Flats Failing Me?

[yobbo89]

I downloaded the Flat_TV1640s image and opened it up in PI. The image below shows how it looks in HistogramTransformation.



The histogram settings are what was explained to me by one of the PI gurus. The main point is that the histogram (the bottom histogram is the one to look at) is only at about 15% of full scale which is low. You want it closer to 50%. It will still work, but, will do a cleaner job if you are able to raise the histogram with longer exposures.

Steve

very nice, i eyeballed it and thought they are a bit to low in exposure aswell,

[fatboy1271]

Interesting find yobbo… I purchased an NXENTC A4 Tracing Light Pad for taking Flats:


Is this not good enough? It seems to have an even glow when plugged in.

[yobbo89]

i made my own flats box ,it has two opaque panels layered at a distance to disperse the light more evenly ,maybe move yours around on the scope says 10-20mm and compare the flats

[fatboy1271]

i made my own flats box ,it has two opaque panels layered at a distance to disperse the light more evenly ,maybe move yours around on the scope says 10-20mm and compare the flats

Will do, thanks!!!

[STEVE333]

Just FYI, I downloaded your M31 image and applied the Surface Blur Noise Reduction technique to it, and, it did indeed remove the dust mote. With the dust mote gone the image could be stretched and processed more. The result is a nice M31 with nice contrast. If you would like to see the result I could post it here. You have some nice data to work with.

Best of success in solving your flats problems.

Steve

Steve, you're awesome! Yes, please, I would love to see the result

I've not used Surface Blur Noise Reduction nor did I know it existed... So much to learn!!!

The Surface Blur Noise Reduction technique is something I learned from a Doug German video tutorial for Photoshop which is what I used when I started doing AP processing. The link I provided is to my adaption of the technique so it can be performed using PixInsight. Sometimes it can be extremely helpful.



Hope you like it.

Steve

[fatboy1271]

Thanks Steve!!! I really appreciate the time you took to share your knowledge and do a process on my image I love it, BTW!

[fatboy1271]

So I'm going crazy with trying to get Flats... I spent some time Saturday morning, after my Friday night session, and all that happened was more confusion and frustration.

In PI I open Stuart's 'flat_red_cluster.' If I stretch it I can see dust motes and in Statistics it reads in the 8000/30000 recommended range. All looks good to me as a reference.

Between BYEOS using the AV mode to set an auto exposure, using NINA's Flat Wizard, and then just taking different exposure lengths myself I could not get an exposure that read higher than 3826 in 14-bit. Hopefully someone can see what I'm doing wrong here and I'm sorry for being that annoying guy just going in circles!

Stuart's flat_red_cluster:

Tv 1/8000sec:

Tv 1/5sec:

Tv 30sec:

How I take my Flats:

[fatboy1271]

How does this "Flat" look? In NINA it has a Mean of 8237, which seems like it's where it should be. However, in PI I'm not getting those numbers.

RAW:


NINA:

PI:

[bladekeeper]

How does this "Flat" look? In NINA it has a Mean of 8237, which seems like it's where it should be. However, in PI I'm not getting those numbers.

RAW:


NINA:
Flat Wizard 8237 Mean.PNG

PI:
Flat in PI.PNG

That seems a bit low to me. I am "flatting" around 32,000.

[fatboy1271]

Thanks Bryan! I don't understand why something so seemingly easy has me so baffled...

Just to verify; Flats should be taken at the same ISO as Darks and Lights, correct?

[yobbo89]

Thanks Bryan! I don't understand why something so seemingly easy has me so baffled...

Just to verify; Flats should be taken at the same ISO as Darks and Lights, correct?

yes, even bias frames, but flats will work correctly if you use a different iso setting.i think it will introduce a small amount of noise, someone will need to dig out some more information about it,

some light panels are just too bright and or your camera has problems at quick shutter speeds,so changing the gain helps with these problems and i find it has little impact

[Juno16]

Hey Patrick,

Take this for what it is. Very much inexperience here. I just started using flats for my last two sessions.

I use an iPad app called Lightbox (credit Bryan) and set the iPad on top of a couple of stretched out t-shirts on the top of my scope in the vertical position. I set the intensity about 3/4 on the slider and mess with the shutter speed to get the histogram in the middle. Then I take my flats at the same iso as the dso target. I know that this is really crude, but it definitely makes a big difference in processing. I use Startools and always had to correct for vignetting. No more with my flats.
Like I said earlier, this is really crude, but it definitely makes a significant difference in processing.

Thanks,
Jim

[fatboy1271]

Hey Jim,

I'm about halfway there... I purchased an LED light panel for tracing artwork on, so I think that should work about the same as your iPad.

My next issue is that I've been pretty dedicated to trying to use NINA full time. Being free and new it has some quirks, but it also has everything I'm looking for: Guiding, Sequencing, and a Flat Wizard. However, NINA seems to hate my 70D most of the time. I'm also very spoiled from a few years of use with BYEOS! Anyway, I think I may have to switch between the Camera mode in NINA for Lights and then I can do Darks and Bias in either NINA or BYEOS. I do think for now though that I will have to switch to BYEOS for Flats. At least until they get more work done with Canon cameras in NINA.

Then... I sure do ramble, eh? So then, I've played around in BYEOS and have not been able to reach the target Mean. I'll keep plugin away! At some point I WILL be successful

Thanks for the info and it doesn't seem all that crude to me!!!

fat

[Juno16]

Hi Patrick,

NINA didn’t seem to play well with my Nikon. I gave up without a fight and moved to Astrophotography Tool which I am very happy with.
Sounds like you are on the path to flats. I’m sure that I can more about shooting them, but what I am currently doing does help a lot.

Thanks,
Jim

[fatboy1271]

Hi Patrick,

NINA didn’t seem to play well with my Nikon. I gave up without a fight and moved to Astrophotography Tool which I am very happy with.
Sounds like you are on the path to flats. I’m sure that I can more about shooting them, but what I am currently doing does help a lot.

Thanks,
Jim

You know what Jim, I changed my mind... You are a pain in the butt!!! Now I have to explore using APT Just kidding about the pain in the butt; I truly appreciate all your comments on my posts!

The NINA guys have been great in their support channel and I don't want to completely abandon them; however, I need something that works consistently well. I'll download the demo for APT and see how that goes. How long have you used it? Do you have the paid version? $21 is a good price if it does what I want it to!

Patrick

[Juno16]

Hi Patric,

No, please use what you are familiar with! I really didn’t give NINA a good effort. It just seemed to me that NINA was more suited to non dslr imaging. APT just had a workflow that I could relate to.

I have only imaged twice with APT. Along with the weather, I have had some other time consuming projects going on that has kept me tied up and unable to get out to Image. I do have the paid version. I have had tremendous support from the APT team. They helped me set up a plan where I can turn on the AVX (after polar alignment), do a quick align (no real alignment, just a best guess), run the APT script plan where the scopes moves close to the imaging target, plate solves, syncs, and centers on the target automatically. Now ready for imaging. No need to align the mount.
I recently posted to APT support to see if there was a way to set a default iso for plate solving. They added that feature in the next version update. Can’t beat that!

That is just my experience with APT as a new user.

Thanks,
Jim

[fatboy1271]

That's awesome Jim! I'm a huge Customer Service guy and that sounds just like what I love about good companies/products.

I'm not tied to NINA in any way. I like the program but it has issues with my 70D for sure. Not being a seasoned veteran means I probably should be using something that "just works." I'm going to willingly try out APT. If you're using a DSLR and have had good success then that works for me.

I'll use the demo so I'm not out anything if I don't like it. I'm curious about the script for the AVX that you're using. Is that tied strictly to your equipment setup? I love the idea of Plate Solving replacing mount alignments.

Just looked at your flickr page... Nice work!!! Also, Jack looks awesome I think I'll have to add Geno to my signature.

[Stuart]

Hi guys,
Sorry I was away. I don't know NINA at all. I'm guessing it spit out the ADU in a 16 bit scale, not a 14 bit scale.
I use an Aurora flatfield panel and I dampen it with a couple of sheets of white copy paper.
Stuart

[Stuart]

Disregard what I said above. I downloaded your flat. The brightness on it is perfect, it might even be a little bright.
For 14 bit scale I get Red 8135, Green 10065.8, Blue 11834.0

[Juno16]

That's awesome Jim! I'm a huge Customer Service guy and that sounds just like what I love about good companies/products.

I'm not tied to NINA in any way. I like the program but it has issues with my 70D for sure. Not being a seasoned veteran means I probably should be using something that "just works." I'm going to willingly try out APT. If you're using a DSLR and have had good success then that works for me.

I'll use the demo so I'm not out anything if I don't like it. I'm curious about the script for the AVX that you're using. Is that tied strictly to your equipment setup? I love the idea of Plate Solving replacing mount alignments.

Just looked at your flickr page... Nice work!!! Also, Jack looks awesome I think I'll have to add Geno to my signature.

Hi Patrick,

Give it a try to see if you like it. I believe the trial for APT is pretty much full featured and doesn’t expire. I think that you will have to stick to the stable versions and won’t be able to download the beta’s with the trial, but I could be wrong there.

Heck, if you like the software, send me a pm and I’ll send you one of my scripts. Super simple. I’m sure it will work with your AVX. Three lines, unpack, goto whatever target you set, solve and sync. Worked great the two times I’ve used it. They sent me a script example to use as a guide. It’s an auto alignment script that sends the scope to four points in the sky (your choosing if you need to dodge trees). Run the script and the mount will automatically calibrate to the entire sky.

Thanks for the kind comments! I’m a baby at this and at my current rate of getting out, it might take me many years to get it together!
Jack is my right hand man!

Thanks ,
Jim