first try could have wrong, are wrong. But I was impressed with myself and I'll try again when I have a chance.
Feel free to pick it apart. I'm not sensitive in the least.
So if you have a full spectrum mod camera, do a custom white balance, add a LP filter if you are shooting from a suburban location and you can get equal blue and reds show up.
interesting bo, so with a full mod astro dslr............... how do you do a custom white balance on it? photo a grey card?
would you suggest the same even with the 60da? (not fully modded)
pat
Hi Pat,
I used a grey card (11-13% from memory) under sunny day to do my custom white balance. I cannot comment on the 60Da but know that it is sensitive to the Ha (656nm) but the in camera processing makes the images taken in daylight look "natural".
You will see on the spectral data that LP filters filter out the unwanted street lights in the sodium and mercury vapour type (yellow and light green) and is therefor only useful in light polluted site. For country dark sites, a LP is not needed for reflectors and an IR.UV filter is needed for refractors.
Raymo, I respectively disagree with your assessment that one needs both modded and unmodded DSLR as a modded DSLR simply opens up the spectral response range. The only difference is when a LP filter is used.
As for my M20, I acknowledge that it does not show up the blue reflection nebula as some others. But bear in mind it was taken with a LP filter on, which does limit the darker blue/violet colours. This is explained in this discussion here https://www.cloudynights.com/topic/5...-modification/
Summing up, a full spectrum mod is very useful to capture the full spectral response of a CMOS sensor, but adding a LP filter limits its response range. A modded DSLR will perform best when used under dark skies without a LP filter.
Cheers
Bo
Try 'save as' and (I use trial & error) to get the image just under 2MB.
Then the brains trust might kick in with helpful advice.
Hi PKay,
You might know more about posting than I do, as I've always been under the impression that 200kB is the largest .JPG you can attach to a post. If there are other instructions on posting images, I have not seen them. I simply scaled the photo down to 200 pxls on the long edge and exported from PS.
Happy to hear back from the more advanced users on how to do that... maybe with a PM or quick point in the right direction so as to not hijack the thread too much.
You might know more about posting than I do, as I've always been under the impression that 200kB is the largest .JPG you can attach to a post. If there are other instructions on posting images, I have not seen them. I simply scaled the photo down to 200 pxls on the long edge and exported from PS.
Happy to hear back from the more advanced users on how to do that... maybe with a PM or quick point in the right direction so as to not hijack the thread too much.
i think you can use 1000 pixels for the long side
pat
I resize my images to 1200 pixels (wide side) then reduce the quality to save it under 200 kb. If you save your tiff file to jpeg before you resize, PS will will give you an estimated final saved size as you reduce the quality with the slider.