Another Night of Deep Sky Photography

[wornish]

Re: Another Night of Deep Sky Photography

Great Images Dave did you use any darks or bias?. The Flame Nebular has come out well and did you have to do some processing to Ainitak to get it to sparkle. I've been there with your experiences, it then gets more expensive and wanting more equipment. Once dew forms on lens game over for the night. I've ended up getting tape heaters for the lens (HitecAstro four channel controller and 3 Astrozap heater tapes). Of course that then required a 12vdc battery pack and the camera is powered from the battery pack and inverter (300W Bestek) because there does not seem to be 12vdc device to power the camera OMD-EM1.

I am still sticking with star tools for the post processing

I just used lights. No Darks, Flats or Biases.

According to this guy Roger N Clark at
http://www.clarkvision.com/articles/...the.night.sky/
they are not required when using a DSLR as modern DSLRs do the dark current removal and other clever stuff in camera. Stand alone CCD/ CMOS cameras apparently do not hence the need.

His gallery is just amazing. I am trying to follow his ideas.


Didn't really do anything consciously to make Ainitak sparkle it just kind of happened.

It is really frustrating that there is no way to externally power my E-M5. I will see how it goes but maybe the grip with a second battery might help but its not cheap.

[birdboy]

Re: Another Night of Deep Sky Photography

It is really frustrating that there is no way to externally power my E-M5. I will see how it goes but maybe the grip with a second battery might help but its not cheap.

I'm a fan of Dr Clark as well but do not have Photoshop to do the post processing hence using Star Tools.

I have the power grip and purchased the Olympus power supply AC3 which I run from the 300W inverter which has a 12vdc cig lighter plug. I have seen many different ratings for the power for the OMD's. The battery states 7.2vDC 1220mAh; the output of the power adapter states 9vDC 3A 27W. Of course what really scuppers you is the type of plug that is required.

[Phill D]

Re: Another Night of Deep Sky Photography

That shot and this thread are great, thanks for posting it and all the helpful info Dave. I'm definitely going to have a go myself when I retire. I get the feeling it is a frustrating experience though until you get it right.

[wornish]

Re: Another Night of Deep Sky Photography

Thought I would add this to the end of a thread I started ages ago. Things move on. This is not taken with an Olympus camera but it shows whats possible. I got myself a birthday present of a mono astro imaging camera.

This image of Bodes galaxy (Messier 81) was taken last night and is made of of 80 x 60 second images captured using the mono camera and dedicated filters for Luminosity , Red, Green and Blue. 20 shots each. These were then combined in post processing.

Its a big step from using a DSLR but good fun.

https://flic.kr/p/28eepYG

[birdboy]

Re: Another Night of Deep Sky Photography

Is this a CCD mono or CMOS mono Dave? Narrow band filter next?

[wornish]

Re: Another Night of Deep Sky Photography

It’s CMOS mono ZWO ASI1600 MM. I bought the narrowband filters as well, but want to take one step at a time. The camera noise levels are very low. I set the temperature for the sensor at -10c for these shots. The BIG difference is the time factor. It is more sensitive so you use shorter exposures but you still have to do a set for each channel . When it comes to narrowband, it really solves the light pollution issue but exposure times are 10x normal. The post processing is also much more time consuming, considerably more.

[birdboy]

Re: Another Night of Deep Sky Photography

Interesting choice Dave, love to see your narrowband processed images when you get them. My own thinking is that CCD are the way to go with narrowband filtering. CMOS sensor have very low read noise but very high thermal noise, so you are better off taking shorter exposure times with a CMOS sensor and lots of them. CCD's have very poor read noise but very good thermal noise particularly if temperature controlled, this enables subs of circa 20mins to capture the photons through narrowband filters. Trouble is CCD imaging cameras are horrendous price for me. Narrowband filtering with mono camera is the next step I would like to go after I have upgraded my Star Adventure mount.

[wornish]

Re: Another Night of Deep Sky Photography

Interesting choice Dave, love to see your narrowband processed images when you get them. My own thinking is that CCD are the way to go with narrowband filtering. CMOS sensor have very low read noise but very high thermal noise, so you are better off taking shorter exposure times with a CMOS sensor and lots of them. CCD's have very poor read noise but very good thermal noise particularly if temperature controlled, this enables subs of circa 20mins to capture the photons through narrowband filters. Trouble is CCD imaging cameras are horrendous price for me. Narrowband filtering with mono camera is the next step I would like to go after I have upgraded my Star Adventure mount.

I really thought about the choice between CCD and CMOS for a long time before taking the plunge. The in built cooling on the latest CMOS cameras mean you can take the temp down to -35 or even -45C and that really lowers the noise.

The big factor for me was CMOS sensors are where all the research money is going because of the mass market, whereas CCD is becoming more specialised and in fact a shrinking market. Every thread I have have read about CCD seems to be full of issues around bad pixels and noise, I have not seen anything about shorter exposures to be honest, plus they seem to suffer from very poor driver software and overall really seem to be a bit stuck in the past.
ZWO in particular seem to be setting the pace.

Maybe I am wrong but so far my experience of CMOS mono is the noise issue has gone away. I did no post processing noise reduction on the image I posted - none, which I don't think would be the case with CCD.

One thing for certain though you have use a mount that supports guiding otherwise you will not get the benefit of any mono camera. Even for 60sec shots guiding is essential , my tracking error on these shots last night was less than 0.5 pixel. When it comes to narrowband nebula you need to be in the 300 - 600 sec exposure range and thats a whole new challenge.

[birdboy]

Re: Another Night of Deep Sky Photography

If you have not come across it before there is a really interesting article on how to pick the best exposure setting. It comes from Robin Glover of Sharpcap and it is worth running his sensor analysis in sharpcap. I have tried it with my guide camera GPCAM ARO130M and gives some really useful exposure settings.

https://forums.sharpcap.co.uk/viewtopic.php?f=35&t=456

[wornish]

Re: Another Night of Deep Sky Photography

If you have not come across it before there is a really interesting article on how to pick the best exposure setting. It comes from Robin Glover of Sharpcap and it is worth running his sensor analysis in sharpcap. I have tried it with my guide camera GPCAM ARO130M and gives some really useful exposure settings.

https://forums.sharpcap.co.uk/viewtopic.php?f=35&t=456

[birdboy]

Re: Another Night of Deep Sky Photography

Could not agree more Dave Sharpcap polar align is the bees knees. I have been able to get 6mins exposures (guided) on my Star Adventure because I have great polar align thanks to Sharpcap. The trouble with 6mins on EM 1 was thermal noise so have gone back to 1-2min exposures. I just hope Robin is able to develop his idea of polar align without sight of Polaris, now that would be something.

[wornish]

Re: Another Night of Deep Sky Photography

6 min exposure is superb, more than enough for most targets. As you say the sensor noise in a DSLR is the only downside.

I think Robin is working on a tool to give you the optimum exposure for a given target for your specific sensor but it won't help with a DSLR unfortunately.