The "No EQ" DSO Challenge!

[Nigel G]

I cashed in my scrap copper I have been saving ( 2 years worth ) and treated myself to a refractor  The Equinox 80ED Pro.

A big problem being I haven't seen any stars for over a week now, I'm itching to use it, first try will be on the Alt-AZ mount but how long will I have to wait.

Monday night looks possible at present.

Nige.

[Filroden]

2 hours ago, The Admiral said:

Not my post, gov! You are responding to Fabien's post.

Ian

You're right. I was quoting Fabien from within your post when I meant to quote Fabien directly. I think your image is representative of what could be achievable though the added light pollution probably means needing to stack many more images to overcome the noise.

[ManixZero]

On 2/6/2017 at 21:52, Nigel G said:

Here's what I mean, these images are cropped from 135mm lens image to compare against 150p images.

They are all similar exposure times, the 135mm lens appears to gather more.

Nige.

 

On 2/7/2017 at 08:26, Stub Mandrel said:

My 135mm lens is f3.5 and some are f2, I think, your scope is f5 which will be some of the difference. To be fair, I think the 135mm images look like they have been processed more aggressively too.

Wow Nige!

 

Definitely going to have at using my f2.8 70-200mm on DSOs - never gave it much of a thought before!

Is it best to try to piggyback the camera onto the telescope and use the goto for tracking or stick it on my std tripod and point and shoot - what did you do?

Also how much did you have to crop? - I also have a MF 135mm f2.5 lens that is smaller lighter and more suitable for the piggyback option?

I guess I will just have to wait for clear skies and give it all a go!

 

Cheers 

MZ

[happy-kat]

Astroboot sell a red dot finder that fits in a camera flash hot shoe. I use it to align my goto fine. Camera is on dovetail bar mounted direct on mount. If you scroll pages back you will see Nige's cameras mounted.

[Nigel G]

9 hours ago, ManixZero said:

 

Wow Nige!

 

Definitely going to have at using my f2.8 70-200mm on DSOs - never gave it much of a thought before!

Is it best to try to piggyback the camera onto the telescope and use the goto for tracking or stick it on my std tripod and point and shoot - what did you do?

Also how much did you have to crop? - I also have a MF 135mm f2.5 lens that is smaller lighter and more suitable for the piggyback option?

I guess I will just have to wait for clear skies and give it all a go!

 

Cheers 

MZ

Thanks.

I use the camera direct on the Alt-AZ mount, I found my 135mm lens better than my 210mm lens, both F3.4.

These images were taken with the 135mm lens.

Here's the original image no cropping other than stacking artefacts. And the camera on the mount.

Well worth using lenses for DSO's.

edit.

I either align the mount with the scope first or just use live view on the camera to align the mount, both work well.

Cheers

Nige.

Edited February 11, 2017 by Nigel G

[Stub Mandrel]

I 3D printed this quick and dirty finder for widefield AP:

[Tangoringo]

Guys and gals,

To all of you can I say a big thank you. Some, if not most, of the shots on here are superb with even fairly basic kit and have rekindled my interest in astronomy. Having bought a second hand ETX 105 I've had some great nights observing prior to the winter clag setting in but after a stroke of luck the other day Ive managed to grab an HEQ5 Pro with a William Optics Megrev 90 for 600GBP. Can't wait now to get my hands on it to have a play. Needless to say, expect a load of help requests over the coming months.

Keep those photos coming though as its always great to learn and be inspired by other peoples work.

Cheers,

I ( Very,very newb!! )

Edited February 11, 2017 by Tangoringo

[rotatux]

On 10/2/2017 at 11:08, The Admiral said:

I'm not sure exactly what's going on here Fabien. Here's an image of the Rosette I made when I first got into astrophotography, and which was posted ages ago on this thread.

[...]

Now this was taken with a 102mm f7 refractor, so from an imaging point of view very similar to your set up. I used 130 x 10s lights, so about half the exposure you used. Admitedly, I'm not in the suburbs of a huge city, and I'm not using a pollution filter, and Orion's belt is clearly visible to me (at least, when this never ending cloud shifts out of the way!). I've found my camera to have a good red response, even though it is unmodified. May be your sky background is just too large. What effect the filter will have I don't know, as I've not used one, but one might hope it would give a significant improvement. It would be interesting to see what the deep red response of your camera is; this site might give you a clue https://kolarivision.com/articles/internal-cut-filter-transmission/, though it doesn't have your actual camera you may be able to identify others with the same sensor. Also, as a previous Olympus user (for general photography) I am aware that the MFT sensors are quite noisy, even the latest ones suffer a bit with long exposures. I fear you may be fighting against the odds here.

As for stars blowing out, I think that is to be expected with exposures used to capture the tenuous nebulosity, particularly with a sensor not specifically designed for well depth. Personally, I don't worry too much about it, and I think if you were to try HDR to capture them then the exposure differences needed would be quite large, much more than a 30s to 20s change would accommodate.

I guess the other alternative in your viewing location would be narrow band imaging, but that would require a dedicated camera such as the AS1600 4/3.

Ian

PS. You might be interested in this review which discusses noise levels in the EM5 and EM1 http://www.wrotniak.net/photo/m43/em1-em5-dark.html

Yes your setup with APS-size sensor and no flattener/corrector has nearly exactly the same FoV as me with M4/3 and ComaCorr. The Rosette framing of both images indeed look the same. Nice picture Ian BTW ;-)

Looked at kolarivision site. I found a cam with same sensor as me, the E-P1. However it's only the characteristic of the filter, not the sensor. I know from sensorgen.info that my sensor has 38% quantum efficiency (though I don't know how to mesaure and check it myself), but I suspect that value also varies with wavelength, so I can't get any conclusion (the net light sensitivity should account for both the filter and the sensor).

About noise: The first generation sensor (12.3mpx) is from Olympus and indeed quite noisy, though manageable. But the 16mpx sensor found in E-PM2/PL5/6/7, E-M5/10 is from Sony and much better (3x less noisy, and 1.6x more sensitive at 60% QE) -- that's what I'm willing to get, maybe second hand. Your 2nd link conforts me in this opinion.

19 hours ago, Filroden said:

I wonder if you've lost some of the data when removing/minimising the light pollution during processing? I found the Rosette, Soul and Orion Nebula all very difficult to process because they filled my field of view, making it difficult to calibrate any background gradient. Pacman was much easier as it occupied much less of the frame.

Here's two of my images of the Rosette - these are both from the same data (just one is rotated 180deg)! The biggest difference between them is that I improved my background model and preserved more of the nebula which existed in the unprocessed image.

Interesting... makes sense given my technique, I need to double check my "NG darks": as the target was rapidly climbing in the sky, I may have captured the wrong gradient and mismatched a bit with the lights background. Oh damn, I have yet to write a blog entry on that "NG dark" technique of mine :-P

 

18 hours ago, Nigel G said:

I wonder if you add bias frames if it would help with noise levels.

You have captured a lot of data, it seems over powered by noise or light pollution. ( your loosing a lot during processing gradients ) maybe a lower ISO setting ?

Getting better though  

Thank you Nige. I don't think separate bias would help as I already use traditionnal (not scaled) darks dedicated to each session or even subject.

I hope it's LP and it can be sorted out, the filter was here to help. I would like lower ISO if I could achieve longer subs, but the mount is so erratic I'm afraid I wouldn't capture any signal as lower ISO + 20s. Will retry on occasion though.

Edited February 11, 2017 by rotatux
removed doubled text

[rotatux]

17 hours ago, Nigel G said:

I cashed in my scrap copper I have been saving ( 2 years worth ) and treated myself to a refractor  The Equinox 80ED Pro.

A big problem being I haven't seen any stars for over a week now, I'm itching to use it, first try will be on the Alt-AZ mount but how long will I have to wait.

 

30 minutes ago, Tangoringo said:

the other day Ive managed to grab an HEQ5 Pro with a William Optics Megrev 90 for 600GBP. Can't wait now to get my hands on it to have a play. Needless to say, expect a load of help requests over the coming months.

With all that new gear for many people, no wonder why it's been rainy or cloudy for several weeks ;-)

Congratulations both, all nice buys.

[The Admiral]

33 minutes ago, rotatux said:

Looked at kolarivision site. I found a cam with same sensor as me, the E-P1. However it's only the characteristic of the filter, not the sensor. I know from sensorgen.info that my sensor has 38% quantum efficiency (though I don't know how to mesaure and check it myself), but I suspect that value also varies with wavelength, so I can't get any conclusion (the net light sensitivity should account for both the filter and the sensor).

About noise: The first generation sensor (12.3mpx) is from Olympus and indeed quite noisy, though manageable. But the 16mpx sensor found in E-PM2/PL5/6/7, E-M5/10 is from Sony and much better (3x less noisy, and 1.6x more sensitive at 60% QE) -- that's what I'm willing to get, maybe second hand. Your 2nd link conforts me in this opinion.

Perfectly true of course, but I've taken the simplistic view that the QE for an unfiltered sensor to Hα will be similar to the QE at other wavelengths, on the basis that if the sensitivity fell off quickly with increasing wavelength there'd be no need for the IR filter in the first place. Might be a totally misguided view of course . What it will show you though is if the filter transmission is very low to Hα then whatever the performance of the sensor itself the result isn't going to be good. And there are some cameras like that. The transmission of 656nm in my camera is over 40%, for ref.

Well, I think the 2nd link shows that the sensor in the EM-5 has better noise performance for long exposures than the EM-1, but I don't think it confirms that either is the best choice for astrophotography, as Wrotniak states "The E-M5 and E-M1 are not cameras designed to perform well in long-exposure astrophotography." Though perhaps the noise performance of the sensor is a moot point when you have a very high level of sky background.

Ian

Edited February 11, 2017 by The Admiral

[Tangoringo]

1 hour ago, rotatux said:

 

With all that new gear for many people, no wonder why it's been rainy or cloudy for several weeks ;-)

Congratulations both, all nice buys.

Hi Fabian,

How right you are. Apologies now for the impending worst skywatching spring ever experienced. :-))

[rotatux]

On 11/2/2017 at 15:10, The Admiral said:

I've taken the simplistic view that the QE for an unfiltered sensor to Hα will be similar to the QE at other wavelengths, on the basis that if the sensitivity fell off quickly with increasing wavelength there'd be no need for the IR filter in the first place.

Makes sense, but if I had to design such a filter as an engineer I would make it such that it only lowers undesirable signals to unnoticeable levels at the sensor's output. Which makes me think the sensor cells are already not very sensitive to IR (and H-alpha), when I see the slope of all the curves on the IR side. For ref, my filter should be at about 35% at 656 which is nearly comparable to yours.

On 11/2/2017 at 15:10, The Admiral said:

as Wrotniak states "The E-M5 and E-M1 are not cameras designed to perform well in long-exposure astrophotography." [...]

All things being relative, as he compares to "full frame" sensors. One should actually look at pixel size rather than whole-sensor size, to get a hint of capture range. Of course FF are ahead of the race, but latest APS DSLR models with 24mpx and more have equal or smaller pixels than the E-M5.

On 11/2/2017 at 14:38, rotatux said:

I need to double check my "NG darks"

My darks were fine, so the problem didn't come from them.

But I think I've pinpointed the "problem". I did a few camera flats, with just the camera, T2 and M48 adapter, and various or no filters, against daylight (or rather, what clouds transmit :-/). Then did stats on the resulting images, all taken at same exposure (ISO and duration).

As Ken hinted, the filters eat on red and green, and let a growing part of blue pass (as show by the relative "B-V" shift). One could object this is on visible light, not H-alpha or O3, but it probably just has the same effect on them, as these are supposed to be wide-band filters.

IMO this explains the severe blueish shift I have with the UHC, not only there is much less total light -- though I wouldn't bet on bad transmission as those stats are with indirect sunlight so much of the spectrum is impacted, not just star/nebula light -- but there is 3x less red transmitted.

So my 20s of Rosette, given it essentially comes in the reds, are equivalent to 6.7s without filter or 10s with Didymium. I would bet that's why I don't get enough absolute signal. I have yet to find a combination of exposure that gets more signal, but that UHC filter may not be part of the solution, as strangely as it sounds.

Edited February 12, 2017 by rotatux
corrected comparison with APS: 24mpx not 18

[The Admiral]

1 hour ago, rotatux said:

Makes sense, but if I had to design such a filter as an engineer I would make it such that it only lowers undesirable signals to unnoticeable levels at the sensor's output. Which makes me think the sensor cells are already not very sensitive to IR (and H-alpha), when I see the slope of all the curves on the IR side.

If one looks at the spectral response for the ZWO ASI1600MM:

it doesn't seem to fall off very rapidly around Hα. Also, I wouldn't expect the UV/IR filter to be of the steep-cut variety given the convergence of the light falling on the sensor. I also remember that Leica made a bit of a boo-boo when they introduced the M8, in that in improving the spatial response they ended up with an excessive infrared response which gave an unwanted colour bias in images with a lot of IR. So much so that they had to hurriedly issue purchasers with an IR filter to stick on the front of their lenses!

2 hours ago, rotatux said:

All things being relative, as he compares to "full frame" sensors. One should actually look at pixel size rather than whole-sensor size, to get a hint of capture range. Of course FF are ahead of the race, but latest APS DSLR models with 24mpx and more have equal or smaller pixels than the E-M5.

May be, but manufacturers can really only push up the pixel count if they manage to improve, one way or another, the inherent sensitivity of the sensor. Otherwise noise would be objectionable in everyday photography. Even so, I wouldn't be looking at 24Mp sensors for astro, whatever the frame size. I do know though that if I wanted to image some low light scenes with multi-second exposures, I'd pick up my 16Mp Fuji rather than my, admittedly now aged, 16Mp GH2. Also, at the back of my mind I think that there was always the thought that Panasonic (suppliers of most of the MFT sensors) would not give Oly their state-of-the-art devices.

2 hours ago, rotatux said:

As Ken hinted, the filters eat on red and green, and let a growing part of blue pass (as show by the relative "B-V" shift). One could object this is on visible light, not H-alpha or O3, but it probably just has the same effect on them, as these are supposed to be wide-band filters.

I think I'd be very careful about comparing results with a broad-band source and extrapolating it to sources of Hα for example. I would have said that the Astronomik UHC is very much not broad-band, removing as it does most of the visible light except for the bands around O3, Hα and S2. But, for those particular wavelengths transmission appears to be very high however, ~100%

 

I would have said that the didymium filter is a whole different ball-game however.

Just my 2 cents worth .

Ian

[Nigel G]

I have a clear sky tonight, First try with the new refractor and the star discovery mount, I took a few subs on M42 again, I am amazed at the difference, much much more ridged and much sharper stars. Much better keep rate. I love it.

I have got to download DSS again as I had PC trouble last week.

I have now roughly polar aligned my new mount and giving M31 another go. Still waiting for my guide cable to turn up though. First impression, quite quick to set up, 15 minutes and starts tracking straight away. Easier than I had imagined. 120s 90 % keep.

Nige.

[The Admiral]

Congrats Nige , but a bit confused . Star discovery, polar aligned, new mount? Must have missed something (there've been a lot of posts!). Do I take it that your EQ3 is the new mount? And you're going over to the dark side?

Ian

[happy-kat]

Look forward to seeing your discovery image.

I guess the ED80 is a similar weight to your 150p or is it heavier? Perhaps better balanced with lens one end and camera the other.

I got success with the Virtuoso tonight the dove bar worked used my 135mm lens.

[Nigel G]

1 hour ago, The Admiral said:

Congrats Nige , but a bit confused . Star discovery, polar aligned, new mount? Must have missed something (there've been a lot of posts!). Do I take it that your EQ3 is the new mount? And you're going over to the dark side?

Ian

I'm heading that way but not giving up on the Alt-AZ imaging at all.

First light with my refractor had to be Alt-AZ  

Once I have re installed DSS I will start the processing.

Must admit though, time spent setting up EQ is gained back with almost 100% keep rate, unguided.

Cheers

Nige.

[Nigel G]

1 hour ago, happy-kat said:

Look forward to seeing your discovery image.

I guess the ED80 is a similar weight to your 150p or is it heavier? Perhaps better balanced with lens one end and camera the other.

I got success with the Virtuoso tonight the dove bar worked used my 135mm lens.

Its about the same weight, balances perfect with the camera fixed, the focuser is smooth high geared and I can rotate the camera without loosing focus.

It tracked very well on the star discovery, so solid compared to the 150p.

Nige.

[SilverAstro]

2 hours ago, The Admiral said:

Congrats Nige , but a bit confused . Star discovery, polar aligned, new mount? Must have missed something (there've been a lot of posts!). Do I take it that your EQ3 is the new mount? And you're going over to the dark side?

Me too, sounds very dark, did this get passed by the committee one wonders.  Can Nige be split in two ? and post as Nigel 1G and Nigel 2G depending which mode he is in ? LOL!

congrats Nige, as the others, I look forward to your new first lights. Going by what you have achieved with the moded Discovery they should be awsome.

 

Edited February 14, 2017 by SilverAstro

[happy-kat]

There is a dedicated EQ3-2 imaging thread so I'm assuming to look there for those :-) be interesting to know keep rate on discovery with ED80

[happy-kat]

Finally I am getting there. This is a single 30 second image as is resized 50% NGC2244 and saved as png just to show that the Virtuoso mount is now tracking great, it was all about gettting the balance and weight distribution right. For observing the original tracking was fine, I just wanted to see if I could improve it.

ISO 800 Helios vintage (1980s era) 135mm lens 1100d 30 seconds f2.8 or f3 I forgot to check this morning when I put the gear away. I would have gone for longer subs but I couldn't get DSLR timelapse to work right I have had a recent update and I need to day time fiddle to get that mastered. I have 37 lights and am about to get DSS going, with flats and bias, might even get to add to this if another clear night comes along soonish. There is a little CA but there are so few bright stars in this area I decided light was more important then fiddling effort afterwards. How long have I waited to get this, ages! Oh and the Celestron litho power tank is excellent that is 5 uses now and still going at 50% charge I try not to think about whether or not the battery has surge protection as I know the mount does not.

[SilverAstro]

1 hour ago, happy-kat said:

be interesting to know keep rate on discovery with ED80

+1

 

[Nigel G]

5 hours ago, happy-kat said:

There is a dedicated EQ3-2 imaging thread so I'm assuming to look there for those :-) be interesting to know keep rate on discovery with ED80

I took 15s and 20s on M42 with a keep rate of about 95%, only about 20 minutes worth in total.

I'll be posting the EQ images in the other thread.

Nige.

[Nigel G]

M42 with 80ED and Star Discovery mount.

20 minutes of 15s + 20s, flats and bias. Could do 30 - 40s without blowing the core I think.

Quite poor seeing caused poor S-N ratio. But impatient me as usual had to try new toys.  

Loads of noise reducing as you can see.

Have had better but conditions were far from perfect, the stars are noticeably better than ever though.

Cloudy for the next few nights, what's going on......

Cheers

Nige.

[happy-kat]

Do you think the better star shapes is the difference between reflector and refractor? I find that observation of your's interesting as the main influencing factor I assumed would be the mount but that was the constant here.

How do the stars compare between ed80 and your 135mm lens. Ian gets great stars with his ED, is that the link a corrected nice refractor. As do others on here with nice refractors.

Edited February 14, 2017 by happy-kat