Canon EOS 7D will not or does not want to take flat frames?

[Cumbrianwolf]

I am having an issue with a Canon EOS 7D unmodified camera not wanting or rather not recording the images to card, place a lens or a telescope on there with a real image and there is no problem. Try to take 75 flat frames thereafter becomes a pointless exercise as it acts as if it cannot see an image, so goes through the motions of taking the shot but then decides it is not worth recording to card. Manual or Bulb mode is the same, which makes it hard to get accurate Flats!  Anyone any idea otherwise I am going to be stuck for stacking issues?

[paul]

I guess you have tried taking a fully manual picture without a lens attached? Set it to ISO800 and 0.01 sec for example. When you press the shutter button does it work as expected and save to Flash card? Work up from there.

[Cumbrianwolf]

34 minutes ago, paul said:

I guess you have tried taking a fully manual picture without a lens attached? Set it to ISO800 and 0.01 sec for example. When you press the shutter button does it work as expected and save to Flash card? Work up from there.

Yes that is correct, it goes through the motion and takes the shot but will not store it to the card. I have since reset it back to factor specifications and formatted the card and will duly try again tomorrow as I feel as though they are needed now, and it allowed me to do it on the last occasion.

[AstronomyUkraine]

On 1/21/2022 at 8:19 PM, Cumbrianwolf said:

Yes that is correct, it goes through the motion and takes the shot but will not store it to the card. I have since reset it back to factor specifications and formatted the card and will duly try again tomorrow as I feel as though they are needed now, and it allowed me to do it on the last occasion.

How are you taking your flats? I have a 7D and took many images in low light, I never had a problem writing to the card.

[Cumbrianwolf]

45 minutes ago, AstronomyUkraine said:

How are you taking your flats? I have a 7D and took many images in low light, I never had a problem writing to the card.

It was the flats that use the white shirt and bright light that I was having an issue with, I am going to hook the interferometer up and take some more today as I have just reset the camera. 

 

As for taking anything other than lights, this is my formula.

Flat frames: Same ISO, temp as the main lights, white cloth over the telescope and a bright torch shone at it.

Bias frames: Manual mode, same ISO with Av at the fastest shutter speed.

Dark frames: Manual mode, same ISO and exposure times as the lights.

[AstronomyUkraine]

4 hours ago, Cumbrianwolf said:

It was the flats that use the white shirt and bright light that I was having an issue with, I am going to hook the interferometer up and take some more today as I have just reset the camera. 

 

As for taking anything other than lights, this is my formula.

Flat frames: Same ISO, temp as the main lights, white cloth over the telescope and a bright torch shone at it.

Bias frames: Manual mode, same ISO with Av at the fastest shutter speed.

Dark frames: Manual mode, same ISO and exposure times as the lights.

Not sure your method of taking flats is the best. Maybe using the T shirt method pointing at the sky at dusk or dawn would be better, just after the sun appears or disappears over the horizon. I just don't understand why the camera won't write to the card though. There is a possibilty the card is damaged, but if that was the case it wouldn't write light or dark frames either.

[Teslar]

There’s a setting in canon cameras that as default stops you taking photos with no lens attached even some manual lenses will refuse to fire the shutter. You can set this toggle off to make it work. Apologies if you already knew that