Hello everyone. First let me list my equipment: - Telescope: William Optics RedCat 71 WIFD
- Camera: ZWO ASI585MC Pro
- Mount: ZWO AM5N
- Guiding: ZWO 30mm Guide Scope (120mm) + ZWO ASI120MM Mini
- Accessories: ASIAIR Plus
- Filter: Antlia Quad Band Light Pollution Filter
For some additional context, I mostly image from my Bortle 8 balcony in the city. Recently I bought the Antlia Quad Band filter to help me get better images. When I was imaging without the filter I was doing 30s exposures. After I started using the filter I was doing mostly 60s exposures, but even on 120s my single image doesn't "look overexposed" to my non-professional eye. So, my question would be: What exposure time should I be using, considering my equipment and the light pollution level in my city? Should I stick to 60s? Should I start doing 120s? I can provide any additional information you need to formulate an answer. Thanks in advance for the help. Clear Skies! ogchicken.
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It also depends on the target you are shooting and how many large stars might get saturated. I have a Redcat 71 with a 2600MC camera and I sometimes use 180s with no filters. I usually do test frames to see if I am happy with the results before I commit to a whole night of shooting.
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It also depends on the target you are shooting and how many large stars might get saturated. I have a Redcat 71 with a 2600MC camera and I sometimes use 180s with no filters. I usually do test frames to see if I am happy with the results before I commit to a whole night of shooting. Thank you for the reply. It makes sense that exposure times will vary as I image different targets. Unfortunately, on my Bortle 8 balcony 180s without a filter is just too much. Even 60 seconds was too much. Also, without a filter I can more obviously see when Im overexposed, but with the filter its not so obvious to me. Do you have any tips/advice to help me notice that i should lower my exposure time? I obviously want to gather as much data from the fainter stars/nebulosity, but at the same time I dont want to go too far.
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It also depends on the target you are shooting and how many large stars might get saturated. I have a Redcat 71 with a 2600MC camera and I sometimes use 180s with no filters. I usually do test frames to see if I am happy with the results before I commit to a whole night of shooting.
Thank you for the reply.
It makes sense that exposure times will vary as I image different targets. Unfortunately, on my Bortle 8 balcony 180s without a filter is just too much. Even 60 seconds was too much.
Also, without a filter I can more obviously see when Im overexposed, but with the filter its not so obvious to me. Do you have any tips/advice to help me notice that i should lower my exposure time? I obviously want to gather as much data from the fainter stars/nebulosity, but at the same time I dont want to go too far.
What gain and offset are you using?
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TiffsAndAstro:
It also depends on the target you are shooting and how many large stars might get saturated. I have a Redcat 71 with a 2600MC camera and I sometimes use 180s with no filters. I usually do test frames to see if I am happy with the results before I commit to a whole night of shooting.
Thank you for the reply.
It makes sense that exposure times will vary as I image different targets. Unfortunately, on my Bortle 8 balcony 180s without a filter is just too much. Even 60 seconds was too much.
Also, without a filter I can more obviously see when Im overexposed, but with the filter its not so obvious to me. Do you have any tips/advice to help me notice that i should lower my exposure time? I obviously want to gather as much data from the fainter stars/nebulosity, but at the same time I dont want to go too far.
What gain and offset are you using? Im using gain 252 (HCG mode turns on) and default offset.
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Anch’io faccio riprese da un cielo bortle 7/8 e uso un Newton 250/1000, Asi 294 MC pro con Antlia Quad Band, arrivo tranquillamente a 300 secondi di esposizione, naturalmente con una buona autoguida, se no puoi avere le stelle strisciate.. dipende comunque molto dal soggetto che vuoi riprendere… con tempi lunghi guadagni più qualità nell’immagine, miglior rapporto segnale/rumore, devi lavorare sul gain (portandolo anche a zero se serve) controllando l’istogramma che vedi sull’asiair plus..
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Luigi Ferrari:
Anch’io faccio riprese da un cielo bortle 7/8 e uso un Newton 250/1000, Asi 294 MC pro con Antlia Quad Band, arrivo tranquillamente a 300 secondi di esposizione, naturalmente con una buona autoguida, se no puoi avere le stelle strisciate.. dipende comunque molto dal soggetto che vuoi riprendere… con tempi lunghi guadagni più qualità nell’immagine, miglior rapporto segnale/rumore, devi lavorare sul gain (portandolo anche a zero se serve) controllando l’istogramma che vedi sull’asiair plus.. Thank you for the reply. I will definitely try lowering the gain and going for longer exposures to compare the images with what Im doing now. At what gain do you shoot when taking 300 second exposures with the setup you mentioned?
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I’m under bortle 4 skies and predominantly shoot narrowband with a 2600MM but even when doing LRGB I’ll shoot 300s exposures unless it’s a very bright target (Orion for example) then I’ll spend an hour shooting RGB at 20seconds purely for unsaturated Stars then combine in post!!
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Hi guys! I usually shoot from a 7/8 bottle sky in my home town and also from a bottle 4 sky (mostly in the weekend). I use both a Asi2600MM and a 294MC. I might say I always try to shoot at 600" and never got a saturated nebula, then as Sam Badcock said I took some lower exposure on the stars…depending on the target this may change from 1s up to 180s. Same thing when you try to make some HDR on Orion or a Galaxy core for example. As for the Gain I mainly use the unit gain or gain 0. I shoot 600" for two main reason: increasing the SNR, but also to minimize the number of picture I have to process (my laptop isn't exactly brand new :smart  . So as far as your mount works, try to increase the exposure!
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Sam Badcock:
I’m under bortle 4 skies and predominantly shoot narrowband with a 2600MM but even when doing LRGB I’ll shoot 300s exposures unless it’s a very bright target (Orion for example) then I’ll spend an hour shooting RGB at 20seconds purely for unsaturated Stars then combine in post!! Gaetano R. Cassarino:
Hi guys! I usually shoot from a 7/8 bottle sky in my home town and also from a bottle 4 sky (mostly in the weekend). I use both a Asi2600MM and a 294MC. I might say I always try to shoot at 600" and never got a saturated nebula, then as Sam Badcock said I took some lower exposure on the stars...depending on the target this may change from 1s up to 180s. Same thing when you try to make some HDR on Orion or a Galaxy core for example. As for the Gain I mainly use the unit gain or gain 0.
I shoot 600" for two main reason: increasing the SNR, but also to minimize the number of picture I have to process (my laptop isn't exactly brand new  ). So as far as your mount works, try to increase the exposure! Thank you for the replies. Next imaging session I will see how long I can take my exposures with 0 gain. My guiding should be good enough for up to 300s.
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I took 600" subs also with my EQM-35 mount. So your AM5 will definitely work. Just be sure to balance well your setup and also polar align the best you can.
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Gaetano R. Cassarino:
I took 600" subs also with my EQM-35 mount. So your AM5 will definitely work. Just be sure to balance well your setup and also polar align the best you can. So far my total guiding error is around 0.5". From what I have seen that is pretty good. I always take my time to get a good polar alignment. Do you have any advice/tips to know if I can keep increasing my exposure time? I read that my histogram should be 1/4 or 1/3 away from the left side. In my images, so far, it was always separated from the left, but never 1/4 separated. Should I increase my exposure time if that is the case? Thank you for the replies.
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Luigi Ferrari:
Anch’io faccio riprese da un cielo bortle 7/8 e uso un Newton 250/1000, Asi 294 MC pro con Antlia Quad Band, arrivo tranquillamente a 300 secondi di esposizione, naturalmente con una buona autoguida, se no puoi avere le stelle strisciate.. dipende comunque molto dal soggetto che vuoi riprendere… con tempi lunghi guadagni più qualità nell’immagine, miglior rapporto segnale/rumore, devi lavorare sul gain (portandolo anche a zero se serve) controllando l’istogramma che vedi sull’asiair plus..
Thank you for the reply.
I will definitely try lowering the gain and going for longer exposures to compare the images with what Im doing now.
At what gain do you shoot when taking 300 second exposures with the setup you mentioned?
Io con galassie o ammassi stellari molto luminosi a 0 gain, invece con galassie meno luminose o nebulose sui 120-180 di gain.. però devi considerare che il mio telescopio ha un buon guadagno in luminosità, essendo un 250 mm. di diametro… devi comunque avere pazienza e fare tante prove, come ho fatto io..
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Luigi Ferrari:
Luigi Ferrari:
Anch’io faccio riprese da un cielo bortle 7/8 e uso un Newton 250/1000, Asi 294 MC pro con Antlia Quad Band, arrivo tranquillamente a 300 secondi di esposizione, naturalmente con una buona autoguida, se no puoi avere le stelle strisciate.. dipende comunque molto dal soggetto che vuoi riprendere… con tempi lunghi guadagni più qualità nell’immagine, miglior rapporto segnale/rumore, devi lavorare sul gain (portandolo anche a zero se serve) controllando l’istogramma che vedi sull’asiair plus..
Thank you for the reply.
I will definitely try lowering the gain and going for longer exposures to compare the images with what Im doing now.
At what gain do you shoot when taking 300 second exposures with the setup you mentioned?
Io con galassie o ammassi stellari molto luminosi a 0 gain, invece con galassie meno luminose o nebulose sui 120-180 di gain.. però devi considerare che il mio telescopio ha un buon guadagno in luminosità, essendo un 250 mm. di diametro… devi comunque avere pazienza e fare tante prove, come ho fatto io.. Thank you for the answer. We have a similar focal ratio, f4.9 for me, f4 for you. We both use color cameras and shoot from Bortle 7/8 skies, so i thought it would be a good reference for me. Of course the gain settings are different between cameras and the telescopes are still very different. I have a lot of testing to do over my next few days of shooting.
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Disregard my answer, it's non applicable since I mixed up your camera for another mentioned in this thread. My only similarity is the mount.
I typically use 300s (5 min) exposures with my AM5N when I shoot in dual narrowband from my home in a Bortle 8 location.
My camera is the budget SVBony 405CC which is the “clone” of the ASI294 and it has two high gain settings (which I absolutely use to swamp out read noise). For dual narrowband (Ha-OIII), I use unity gain at 150 and offset 30.
Broadband is a little different since my ED Doublet has significant chromatic aberration and I have to use a Purple Fringe Killer filter which also dims down my subs.
So, for Broadband I will be using HCG gain 121 and offset 30 at 60s subs after the monsoon (rainy season) is done in September. |
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This thread is killing me. Disregard any answer from anyone who doesn't image with your exact camera or very similar. The ASI585MC Pro has one of the smallest well depths of any camera released in the last 5 years. It's also very noisy below gain 252. Most of the guys above have either 294 or 571 cameras which are totally different (I have them as well). The very best way to figure out the 585 is by monitoring saturated pixels. This number tells you how close you are to blowing out the stars. This is by far the limiting factor with a 585 sensor, especially the ASI version. Unfortunately the ASIAir doesn't give you this number. With my 585 camera which is setup the same as yours, I use gain 252 and subs between 60s and 120s depending on the speed of the scope. 60s is best on my f/4 newt and f/4.5 refractor, 90s for my f/5.6 scope and 120s at f/7. If I use a dual NB filter (10nm or less) then I use 180s-300s. Always gain 252. Your quad band filter shouldn't change these numbers much if at all. It's all about the stars with this sensor. Hope this helps. This is a 585, 60s subs with my f/4 Newt. I have dark skies so just a UV/IR filter.  |
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Joe Linington:
This thread is killing me. Disregard any answer from anyone who doesn't image with your exact camera or very similar. The ASI585MC Pro has one of the smallest well depths of any camera released in the last 5 years. the small well depth is likely because it has small pixel area. Comparing pixel full well capacities should normalize for pixel area. A smaller pixel area at fixed photon flux obviously means fewer incident photons.
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Arun H:
Joe Linington:
This thread is killing me. Disregard any answer from anyone who doesn't image with your exact camera or very similar. The ASI585MC Pro has one of the smallest well depths of any camera released in the last 5 years.
the small well depth is likely because it has small pixel area. Comparing pixel full well capacities should normalize for pixel area. A smaller pixel area at fixed photon flux obviously means fewer incident photons. The tiny well depth is a result of a 12bit DAC (which becomes the limiting factor, not the sensor) and the fact that ZWO placed the HCG nowhere near unity gain. It is a common criticism of the ZWO version of the 585 and others like QHY, ToupTek and Player One didn't make the same mistake. At gain 252 which is the HCG crossover the well depth for the ZWO 585 cameras is 2048. In other versions it is double that but the OP already has the ASI585MC Pro so he has to learn what he's got. I have the SVBony 705C and QHY5III585M and they are both setup like the ASI camera which is a setup more for planetary and EAA and not DSO. In short, this particular camera does not normalize due to pixel size like you would expect. It is artificially limited to less than half the normalized well depth when compared to a 294 or 571 sensor.
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Joe Linington:
This thread is killing me. Disregard any answer from anyone who doesn't image with your exact camera or very similar. The ASI585MC Pro has one of the smallest well depths of any camera released in the last 5 years. It's also very noisy below gain 252. Most of the guys above have either 294 or 571 cameras which are totally different (I have them as well). The very best way to figure out the 585 is by monitoring saturated pixels. This number tells you how close you are to blowing out the stars. This is by far the limiting factor with a 585 sensor, especially the ASI version. Unfortunately the ASIAir doesn't give you this number. With my 585 camera which is setup the same as yours, I use gain 252 and subs between 60s and 120s depending on the speed of the scope. 60s is best on my f/4 newt and f/4.5 refractor, 90s for my f/5.6 scope and 120s at f/7. If I use a dual NB filter (10nm or less) then I use 180s-300s. Always gain 252. Your quad band filter shouldn't change these numbers much if at all. It's all about the stars with this sensor.
Hope this helps.
This is a 585, 60s subs with my f/4 Newt. I have dark skies so just a UV/IR filter.
I totally agree with Joe on this. I've been shooting with a 585 for a few years now and have found that the two best settings for me are a gain of zero when I really need to maximize the dynamic range and 255 which puts the camera in a mode where read noise goes down to practically nothing. I shoot with an F/6 Newtonian and am under bortel 8 skies. My basic exposure time for deep sky objects with no filter or with a UV/IR cut are 15 sec. In dual band I'll go 30 to 60 sec, depending on the target. In all cases my biggest source of noise is shot noise from the high degree of light pollution and not the noise from the camera. The best thing to do is just get out there and shoot but hopefully those numbers give you a good starting point.
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Joe Linington:
Arun H:
Joe Linington:
This thread is killing me. Disregard any answer from anyone who doesn't image with your exact camera or very similar. The ASI585MC Pro has one of the smallest well depths of any camera released in the last 5 years.
the small well depth is likely because it has small pixel area. Comparing pixel full well capacities should normalize for pixel area. A smaller pixel area at fixed photon flux obviously means fewer incident photons.
The tiny well depth is a result of a 12bit DAC (which becomes the limiting factor, not the sensor) and the fact that ZWO placed the HCG nowhere near unity gain. It is a common criticism of the ZWO version of the 585 and others like QHY, ToupTek and Player One didn't make the same mistake. At gain 252 which is the HCG crossover the well depth for the ZWO 585 cameras is 2048. In other versions it is double that but the OP already has the ASI585MC Pro so he has to learn what he's got. I have the SVBony 705C and QHY5III585M and they are both setup like the ASI camera which is a setup more for planetary and EAA and not DSO.
In short, this particular camera does not normalize due to pixel size like you would expect. It is artificially limited to less than half the normalized well depth when compared to a 294 or 571 sensor. Tony Gondola:
Joe Linington:
This thread is killing me. Disregard any answer from anyone who doesn't image with your exact camera or very similar. The ASI585MC Pro has one of the smallest well depths of any camera released in the last 5 years. It's also very noisy below gain 252. Most of the guys above have either 294 or 571 cameras which are totally different (I have them as well). The very best way to figure out the 585 is by monitoring saturated pixels. This number tells you how close you are to blowing out the stars. This is by far the limiting factor with a 585 sensor, especially the ASI version. Unfortunately the ASIAir doesn't give you this number. With my 585 camera which is setup the same as yours, I use gain 252 and subs between 60s and 120s depending on the speed of the scope. 60s is best on my f/4 newt and f/4.5 refractor, 90s for my f/5.6 scope and 120s at f/7. If I use a dual NB filter (10nm or less) then I use 180s-300s. Always gain 252. Your quad band filter shouldn't change these numbers much if at all. It's all about the stars with this sensor.
Hope this helps.
This is a 585, 60s subs with my f/4 Newt. I have dark skies so just a UV/IR filter.
I totally agree with Joe on this. I've been shooting with a 585 for a few years now and have found that the two best settings for me are a gain of zero when I really need to maximize the dynamic range and 255 which puts the camera in a mode where read noise goes down to practically nothing. I shoot with an F/6 Newtonian and am under bortel 8 skies. My basic exposure time for deep sky objects with no filter or with a UV/IR cut are 15 sec. In dual band I'll go 30 to 60 sec, depending on the target. In all cases my biggest source of noise is shot noise from the high degree of light pollution and not the noise from the camera. The best thing to do is just get out there and shoot but hopefully those numbers give you a good starting point. Thank you for the in depth explanations. The main reason i was only using gain 252 is because of the low read noise. And the few youtube reviews i watched also said that gain 252 is the best to use. However no one went into details around exposure times. I will still test what 0 gain looks like for me, but from your answers i will more than likely keep using 252 gain. Also thank you for providing an example exposure. if you have any more advice for a beginner like me regarding this topic i will gladly listen.
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I mostly use 255 as my default 90% of the time. I'll only go to zero gain if I'm trying to get a very bright galaxy core or I want to resolve a globular right to the core. Lunar too but that's a totally different subject. I will say that worry about well depth is overblown as long as your exposures arn't too long which they won't be on the 585. I've gone as low as 1500 (e-) on a QHY camera I it was fine, at least at 15 sec. Remember that your final image will be 8 bit, 256 shades of gray so you have more headroom than you think. It's another area where not going too long helps.
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Joe Linington:
Arun H:
Joe Linington:
This thread is killing me. Disregard any answer from anyone who doesn't image with your exact camera or very similar. The ASI585MC Pro has one of the smallest well depths of any camera released in the last 5 years.
the small well depth is likely because it has small pixel area. Comparing pixel full well capacities should normalize for pixel area. A smaller pixel area at fixed photon flux obviously means fewer incident photons.
The tiny well depth is a result of a 12bit DAC (which becomes the limiting factor, not the sensor) and the fact that ZWO placed the HCG nowhere near unity gain. It is a common criticism of the ZWO version of the 585 and others like QHY, ToupTek and Player One didn't make the same mistake. At gain 252 which is the HCG crossover the well depth for the ZWO 585 cameras is 2048. In other versions it is double that but the OP already has the ASI585MC Pro so he has to learn what he's got. I have the SVBony 705C and QHY5III585M and they are both setup like the ASI camera which is a setup more for planetary and EAA and not DSO.
In Sorry it is a common misconception that a 12 bit ADC in any way limits the total available full well capacity. A 12 bit ADC can handle the 40,000 ADU full well capacity just fine, by scaling the signal appropriately. And as long as the least significant bits lost due to scaling is smaller than the bits holding the noise, it really makes no difference. The 294MM also has a 12 bit ADC. I did not comment on the noise and HCG issue, since I am not knowledgeable enough about that aspect. That part may well create limitations and I did not refer to it in my comment. edit: sorry - the 294 has a 14 bit ADC, not 12. Nevertheless a 12 bit ADC will not pose a limitation to hold a Fwc of 40000, because the shot noise is 200 which requires 8 bits to hold. So there are more than enough significant bits, with proper scaling, to contain 40000.
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Tony Gondola:
I mostly use 255 as my default 90% of the time. I'll only go to zero gain if I'm trying to get a very bright galaxy core or I want to resolve a globular right to the core. Lunar too but that's a totally different subject. I will say that worry about well depth is overblown as long as your exposures arn't too long which they won't be on the 585. I've gone as low as 1500 (e-) on a QHY camera I it was fine, at least at 15 sec. Remember that your final image will be 8 bit, 256 shades of gray so you have more headroom than you think. It's another area where not going too long helps. Thank you for the reply. I will keep that in mind, thank you. I checked out your gallery of images and I must say your work is amazing. Seeing what you accomplished with the same camera made me realize I still have a lot to learn and improve on.
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Tony Gondola:
I mostly use 255 as my default 90% of the time. I'll only go to zero gain if I'm trying to get a very bright galaxy core or I want to resolve a globular right to the core. Lunar too but that's a totally different subject. I will say that worry about well depth is overblown as long as your exposures arn't too long which they won't be on the 585. I've gone as low as 1500 (e-) on a QHY camera I it was fine, at least at 15 sec. Remember that your final image will be 8 bit, 256 shades of gray so you have more headroom than you think. It's another area where not going too long helps.
Thank you for the reply.
I will keep that in mind, thank you.
I checked out your gallery of images and I must say your work is amazing. Seeing what you accomplished with the same camera made me realize I still have a lot to learn and improve on.
Thanks, still got a ways to go and still experimenting but the ZWO 585 has been a great little camera. I waiting for all this tariff nonsense to settle down in the US so I can pick up the Minicam8 mono version.
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Arun H:
Sorry it is a common misconception that a 12 bit ADC in any way limits the total available full well capacity. A 12 bit ADC can handle the 40,000 ADU full well capacity just fine, by scaling the signal appropriately. And as long as the least significant bits lost due to scaling is smaller than the bits holding the noise, it really makes no difference. The 294MM also has a 12 bit ADC. I did not comment on the noise and HCG issue, since I am not knowledgeable enough about that aspect. That part may well create limitations and I did not refer to it in my comment.
edit: sorry - the 294 has a 14 bit ADC, not 12. Nevertheless a 12 bit ADC will not pose a limitation to hold a Fwc of 40000, because the shot noise is 200 which requires 8 bits to hold. So there are more than enough significant bits, with proper scaling, to contain 40000. You are correct about the bit depth and scaling and I should have been more precise. If everything is properly setup a 12bit ADC will limit the full well depth and dynamic range at unity gain to 4096. So a 12bit ADC limits the full well capacity where it matters most. If you look at sensors like the 294 in 14bit mode, the 533 (14bit) and the 571 (16bit) the physical capability of the sensor limits the full well at unity gain ie the full well is less than the address space. But in many 12bit sensors the full well at unity gain is also the full address space implying that there may be some sensor performance left on the table. There are many discussions about why we want to ideally use unity gain so I am not going to dive into it here but compared to sensors with better ADC's the 585 has a limited well depth at unity gain due to it's 12 bit ADC. Your edit is interesting because the 294M is a jekyl and hyde sensor that operates in 12bits in it's extended resolution with all of the challenges and issues associated with that including using the full address space at unity gain. But in Bin2 mode or native mode it has a 14bit ADC and can tolerate some very long exposures.
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