The "No EQ" DSO Challenge!

[SteveNickolls]

Hi Max,

Thanks for your reply. I'm thinking you ought to be able to get longer exposures from the mount but without actually owning one I'm at arms length to give specific advice. I have the earlier Skywatcher mount, the Synscan Alt-Az and reading through Joe Ashley's book, "Astro-photography on the Go Using Short Exposures with Light Mounts" https://www.firstlightoptics.com/books/astrophotography-on-the-go-book.html I did a number of tweaks that allowed, depending upon the position of the object, 60 second exposures with usually all good frames but which fell off suddenly at 70 seconds. That was with a 2.5kg 102mm SkyWatcher Startravel achromat. I would really have expected the new mount to be a better performer than the old type. I found that keeping the telescope/camera 'bottom heavy' actually stabilized imaging against wobbles and I added a 3kg house brick onto the eyepiece tray, again to improve rigidity. I just realised I don't know how heavy your equipment is compared to the capability of the mount, nor am I familiar with your type of telescope. 500mm FL is not excessive.

In his book Joe mentions that aiming for two hours of sub exposures is an ideal but in this country and with field rotation to take into account that is not always possible. Certain targets like globular clusters don't need so much exposure to reveal their detail. I would suggest either taking more dark frames (say x50) or taking none at all. I've tried both in the past and because our camera's have no temperature control you can potentially do more harm than good using dark frames taken at temperatures wildly different to your light frames. Flat frames are always useful to take as are bias frames. One other factor is the level of light pollution where you live. If you have dark skies that is a definite plus as your signal to noise ratio will be higher and that's mostly what we are trying to achieve with all the exposures taken.

Good luck with more attempts.

Cheers,
Steve

Edited December 3, 2017 by SteveNickolls

[happy-kat]

18 hours ago, maxchess said:

I think 20 secs is pretty much the limit on the AZ-Gti. You can see that my raw stars are slightly elliptical, just starting to trail. But I will try more exposures next time.

You might find this member's trail go useful to see. Maybe it's a combo of angle of target and balance that might help push up slightly more in exposure length.

link here

[maxchess]

Ok,

So based on the previous advice, pushed the exposure to 25 secs, 1600. 47 lights, 26 dark, 20 flat , 20 bias for M42. Also tried some of the tricks suggested by Steve. Probably still need to spend more time understanding Startools, particularly how to bring out more nebulosity, wile keeping a black sky.

[maxchess]

It didn't look so bad on my PC, but now I have posted it the blue halos round the stars look ugly, so its back to StarTools. Any ideas?

[happy-kat]

Yes there is a filter in startools called fringe killer.

If you search this thread I put a brief how to on using it.

Edited December 14, 2017 by happy-kat

[maxchess]

8 hours ago, happy-kat said:

Yes there is a filter in startools called fringe killer.

If you search this thread I put a brief how to on using it.

OK, I used that. I also have been following this guide http://astro.ecuadors.net/processing-a-noisy-dslr-image-stack-with-startools/   and it notes that Decon can have the effect of creating Halos. It recommends that you mask stars and grow the mask. That had the effect of lessening the Halos, which I then further processed using the Fringe Killer.  A big improvement I think.

[furrysocks2]

Here's my first wide-ish-field effort... 16.4 arcsec/pixel, 5.5x4 degrees roughly - had to crop out the drift. I'm down to mag 13 I think.

Exposure set to 2.5s, gain to 75%, average of 20 darks subtracted in SharpCap, 100 frames captured, 50 stacked in DSS, curve and crop in GIMP.

 

Taken using a Datyson T7M (ASI120MM clone) with a 50mm focal length f/1.4 CCTV lens, wide open, zip tied to a pistol-grip tripod head with some pluck-foam padding, bolted to a board of wood, three screws sticking out the bottom for feet.

[rotatux]

M38, the Starfish cluster, and its nice little friend NGC1907.

Which is the full size for image posted in my gallery here:

 

[happy-kat]

If we ever get a clear sky and it is not a work day and Orion is still in a reasonable position and not sat on the street light I aim to use the Nikkor Q200 lens I have on the Virtuoso mount.                              

[SteveNickolls]

1 hour ago, happy-kat said:

If we ever get a clear sky and it is not a work day and Orion is still in a reasonable position and not sat on the street light I aim to use the Nikkor Q200 lens I have on the Virtuoso mount. 

He, he happy-kat, that is the absolute definition of being optimistic. 

At the moment I have a cold that is lingering on and on and dare not set the gear up outside to image so I'm happy to have excuses for staying instead in the warm.

I'm sure though that once this spate of wintry weather passes we will get chance to brave the elements with our bits of glass and mounts.

Cheers,
Steve

[happy-kat]

I hope so and hope you get shot of that cold. I've learnt a lot more about using StarTools recently given the cloud and limited data.

[happy-kat]

This will be the framing size so hopeful and I can use it wide open at f4 though optimum sharpness is at f5.6. it's the first edition of this lens circa 1961-1969 reading up on it though I haven't identifed which of the three iterations it is.

[The Admiral]

21 minutes ago, happy-kat said:

it's the first edition of this lens circa 1961-1969 reading up on it though I haven't identifed which of the three iterations it is.

Have you looked at this site happy-kat?

http://www.photosynthesis.co.nz/nikon/serialno.html#200

Ah, just realized I had one of those until about 5 years ago, but sold all my Nikon gear. I didn't use any of it for astro then.

The serial number was 622056.

Ian

Edited February 6, 2018 by The Admiral

[happy-kat]

Oooh thanks Ian that is a new site to the one I had found. The lens is in the garage so not got it to hand to check the details, it is a Q200 early one so it is an F just not sure yet which one.

[happy-kat]

Great link thank you.

It's a 1971-1973 serial number build.

Clear night, not a work night and not too cold, what could go wrong.... Could I get the virtuoso to track in altitude... No.

Freedom find works a treat very useful given I kept taking the camera off, changed lens from 200mm to the 135mm still not tracking altitude.. Scratch head... Dinner time so came in... Not sure right now as I have got the balance right before and I tried the L bracket with ball head flat back and the straight dove bar. 200mm is close enough on Orion I think with my camera for framing. A bit cheesed but not alot I can do about it will try another night... Had a good direction with no lens flare from the street lights typical!

[happy-kat]

Got it sorted. Charged the battery yesterday and tonight (c ccc cold it was!) The virtuoso mount was tracking fine with the 200mm lens. Unfortunately even going to Rigel wasn't enough with hiked ISO to show in live view so focus was tedious the old never knowing if it really is the best you can do. Lens was better at f5.6, full open at f4 too much CA showing for my liking. Orion was the target and started with 30 seconds going down to 15 seconds as it got very south even though only 33° high. Took an hours worth or so. Processing will have to wait a day or two.

[The Admiral]

10 hours ago, happy-kat said:

Lens was better at f5.6, full open at f4 too much CA showing for my liking.

I don't think the Q200 was one of Nikon's finest lenses! Anyway, it'll be interesting to see what you get out of it.

Ian

[happy-kat]

The cold light of day....

It was f8 I had used.... And I had thought I was in from full max focus adjustment but testing the remaining play there was none in the focus ring, which is a concern was I actually focused, this will need more testing.

[The Admiral]

Well I guess whether you achieve infinity focus will be down to your Nikon-Canon adapter. Hopefully it will be sized so that infinity will be slightly beyond the focus range, in order to guarantee it.

Ian

[happy-kat]

I bought the lens with adapter already attached from a member on here so I'm hopeful.

[The Admiral]

The lens is not without it's issues. The early coatings were not as effective as they now are. Here's a pic I took, I suppose in the mid-70's, on film of course, so it's a scanned image. You can see the flare well defined, but then again the sun is quite bright. I was able to remove it in post-processing of the scanned image, not something you could do with an astro image. Incidentally, that's the natural colour, no filters were used. Well, I say that, but I probably had a skylight protection filter on it, so I guess the flare could be from that. It'll be interesting to see how it copes with bright star sources. Takes me back though .

Ian

Edited February 12, 2018 by The Admiral

[happy-kat]

That's a nice scene you captured. Must have been very still.

I'll review the images later, work day for me.

[The Admiral]

1 minute ago, happy-kat said:

Must have been very still.

Thanks happy-kat. Yes, it was a frosty foggy morn,  not long after sunrise. They don't make sunrises like that any more!

Ian

[happy-kat]

It could only get better... tomorrow!! Brain not in gear how could I fail to miss that my target was well not in frame, well I did must have been the cold!! So I have a fairly none event star field with NGC1924 and others...

10, 15, 20 and 30 seconds. 33 lights, bias, flats, and dark flats. 1100d 200mm lens at f8 Virtuoso mount

Noise what can I say but images taken out front (or might just be coincidence on lens choice) is hideous blotchy patterned stuff on the raw files. I got rid of most of it but the image doesn't warrant further effort. Field rotation evident bottom right in the cropped image. Also hideous gradients out the front I suspect the proximity of three street lights. So a warts and all post!

[Filroden]

1 hour ago, happy-kat said:

So a warts and all post!

Well...it's in focus at least