extra long exposures (split from: Hardcore modding on a A530, thanks to CHDK!

ewavr

RaduP
Regarding the sensor exposure, it may be that the sensor has a 16b internal counter, in 1ms increments, so 65 seconds is the most it can get until the timer overflows. I don't see any other reason why it would stop at this magic number.

Of course, this is software-only limitation.
For example, picture taken with 150s exposure (without dark frame subtraction) - http://ewavr.nm.ru/chdk/for_test/IMG_0260.JPG (4 Mb).
Image quality is really horrible.

How? This is my secret 😀.

Well, we call modified SetShutterSpeedWithMecha() (more precisely, modified sub_FFCA400😎 in capt_seq_hook_set_nr():

void capt_seq_hook_set_nr(){
.....
sub_FFCA4008_my(-694); // = 150s
.....
}

sub_FFCA4008_my is exact copy of sub_FFCA4008, except:

ROM:FFCA4060 MOV R0, R4
ROM:FFCA4064 BL sub_FFCA5104 ; convert Tv in APEX units to microseconds; limitation is here!
ROM:FFCA4068 MOV R4, R0

replaced with

"MOV R0, R4\n"
// "BL sub_FFCA5104\n"
"LDR R0, =150*1000000\n" // exposure time in microseconds
"MOV R4, R0\n"

Of course, this is quick working example only, not complete solution.

edit:

Finally I did it for A710 private build (http://trac.assembla.com/a710/changeset/42).
Here is 160s exposure time with dark frame subtraction : http://ewavr.nm.ru/chdk/for_test/IMG_0271.JPG
Image quality is still very bad.

Leonardo Miguel Delgado

RaduP, yes, on the LCD and the 114/500 telescope (f/4.4 theorical) I can see stars up to magnitude 5 and a little more. Open cluster M7, its brighest stars appear in real time.

ewavr: THIS IS GREAT! I wonder if it's possible to do the same on my A530. Tell me, if it is possible, what can I do to change the exposure time? I'm not a programmer guy, however I'll take a look at your work.

Leo

ewavr

Leonardo Miguel Delgado
I wonder if it's possible to do the same on my A530.

I'm very unsure about a530, it have different from a710 firmware structure 🙁.
Here is test version - http://ewavr.nm.ru/chdk/for_test/a530.zip
Set in extra photo operations:
- shutterspeed enum type = Factor
- Value factor = desired factor (10, for example)
- 0verride shutter speed = desired shutter speed (10, for example; total time in this case is 100s)

If in this case exposure time is still 64s, please write bug-report.

Leonardo Miguel Delgado

Man, you are AWESOME!

It worked right away. I loaded the CHDK like always, and setted the new exposure times, as follows:

30 secs - OK
60 secs - OK
90 secs - OK (!!)
120 secs - OK
180 secs - OK
240 secs - OK
300 secs - OK
480 secs - OK (8 minutes exposure time!!)

Didn't tried more time.

The extended exposure times, I believe, is a feature that must be on the official CHDK releases.

Here I attach some images, with the amp off at ISO 100

A big thank you from Argentina!!

PhyrePhoX

niiice.
leonardo - adding this to the main chdk branch certainly would/will take a while, as only a few people are able to do it, as it involves asm "magic" and most certainly a lot of time.

ewavr

Leonardo Miguel Delgado
Didn't tried more time.

I tried even 10 minutes exposure (+10 minutes dark frame) - http://ewavr.nm.ru/chdk/for_test/IMG_0276.JPG (ISO80, F/😎. In this mode battery life is 5-10 shoots 😁.

The extended exposure times, I believe, is a feature that must be on the official CHDK releases.

This is a lot of work 🙁. Now I can add to "official" release a530 and a710 only (diff is attached).
If somebody really needs this feature, please report me via PM or forum.

edit: edit. edit. edit.

exp.zip

4.94KB

Leonardo Miguel Delgado

Thanks ewavr.

If you ever need to do beta testing on other camera models, I have a lot of astro-friends that shoot with A570 (mostly) and A620.

Regards, Leo

RaduP

Would it be possible to post some long exposure stuff converted from RAW? In the pictures you posted (the 10 minutes exposure), there is a lot of noise sharpening, so 1 bad pixel affects 10-20 pixels.

fudgey

I'll try this out for a570 100e today, at first glance it looks very similar to a710 (will update later, I'm posting this to prevent unnecessary duplicate work).

edit: I just did my first 120 second exposure on a570is 100e. 🧑‍🎄
I'll need to test it a bit more, clean up the code and see if 101a can use the same or almost same code before I post it.

ewavr

RaduP
Would it be possible to post some long exposure stuff converted from RAW?

RAW is not better than JPEG.
Here is DNG for 10 min exposure - CRW_0276.7z - 6.25MB

A630Lover

Hey, I was wondering...would it be possible to create a b-pose function via remote? Like on a slr, the shutter staying open as long as you do not press the remote button again, or realese the remote button (the former being a better idea, imho)?

Leonardo Miguel Delgado

Fudgey, great work!!!

Please, if it's posibble, I'd like to try out your modded CHDK on a A570. I'll beta-test your version too.

PM me or post it here!!

RaduP

ewavr
RAW is not better than JPEG.
Here is DNG for 10 min exposure - CRW_0276.7z - 6.25MB

I think it looks much better. The noise pixels are confined to their place, they don't look like big spots on the picture 😀 That's basically what I hate the most about the camera sharpening.

fudgey

Okay, here are a570is 100e and 101a beta binaries (install them over a full CHDK trunk 727 autobuild package). I have shortly tested the 100e one, I don't have access to 101a. Download link:

http://www.zshare.net/download/58199254a416d0fb/

Attached my patch to trunk 727. It includes ewavr's patch, i.e. this should work on all supported a530, a570 and a710 cameras.

It's possible that I have made typos that could cause bugs not present in ewavr's code. That's because I had to do a lot of manual work since I couldn't get the same sort of labeled disassembly from objdump that IDA outputs. I did test both long (up to 3 minutes) and short exposures and everything seemed fine, but I'm sure there are asm snippets there that aren't regularly jumped to in short tests where everything's going smoothly.

edit: updated patch and dl link according to ewavr's fixes below... 😀

longexp-a530-a570-a710-trunk727.patch.gz

7KB

ewavr

@ fudgey:

100e/capt_seq.c:

line 645 : "MOV R1, R4\n"
Original code @0xFFD2467C: "MOV R0, R4"

line 668: "MOV R0, #0\n"
original code @0xFFD246CC: "MOV R3, #0"

~~I'll check other code tomorrow.~~ I'm using TortoiseMerge (and IDA+asmify.sh) to verify large pieces of code.

edit:

101a/capt_seq.c:

line 570: "MOV R1, R4\n"
original code @0xFFD2467C: "MOV R0, R4\n"
line 593: "MOV R0, #0\n"
original code @FFD246CC: "MOV R3, #0\n"
line 678: "BL sub_ffebcf48\n"
original code @FFEBCFBC: "BL sub_FFEBCFBC"

Finished.

edit2: diff is attached.

exp.zip

7.52KB

Leonardo Miguel Delgado

Wow people, just WOW !!

Well at least we have A530, A570 and A710 !!

I'll grab the A570's and try it out.

Regards

Neanderthal_Man

Thanks EWAVR you made a great cam SPECTACULAR! 😛

esu

What should I do to make this work in a S5 IS?

fudgey

Looks like ewavr added long exposures for a530, a710, ixus80, s3is, sx10 to trunk.

Any news on testing a570 101a so that we could add a570 too? a570 100e works fine for me already.

PhyrePhoX

ewavr, it doesnt seem to work on the s3is. 60 seconds - ok. 70 seconds and longer - not ok.

behaviour: when i set 70 seconds, and do a halfpress, the cam already shows 15", so it DOES notice the longer shutter. when i then press fully it takes a picture, but only with a very short duration. now here is the catch - the picture is very dark, so the real shutter that was used must be very short. BUT when i view this image in playmode, camera tells me it was shot with a 15" exposure.
very weird. no crash or the like.
thanks for your work!