Dark Frame Library With Nikon DSLR

[goldstar]

I have use the ice chest method myself and was VERY surprised to find that in spite of enough ice packs loaded to the gills with barely enough room for the camera that it was a long wait (if ever !) before the camera reached a stable low temperature of even 5 C!
I think the internal heat generated in the camera by the electronics was too much for ice box to handle where there is little circulation of air.
I found that freezing the camera in the fridge freezer compartment was better. I achieved a camera temp of -4 C in the compartment at - 14 C.

This is certainly not a factor for you down by the Gulf Coast (I hope! But certainly up here in the winter NW)) but worth realizing.

[JayTee]

Yeah, the icebox was recommended because of his location. If his camera ever sees a temp below 50°F (even the dead of winter), I'll be very surprised.

Cheers,
JT

[Juno16]

You are right about that JT!

I used a rubber band to strap the TEMPerHUM to the back of the camera, placed it into an open freezer bag and into the ice chest packed with blue freezer blocks.
Man, it was a struggle to get the temperature down! I had no idea that the camera would generate so much heat. I had to rearrange and replace blue blocks until I finally got some darks down to 42 degrees F.

This morning, I connected the TEMPerHUM to the PC, but not banded to the camera. I snapped darks to warm the camera up while getting good ambient temperature readings in the room. After about 45 minutes, I attached the TEMPerHUM to the back of the camera with a rubber band while still snapping darks.
The temperature rose 10 degrees F and stabilized! I was floored! I had no idea the camera generated that much heat!!!

I guess that I will have to have the TEMPrtHUM banded to the back of the camera while imaging.
Dang, I was hoping not to have another cable!

Just a quick question. If I start imaging at say 75 degrees, and finish imaging at 65 degrees, do I use master darks of several different temperature groups when stacking?

Thanks,
Jim

[goldstar]

If your temp. range band was 10 F I would not worry too much.
Purists will say yes, select your darks to match the light temps and group them for stacking.
I ,on the other hand ,am pretty lazy and am aware that a reported EXIF camera temp of say 20 C may in fact be 20.1 or 20.9 C. Who knows how the value is rounded up or down?
I also note that on a night where ambient can swing by 10 C that the mass of the camera slugs it down to maybe 5 C depending on a breeze blowing, frame length or delay between frames.
It all seems like too much finickiness for a result that doesn't look any different when I have used the grouping method.
Eyes will roll I know but often I don't use darks at all.
I'm just an amateur AP'er having fun, not a bean counter !

[Juno16]

If your temp. range band was 10 F I would not worry too much.
Purists will say yes, select your darks to match the light temps and group them for stacking.
I ,on the other hand ,am pretty lazy and am aware that a reported EXIF camera temp of say 20 C may in fact be 20.1 or 20.9 C. Who knows how the value is rounded up or down?
I also note that on a night where ambient can swing by 10 C that the mass of the camera slugs it down to maybe 5 C depending on a breeze blowing, frame length or delay between frames.
It all seems like too much finickiness for a result that doesn't look any different when I have used the grouping method.
Eyes will roll I know but often I don't use darks at all.
I'm just an amateur AP'er having fun, not a bean counter !

I got you there! Sounds like a good way to look at it. Close counts.

Thanks,
Jim

[JayTee]

The temperature rose 10 degrees F and stabilized! I was floored! I had no idea the camera generated that much heat!!!

Scary isn't it. You and I live in similar conditions. My sensor temperature rarely goes below 85°. More times than not it's in the 90s. Fortunately for you your D5300 generates less heat noise than does my Canon T3i.

As to what temperature darks to use, in the case given, I choose temperatures centering around 70° some higher some lower.

I'm sorry, but I don't like the notion of the sensor rubber-banded to the camera and then a cable running off of that. This is just one more item to cause a snag and ruin your guiding. I've always just put my temp sensor close to my camera and accepted the air temperature it gave me even though my Canon does have a sensor temp, even though it's more like a circuitry temp.

Maybe you should do an experiment to determine the temperature differential between the actual air temperature and the temperature your sensor picks up when strapped to the back of the camera. If it's a consistent differential you can just add that number on to the temperature your sensor reads for air temperature. Now, you don't have to have something strapped to the camera. Remember, it only has to be close, not perfect.

Cheers,
JT

[Juno16]

The temperature rose 10 degrees F and stabilized! I was floored! I had no idea the camera generated that much heat!!!

Scary isn't it. You and I live in similar conditions. My sensor temperature rarely goes below 85°. More times than not it's in the 90s. Fortunately for you your D5300 generates less heat noise than does my Canon T3i.

As to what temperature darks to use, in the case given, I choose temperatures centering around 70° some higher some lower.

I'm sorry, but I don't like the notion of the sensor rubber-banded to the camera and then a cable running off of that. This is just one more item to cause a snag and ruin your guiding. I've always just put my temp sensor close to my camera and accepted the air temperature it gave me even though my Canon does have a sensor temp, even though it's more like a circuitry temp.

Maybe you should do an experiment to determine the temperature differential between the actual air temperature and the temperature your sensor picks up when strapped to the back of the camera. If it's a consistent differential you can just add that number on to the temperature your sensor reads for air temperature. Now, you don't have to have something strapped to the camera. Remember, it only has to be close, not perfect.

Cheers,
JT

I feel the same way about the extra cable. I already have five cables and really don’t want to deal with another.

My test started his morning was at 74 degrees ambient. I’ll try something in the 60’s or a bit lower to see if the camera temperature rise (~10degrees) is similar or close.

Since I really can’t measure sensor temperature, I just kinda shooting in the dark (no pun!). Close counts!

Thanks for all of the help JT.

Jim

[pmwolsley]

JIm,
Overall I really like your image. I have done a lot of DARK frame testing with my D5300 and I found that it takes quite a while for the camera to reach thermal equilibrium. If I take 300s DARKs at room temperature it will take close to 2 hours for the DARK noise to reach a steady state value. I experimented with cooling the camera and settled on fixing a low vibration computer fan onto the back side of the camera. A fan with more than 4 blades will typically have less vibration. The benefit of doing this are two fold. Firstly, the camera will reach thermal equilibrium much faster. My tests indicated the camera reaches equilibrium in 30 minutes. The second benefit is that the camera now operates cooler which means that the DARK frames have close to 60% the noise. Using an external fan to cool the D5300 can reduce the dark noise by close to 40%. I shoot using a cooling fan all the time.

Benefit of Fan cooling your DSLR for Astrophotography.pdf

(921.21 KiB) Downloaded 105 times

I attached a PDF that I created for my local astronomy guild outlining my findings

Peter