The "No EQ" DSO Challenge!

[The Admiral]

2 hours ago, happy-kat said:

My red dot finder that goes in the camera hot shoe is my alignment and works very well.

Steve I like your different approach but that looks ever more lens front heavy bias and unbalanced.The kit lens is light the vintage lenses even the 50mm are at least as heavy as the camera and protude further and I currently have no adjustment to move the camera to improve that balance. Azimuth movement is fine, it is downward altitude tracking which I think is being effected as if the camera is aimed at a reasoably high elevation then the motors appear unable to bring the camera back down, I have to hand support it from the rear and I think this is balance impaired.

If in Steve's arrangement the camera faced the other way, would that help?

Nige's arrangement should be able to reach balance with a single camera and heavy lens, I should have thought.

Ian

[Nigel G]

20 minutes ago, The Admiral said:

If in Steve's arrangement the camera faced the other way, would that help?

Nige's arrangement should be able to reach balance with a single camera and heavy lens, I should have thought.

Ian

The advantage with a bar is you can mount the camera behind the mount clamp, quite easy to balance with 210mm lens.

Nige.

[SteveNickolls]

3 hours ago, happy-kat said:

but that looks ever more lens front heavy bias and unbalanced.

Hi,

The L bracket can be moved to bring the camera and lens closer to the mount head and the ball head moved closer on the L bracket to the mount arm to reduce the forces acting on the set up. I did wonder at first about the ball head being able to cope with a long lens on the camera but it easily holds the camera firm and allows for precise alignment. I recall it's rated at holding 8kg. These posts do show how inventive we all are. I guess it's whatever works for us.  And on that note I do rather like Nige's 'two gun' approach, that's serious firepower and has balance. 

I know a balanced set up should maximise the life of the mount. I recall Joseph Ashley mentioning that he used to like having his telescope and camera set up bottom heavy as it seemed to help with tracking. When I use my telescope and camera the whole assembly is certainly back heavy and I always felt it added some inertia against small wobbles that a balanced set up would not cope so well with.

Cheers,
Steve

[Nigel G]

Happy new year fellow Alt-Azers and all. Best wishes and clear sky's for 2017.

Cheers 

Nige 

[The Admiral]

Thanks Nige, and I second that 

Ian

[SilverAstro]

I third it all gone quiet outside, festivities over, musing on sgl with a glass of amber nectar and got to thinking -

is anyone using a GoTo dob ? I think most of you have alt-az on tripods ( Discovery, Evo etc) ? Are the dobs not up to it (too weighty to be moved smooth maybe) ?

HNYetc

 

[Nigel G]

44 minutes ago, SilverAstro said:

I third it all gone quiet outside, festivities over, musing on sgl with a glass of amber nectar and got to thinking -

is anyone using a GoTo dob ? I think most of you have alt-az on tripods ( Discovery, Evo etc) ? Are the dobs not up to it (too weighty to be moved smooth maybe) ?

HNYetc

 

I almost bought a motorised mount for my 200p but went for the tripod setup instead. It was the cost that made my choice,  a motorised dob mount was around  £400  from memory.  My scope and mount was less. So I sold the dob. I have seen somewhere some great images taken with a 8" dobsonian. 

[Nigel G]

My first image taken this year, I only managed to get 30 minutes before freezing dew and cold hands stopped play.

It seems every time I image an object the light frames get darker. I'm using 1600 ISO all the time, conditions vary but my first image, Rosette subs were mid blue in general colour now they are very dark blue, same exp time. each time its a little darker. Final image always ok.

Anyone have any idea what might be going on ?

Monkey head Nebula. 60x30s ISO 1600, modified 1200d & CLS, 150p Alt-AZ. DSS & ST.

Cheers

Nige.

[happy-kat]

That's comes out great.

Varying moisture levels in the air?

[alacant]

30 minutes ago, Nigel G said:

light frames get darker

Hi. I find that too. I think it's that the sky is getting darker as the night proceeds: between snaps using APT you can see the histogram moving progressively left. HTH.

[Nigel G]

14 minutes ago, alacant said:

Hi. I find that too. I think it's that the sky is getting darker as the night proceeds: between snaps using APT you can see the histogram moving progressively left. HTH.

I mean overall,  not during a night.

My first set of sub's ( Rosette ) were a mid to light blue, Time taken 10pm, no moon. About a month ago.

My last set of sub's ( Monkey ) were very dark blue, time taken 9pm Last night.

Every set in between are a shade darker the later DATE taken.

Everyone of the 14 mosaic images, each set of sub's taken over 2 nights was a shade darker than the previous set.

It would seem the camera is gathering less light each session. But doesn't seem to affect the final image ( yet )

Nige.

Edited January 3, 2017 by Nigel G

[Filroden]

Is it just the ambient temperature dropping over the month? That could reduce noise which could darken the overall image. 

[Nigel G]

34 minutes ago, Filroden said:

Is it just the ambient temperature dropping over the month? That could reduce noise which could darken the overall image. 

Ken, that's possible, the ambient temp has fallen quite some the last 4-6 weeks.

Nige.

[Victor Boesen]

Could the reason be less LP the higher the object rises on the sky?

[Nigel G]

51 minutes ago, Victor Boesen said:

Could the reason be less LP the higher the object rises on the sky?

I don't think so, the 3rd image to come from the camera was the Heart and soul nebula which was high altitude approximately 80°  still had lighter subs than those of later dates.

Anything is possible though, that could be a contributing factor.

Cheers 

Nige 

[Filroden]

Higher altitudes will give darker skies if there is any light pollution (even with a filter) so it could contribute. Likewise, as it got closer to Christmas light pollution will have got worse as people put their outdoor Christmas lights on.

Another factor is time of night as it will get darker through the night as more lights are turned off.

However, I don't think those would give such a pronounced and consistent change. I'd say it was either a sensor issue (unlikely) or something environmental like temperature or humidity. I wonder if you could test temperature someway? Maybe taking shots of the same spot of sky (not the same object, just the same location of sky to maintain a similar level of light pollution) at different temperatures. Maybe a 60s sub every degree change and see if that's having an effect? It may take a few nights to get a decent range of temperatures but I've seen early evening temperatures in the last month from +8 down to -2!

[Stub Mandrel]

Thin haze can make subs a LOT lighter looking through mine from last night the variation in individual subs is enormous even though I could barely see the difference by eye.

[happy-kat]

I think it's varying moisture levels, higher moisture reflects more light I think.

[Nigel G]

Thinking about it, the camera since the modification is very sensitive to light change, I had an aeroplane through 1 sub which whitewashed that frame, not normally a problem, and its not possible to image with a moon around either. I can with the unmodified camera.

Hopefully its not a sensor problem, final image does not seem to be effected at all.

we'll see on the next session.

Cheers

Nige.

[The Admiral]

On 03/01/2017 at 18:54, Nigel G said:

I don't think so, the 3rd image to come from the camera was the Heart and soul nebula which was high altitude approximately 80°  still had lighter subs than those of later dates.

Anything is possible though, that could be a contributing factor.

Cheers 

Nige 

Coming along well with your modded camera Nige.

80° . Good grief, what sort of exposures were you using to keep field rotation in check?

Ian

[Nigel G]

7 minutes ago, The Admiral said:

Coming along well with your modded camera Nige.

80° . Good grief, what sort of exposures were you using to keep field rotation in check?

Ian

Thanks Ian.

I love it, so much more detail in Ha nebula.

The H&S was with the 135mm lens so 30s was no problem. 100% keep rate.

Nige.

Edited January 5, 2017 by Nigel G

[The Admiral]

Last night was the first clear night for quite a while where I'd be able to image, so as these moments are pretty rare I pushed on well into the night (for me!). Little dew, and a light frosting by the end of the session. First up was a re-image of M42 using short subs, because the last lot I'd taken before the New Year had poor focus. I can just about make out the Trapezium now and I'm planning to blend that with a set of longer subs, when I get a chance to process it. Next up was the Flame and HH. I took 180x30s subs, but by the time I'd aggressively weeded out the poorer ones, including some where I'd imaged a tree , I was left with just 100. The total time is barely longer than my previous attempt last March. I might try stacking more of the subs and see what difference it makes, and/or perhaps add to it later. I then spent an hour on the Rosette, though I haven't looked at that yet.

So here is the first rush of the Flame and HH nebulae. Usual set-up, Fuji X-T1 through an Altair 102mm f/7 Super ED with a TS Photoline 2" 0.79x reducer/flattener. Mounted on a Nexstar 6/8SE Alt-Az mount. RAWs stacked in Astroart, processed in StarTools, and finished in Lightroom. 100 x 30s subs, ISO1600, 60 flats, 60 darks, generic bias.

Ian

 

 

[Nigel G]

Great image Ian, I love the colours too. Plenty of detail

Well done.

Cheers

Nige.

[The Admiral]

Thanks Nige. I've had a look at adding to the number of subs, but realistically I can only add another 22, making 122 in total. I've reprocessed it, and I expect any difference is down to the processing than the extra subs. I also applied the extra luridity control (aka colour module). Here are the two results, the first without the colour module, and the second with.

 

 

Colourful or what? I prefer the first one.

Ian

[Nigel G]

Cracking image.

I prefer the first too, very colourful

I found the stars quite difficult to control with these, you have them spot on.

Cheers.

Nige.