Is it worth turning off long exposure noise reduction (LENR)?

[matt_baker]

I've been imaging the past couple of nights and noticed how much time gets taken away by the camera having to process a dark frame after the initial exposure. In the end I only got 20 minutes of raw exposure before the target went out of site when I technically should've got 40. Is it worth turning it off? I'm doing 15 second 800 ISO shots due to having an alt-az mount. How much of a difference will it make? I can also add my 20-30 dark and flat frames in at the end of the imaging session and process them in DSS, so does that compensate for LENR being turned off?

 

Thanks, Matt

 

P.S I managed to get this with my 130SLT last night

[wxsatuser]

In AP it's normally turned off, maximize your imaging time to increase your SNR.

Calibration frames will certainly help, if done correctly.

Nice colour in M42 btw.

[Demonperformer]

Hi Matt.

Yes it will definitely be more efficient. You say you are using ISO 800, so presumably a DSLR, and therefore also presumably not cooled. When using a DSLR for long exposures I always used to do half of my darks at the start of the session and the other half at the end in order to try to compensate for any changes in temperature during the imaging run. Don't know that that is strictly necessary, but it seemed to work ok.

[Tim]

The LENR in effect subtracts a dark frame from your exposure, in camera. In theory this is the most accurate way to remove noise, amp glow etc. For single exposures of bright objects it works just fine.

As we are stacking multiple images though, and have the means to subtract an averaged dark frame from every exposure before stacking, it is deemed a waste of precious clear sky time for the camera to spend half its time doing something we can do at the end of a session or even on a different day.

Well done on the M42, it is not easy to avoid blowing the trapezium region.

[ollypenrice]

^^ Exactly.

Olly

[Sunnieboy]

Hi

 

I have same problems as the OP. Further question, in addition to LENR my Nikon D5500 also has high ISO NR should this also be turned off? Using 200-800 ISO 30sec subs via camera intervalometer on HEQ 5 Pro unguided, until fully set up with ATP.

TIA

Sunnie

[wxsatuser]

5 hours ago, Sunnieboy said:

Hi

I have same problems as the OP. Further question, in addition to LENR my Nikon D5500 also has high ISO NR should this also be turned off? Using 200-800 ISO 30sec subs via camera intervalometer on HEQ 5 Pro unguided, until fully set up with ATP.

TIA

Sunnie

Definately off.

[Demonperformer]

Agree. I would say that almost any form of NR in-camera is going to be a bad deal for DSO work. Maybe it has a place if you are taking single shots of something like the moon (I don't have the expertise on that to comment), but it seems to me that, when you are taking hours of subs on an object, making and using single master calibration frames is always going to be time-effective in the end.

[Sunnieboy]

Guys

Thanks for this, much appreciated.

Sunnie

(not today tho')