Libraries: Bias, Darks, Flats

[fatboy1271]

What's the general opinion on keeping a library for Bias, Darks, and Flats?

• I was under the impression that at least Darks should be at the "same" temperature as your Lights.

• Flats help with dust motes and such so I'm guessing that as long as you don't remove the camera you could reuse them?

[bobharmony]

I have kept Dark libraries from time to time. Yes, they should match the lights for temperature, ISO (for DSLRs), and exposure time. General guidance I have heard is that they should be effective for about 6 months before needing to be recreated.

I take flats for every session. Even if the camera is not removed, dust has a way of getting into, or shifting around in, a closed system. They don't take long so it is a minor chore to get a fresh set each time out.

I set up a Master bias every six months or so as well. For a DSLR, using the shortest available exposure time works well, and it is easy to run a couple of hundred off, then combine them into a master.

Bob

[fatboy1271]

I have kept Dark libraries from time to time. Yes, they should match the lights for temperature, ISO (for DSLRs), and exposure time. General guidance I have heard is that they should be effective for about 6 months before needing to be recreated.

I take flats for every session. Even if the camera is not removed, dust has a way of getting into, or shifting around in, a closed system. They don't take long so it is a minor chore to get a fresh set each time out.

I set up a Master bias every six months or so as well. For a DSLR, using the shortest available exposure time works well, and it is easy to run a couple of hundred off, then combine them into a master.

Bob

Thanks Bob! May I ask what your Flat taking process is? I use my laptop screen and a t-shirt:

• Not sure if the laptop screen is the right way to go

• Should the t-shirt method be just one layer, like the front of it, or both layers?

• I've used the AV setting on the 70D but also have no idea if that's working correctly

[Aidi]

Laptop screen with a T-Shirt to defuse the light works just fine. The other popular option is a LED light panel from Amazon which can be dimmed. Circa $20-30. Again with a T-Shirt proved very effective.

The amount of layers used will depend on how intense the light source is. With the above mentioned light panel, I only use one layer of a t-shirt and dim/brighten the light source as required to meet the required ADU.

If you ever have a plan to move away from DSLR to a dedicated AP camera, the SGP has a very good Flats Capture feature. Once you have that up and working, its difficult to not capture flats correctly.

As for storing and reusing flats, you are right with regards to reusing if nothing changes. Where possible always do new ones at the end of the session. For the time it takes to do them.. If you have just spent hours collecting data and the older sets of flats dont work correctly, then you risk having to do a lot of processing to compensate for lack of good flats.

[fatboy1271]

Laptop screen with a T-Shirt to defuse the light works just fine. The other popular option is a LED light panel from Amazon which can be dimmed. Circa $20-30. Again with a T-Shirt proved very effective.

The amount of layers used will depend on how intense the light source is. With the above mentioned light panel, I only use one layer of a t-shirt and dim/brighten the light source as required to meet the required ADU.

If you ever have a plan to move away from DSLR to a dedicated AP camera, the SGP has a very good Flats Capture feature. Once you have that up and working, its difficult to not capture flats correctly.

As for storing and reusing flats, you are right with regards to reusing if nothing changes. Where possible always do new ones at the end of the session. For the time it takes to do them.. If you have just spent hours collecting data and the older sets of flats dont work correctly, then you risk having to do a lot of processing to compensate for lack of good flats.

Thanks Aidi! For $20-$30 I think I'll be ordering that LED light panel today!!!

I really do want to move to a dedicated AP camera but I'll have to save up for one. It's good that my wife spent all that money on the 70D and then never needs it...

[SkyHiker]

What's the general opinion on keeping a library for Bias, Darks, and Flats?
I was under the impression that at least Darks should be at the "same" temperature as your Lights.

Yes.

Flats help with dust motes and such so I'm guessing that as long as you don't remove the camera you could reuse them?

And yes. Don't remove the camera, don't turn it and don't wait until the dust motes have moved.

I take my flats by pointing the OTA at a white wall that I light with my headlamp. Because the wall is out of focus I don't need a T shirt. Sometimes when I am lazy I do it the next morning against the sky with a paper towel on top. I select the exposure by checking if it looks grayish on the LCD. Lots of methods work, it's not all that critical how you do it but it is important that you do it. It is quick so why not.

[fatboy1271]

What's the general opinion on keeping a library for Bias, Darks, and Flats?
I was under the impression that at least Darks should be at the "same" temperature as your Lights.

Yes.

Flats help with dust motes and such so I'm guessing that as long as you don't remove the camera you could reuse them?

And yes. Don't remove the camera, don't turn it and don't wait until the dust motes have moved.

I take my flats by pointing the OTA at a white wall that I light with my headlamp. Because the wall is out of focus I don't need a T shirt. Sometimes when I am lazy I do it the next morning against the sky with a paper towel on top. I select the exposure by checking if it looks grayish on the LCD. Lots of methods work, it's not all that critical how you do it but it is important that you do it. It is quick so why not.

Thanks SkyHiker! I didn't know about the "checking if it looks grayish on the LCD." That's the other thing is that I never know if I'm getting the right exposure.

[bobharmony]

Thanks Bob! May I ask what your Flat taking process is? I use my laptop screen and a t-shirt:

• Not sure if the laptop screen is the right way to go

• Should the t-shirt method be just one layer, like the front of it, or both layers?

• I've used the AV setting on the 70D but also have no idea if that's working correctly

My process is very similar to yours. Instead of the laptop screen, I use a light panel, as some of the others have mentioned. I use the AV setting for the 60D, and one layer of t-shirt. Exposure times usually fall around 1/250". Works just fine for me.

Lots of good advice from folks here.

Bob

[fatboy1271]

Thanks Bob! May I ask what your Flat taking process is? I use my laptop screen and a t-shirt:

• Not sure if the laptop screen is the right way to go

• Should the t-shirt method be just one layer, like the front of it, or both layers?

• I've used the AV setting on the 70D but also have no idea if that's working correctly

My process is very similar to yours. Instead of the laptop screen, I use a light panel, as some of the others have mentioned. I use the AV setting for the 60D, and one layer of t-shirt. Exposure times usually fall around 1/250". Works just fine for me.

Lots of good advice from folks here.

Bob

I just ordered a light panel on Amazon! Will be here on Friday... I'm so impatient!!!