MarsG76

Great reports of all three nights of observing. I enjoyed reading this as I do not have time to observe away from home these days and it bought back memories of my remote nights under dark star spangled skies.

15 hours ago, rsarwar said:

I only started astro last year. I used Canon before in early 2010s - 550d and 70d. The nikons cameras post 2013 all use sony sensors and have better SNR and DR. Prior to 2013, i nikon's offerings were below below par. Notice the last three entries:

 

I took these last night. Stacked. total integration 2 hour for both

QHY 300 sec (gain = 2.2*unity)😞

D7000 600sec (gain = 3.3*unity):

same stretch, qhy on the left.

 

That comparison data sheet is exactly what I'm trying to get away from... this is obviously biased and canon biased comparisons are there too.. one can find what ever data or statistics they want to see, hence why I started this thread asking about real world comparisons.... and what you're showing is that there is not a phenomenal difference between the qhy and the nikon... than again you're posting severely scaled down low res examples, how about full res or full res center cropped comparisons... there has to be more improvement!!!

8 hours ago, rsarwar said:

i dont think D7000 is something that should be put aside.

My DSLR will still be in operation once my cam arrives.. but I imagine it'll be near exclusively used for natural color data to colorize the luma mono exposure stacks.

That said, who knows how long it'll be before I get the cam.. been over 2 months now and I'm not getting replies from the shop.... it's a big shop so I know that they are doing a runner.. but the service from china (ZWO) is abominable... pffft china.

15 hours ago, rsarwar said:

Running a proper mock session on the heat nebula with readmode=1, gain = 56 and offset = 25. this would be my standard setup. this is approx 2. compared to D700 at iso800 (3.3 * unity gain) the brightness is exactly the same (runing 600 sec subs). however, the level of detail is still as impressive as before thanks to DR and bit depth in my opinion.

I'd like to see some of your astroimages... post some here.. or do you post them to another site??

19 hours ago, rsarwar said:

I dont want to deflate you however... poor dynamic range of canon cameras. 

You wont deflate anything... don't worry... what Canons were you using? The Canons I used delivered better images than any Nikon I've seen, especially in AP... there's a reason why Canon DSLRs are the DSLR of choice in the vast majority of astroimagers. 

What a fantastic collection... congratulations on a great looking image.

On 13/04/2021 at 20:36, rsarwar said:

Okay I did some testings on the heart nebula. very rough ones. but using the same target and same telescope (130 pds). I live is bortle 6.

DSLR: D7000, 16 MPix APS-C IMX071 (same was ASI071) with full spec modd + custom firmware to disable onboard post processing, i.e. true darks + no star eating stuff. The pictures (always the right hand side of each screenshot) were taken a weeks ago (zero moon with the nebula fairly high in the sky) when i got the M48 Astronomik 12 nm Ha filter and wanted to see how well it worked and how an OSC handles it. ISO was set at 800 and time was 600 sec. according to the link sharkmelley gave, and according to this link, it equates to a gain of approx 3.3 * unity. ambient temp was about zero. only showing the red channel here - as it is  a Ha filter

QHY268M with the same filter, no moon, and readmode=0, offset=25 and gain=56 (6.6 time unity) but took a 300 sec frame (i was having issues with backfocus and wanted to investigate it so wanted a shorter exposure - it did saturated some of the stars). so I did not frame the target - just point and shoot. camera cooled to -15 C. image was taken when the nebula was fairly high in the sky.

 

Firstly, the autostreched images on PI. the left image, taken by qhy is clearly shows more detail and is brighter.

Secondly, same images but zoomed in to the core; ignoring the obvious backfocus/focus issues the Max value of a pixel on the nebulocity was 0.178 and 0.131 for the qhy and d7000 respectively. that makes the qhy 1.36 times faster. [D7000 is 4.7um with an eff of 35-40pc, so i was would have expected 1.20 times better.] However the level of detail is phenomenal in my opinion. qhy has less noise. so less stacking is needed. I also have a 1200 sec frame from the D700, and it is still not able to match the level of details

final picture is that of the same images, but using the same stretch.

@MarsG76 I dont think you will be disappointed

 

Good stuff...

I'm still waiting for my camera.... taking a while...

Looking at your test shots, you can definitely see improvement, and what makes me happy is that you're comparing 300s QHY subs to 600s DSLR subs.. and the QHY subs have more signal... so that is at least more than half the exposure time... possibly 4 time quicker, as you said that a 1200s DSLR exposure was not as bright at the 300s test...

I can't wait to do a test of my own.

6 hours ago, neil phillips said:

6 hours ago, neil phillips said:

Very nice. I missed the boat this time around

Bring on 2022 opposition for another chance...

19 hours ago, rsarwar said:

Dont forget you will get less noise - meaning to get to the same quality as a DSLR, you would need to stack far less frames. i.e. your exposure time for a single frame will not shorten by more than 1-1.5 times, but the total integration time will be lot shorter, albeit you need 3-4 channels to work with.

 

I am still awaiting for my QHY268. got some clear skies today with quater moon only rising at 5 am. 

Do you know this for a fact or are you speculating/estimating like me?

6 hours ago, sharkmelley said:

The main difference is the noise reduction from the cooling.  Otherwise a modded DSLR/mirrorless can produce very similar results because in many cases dedicated one-shot-colour astrocams use the same sensor as a modded DSLR/mirrorless camera.

Mark

I'm starting to think that I'll have minimal benefit from the camera as my DSLR is active cooled.... only hope I have now is detail captured due to no bayer matirx on the mono camera. Also hoping for faster photon aquisition.

Yes that is normal... you obviously have a high amount of light pollution, and the astromodded DSLR does shift your colors toward red... as expected because its a lot more sensitive to the red spectrum.

Once you black balance the image than all of your stars and object will be a normal color.

The star discoloration is caused by either not being perfectly focused or your lens is causing chromatic abberations... this can also be fixed in post.

I see your point but this can not be right... if it was it would all but make it pointless to spend the premium money on Astro cams, and sticking to modded DSLRs with big pixels would deliver same or similar results...

I'll definitely be makng a comparison between the two and if the 2600MM is no better or marginally better than the 40D... I'll be severely [word removed] off.

Time will tell...

This is NGC3603 and NGC3576 (AKA The "Statue of Liberty" nebula), a massive H-Alpha region containing a very compact open cluster, located in the constellation "Carina" about 20,000LY away.

I took this photo during two nights, 14th and 15th March 2021.

Imaged using a active cooled and full spectrum modded Canon 40D DSLR attached to a 80mm f6.25 refractor on a CGEM equatorial mount.

Total exposure time was 3 Hours and 31 minutes in natural color through UV/IR Cut filtered subs from a semi rural sky.

RGB: 19x60s, 19x120s, 18x180s and 20x300s subs @ ISO1600.

CS, MG 

Hi All,

Sharing with you my latest image, this is NGC3603 and NGC3576 (AKA The "Statue of Liberty" nebula), a massive H-Alpha region containing a very compact open cluster, located in the constellation "Carina" about 20,000LY away.

I took this photo on multiple nights, between 19th February and 15th March 2021.
Imaged using my cooled and full spectrum modded Canon 40D DSLR attached to a Bosma 80mm f6.25 refractor on a CGEM equatorial mount.

Total exposure time was 22 Hours and 1 minute using 7nm HII, OIII and SII Narrowband filters and stars are from natural color (UV/IR Cut filter) subs... imaged from a semi rural sky.

HII: 6x600s, 6x900s and 4x1200s subs,
OIII: 10x900s, 8x1200s and 1x1800s subs
SII: 18x1800s subs
RGB: 19x60s, 19x120s, 18x180s and 20x300s subs @ ISO1600.
 

This is quite possibly the last narrowband photo I'll imageusing the modded 40D DSLR before my ZWO 2600MM arrives... now said to be mid April.

Clear Skies,

MG

7 hours ago, sharkmelley said:

Which part of what I said?

Mark

That recent sensors are more sensitive, higher QE, than the one in the 40D, even though the 40D sensor has physically bigger pixels and hence a greater surface area to capture photons.

15 minutes ago, rnobleeddy said:

I don't know how accurate it is, but see https://www.dpreview.com/forums/thread/2750802 - if that's believed, the older DSLR sensors are quite a bit worse.

 

Anecdotally, I also owned a colour Atik 383 which is famed for having one of the worse QE of any astro camera, somewhere in the 40s. I didn't find that a massive improvement over my DSLR.

I don't find my modded and Cooled 40D that bad at all... in actual fact I'm very happy with my results that I get with it.... I'm more hoping that the increased QE and no bayer matrix will cut my exposure time down by 5-10 times over expecting an increase in detail/resolution since the atmosphere is probably a big limiter of detail at 2000mm focal length.

10 hours ago, sharkmelley said:

The Canon 40D uses an old sensor with very low QE (quantum efficiency).  A more recent camera will have vastly improved QE.  You can choose either a modern consumer camera and have it modified or a dedicated OSC astro-camera because in many cases they use exactly the same sensor.  Both will be a huge improvement over the modified 40D.  Obviously the dedicated astro-camera will have much lower thermal noise because of cooling.

Mark

Do you know this for a fact??? I seen similar statements online in various forums but no head-head comparisons.

My 40D is cooled so thermal noise is of no issue...

Eitherway, my 2600MM should be here within days so I'll compare the two and see the difference between the two when used in real world practice... graphs and company generated numbers hardly ever reflect real life use.

4 hours ago, Peeetr said:

Hi, I thought that the peltier is directly on the CMOS sensor where isn´t enough space. and copper plate conduct out heat. Now it´s clear. Peltiers are outside.  How temperature did you reach on the CMOS?

It would be much neater (and WAY more efficient) to directly place the peltier up against the back of the sensor... but unfortunately this is not an easy option. Doesn't seem impossible but definitely would introduce new problems...

This solution has allowed the camera to work for me for over a year now, and the only thig I had to keep an eye on, is the dew point temperature, and not cool the sensor more than (a MAX of) 4-5°C below that... I found that when I wrapped dew heaters around the front of the camera/filter wheel/OAG join (and had a fan lightly blowing at the camera side), that it didn't allow any dew to settle on the sensor. Now I'm not sure whether the fan actually stopped the dew from forming at a lower temperature by moving the wet air around, but I did have it on.  

Once I did cool down to almost freezing (hovering between 1-2°C)  without the heater straps or the fan, during a night where the dew point was at 10°C and I did get condensation on the sensor bloating the stars.... at this point I turned off the cooling, continued "exposing" and within 30 minutes the sensor heat cleared the sensor. This is when I raised the temperature to be between 7 & 8°C and successfully completed the reminder of the imaging night. 

To answer your question the temperature drop is generally approximately 13°C below ambience (but can be slightly more).

During testing, the two peltiers cooled the copper plate to -18°C on the test bench, but this is here the sensor was sandwitched between the two peltiers.

The copper plate outside the camera reached a temperature of -8.6°C in the field where the ambient temperature was 18.2°C, this is the temperature of the plate right next to the coolers that were running at max. The sensor temperature reached -0.7°C when not exposing and raised to 5.4°C when exposing non stop for 30 minutes... this 13C below ambience was sustained throughout.

The time when I got condensation on the sensor, the ambient temperature was 16°C so that night I was 15°C below ambience... so obviously the less heat that the system has to fight, the greater the potential drop will be from ambient (to a point)...

To put into perspective, the uncooled DSLR sensor heats up to around 33C during the long exposures... so I think that it's a considerable improvement.

My subs, including the narrowband subs, are virtually noise free... comparing to what it was, it's like night and day... before I had white noise point throughout the whole frame that had to be noise reduced, no doubt losing signal and detail, now I get a white noise point here and there... and frequently the 60-300 second RGB subs have no white spots whatsoever. 

Another benefit to this cooling is that by setting the cooling a few degrees above max cool down level, I'm able to generate and apply dark frames at the imaging temperature, and I did notice an improvement in the stack after I started applying darks... particularly some lighter vertical "slight glow" like pattern which as in all of my stacks in the past.

I'm more than happy with the level of cooling and the results I'm getting with the 40D after cooling it. To the point where I was putting off getting a dedicated Astro cam for a long time.

Let me know if you're going to mod cool your 40D as I'd like to see how you go, and see your results.

Hi All,

I finally got a chance to create this compilation image of my better captured images of Mars during this years (2020) opposition season of Mars.

All of the images were taken using a 8" SCT at 6764mm focal length (f33.3) with an Celestron Skyris 618C CCD.

All of the images were taken with the same telescope at the same focal length so shows the size of the martian disc as it was closer, at opposition and further from Earth.

I generally capture10x3500 frames at 60-80fps and stack and de-rotate the best 15%... 

CS

MG

That amount of detail is staggering... well done.

That animation is really cool...

Awesome detail... 

On 17/03/2021 at 10:29, Peeetr said:

Hi, I´m preparing my 40D for cooling and I measured there is no space between sensor and metal cover on the mainboard. Please how did you solve it, are you spaced board? How thick you used the copper plate? How thick is your peltier? If you space it, how you connect bottom flat connectors? There is no additional length. Hmm and if board is spaced, how to cover it all? Thanks Petr

Some photos of the camera with the copper plate, PCB dew insulation using a hot glue gun, than the final version of the mod...

By the way, don't forget to remove the IR cut filter from m the sensor to increase your Halpha sensitivity...

On 17/03/2021 at 10:29, Peeetr said:

Hi, I´m preparing my 40D for cooling and I measured there is no space between sensor and metal cover on the mainboard. Please how did you solve it, are you spaced board? How thick you used the copper plate? How thick is your peltier? If you space it, how you connect bottom flat connectors? There is no additional length. Hmm and if board is spaced, how to cover it all? Thanks Petr

Hi Peeetr,

Before you mod your camera remember that my mod draws 4 Amps of current for the two peltiers and effectively renders your 40D useless for everything other than astro photography.

The other thing I want to warn you about is that I destroyed 4 PCBs during my adventures in modding the cam, but mostly because I didn't protect the electronic from condensation.

I used a copper sheet that is only 1mm thick and it fit in the space between the sensor and the main PCB, it was a tight fit, but it fit. 

Make sure that you insulate your PCB from condensation, fill out the gaps with some foam sheets and insulate as much of the camera entry point as much as possible... I used expanding foam... I'll attach some pictures from my final version of my camera that worked well now for around a year....  

Good luck.... but when you get it working, the difference in subs quality is worth it with almost no noise and much cleaner stacks.

19 minutes ago, AndysAstroPix said:

Yes, I was lucky enough to win the camera in the QSI imaging competition in 2019 with this image. It's a fabulous camera but the 2" Chroma filters cost an arm & a leg! (worth every penny though!) 😂

So basically you won a beast with the eye of a beast image... imaged using a mini beast of a camera...