Nigel G

2 hours ago, The Admiral said:

 

4 hours ago, SilverAstro said:

I cant see it !

You are right, I cant see frame rotation, interesting !

Perhaps you could post a streaky one because I dont think I have seen a picture of this frame rotation wot everyone is on about   (people dont generally post their duds, but they can often be as informative, like what not to do ! as the good ones ) As you say, high in the south is supposed to be the poor direction, very interesting.

Quote

Here's one with slight frame rotation,  it's an image of  Polaris. Taken 6 months ago 4 hours of 30 second subs

? ? 

Nige.

 

Field rotation over a long session will leave the final image to be cropped quite a considerable amount to reduce stacking artifacts.  With M31 this crops out wanted details so it would be better to gather the subs over a few nights .

Nige.

Steve,  great images plenty of detail, I was wondering how M 33 would turn out, it's not quite in my field of view yet.

I have always use kappa sigma in dss, something I had thought about but not experimented with. Perhaps I should. 

I  too have been building my camera lense collection,  I have a 135mm a 210mm and a x2 adapter . 

Using M31 as a target I have images with a 55mm and 135mm lenses and my 150p scope. Just waiting for good sky's  to get images with the 210mm and 420mm lenses before I  post them.

For the first time ever I'm looking forward to the nights drawing in ☺

Nige.

A possible target for the test could be M17 Omega nebula, around the same altitude as Saturn in the southern sky atm.

I took this during the full moon last night and it was close to the target, because of the moon I could only get 15s exposure at 400 iso and only 30 minutes worth before the faint clouds started to arrive. 

Nige.

3 hours ago, SilverAstro said:

  yep really now I am seriously worried, what is going on, the top one is pale, the middle one is orange-ish with a "Paint" dialog wee box lower left and the bottom one is pale yellow with ummm yellow-green in the spiral, but the sun is creeping up on my monitor , how strange

These are the 3 part URLs

PSX_20160718_215237.jpg.c1dce7c6219f4a10aea5dda143a7306e.jpg
PSX_20160718_215704.jpg.10c2840ba70cc6f89d9f1f9aa2615d6c.jpg
PSX_20160719_121341.jpg.d8d0b5fd53451753223adbe6c4ccbfeb.jpg

which am I missing, is it also a jpg or something else that my browser is rejecting ?

What if I re-quote it all , how many remain ? :--

 

I think there's 4 there, on my mobile there's none there ☺ now the colours I was trying to decide what colour  I wanted it to be ?, for me it's the hardest dso to process so far,  getting the colour the same as you can see is blooming hard, I spent ages on colours. The little box in the bottom left of one is a copy paste mistake,  I only noticed after I had closed startools ?. 

Nige.

I stand corrected,  after processing all 4 M31 images I find a little more detail as more subs are added.  Few, I thought I was running out of room for improvement. 

The 4 images . No1  = 40 x 45s during quite poor seeing.  No2 = 120 x 30s during good seeing and low light pollution . No3 = 120 x 30s plus 40 x 45s during full moon. No4 = everything 120 x 30s + 80 × 45s . 

There is a small difference between them , a bit more detail on the outer spirals, I find M31 a difficult dso to process. 

I get a lot of noise to deal with even after stacking  200 subs. I think this is due to the camera and sensor limits rather than the scope.

Nige.

1 hour ago, The Admiral said:

Remind us what camera you are using please Nige.

Ian

Canon eos 1200d unmodded. 

Nige.

On Monday, July 18, 2016 at 06:38, wxsatuser said:

If your imaging low down in the sky the colours become more orange.

One thing, if you want correct colours with a dslr do not equalize the histogram and do not modify the camera.
Modifying just makes nebulae more red and tends to hide all the other colours like blue and green.
If a dslr can see 20 to 30% of Ha, thats more than enough, modifying should only be done to cameras that see next to nothing of Ha.

There is a way to better your images but it means more money, you get what you pay for.

A 6D or 7DMK2 coupled to a fast lens will allow stunning short images.

An example with an unmodded  6D at f/2.8 50mm 7 x 30sec exposures ISO 1600.
Not properly processed as it was just a test but you can see what I mean.

 

 

 

Looking at this image  and my attempt it looks like I have a shed load of noise,  what is going on,  my image shows far more apparent nebulosity which isn't on other images. Is that noise ? Have I hit a brick wall? 

I have been experimenting with M31 . I have 60 minutes of good 30s  subs and 60 minutes of mixed 45s ( some have quite heavy light pollution  some have moon light interference  some are  good) I have stacked 4 different sets of images. 

1st , 1 hour of 30s........2nd 1 hour of 30s plus 30 minutes of street light polluted 45s.........3rd 1 hour of 30s plus 30 minutes taken with full moon up........ and 4th everything stacked 2h exposure. 

I still have to process the 2 hour image but there's hardly any difference if any between the images already processed,.

Have I reached the limit of my camera or scope ?  I notice the central 30% of my images seems to be good in detail  but outside that a quick loss of detail.

Camera or scope or both ?  

At the moment I can't seem to improve my images,  have I come to the point where upgrades are needed?

I'll post the M31  images once completed. 

Nige. 

2 hours ago, SilverAstro said:

In the end I suppose I could buy one of each and try them ! Oh, hang on an idea is germinating, , , , "try them"  measure them !! Nige, Admiral, me and others I am sure like a good experiment soooo being as there are many owners of many models, mod and not mod, on the forum  can the collective come up with a standard model (standard target?) and standard method free of user bias to determine the %Ha  for each ?

Henceforth to be known as the loadsaHa challenge   " %Ha Challenge"

Edit PS is it a bit odd that Canon have different filters for different models ? For viz light cameras one would have thought that they would have determined an optimum cut-off and stuck to it through the range ??

EDIT 2 ) A. a reflection and emission nebula in close proximity, ie. a convenient field frame size

 B. stacking OK ? but no curves / gamma etc.

 C. ?

 

A good idea, certainly should gather some useful information,  something like orion neb although that's a few months off yet, 

30 minutes of subs  limit  ? Although light pollution in different areas could play a part in the result. Plus aperture. 

Still a good idea and worth trying. 

Nige.

28 minutes ago, Stub Mandrel said:

Great star colour as well.

I think I prefer the one with unreduced stars; perhaps blend the two together to get around 60:40 the first one?

Modern software and digital images makes editing easy these days, It's really quite difficult to get an image with its true colours and shades though ☺

I had a chance to get about 1 hour 40 minutes of subs on the North American nebula with the 55mm lense a few nights ago, nice clear sky's but before 1am so street light pollution had to be delt with. The subs were 120 x 30s the rest 45s , plus 30 dark frames and the usual bias. Star discovery mount, Canon eos 1200d with standard lense at 55mm, iso 1600 f5.6 with a converted flowerpot dew shield  ( which worked great ) DSS and StarTools. 

I have posted 2 images, one with the stars reduced.

Taking into account the camera is the cheap end of the dslr range and you can't get much cheaper alt az goto mounts this has turned out pretty good. 

I think I need to add a half decent 200mm lense to the collection. 

When I see the size of this nebula I realise it would take around 8 to 10 images from the scope stitched together to get the whole picture. 

Nige.

1 hour ago, happy-kat said:

And you can make an aperture mask if you don't want detraction spikes. It would make a near refractor experience.

Aperture mask for my scope , wouldn't that reduce the field of view? 

I just looked up aperture masks,  now would I need to make a hole as big as possible for my scope?  ie missing the secondary mirror and supports.

also the scope cover cap has a small cap on it about 2.5 " diameter would that be of any use ?

Talking of aperture what would a good setting be with camera lenses for dso's, higher or lower value. I set mine on lowest value for this image. 

I like the dew shield flowerpot ☺I had a simular idea last night with a small lightweight resin pot.

Nige.

Last night I had nothing to do but worry and the sky's were clear. So I  decided to try my camera and 55mm lense on the mount. Starting around 11pm I thought I'd get 2 or 3 hours subs on ngc7000 wide field. 

I aligned the mount with the scope then swapped to the camera.  The first thing I noticed was not one sub was unusable , I took a couple of quick 10s to get my bearings. Then a couple of 45s, no visible trails but quite a bit of street light pollution, not as bad as with the scope though. So I  dropped the subs to 30s. 

Every sub was good, the only trouble was they started to fade in detail after about 20 minutes? I thought it must be dew on the lense, a quick check and no dew? What the heck. 

Look up you fool it's getting cloudy ?

So this image is only a tad over 20 minutes exposure with dark and bias. DSS and StarTools. Canon 1200d 55mm lense F 5.3 1600 iso on alt-az mount.

There is bags of potential for wide field imaging. I'm hoping tonight will be better to add to the data. The forecast is good. With a couple of hours subs I think much more detail will come.

Another thing I noticed was the rotation appeared to be much less  ( impossible but )

The stars are smaller and the field bigger probably making the rotation less obvious. Normally when I scroll through the raw images there's a very apparent field rotation, with these I could see no rotation but there is only 25 minutes total imaging time.

I have cropped about 20% around the image. The second image has had a touch of noise reduction and contrast . 

Nige.

1 hour ago, The Admiral said:

 

I'm not sure why you'd need a filter for your 150P, at least not a blue/violet blocking filter designed to improve the image from a semi-APO.

I was wondering nebula filter would fit and be of benifit , and whether a LP filter would be of benifit while the street lights are on before 1am. 

I have found a solution to adding filters . 

A piece of 1.25"  plastic waist pipe ☺slotted and sleeved around the nose of a t ring fits nice and snug into the drawtube the end thread on the nose is now available for use ☺☺

first and second pics  is the idea, the last is fitted and focused. A 5 minute job ☺

Op went well and no infection found ☺they have removed part of the lower intestine, I think it helps having a sister who is a theatre nurse and a brother in law who is a consultant surgeon,  not that it should but it does. 

I mount my camera via a home made thingy.

this is the camera,,,, homemade thingy,,,,, draw tube setup and attached at focus distance.  . I have no threads to attach threaded filters etc.

I wish I could say all is well BUT

Unfortunately mum is now in theater,  she has to have a stoma.  It's quite a bit worse than expected. 

Keep the thread alive with your image's, ideas and suggestions and I'll be back to catch up.

Nige.

16 minutes ago, The Admiral said:

Thinking a bit more about this, probably the biggest improvement might be in the form of a focal reducer. I bought a 0.79x reducer for my refractor so that I can image larger scale objects, as I always have to crop off the outer parts of an image because of field rotation. I've not had a lot of opportunity to use it yet, but I have found it gives higher scores in DSS, presumably because the mount movements impact the image less and therefore the stars are rounder, and of course an object will be that little bit brighter (i.e. more photons per pixel than without using it). The image of M57 I posted on May 29th used the reducer. The only thing is I'm not sure how well they work with Newts, I think I read somewhere that achieving focus might be a problem. Perhaps someone with knowledge on Newts can come in here. I see that there is a coma corrector for the 130P-DS which has a 0.9x reduction, though that's not a lot. I'm not sure how these would reduce coma either, or whether one could be found that would work with your 150p.

Glad to hear that your Mum is making progress.

Ian

I'm not sure but think I have the same trouble with attaching the focal reducer as I would with filters sadly.  I am looking at 200 to 300 mm lenses for my camera,  just looking at costs and quality , I'm going to give it a go with my 55mm lense. I have a camera mount for my mount ☺

21 hours ago, SilverAstro said:

 

Ah yes I see, note that I have cut out "big", on the grounds that your results are already amazingly impressive ! Thanks 

So, mindful of your desires and knowing of your mechanical skills and expertise with a lathe, how about a Field Derotator ?

It's something I had thought about but come up with problems,  main one being I cannot fit anything in front of the camera due to having to cut the focuser already. I also looked into making a wedge but that would disqualify for the no eq. However a wedge is possible, but would my synscan work or need reprogramming,  then as people have pointed out you will still be limited by the az capabilities. Guiding would be needed. I do happen to have a guide camera but no scope. But this would put me well over weight for my mount so a no go. 

I think the best way for now is to remove the 1 inch section of draw tube that protrudes into the main tube and be very particular about what subs are kept. I know I can improve some there. Also stop being impatient and focus more on one target rather than getting greedy trying to get 2 or 3 in a night as Happy-kat as already pointed out to me ☺ 

One problem I have with the star discovery is I don't think I could use any filters ( nebula or LP ) because of the modifications.  Correct me if I'm wrong please.

Thanks for all your well wishes, 

Mum's in for tests after having very bad pains and loosing quite a bit of blood, looks like it's diataviculitus, don't know if I spelt that right but waiting for scan to see the extent of the problem. I am aware of the condition as I  very nearly lost my longest and  bestiist  friend to it a few years back.  Mother has caught this nice and early so fingers crossed.

Thanks again, I will catch up on the posts this evening ☺☺

Hey guys.

Sorry for not contributing,  my mother has been taken into hospital,  I will catch up on posts later on. But for now I have a mother who needs her son.

Nige.

6 hours ago, SilverAstro said:

I fear I might have lost the plot here ( long day + some amber nectar!) -
but why do you want to downscale from your 150 reflector to a 130 reflector ? ( going to a refractor is a whole other kettle of fishes ! )
In an Alt-Az context duration of exposure, and number thereof, is the (main?) problem so 150 wins over 130 for photons captured. A secondary problem is the stability of the mount vs. size of scope but you have already proven that is OK for your 150.
Another prob might be the focuser (DS vs not DS) but again you have that sorted !
The 130P-DS (if it is like the 150P-DS) has the secondary closer to the primary for photography at prime focus, but you sorted that with your hacksaw.

Another prob is criticality of collimation at f5 of the fixed 150 vs the adjustable 130, but you sorted that by un-fixing the 150 !

So I am not seeing why you want to go down to a 130 ?

120 refractors are above my paygrade/competance

 

 

I'm not sure really, I think there's big room for improvement without costing hundreds and I'm on the hunt for improvement.   I'm fishing for info, my thoughts were if suggestions were leaning towards refractor then a change over to refractor was the way to go, if reflector then hold on for a while and do the modifications I think mine needs, I would like to keep a 6" rather than a 5" but the only 150 light enough for my mount is the one I have which is far from ideal although it gets fairly good results. The 150pds is 4.9 kg without camerase my camera is 1 kg . My weight  limit  is 5 kg the 120 star travel  and 130p-ds  are both 3.9 kg and within limits with camera  attached 

for now do modifications and keep searching for the bargain. .

Nige. 

Thanks for your replies, I'm learning ☺

I'm thinking the 130p-ds, do you think I would be wise to get a coma corrector and can I use a coma corrector with a dslr? 

Will a coma corrector be of benefit when using an alt az mount .

So many questions,  maybe not the right place to post but as it's for use on the alt az mount imaging dso's this seems the right place, 

Nige.

1 hour ago, Herzy said:

 

There is a quick rundown, hope it helps!

Herzy,  thanks for explaining,  that helps a lot ☺

Nige.

4 hours ago, happy-kat said:

The 130p-ds is a given performer. I have seen a stunning narrow band image from the ST120 but you will have CA to process out and you could have other lens abberations as well. But adding a field flattner to the p-ds makes the cost shoot up. 

I'm afraid I don't know anything about flattners or where to put them or CA, need to research a bit.