Pleiades and Orion

[Daf1983]

A couple of clear nights gave me chance to try out my new Carl Zeiss Jena 135mm lens. Managed to capture pleiades and Orion belt with m42. My other equipment include the omegon minitrack lx2 and a canon 600d. 

Pleiades was taken at iso800, and I took about 45 light frames, which were 25 seconds each, also took 15 dark and bias frames.

Orion was taken at iso 1600, light frames 10 seconds x100 along with dark and bias again. Both pictures were stacked in dss and processed with siril and gimp.

Although far from perfect, as a complete novice, I'm quite happy with the results. I'm also pleased with the performance of the lens, considering what I paid for it. Although it does need stopping down to f5.6 to get decent results.

My main issue at the minute seems to be how noisy the images are. I assume I need to up the total exposure time to improve this?

Any suggestions and constructive criticism

 are welcome.😁

 

 

 

[Aramcheck]

Pictures from my 600d also have a lot of noise & ISO 800 is said to be optimum for that model (http://dslr-astrophotography.com/iso-values-canon-cameras/)

Increasing the total exposure time will help, as will more careful processing when stretching the image & also when effectively blurring out the background noise.

More dark & bias frames might be an idea too - these can be reused for the same camera settings, so it's worth making a master dark & master bias. You may also find that processing without darks is better (although I've found darks do help with the 600d).

It's also worth covering up the viewfinder, to prevent any light leakage.

Some folks also advocate leaving the flip screen open to help cool the camera, and to minimise the use of the liveview screen.

Cheers
Ivor

 

[Daf1983]

Thanks the suggestions! I will definitely try  these out next time. 👍

With regards to processing, what do you mean by 'blurring out background noise'?

[happy-kat]

Flats and dark flats you could also do and these I find help an image background noise.

[Daf1983]

2 minutes ago, happy-kat said:

Flats and dark flats you could also do and these I find help an image background noise.

I thought someone would suggest this. I've been putting off doing flats, mainly because I don't really know how to, and it seems very fiddly. I will have to look into it and give it a go😁

[happy-kat]

Use same focus, same iso, same aperture, same lens

Put camera in av mode (turn lens to manual focus where applicable)

In av mode the camera will work out exposure length so the light histogram is in the middle for you.

Aim camera square on to clean light source, I balance a tablet running lightbox app on the lens, use remote trigger and take 30.

Note settings from above put camera in manual mode and set up exposure length to match flats, put lens cap on take another 30.

[Budgie1]

Flats can be done after the session.

1. Keep the camera and lens/scope attached and don't move the focus.
2. Get a white T-shirt and place it over the end of the lens/scope (I find a double layer of material is best but experiment).
3. Open a blank white Word document on your laptop or PC screen and get the opening of the lens close to the screen.
4. Set the camera to AV mode, so the camera selects the shutter speed, and take 10-20 images.  

I had a shadow at the top of my first flats, which turned out to be from the mirror lifting. The shutter speed was too fast as I only had one layer of T-shirt over the lens. This was cured by adding a second layer, which slowed the shutter speed and allowed the mirror to fully retract.

Looks like @happy-kat and I were typing at the same time.

Edited November 29, 2020 by Budgie1

[alacant]

5 hours ago, Daf1983 said:

how noisy the images are

Hi

Excellent shots. Some of the old lenses are really good. To lose the spikes, leave the lens wide open and use a 49mm to 42mm step down filter ring.

There are some good denoising algorithms in modern software. This is the m45 jpg (converted to tif so not ideal) then passing through StarTools' denoise. The latter can also produce excellent synthetic flat and bias for you. Good for when you've forgotten or just can't be bothered!

Cheers

 

Edited November 29, 2020 by alacant

[Daf1983]

Thanks everyone👍 I'll have a go at taking some flats next time. 

15 minutes ago, alacant said:

Hi

Excellent shots. Some of the old lenses are really good. To lose the spikes, leave the lens wide open and use a 49mm to 42mm step down filter ring.

There are some good denoising algorithms in modern software. This is the m45 jpg converted to tif using StarTools' denoise. The latter can also produce excellent synthetic flat and bias for you. Good for when you've forgotten or just can't be bothered!

Cheers

 

Thanks for that, will have a go with that software. Where could I get hold of a filter ring?

[alacant]

2 hours ago, Daf1983 said:

a filter ring

They're only cheap items and it saves you the hassle of blu-tak and glue DIY.

For f5.6, the nearest I could get without a longer search, is this and this which gives you an aperture of 28mm; around f5. For exactly 5.6 you need to step down to 24mm.

HTH.

 

[Daf1983]

56 minutes ago, alacant said:

They're only cheap items and it saves you the hassle of blu-tak and glue DIY.

For f5.6, the nearest I could get without a longer search, is this and this which gives you an aperture of 28mm; around f5. For exactly 5.6 you need to step down to 24mm.

HTH.

 

Thank you for taking the time to look for them👍 Where/how do they attach to the lens? Does it have to be specific type for a specific lens? (Sorry for all the questions)

[alacant]

24 minutes ago, Daf1983 said:

how do they attach to the lens?

Hi

I'm assuming it's a Zeiss 135mm f3.5 (?) in which case at the front of the lens is a 49mm female thread into which the 49mm of the first filter ring will thread.

If not, please post the exact specification and/or a photo of the lens so we can recalculate.

Cheers

 

 

 

 

[Daf1983]

Yes it is the f3.5. Thanks for the help, that makes sense now👍

[Aramcheck]

6 hours ago, Daf1983 said:

With regards to processing, what do you mean by 'blurring out background noise'?

It depends on the software you're using, but the idea is to mask off areas of high signal & to blur the background. In Pixinsight I use the MultiscaleLinearTransform (MLT) tool on the linear image & ACDNR once the image has been stretched & is non-linear. At the end of processing I sometimes then use a PixelMath expression to try to reduce any remaining DLSR mottling.

The screen grab shows a before & after image of the MLT process on a small area of background.

Cheers
Ivor

[Daf1983]

1 hour ago, Aramcheck said:

It depends on the software you're using, but the idea is to mask off areas of high signal & to blur the background. In Pixinsight I use the MultiscaleLinearTransform (MLT) tool on the linear image & ACDNR once the image has been stretched & is non-linear. At the end of processing I sometimes then use a PixelMath expression to try to reduce any remaining DLSR mottling.

The screen grab shows a before & after image of the MLT process on a small area of background.

Cheers
Ivor

I've only used free software to do my processing so far (gimp and siril). I'm guessing they don't have the features you've described above? 

Edited November 29, 2020 by Daf1983

[happy-kat]

The process is also possible to replicate using GIMP. I may find a link later

[alacant]

11 minutes ago, Daf1983 said:

gimp

The gmic plugin for gimp gives you around 50 different denoise routines to suit all situations. If you can't find a method there, it doesn't exist!

HTH

 

[rickwayne]

Orion shot looks much better focused than the Pleiades. What are you using for focus assist?

A simple brute-force antinoise tactic: simply to pile on the integration time. But it's a square-root relationship, so four times the integration merely doubles the signal/noise ratio.

[Daf1983]

5 minutes ago, happy-kat said:

The process is also possible to replicate using GIMP. I may find a link later

Thanks again, everyone has been very helpful! Up to about 2 months ago, I had done zero image processing. Feel like I have learned a lot in that time(mostly from reading and getting advice on here), but also feel I have a LOT still to learn

[Daf1983]

4 minutes ago, rickwayne said:

Orion shot looks much better focused than the Pleiades. What are you using for focus assist?

A simple brute-force antinoise tactic: simply to pile on the integration time. But it's a square-root relationship, so four times the integration merely doubles the signal/noise ratio.

At the minute, I'm focusing using live view at x10 magnification. I suppose a bahtinov mask would help?

[happy-kat]

Yes it makes it easier but need a very bright star, could make a simple Y Lord mask out of cardboard.

Personally I use DSL Controller and an Android device makes things so much easier with the Canon 1100d.

There is an Infinity YouTube on processing Orion by one of Serif's staff, that is good to follow as GIMP likely do it all.

Also there is in Infinity StarGaZine video if you look through the various StarGaZine episodes forum on here. 

[Daf1983]

9 minutes ago, happy-kat said:

Yes it makes it easier but need a very bright star, could make a simple Y Lord mask out of cardboard.

Personally I use DSL Controller and an Android device makes things so much easier with the Canon 1100d.

There is an Infinity YouTube on processing Orion by one of Serif's staff, that is good to follow as GIMP likely do it all.

Also there is in Infinity StarGaZine video if you look through the various StarGaZine episodes forum on here. 

I've thought about making a Y lord mask, it might be worth a shot, and I will have a look at the videos you mentioned when I have time. I followed one of Serif's (I think) when trying to process andromeda a couple a months back.

Regarding a dslr controller and android app, how would that aid focusing?(excuse my ignorance)

Thanks again

[happy-kat]

you get a nice big screen to control your 600d from, focus becomes so much easier 

I don't use a laptop. Perhaps you are already using a laptop in which case you already have a big screen.

Edited November 29, 2020 by happy-kat

[Stardust]

I found f5.6 right when I had that lens

 

[Daf1983]

Just now, Stardust said:

I found f5.6 right when I had that lens

 

That's also what I've found in the short time I've been using it