Magnum

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On 21/04/2021 at 23:14, gorann said:

Maybe I am swearing in church and this comment is not immediately helpful for the OP but there is the new generation of cooled CMOS. Here is a dark from my ASI2600MC (5 minutes at gain 100), and a stretched frame grab of it from PI. I can forget darks or dithering or bad pixel/column processing or waiting for download😉

2021-04-06-1238_7-CapObj_0014.FIT 49.77 MB · 13 downloads

Id agree with most of that, but we can't forgo dithering with cmos, as they all have a faint fixed pattern noise that CCD doesnt have. you can see this become evident if you stack a load of bias or darks from even the latest zero amp glow models, a pattern quickly emerges. In real world imaging with the 533 I too dont use darks or bias, but if I dont dither I get diagonal banding pattern to the noise, ie walking noise which I dont see with my CCD's. luckily dithering completely solves  it and I always dither with either CCD or CMOS, so yes the 533, 2600 & 6200 are probably the closest cmos has got to CCD so far.

Lee

Great image Peter,

9 hours ago, gorann said:

Maybe I am swearing in church and this comment is not immediately helpful for the OP but there is the new generation of cooled CMOS. Here is a dark from my ASI2600MC (5 minutes at gain 100), and a stretched frame grab of it from PI. I can forget darks or dithering or bad pixel/column processing or waiting for download😉

2021-04-06-1238_7-CapObj_0014.FIT 49.77 MB · 11 downloads

I have a 533mc with is smaller version of that chip, yes the individual subs are cleaner, but I find I have to stack loads of them to get a good final image, yet the Atik383 gets super smooth in just a handful of 10-15 min subs, I dont use darks with any of my cameras, but do use dithering, actually I find dithering has the most benefit on the cmos or I get walking noise.

If I had to pick one camera to keep out of my 3 it would be the 383 .

9 hours ago, ollypenrice said:

 

 

I've lent the camera to Tom for a while for his robotic rig so don't have a dark in stock but snowstorm is the word. Who cares? It's the picture that matters:

 

 

no exactly the point I was trying to make, as your images are world class 🙂

Thought I might as well sow the quality of data the 383 produces when used at 13.8volts @ -20C, ive attached screenshots of uncalibrated single 900 sec subs of the Pelican and Heart nebula's both at 100% to show how clean the subs are, and also the final images which are both only 15 x 900 secs each using just bias frames and dithering.

Please don't give up on the camera unless you want to give it to me really cheap LO 😛

Lee

On 19/04/2021 at 22:44, newbie alert said:

I've heard from a very reliable source that the 383 needs a decent power source .. because of its very deep well depth it also likes long subs.. and calibrates out clean as a whistle

Yes it needs 13.8V

ok firstly the 2x2 binning sub you posted  will look worse than 1x1 on this camera in my experience, I never use binning anyway.

this camera needs more than 12 volts and cooled to -20C, i had similar amount of hot pixels opwhen i first got my camera but after speaking to Vince at Atik he told me The Kodak Atiks can safely use upto 15v and they are cleaner with more voltage, i did some tests and once i got to 13.8v the warm / hot pixels greatly reduced to a similar lever as my Sony sensor Atik460, i got no improvement above 13.8 and thats quite convenient as most Bench power supplies are in fact 13.8V anyway. So I use my old Maplin bench supply with the 383. The 460 is happy on standard 12v laptop style supply. 
similarly if you use it warmer than -20C you will see a few more hot pixels coming back.

so 13.8v at -20C is the cleanest it gets.

I agree with Olly, I prefer my Atik383 to my 460 for the final images they produce. The only time i dont like the 383 is when focussing and searching for the DSO as it looks noisy and dramatically thin compared to the 460, However the actual 10 - 15 min ha subs look as clean as the 460, and i actually find that the hot pixels  disappear into the stack much quicker in the 383 so much so that I dont really need to dither with the 383, (on the 460 dithering is essential) and  I dont use darks either though I do take bias frames as they fix the left edge of the frame which without them is a little brighter than the rest of the frame.

Sarah wager also found she prefered the final image noise profile of the 8300 chip compared to her previous sony sensor and had QSI swap the sensor in her cam.

I would say the Kodak 8300 is actually the cleanest Kodak sensor you will ever use, if you want to see a snowstorm, Olly might show you what the 11000 looks like in single subs LOL. 

There is one for sale on here at the and im tempted to get another one LOL, so i must be quite a fan. 

Nice, I did this myself last night after seeing your one

Lee

Great job , ive been plugging away at this also with my samyang 135, i pick it up in my mono ccd but barely get anything in my OSC cmos, can i ask what bortle your imaging in? What f stop did you use the samyang at, and what gain please?

cheers

lee

1 hour ago, vlaiv said:

It has been suggested a number of times, but it is down to the OP to do so if he wishes / has the time.

You are quite right that this highly technical and rather heated discussion might not be helping OP much - but I don't think it is irrelevant.

I apologize if the tone of discussion caused discomfort to some readers - that certainly was not my intention, and I can only hope that it will indeed provide some value to people that are interested in the topic.

 

I didn't mean you or anyone in particular Vlaiv, I was including myself too 😛

But yes its all interesting

This is all not really helping the original post that much.

Johan can you upload a single sub as the original raw fits file then we can have a play with it as Gorran suggested, won't take long for us to collectively see if there is anything wrong with the camera, or if its just the colour scaling.

cheers

Lee

I Kessler syndrome will take effect before they decide to regulate them. It just ridiculous having no regulation at all.

48 minutes ago, vlaiv said:

If you shoot with broad band filters you can actually find scaling factors from F2 class star in the image - it needs to be roughly white - so measure pixel values in such star (it's best to measure average value on star selection in each channel) and derive scaling factors from that.

Alternatively - what you are doing is also fine - fiddle around with values until you find what looks natural. Problem is that what we think is natural is often impacted by other images of the object that we've seen so far - and those might not been properly color calibrated - so our sense of right might be wrong

With this technique you can get pretty good results - I did it as a step in above example to demonstrate - and it was rather easy as I had gray patches in the image:

reference again, and just simple RGB balance:

gray patches are grey - so that is fine - but colors don't match as well as they could. Overly saturated, some are darker and some have noticeable different hye as well. Gamma is also not good - which can be seen in gray row gradient - it is not uniform as in reference image.

 

Yes star calibration is the most accurate for broadband. Maxim is very good for dealing with scaling factors, I like the way you can set in one tool then the other tools can make use of it and it also remembers the setting until you change. So if working on a project for weeks I know that each time I add more data the colour stays the same and don’t have to think of it again until I change to another filter or project.

Lee

When I use my 553C in Maxim I find that it can be very green biased if I use a Tri band or L enhance filter, but if I use my CLS filter is more neutral. 

I really think colour casts should be dealt with at the debayer stage not allowed to get into the stack, in Maxim this is easy as the colour convert tool has colour scaling, so depending on what filter im using I just lower the green value by trial and error until the image looks roughly neutral, you only have to do it for 1 sub, then close the window, then when stacking the stack window uses whatever value was last set in the colour convert window. For the Triband I find 65-70% for green is about right. it hasn't got to be perfect just as long as its roughly neutral then it can be tweaked in post. 

Ive noticed a lot of tutorials skip this step especially ones for pix insight, then they try and correct later with other tools but they always look horrible to me. I think you get a much better result if you start with a neutral stack.

Here is a screen shot showing what I mean.

47 minutes ago, Adreneline said:

Yes I am sure I have the spacing correct. The focus position is within the foot of the 'L' mark. I am using the lens at f2 so I am not surprised star shapes in the corners are less than perfect. To be honest the fov with this camera is such that I tend to crop off the edges anyway.

In my opinion, being contenscious, the Samyang 135mm is not a lens suited to pixel peepers - it is more suited to imagers who want a large field of view without necessarily having to get into mosaics. I like the fact I can image all of IC1396 for example and the surrounding space and enjoy the majesty of the whole thing. I am not interested in looking at detail at the stars in the corners.

Let's not lose sight of the fact that this is not an astronomical telescope, it is a consumer photography lens, and a budget manual one at that. Sounds like you have a good one and maybe I don't.

 

you have the 18 point diffraction spikes though so it looks like it was stopped down at least 1 click as when its wide open it dopant give spikes?

I would disagree about the lens not being for pixel peepers as its the best optic ive ever bought, but I have heard they can vary from copy to copy so maybe I just got a really good one. Ive been so happy how pinpoint the stars are in the corners, far better than any of my triplet scopes with flatteners and reducers..

Lee

great image, and very impressive for uncooled DSLR data

1 hour ago, Adreneline said:

I've just started using a ASI294MC-Pro with my Samyang 135mm and so far I've been pleased with the results.

That said I've been using it to try to image IFN where I am not so bothered about the undersampling - pixel peeping at the stars can be disappointing.

 

Are you sure you have the spacing correct ? and what f stop are you using as my copy of the lens seems to give perfect pinpoints into the corners using same size sensor, as long as I stop it down to f2.8.

Great image anyway, I tried this a couple of weeks ago but picked up no IFN at all, im in Bortle 5 but live right next to the motorway so never sure if the IFN is getting washed out even if I use a light pollution filter. or maybe I just need a huge number of hours on it.

Lee

Captured a quick wide field view of the brightest objects in Gemini on Friday night. IC443 the Jellyfish Nebula, Nebula IC 444, NGC2174 the Monkey Head nebula and Open Cluster M35.

Only managed 1.5 hours of data before target lost below the roof line at 10:30pm, comprising of 5 & 10 min subs in ha with My Samyang 135mm f2 lens set at f2.8 & the Atik 383L mono CCD camera.

Guided, captured, stacked and stretched in MaximDL, processed in Photoshop. No darks, just dithered.

Lee

very nice , I like the 2nd one too as that s the colour scheme I normally use myself.

I was thinking of getting the Antlia 3nm ha, do you have any comparison images taken with your previous wider filters?

Lee

6 hours ago, ollypenrice said:

Ah, but the thing about Starnet is that you don't have to remove the stars and call it a day. You can remove them and put them back at a reduced opacity, which doesn't require the same signal strength as a full removal. I've only done limited experimenting but I put the stars back using blend mode lighten as a top layer in Photoshop. (Put the linear image on top of the stretched starless, choose blend mode lighten, and stretch the top layer to taste.)

Olly

yes ive done that manually in the past, but using the stand lone Starnet I havent figured it out as it just outputs the starless version, cant see any there file of just the stars, Maybe that's only in the pix insight plugging version?

On 02/03/2021 at 14:37, Paul1 said:

Hello everyone

I have trouble in focussing infinity with Samyang 135 lens, focus ring stops before star is fully focussed. I used Bahtinov mask to focus on a bright star

Are there members here with the same problem. And is there a solution

Regards 

 

you can undo some locking screws under the rubber focus grip and just it to gain a little bit of back focus. but first tell us how you are3 connecting the lens to the ccd, some adapters are too thick.

Lee

1 hour ago, ollypenrice said:

That's a glory, Lee! The Samyang lens is a stunning asset to astrophotography. In conjunction with Starnet for star reduction it must be the definitive widefield setup. 90 mins with a 7nm filter is incredible.

Olly

Here you go Olly, a Starnet version, I dont think I have enough data to stand up to being starless, it got very noisy after I run it so then had to run another iteration of Noels Deep space noise reduction.

Lee

1 hour ago, ollypenrice said:

That's a glory, Lee! The Samyang lens is a stunning asset to astrophotography. In conjunction with Starnet for star reduction it must be the definitive widefield setup. 90 mins with a 7nm filter is incredible.

Olly

Thanks Olly, I would say the Samyang lens is the best Astronomy purchase ive ever made, at f2.8 the stars are perfect and it blows the socks of the Askar 180 which I returned. Funny thing is ive seen people saying the complete opposite. 

I wish id got more data on it, as I really had to work hard with the processing. problem is I think its been the worst winter for imaging in the UK, we've only had a handful of clear nights in about 4 months, and now the weather has turned for the better its been full moon, and loosing Orion by 9:30pm behind the conifers 😞

I will do a Starnet version shortly and see how that looks.

Lee

Rosette and Cone Nebula wide field. I came across a great image of this area today and thought now that's a nice field, so rushed out when I got home and managed to capture a quick 90 mins of data tonight before Orion went behind our trees. 9 x 10 mins with my Samyang 135mm f2 lens @ f2.8 & Atik 383L CCD camera + Baader 7nm ha filter. Guided, captured, stacked and stretched in MaximDL, processed in Photoshop. Work in progress along with a few other projects ive got going around Orion at the moment, but quickly running out of time for this season so may have to wait until the next winter to finish them.

Lee