Stub Mandrel Posted July 19, 2016 Share Posted July 19, 2016 What about the Dumbbell M27? Unmodified Canon 10D - 30 second exposures at ASA1600 in 2015: Modified Canon 450D - 30 second exposures at ASA1600 in 2015 OK, not the same camera and my processing is better than it was, but same scope, same place and the first picture was done on 5 May the second on 5 July so much less favourable conditions... 2 Link to comment Share on other sites More sharing options...
The Admiral Posted July 19, 2016 Share Posted July 19, 2016 Neil, that's a possibility, though one that isn't a summer object would be better from my point of view. I'm a bit concerned about how we do this though, because it's only after fiddling with StarTools that colour is revealed in my images, as a rule (the Orion neb was a bit different though, as it's so bright). I need to think about this some more Ian Link to comment Share on other sites More sharing options...
SilverAstro Posted July 19, 2016 Share Posted July 19, 2016 35 minutes ago, Stub Mandrel said: What about the Dumbbell M27? and my processing is better than it was Good candidate (I think, but my knowledge of it is limited !!) and that is the big problem, how to avoid processing distorting the ratio, it may look pretty but may not be quantifiable. Some way of doing it raw-ish would need to be defined Very interesting folks, cant stop - due into the clutches of the NHS, will be back later to comment better Link to comment Share on other sites More sharing options...
Nigel G Posted July 19, 2016 Share Posted July 19, 2016 1 hour ago, The Admiral said: Remind us what camera you are using please Nige. Ian Canon eos 1200d unmodded. Nige. Link to comment Share on other sites More sharing options...
Nigel G Posted July 19, 2016 Share Posted July 19, 2016 I stand corrected, after processing all 4 M31 images I find a little more detail as more subs are added. Few, I thought I was running out of room for improvement. The 4 images . No1 = 40 x 45s during quite poor seeing. No2 = 120 x 30s during good seeing and low light pollution . No3 = 120 x 30s plus 40 x 45s during full moon. No4 = everything 120 x 30s + 80 × 45s . There is a small difference between them , a bit more detail on the outer spirals, I find M31 a difficult dso to process. I get a lot of noise to deal with even after stacking 200 subs. I think this is due to the camera and sensor limits rather than the scope. Nige. 2 Link to comment Share on other sites More sharing options...
The Admiral Posted July 19, 2016 Share Posted July 19, 2016 I think you've got some splendid images there Nige, don't be too hard on yourself. Of all, I think I prefer the second one, small core and pleasant colour. I think M31 is one of those objects where the deeper you go, the bigger it gets. Ian 1 Link to comment Share on other sites More sharing options...
The Admiral Posted July 19, 2016 Share Posted July 19, 2016 3 hours ago, SilverAstro said: Good candidate (I think, but my knowledge of it is limited !!) and that is the big problem, how to avoid processing distorting the ratio, it may look pretty but may not be quantifiable. Some way of doing it raw-ish would need to be defined Very interesting folks, cant stop - due into the clutches of the NHS, will be back later to comment better My mind has turned to means other than astro! LEDs which emit around 656nm are available, even 700nm, and so I'm thinking perhaps one could photograph such an LED along with, say, a green one and compare. You won't get an absolute measure, but at least different cameras could be compared. They'll be bright enough so that noise won't be an issue and image processing simplified. I'll keep thinking Ian 3 Link to comment Share on other sites More sharing options...
SilverAstro Posted July 19, 2016 Share Posted July 19, 2016 4 hours ago, Stub Mandrel said: What about the Dumbbell M27? Unmodified Canon 10D - 30 second exposures at ASA1600 in 2015: Modified Canon 450D - 30 second exposures at ASA1600 in 2015 OK, not the same camera and my processing is better than it was, but same scope, same place and the first picture was done on 5 May the second on 5 July so much less favourable conditions... Perfect example of the sort of embryo that was in my mind, thanks SM, 2 cameras from the same source brill ! Do you still have the frames as they came out of the cameras so you can do the same (or lack of !) processing on them both ? Just by way of example of how I thought a protocol might develop here is what I was thinking we might do in IRIS, it has a slice tool to take a histogram across an image, first I reduced them to b&w to compare levels, we could discuss how to compare colour amplitudes in a colour image later(?) Iris did not allow me to do a screen capture of where I placed the slice so I added the green arrow later in the approx position , the slice on the left shows that the level in the Ha light region ( short green line ) is well below that in the right pic (and as I type this Ian has added a right good idea !) but let me not waste my cunning Iris plan :- Link to comment Share on other sites More sharing options...
SilverAstro Posted July 19, 2016 Share Posted July 19, 2016 9 minutes ago, The Admiral said: My mind has turned to means other than astro! How dare you sir you could get Black-balled for that or Ha-balled but at least different cameras could be compared. We would have to make sure that each camera owner bought the same LEDs ? and not all will be happy with the electricals etc perhaps ? But I like it so far, good laterals ! 2 Link to comment Share on other sites More sharing options...
SilverAstro Posted July 19, 2016 Share Posted July 19, 2016 3 hours ago, Nigel G said: unmodded. Oh ! I am amazed, I thort you had a modded one, , , and isnt the NA mostly Ha emission ? so you are not lacking for much, mummble mummbl, think I'll forget all this stuff about measuring the response of various and just go buyme a 1200d like wot my chum Nige has 2 hours ago, Nigel G said: The 4 images . No1 = 40 x 45s during quite poor seeing. No2 = 120 x 30s during good seeing and low light pollution . No3 = 120 x 30s plus 40 x 45s during full moon. No4 = everything 120 x 30s + 80 × 45s . Luvverly stuff, but am I going blind - I can only see 3 1 Link to comment Share on other sites More sharing options...
The Admiral Posted July 19, 2016 Share Posted July 19, 2016 17 minutes ago, SilverAstro said: But I like it so far, good laterals ! Hmm, yes, I did wonder whether imaging something other than an astronomical object might meet with some opposition I suppose if it's cheap enough one could be passed around. At least that way all the cameras will be compared equally. Ian 2 Link to comment Share on other sites More sharing options...
The Admiral Posted July 19, 2016 Share Posted July 19, 2016 12 minutes ago, SilverAstro said: Oh ! I am amazed, I thort you had a modded one, , , and isnt the NA mostly Ha emission ? so you are not lacking for much, mummble mummbl, think I'll forget all this stuff about measuring the response of various and just go buyme a 1200d like wot my chum Nige has Luvverly stuff, but am I going blind - I can only see 3 Really? Ian 1 Link to comment Share on other sites More sharing options...
SilverAstro Posted July 19, 2016 Share Posted July 19, 2016 11 minutes ago, The Admiral said: Really? yep really now I am seriously worried, what is going on, the top one is pale, the middle one is orange-ish with a "Paint" dialog wee box lower left and the bottom one is pale yellow with ummm yellow-green in the spiral, but the sun is creeping up on my monitor , how strange These are the 3 part URLs PSX_20160718_215237.jpg.c1dce7c6219f4a10aea5dda143a7306e.jpg PSX_20160718_215704.jpg.10c2840ba70cc6f89d9f1f9aa2615d6c.jpg PSX_20160719_121341.jpg.d8d0b5fd53451753223adbe6c4ccbfeb.jpg which am I missing, is it also a jpg or something else that my browser is rejecting ? What if I re-quote it all , how many remain ? :-- 3 hours ago, Nigel G said: I stand corrected, after processing all 4 M31 images I find a little more detail as more subs are added. Few, I thought I was running out of room for improvement. The 4 images . No1 = 40 x 45s during quite poor seeing. No2 = 120 x 30s during good seeing and low light pollution . No3 = 120 x 30s plus 40 x 45s during full moon. No4 = everything 120 x 30s + 80 × 45s . There is a small difference between them , a bit more detail on the outer spirals, I find M31 a difficult dso to process. I get a lot of noise to deal with even after stacking 200 subs. I think this is due to the camera and sensor limits rather than the scope. Nige. 2 Link to comment Share on other sites More sharing options...
SilverAstro Posted July 19, 2016 Share Posted July 19, 2016 Thanks Ian, the plot thickens, it is Nige's 1st one PSX_20160709_031747.jpg.8ba22b25002c6d8aaf4f284fb7c5ffd6.jpg that has gone AWOL, I can see it if I revert to Firefox but for some reason yet to be determined K-Meleon ( based on Firefox) cannot see it and even worse did not put up a blank icon to signify I wonder what else it has been not showing me I think a trip to K-Meleon site is on the cards ! 1 Link to comment Share on other sites More sharing options...
The Admiral Posted July 19, 2016 Share Posted July 19, 2016 21 minutes ago, SilverAstro said: Thanks Ian, the plot thickens, it is Nige's 1st one PSX_20160709_031747.jpg.8ba22b25002c6d8aaf4f284fb7c5ffd6.jpg that has gone AWOL, I can see it if I revert to Firefox but for some reason yet to be determined K-Meleon ( based on Firefox) cannot see it and even worse did not put up a blank icon to signify I wonder what else it has been not showing me I think a trip to K-Meleon site is on the cards ! I'm on firefox. Ian 1 Link to comment Share on other sites More sharing options...
Filroden Posted July 19, 2016 Share Posted July 19, 2016 To test red response wouldn't it be simpler to attach a narrow band that only passes red and photograph a source of infrared such as an electric heating element whose power can be controlled? Then you're just comparing resulting amplitude of the capture in a fixed duration... 1 Link to comment Share on other sites More sharing options...
The Admiral Posted July 19, 2016 Share Posted July 19, 2016 Well, an NB filter ain't cheap, and I don't own one. Also, doesn't one need to be able to compare responses at ~ 656nm with that well in the visual band? Otherwise, presumably one would need to determine the output of the fire (black body?) to get some measure of absolute sensitivity. Methinks that might not be easy. Ian Link to comment Share on other sites More sharing options...
Filroden Posted July 19, 2016 Share Posted July 19, 2016 To get absolute responses yes, but to get comparative measures of cameras probably not. Link to comment Share on other sites More sharing options...
Nigel G Posted July 19, 2016 Share Posted July 19, 2016 3 hours ago, SilverAstro said: yep really now I am seriously worried, what is going on, the top one is pale, the middle one is orange-ish with a "Paint" dialog wee box lower left and the bottom one is pale yellow with ummm yellow-green in the spiral, but the sun is creeping up on my monitor , how strange These are the 3 part URLs PSX_20160718_215237.jpg.c1dce7c6219f4a10aea5dda143a7306e.jpg PSX_20160718_215704.jpg.10c2840ba70cc6f89d9f1f9aa2615d6c.jpg PSX_20160719_121341.jpg.d8d0b5fd53451753223adbe6c4ccbfeb.jpg which am I missing, is it also a jpg or something else that my browser is rejecting ? What if I re-quote it all , how many remain ? :-- I think there's 4 there, on my mobile there's none there ☺ now the colours I was trying to decide what colour I wanted it to be ?, for me it's the hardest dso to process so far, getting the colour the same as you can see is blooming hard, I spent ages on colours. The little box in the bottom left of one is a copy paste mistake, I only noticed after I had closed startools ?. Nige. Link to comment Share on other sites More sharing options...
The Admiral Posted July 19, 2016 Share Posted July 19, 2016 13 minutes ago, Filroden said: To get absolute responses yes, but to get comparative measures of cameras probably not. I think this would only work if one person was testing all the cameras on his fire, I don't see it working with everyone testing their own camera on their own fire. It'll be the temperature of the fire that will dictate the output, and that won't be the same even if the powers are the same. Ian 2 Link to comment Share on other sites More sharing options...
SilverAstro Posted July 19, 2016 Share Posted July 19, 2016 1 hour ago, Nigel G said: The little box in the bottom left of one is a copy paste mistake, I only noticed after I had closed startools No worries Nige, I only mentioned the little box as an aid in identifying (with Ian's help) which picture I was not seeing, all sorted now = a fault with my browser which will have to be replaced ! 1 Link to comment Share on other sites More sharing options...
Nigel G Posted July 20, 2016 Share Posted July 20, 2016 A possible target for the test could be M17 Omega nebula, around the same altitude as Saturn in the southern sky atm. I took this during the full moon last night and it was close to the target, because of the moon I could only get 15s exposure at 400 iso and only 30 minutes worth before the faint clouds started to arrive. Nige. Link to comment Share on other sites More sharing options...
wxsatuser Posted July 20, 2016 Share Posted July 20, 2016 On 7/19/2016 at 09:34, Nigel G said: Looking at this image and my attempt it looks like I have a shed load of noise, what is going on, my image shows far more apparent nebulosity which isn't on other images. Is that noise ? Have I hit a brick wall? I have been experimenting with M31 . I have 60 minutes of good 30s subs and 60 minutes of mixed 45s ( some have quite heavy light pollution some have moon light interference some are good) I have stacked 4 different sets of images. 1st , 1 hour of 30s........2nd 1 hour of 30s plus 30 minutes of street light polluted 45s.........3rd 1 hour of 30s plus 30 minutes taken with full moon up........ and 4th everything stacked 2h exposure. I still have to process the 2 hour image but there's hardly any difference if any between the images already processed,. Have I reached the limit of my camera or scope ? I notice the central 30% of my images seems to be good in detail but outside that a quick loss of detail. Camera or scope or both ? At the moment I can't seem to improve my images, have I come to the point where upgrades are needed? I'll post the M31 images once completed. Nige. I think the improvement can only really come from longer exposures, better QE camera, faster optics, all the usual stuff that costs money basically. Personally I found that a minimum exposure of 120secs gets a reasonable image but 300secs makes a huge difference. The 6D has a far better QE than consumer cams, 47% and the 7DMK2 IS 59%. Jerry Lodriguss has a nice article about modding. http://www.astropix.com/HTML/I_ASTROP/DSLR_HA.HTM 1 Link to comment Share on other sites More sharing options...
SilverAstro Posted July 20, 2016 Share Posted July 20, 2016 (edited) 1 hour ago, wxsatuser said: Jerry Lodriguss has a nice article about modding. http://www.astropix.com/HTML/I_ASTROP/DSLR_HA.HTM An interesting read but I am bothered about his second NA pic., the 'mouse over' one. How can you get more red light by interposing a filter ! More contrast yes, but not more light which is what he seems to be implying?, and makes it look like, in that example. However, he has committed a basic sin of comparative experiments (!), he has changed two variables at once, a ) inserted a filter and b ) changed the method of exposure. I would like to see that replicated by someone else. Edited July 20, 2016 by SilverAstro 1 Link to comment Share on other sites More sharing options...
wxsatuser Posted July 20, 2016 Share Posted July 20, 2016 1 hour ago, SilverAstro said: An interesting read but I am bothered about his second NA pic., the 'mouse over' one. How can you get more red light by interposing a filter ! More contrast yes, but not more light which is what he seems to be implying?, and makes it look like, in that example. However, he has committed a basic sin of comparative experiments (!), he has changed two variables at once, a ) inserted a filter and b ) changed the method of exposure. I would like to see that replicated by someone else. I believe the more light is via the longer exposures you get with LP filters, the total exposure in both images is the same. The darker skies do have a big advantage. I have tried to replicate the images Roger Clark does with his 7DMK2, I believe from a dark site, but even with an LP filter it's just not possible. 1 Link to comment Share on other sites More sharing options...
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