DLSR - Continuous or Intermittant Subs?

[Aramcheck]

When shooting a set of subs with a DLSR is it advisable to either take short sets of exposures with a gap to allow the camera to cool down, or to take one long continuous set of subs? And if shooting a continuous set, is it better to leave a gap between the individual exposures, or doesn't it matter?

At present I usually shoot 60sec subs with a few seconds between each to allow the camera to finish processing & a 2 sec delay between raising the mirror & starting each exposure. I'm wondering if at affects noise?

Any advice much appreciated!

Cheers
Ivor

[happy-kat]

You could try shorter and compare the noise, though if I was able to take 60s subs I would but would also make sure I had bias, flats and dark flats leaving darks to test whether helped with noise or not during processing. 

[don4l]

Try it and see.

The only thing that matters is the image that you get at the end.

Generally speaking, the more data that you collect the better.  If you see a problem with continuous imaging, they try leaving a gap to see if that fixes your problem.

 

[MarkAR]

I'd leave a gap between each exposure to let the sensor cool a bit. Possibly 5-10 secs.

[Spaced Out]

I use APT for long exposures with DSLR (5 - 10 mins), set up the imaging plans with anti-vibration pause of 10 secs on mirror lock up and also pause for 30 secs between exposures to allow the sensor a little cooling time. Not sure of this is the correct approach but it works OK for me. I read somewhere that if you leave the mirror locked up or use liveview on the DSLR screen it can cause noise/glow problems, again, not sure if this is true or not ?!

[happy-kat]

Live view can make the camera hot. Not the same as mirror lock up which I think is just the mirror up.

[alacant]

On 09/03/2020 at 22:14, Aramcheck said:

short sets of exposures with a gap

Hi

Canon 700d.

We image all year, including summer where sensor temperatures can hit ~40º. We dither in between frames, thus giving around 30s of sensor inactivity. However, the 30s does little or nothing to the sensor temperature; you'd need a lot longer than 30s to do anything like in that respect. We go 5 minute frames all night with perfectly acceptable noise levels.

Conclusion: don't waste precious imaging time by waiting.

Just our €0.02 but HTH.

Edited March 12, 2020 by alacant

[Aramcheck]

Thanks everyone - much appreciated!

Cheers
Ivor

[Rush]

Well,

dithering + Lp filter is more essential than long cooling intervals in my experience.

Keep ISO low, for instance 400, exposure time 120 seconds and shoot one or many nights the same object.

Try not to use Live view screen. Its quiet true what mate Alacant says.

On the other hand if u r really concerned about cooling the camera, use a table FAN and blow on the Camera at a slow rotation naturally.

Cheers

Rush

[MarkAR]

Or rig up a small computer fan to the camera back.

Ideally what you want is a peltier cooling modification but that means getting into the camera.

[rickwayne]

Ideally what you want is a cooled astro camera.

Sorry. I know, we can't have all the toys we want. And DSLRs have sensors that most astro-camera folks envy. The Sony in my Pentax K5-iis is WAY better than the IMX183 in my nice cooled mono ASI. Since astro cameras are a tiny niche market you will spend through the nose for an APS-C sized sensor, especially one with the dynamic range and low noise typical of DSLRs.

There. Is that better? May I be not flamed now?

[alacant]

23 hours ago, rickwayne said:

Is that better?

Yes. It sums up much of what I feel too. I think big DSLR sensors with their rugged protective bodies which are designed for harsh conditions beat flimsy, temperamental cooled cameras with tiny sensors which cost three times more (catches breath!) in many respects. 

Cheers.

 

[david_taurus83]

I made a a small cool box out of a plastic tub and lined it with insulation and stuck a peltier cooler on top so I could shoot temperature controlled darks. With both my old 600D and current 6D, I can tell you that the sensor temperature does not keep increasing with long subs shot one after another. I've taken darks up to 5 minutes so far and as long as the ambient temperature remains static the sensor temp levels out at around 5-6°C above ambient. This is true for around 10°C ambient and below. As the ambient is raised up to 15 or 20, the sensor temp gap does increase to 8-10°C, but it does level out and stays even.

As above, dont waste time trying to let the sensor cool, keep grabbing those photons!