M78 from 3 weeks ago, fixed by using properly exposed flats from 12 hours ago

[EyeGuy]

Date: 17th March 2018

Location: Ballycroy international dark sky site in Co. Mayo, Ireland

Telescope: Takahashi FS-128 with 0.75 reducer flattener

Camera: Nikon D750

Mount: Vixen AXD2

 

Just 20 x 120s subs for 40 mins integration (far too little!).

Same circumstances as the previous images I've posted lately - severely underexposed flats ruined images. Helped by this forum to realise problem. New flats with slightly different setup miraculously fixed problem.

Comments and criticisms welcome, and thanks for looking.

Barry

Okay, I promise I'll stop spamming images now!

[carastro]

Looks good, would be interesting to see the original image with the bad flats for comparison.

Carole 

[EyeGuy]

22 minutes ago, carastro said:

Looks good, would be interesting to see the original image with the bad flats for comparison.

Carole 

For some reason this one wasn't so badly affected, but I couldn't pull so much out of the nebula without the background going nuts. Here's my previous effort. This really needs a tonne more data to do it justice.

[EyeGuy]

25 minutes ago, carastro said:

Looks good, would be interesting to see the original image with the bad flats for comparison.

Carole 

Actually, the new one looks a little "muddy" by comparison. Maybe I shouldn't have touched the colour at all?

[pipnina]

33 minutes ago, EyeGuy said:

Actually, the new one looks a little "muddy" by comparison. Maybe I shouldn't have touched the colour at all?

I find the colour data I get from my D3200 to be awful. Since your camera is much higher end than mine I think it could be a symptom of DSLRs/CMOS sensors or even just bayer matrix in general.

I think the new image looks a lot better. The only complaint is that barnard's loop is squandered compared to the old version.

[EyeGuy]

29 minutes ago, pipnina said:

I find the colour data I get from my D3200 to be awful. Since your camera is much higher end than mine I think it could be a symptom of DSLRs/CMOS sensors or even just bayer matrix in general.

I think the new image looks a lot better. The only complaint is that barnard's loop is squandered compared to the old version.

I'm sure there are all kinds of compromises, but I like the D750 a lot. It's pretty sensitive, has good battery life and the tilting screen is a godsend. Having said that, I want to transition to dedicated astro camera. I have a OSC Moravian CCD, but am still getting used to it and didn't bring it on my trip to Mayo.  I feel very confident with the D750 and I was also worried that the Moravian might use too much power and that I'd be out of juice before the night was through!

Barry

[Guest]

I put the pictures through a gif maker so I could see the difference clearly

It sure looks like you're getting more nebulosity in the new image - good effort :-)

David

 

[pipnina]

14 minutes ago, EyeGuy said:

I'm sure there are all kinds of compromises, but I like the D750 a lot. It's pretty sensitive, has good battery life and the tilting screen is a godsend. Having said that, I want to transition to dedicated astro camera. I have a OSC Moravian CCD, but am still getting used to it and didn't bring it on my trip to Mayo.  I feel very confident with the D750 and I was also worried that the Moravian might use too much power and that I'd be out of juice before the night was through!

Barry

I believe CCDs require a computer to be attached for them to take pictures as well? I've never used one but that would definitely be a drawback.

I have found I can get around the colour noise somewhat if I dither the camera a bit. My 105mm lens and D3200 on the Star Adventurer drift slightly (over 30 minutes maybe 50 pixels). An image I took of orion in two nights (one 30 mins, another night an hour so 1h:30m total) was obviously not quite in the same place the second time around and I think the biggest difference was in the colour.

You can see "streaks" as the frames drift (these were 30 second exposures, nowadays I try for 2 mins or even 3) but it looks a lot better in the second image (and I suspect not just because of the extra data) If you don't dither already, it might be worth a try

[EyeGuy]

25 minutes ago, David_L said:

I put the pictures through a gif maker so I could see the difference clearly

It sure looks like you're getting more nebulosity in the new image - good effort :-)

David

 

Thanks so much for that David. I find it very encouraging. The GIF really shows the difference!

Barry 

[EyeGuy]

17 minutes ago, pipnina said:

I believe CCDs require a computer to be attached for them to take pictures as well? I've never used one but that would definitely be a drawback.

I have found I can get around the colour noise somewhat if I dither the camera a bit. My 105mm lens and D3200 on the Star Adventurer drift slightly (over 30 minutes maybe 50 pixels). An image I took of orion in two nights (one 30 mins, another night an hour so 1h:30m total) was obviously not quite in the same place the second time around and I think the biggest difference was in the colour.

You can see "streaks" as the frames drift (these were 30 second exposures, nowadays I try for 2 mins or even 3) but it looks a lot better in the second image (and I suspect not just because of the extra data) If you don't dither already, it might be worth a try

 

At the moment I rely on my incompetence to do the dithering for me

My AXD can dither when controlled by ASCOM, but I don't do that! The Vixen mounts have a magical ability to self guide, which I find absolutely liberating. The signal from the guidescope goes straight to the mount hand controller (called Starbook Ten), and it does all the guiding without any laptop or other cables or complications. It means that with the DSLR you don't need a laptop at all.

In fact, the AXD also controls the DSLR as a really easy to program intervalometer. The simplicity is a real boon when you want to visit a dark site. The Vixen Starbook ten would be hard to do without at this stage.

You're right that to use a CCD you need the laptop, which is another mode of failure. I've found the connection between the computer and the CCD is unstable. I'm not sure if this is a driver issue, but it makes me nervous to leave it imaging for hours at a time, which is no problem with the DSLR.

Barry

[des anderson]

Terrific images, all of them; something to be proud of well done. Des

[EyeGuy]

15 minutes ago, des anderson said:

Terrific images, all of them; something to be proud of well done. Des

Thanks so much Des. It's great to show them to people who care about astronomy and understand the challenge! I'm not a fan of social media - at all - but I find it very encouraging to hear people's comments and criticism.

Barry

[pipnina]

31 minutes ago, EyeGuy said:

Thanks so much Des. It's great to show them to people who care about astronomy and understand the challenge! I'm not a fan of social media - at all - but I find it very encouraging to hear people's comments and criticism.

Barry

I like to think Forums as separate from social media. It's more like a society meeting that's going on all the time, and with people from all across the world. From the comfort of your phone or PC (my favourite part)

[EyeGuy]

2 minutes ago, pipnina said:

I like to think Forums as separate from social media. It's more like a society meeting that's going on all the time, and with people from all across the world. From the comfort of your phone or PC (my favourite part)

I absolutely agree. And far less likely to influence the outcome of any elections.

[MarsG76]

That's awesome for only, especially at only,  40 minutes of integration... great work.

 

[EyeGuy]

12 minutes ago, MarsG76 said:

That's awesome for only, especially at only,  40 minutes of integration... great work.

 

Thanks so much. That is high praise indeed - I just had a look at your gallery and was humbled by your images.

Barry

[alacant]

Hi. Great effort.

In this target, I think we're seeing the limit of what dslrs can do for us. Here's my 4 hours worth. Whilst other targets respond well to extra data, I get the feeling that another 4 hours on m78 would show no further improvement. With your bigger pixels, you may be able to prove the limit wrong. Hope so and good luck:)

 

[EyeGuy]

37 minutes ago, alacant said:

Hi. Great effort.

In this target, I think we're seeing the limit of what dslrs can do for us. Here's my 4 hours worth. Whilst other targets respond well to extra data, I get the feeling that another 4 hours on m78 would show no further improvement. With your bigger pixels, you may be able to prove the limit wrong. Hope so and good luck:)

 

That's a really interesting thread - and thanks for pointing me to it. I love your image btw - beautiful colour and composition. If I push mine like that the wheels fall off quite rapidly :-)

I have a Moravian G3 cooled CCD (OSC), which for various reasons I'm still just getting to grips with. I imagine the next time I shoot this object it'll be the G3 on the TEC 180. M78 is such a beautiful and "moody" object I think it bears a fair bit of effort. You obviously agree with that sentiment!

Kind regards,

Barry