Hello everyone
I am looking for the best gain and offset for my 1600mm pro. Exposure time: 180S (LRGB) and 300S (SHO).
Thank you for your help
Clear sky
Nico
|
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
Hellllo
on my site (Torun/Poland/EU) Brotle 7/8 I use 139 and 10 (typical set from Kstars & Indii)
subs - like U - 300 sec for SHO and 60 sec for UvIR filter
Clear SKY  |
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
Hi,
I am in rural blueish sky, my settings are 300s x LRGB Gain 0 Offset 10, 300s x HA (unity gain) Gain 139 Offset 21. These generally do not saturate stars and leave enough room for DSO details. These settings are not ideal for moon lit nights but I don't bother changing these to avoid dark and flats recapture. I keep exposure the same, for no good reason except consistency.
This post by Shiraz was extremely useful in working out my broad brush settings:
https://www.cloudynights.com/topic/573886-sub-exposure-tables-for-asi-1600-and-maybe-qhy163/?p=7825314 |
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
|
I forget: i have à 200/800 quattro newton and coma reducer 0.95x. Skie bortle 6
|
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
|
I used to do everything with gain of 139 offset of 21, however, about a year ago I switched my LRGB to gain 0 and I found my stars weren't sataurated. I have had much better results since making the change. SHO is still 139 gain. I always shoot SHO at 240s and LRGB at either 120s or 240s. I do live in bortle 2 skies though.
|
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
Anne-Maree McComb:
I used to do everything with gain of 139 offset of 21, however, about a year ago I switched my LRGB to gain 0 and I found my stars weren't sataurated. I have had much better results since making the change. SHO is still 139 gain. I always shoot SHO at 240s and LRGB at either 120s or 240s. I do live in bortle 2 skies though.
bortle 2.. the dream  |
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
Hello All,
I am in the same boat as I have been using 139 for everything, both SHO and LRGB however after reading some of the great comments here, I will try to adjust my LRGB to 10 or 0 as some have suggested due to the bloating stars I have seen. Wishing you well on any changes you may make.
Clear Skies,
DJ
|
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
Hello.
I am at bortle 4 and use Gain 300 - 300 sec. at SHO and Gain 0 - 120 sec. with LRGB and Gain139 - 300 sec. with Broadband.
All at -20 Celsius
CS
morian
|
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
|
Sorry I forgot, All at offset 50
|
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
|
Offset is easy, follow the offset specified by ZWO as a function of gain. Gain setting is a difficult question to answer without any context. What are your sky conditions, phase of the moon, location of the moon wrt the target, temperature, humidity, seeing/transparency, the target brightness? What filters are you using? Here is really no universal "best" gain setting for your camera, you need to experiment with your rig at your location over various exposure times and figure your what works best for you. Good luck!
|
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
Hi All,
Yes, I also forgot, my sky conditions are bortle skies are 4-5 and I did try 0 at first and then found out for this camera, under my conditions, I find that when using the SHO filters, 139 seems to work rather well. It's when use the LRGB filter that my start seem to get bloated and washed out so I am going to try ing the 0 gain and see if that helps.
Thanks,
Clear Skies,
DJ
|
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
Hi,
I image from the city - Bortle 8/9.
The discussion about gain / offset is not a topic that can be understood on its own. It is rather a multi-variable analysis that must be done.
When capturing images, one need to consider not only gain / offset, but also bit depth of your camera, the f/ ratio of your scope, the length of your subs, your environment - i.e. pristine dark skies or light polluted city environment, and a variety of other factors.
Lower gain increases full well capacity of your camera. It also increases noise. The subs get longer as a result of the lower sensitivity. The uptake is you increase the dynamic range of the camera, i.e. more image gradient. It also improves your ability to prevent the stars from bloating - from exceeding well depth.
So the factors to consider with low gain:
- longer subs
- increase in noise - more dithering and more subs required to filter out the noise
- better mounts / tracking, especially if you use longer than 5 minutes subs
- lower f/ ratio scopes
- chance of interference from wind gusts, satellite trails, airplanes, etc.
- Longer subs also mean heat glow from the sensor. I use the ASI1600mm, so heat glow is a factor.
Higher gain on the other hand seem to be better at first glance. The subs are shorter due the increase "sensitivity" of the sensor. However, it is not all that rosy either. Higher gain will reduce the length of capture process, but it does so at the cost of a decrease in well depth. That means that the shallower well depth will fill up with electrons faster. This causes a lower dynamic range. The images will be "flatter", missing the tone separation and contrast that give the image its 3D look.
So the factors to consider the higher gains:
- More subs due to well depth being shallower. This means more processing from more subs.
- Lower noise
- Decrease well depth leads to a loss in dynamic range
- More of a chance to have bloated stars. The lower well depth means that it is easier to fill and bloat the stars.
- More wear and tear on your imaging train.
As for my situation, since I image from a light polluted site, everything has to be a compromise:
For LRGB, I use either 75 or unity gain of 139.
This allows me to capture longer subs for bright objects and reasonable subs on dimmer objects.
In all cases, I never exceed 5 minute subs. I found that this a good a tradeoff: The shorter 5-minutes, as opposed to the longer 10 minute subs means that I will be less affected by by having to a satellite trail / clouds / wind , etc... and more importantly, sensor heat glow. I typically guide in the 1 - 1.5 pixel range, so 10 minute subs would not be a problem. I simply chose not to do them.
For narrowband ( which I do a lot of, due to light pollution ) - I use either gain 139 or 200. I never exceed 200 because of dynamic range.
This allows me to capture a "reasonable" amount of subs. I.e. 1 hour of imaging = 12 subs. I do have to deal with star bloat, but for narrowband, it usually is not much of an issue.
Lastly, I also have to deal with the loss of dynamic range - i.e my images look "flatter". I try to process and do a color separation to give me more contrast that will make the image look more "3D".
For both cases, I use offset of 50. The high offset help separate the histogram curve from 0 signal. It prevents clipping on the black.
If you look look at your histogram, it will tell you if you are using the correct gain / offset. You want the curve to be well separated from 0 signal on the left.
I aim to have a distinct signal curve about 1/3 of the histogram. This is easier to achieve on LRGB. Much harder to achieve with narrowband. My 5nm filters typically need more signal, so higher gain and 5 minute subs.
You will also need to consider your bit depth in the capture software / camera driver. ZWO publishes that the bit depth for the ASI1600mm is 12 bits. However, what they don't tell you is that the driver automatically converts it to 16-bit. The lower bit depth only takes a fraction of the ADU. I have switched to 16-bit and noticed a notable improvement in the performance of the camera.
Sorry to ramble on, but in a nutshell, that's what works for me.
Have fun !
|
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
All of this really depends on your f stop, sky condition and NB filter width.
From home (bortle 6/7)
LRGB gain 76 offset 50 exp length 60s
SHO gain 139 offset 50 exp length 600s
thats with an f7 scope and 3nm NB filters
From dark site (bortle 1/2)
RGB gain 76 offset 50 exp length 300s
L gain 76 offset 50 exp length 180s
SHO gain 139 offset 50 exp length 600s
gain 0 on the 1600 has some serious banding artefacts that is not happening at other gain settings… so I stopped using it
FYI Francois answer above is all you need to know! Really well explained. One other thing to consider with LRGb from polluted skies is that longer sub will create more pronounced gradients in your images. I use 60s only now from home and I found that I can manage most gradients in stacks with linear normalisation as well as dynamic background extracting during pre processing.
|
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
Francois Theriault:
Hi,
I image from the city - Bortle 8/9.
The discussion about gain / offset is not a topic that can be understood on its own. It is rather a multi-variable analysis that must be done.
When capturing images, one need to consider not only gain / offset, but also bit depth of your camera, the f/ ratio of your scope, the length of your subs, your environment - i.e. pristine dark skies or light polluted city environment, and a variety of other factors.
Lower gain increases full well capacity of your camera. It also increases noise. The subs get longer as a result of the lower sensitivity. The uptake is you increase the dynamic range of the camera, i.e. more image gradient. It also improves your ability to prevent the stars from bloating - from exceeding well depth.
So the factors to consider with low gain:
- longer subs
- increase in noise - more dithering and more subs required to filter out the noise
- better mounts / tracking, especially if you use longer than 5 minutes subs
- lower f/ ratio scopes
- chance of interference from wind gusts, satellite trails, airplanes, etc.
- Longer subs also mean heat glow from the sensor. I use the ASI1600mm, so heat glow is a factor.
Higher gain on the other hand seem to be better at first glance. The subs are shorter due the increase "sensitivity" of the sensor. However, it is not all that rosy either. Higher gain will reduce the length of capture process, but it does so at the cost of a decrease in well depth. That means that the shallower well depth will fill up with electrons faster. This causes a lower dynamic range. The images will be "flatter", missing the tone separation and contrast that give the image its 3D look.
So the factors to consider the higher gains:
- More subs due to well depth being shallower. This means more processing from more subs.
- Lower noise
- Decrease well depth leads to a loss in dynamic range
- More of a chance to have bloated stars. The lower well depth means that it is easier to fill and bloat the stars.
- More wear and tear on your imaging train.
As for my situation, since I image from a light polluted site, everything has to be a compromise:
For LRGB, I use either 75 or unity gain of 139.
This allows me to capture longer subs for bright objects and reasonable subs on dimmer objects.
In all cases, I never exceed 5 minute subs. I found that this a good a tradeoff: The shorter 5-minutes, as opposed to the longer 10 minute subs means that I will be less affected by by having to a satellite trail / clouds / wind , etc... and more importantly, sensor heat glow. I typically guide in the 1 - 1.5 pixel range, so 10 minute subs would not be a problem. I simply chose not to do them.
For narrowband ( which I do a lot of, due to light pollution ) - I use either gain 139 or 200. I never exceed 200 because of dynamic range.
This allows me to capture a "reasonable" amount of subs. I.e. 1 hour of imaging = 12 subs. I do have to deal with star bloat, but for narrowband, it usually is not much of an issue.
Lastly, I also have to deal with the loss of dynamic range - i.e my images look "flatter". I try to process and do a color separation to give me more contrast that will make the image look more "3D".
For both cases, I use offset of 50. The high offset help separate the histogram curve from 0 signal. It prevents clipping on the black.
If you look look at your histogram, it will tell you if you are using the correct gain / offset. You want the curve to be well separated from 0 signal on the left.
I aim to have a distinct signal curve about 1/3 of the histogram. This is easier to achieve on LRGB. Much harder to achieve with narrowband. My 5nm filters typically need more signal, so higher gain and 5 minute subs.
You will also need to consider your bit depth in the capture software / camera driver. ZWO publishes that the bit depth for the ASI1600mm is 12 bits. However, what they don't tell you is that the driver automatically converts it to 16-bit. The lower bit depth only takes a fraction of the ADU. I have switched to 16-bit and noticed a notable improvement in the performance of the camera.
Sorry to ramble on, but in a nutshell, that's what works for me.
Have fun !
Verry thanks!!! I can try gain 200 and offset 50 for my sho (5Min), my skie is in a bortle 6... I am still at gain 139 and offset 10. The same for LRGB 180s.........
|
You cannot like this item. Reason: "ANONYMOUS".
You cannot remove your like from this item.
Editing a post is only allowed within 24 hours after creating it.
You cannot Like this post because the topic is closed.
0.00
0.00
0.90
1.20
4.22
0.00
0.00
1.91
10.80
