How to exposure stack RAW photos while also outputting a raw photo?

So I have .DNG files that I have taken from an iPhone and I’m trying to figure out how to stack them and then output the stacked photo as a .DNG file as well (or any RAW format tbh).

I know how to code fairly well so I am able to stack them using python and the rawpy module. The problem is that rawpy currently has no way to output RAW files. So when I stack them, I can output as JPG, but that’s not what I want.

Going through astro photography forums, I’ve seen threads that say that Deep Sky Stacker can be used to read and stack RAW files, but I couldn’t find any guides that can tell me how to export an image as a .DNG file.

Does DSS output stacked photos as RAW? (format doesn’t matter, but DNG would be preferred) Is there a way to do this through Lightroom, maybe? Is there any way to do this programmatically?. I’m fairly new to all this so any help would be appreciated.

How to get exposure right in night photography?

In this link there are some wonderful night time scenes (#4,6,7,9,10,11,13). I’m wondering how the photographer got the exposure right. In my experience my camera metering will overexpose everything once it gets darker.

Would the photographer have used a manual setting and just hope it was right, or are there some metering settings that work in low light conditions?

What are the options?

ND filter or exposure compensation?

I was at the camera shop a few weeks ago looking for a neutral density filter, so I could play around with long exposure shots without overexposing.

The guy at the camera shop told me I didn’t need a ND filter I could just use exposure compensation.

I’ve got a general idea of what exposure compenstation does … but really don’t understand what the guy was talking about.

Could someone elaborate?

How to calculate difference in exposure between to given frames

I have a question regarding exposure.

I have a project I am working on where I need to be able to calculate the exact number of stops between two given exposures, with the end goal being to match the exposure of the two frames. Using metadata to match exposures isn’t possible as much of the difference will be due to ambient light changing.

I initially tried calculating average luminosity across each of the two frames, but due to the fact that exposure is a effectively multiplier on each individual pixel (and thus summing the pixels and multiplying from that value is not equivalent), this technique led to very significant error.

I can adjust one of the images using trial and error visually to approximate the value (just fiddling a slider in RawTherapee), but that’s neither accurate enough, nor fast enough (hundreds of frames will be processed). If an intelligent (i.e. not brute forced) method of achieving the same goal does exist, I will be able to run it automatically through a small script.

Does anyone know an accurate mathematical way to calculate the difference in exposure in stops between two frames?

I understand it’s a very specific question, so thanks in advance to anyone who has any advice. Anything at all is a great help

Derma Joie and red with exposure to cold or heat

Derma Joie sufferers and those with sensitive or slim Derma Joie and dilated capillaries may be especially vulnerable as dried-out Derma Joie improves pain and sensitivity. The organic level of acidity mantle (oil barrier) diminishes creating Derma Joie vulnerable. Nasal decongestants and many medications designed for common winter illnesses disrupt Derma Joie greatly when used for more than a day or two. They are not intelligent enough to…

Derma Joie and red with exposure to cold or heat

What is the relationship between lens diameter and exposure?

All of the online calculators for exposure, I have seen, factor in time, film speed, and appature (which is a function of the real appature diameter and the focal length of the lens)

However I would have thought a lens with a larger diameter (with the same focal length and appature) would collect more light and therefore be faster!

Am I just looking at rubbish exposure calculators, or am I missing something?

Exposure settings for film using digital camera

I have Fuji X-T100 and it’s lowest ISO is 200. Now, I’d like to shoot some slides like Provia 100 or Ektachrome 100 as well as Portra 160, using my Fuji as light meter (it works pretty well for Portra 400 when I set iso to 400 on my Fuji, and then adjust aperture and SS and use those settings on my analogue camera). What can I do? I don’t really wanna push those films to ISO 200…

Will several long exposure timelapses affect sensor lifetime or performance?

I’ve been recording some stormy nights on my canon EOS 80d, making use of its built-in timelapse function. Exposure settings varied between 4″ f/3.5 iso800 and 30″ f/3.5 iso3200, and dead time between exposures was between 1 and 5 seconds.

This built-in function makes no shutter actuations, it simply locks up mirror and lets sensor exposed for the determined lapse of time.

I wonder if the sensor is turned on and off once and again to take the programmed exposures. If so, ¿Would these kind of timelapses, done frequently, reduce sensor’s lifetime or affect its performance?

Exposure in Astrophotography

So, when taking a photo of the stars, I’ve generally taken photos at about ISO 3200, 20 seconds, f/3.5. I subsequently stack about 5 of them to get rid of the noise, which seems to work relatively well, however my Milkyway shots are nowhere near as clear (no distinct dust clouds) or vibrant (can’t see red H-alpha emission even with the red saturation at max) as others.

First question: If I stack 5 photos at ISO 3200, the brightness of the image should be the same as a stack of 10 images at ISO 1600 right?

Second question: Assuming I do 10 images at ISO 1600, would it have a greater contrast/saturation/dynamic range, than the first situation?

Third question: Taking a photo at ISO 200, the image will be more-or-less black, but if I stack 80 of these, will I get the same exposure as the first situation or is there a limit to how far I can push it (for example 160 images at ISO 100)?

Fourth question: Negating the star trails formed (let’s say I have a star tracker mounted), would the first situation of x5 ISO 3200, 20 secs etc. give more or less contrast/saturation/dynamic range (and sharpness!) than a single ISO 3200 at 100 seconds?

Thanks if you answer this, I’m quite new to astrophotography and from what I’ve gathered my assumptions are correct, but I want to be sure because most places don’t address these issues specifically.