The "No EQ" DSO Challenge!

[Nigel G]

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 ☺

[SilverAstro]

The Celestron SE mounts use spur gears, the Evolution mounts use (supposedly better) worm&wheel and was big in the publicity when they were introduced, I dont know what the Discovery uses ?? I suppose a big beefy eq could be de-wedged ! depends on how clever the software spherical trig is I suppose.

Does the jerkyness of the mount tracking mean that it is advantageous to use many short exposures, even in the East or West where 90sec could be done it may still be better to do 9 x 10sec say, and give DSS a better chance of using them ?

Blue star bloat in (who's was it ?) Achro,  wild idea = is there such a thing as a red & green pass filter ? a 2 position filter wheel with exposures made by red&green + blue.  Thus similar as the big long boys do R + G + B + luminance + whatever other channels they fancy   ok I'll get my coat

Nige - fingers and everyting xxed for your Mum, best wishes.

 

Edited July 13, 2016 by SilverAstro

[Stub Mandrel]

Cheap lens ideas;

Zeiss Sonnar 135mm x f3.5 lenses go for about £20 on ebay. I have had one since the 80s and its incredibly sharp at full aperture. This was taken with an unmodded Canon D10 (which is not a brilliant astro camera as its only 12 bit).

Prinz Galaxy 400mm, a very cheap telephoto readily available on the bay, not as high quality as the Zeiss by a few furlongs, but still capable:

 

Excuse the processing, I can do better now, but its the star sharpness across the image you need to be looking at.

andromeda X.tif

[The Admiral]

52 minutes ago, SilverAstro said:

The Celestron SE mounts use spur gears, the Evolution mounts use (supposedly better) worm&wheel and was big in the publicity when they were introduced, I dont know what the Discovery uses ?? I suppose a big beefy eq could be de-wedged ! depends on how clever the software spherical trig is I suppose.

Does the jerkyness of the mount tracking mean that it is advantageous to use many short exposures, even in the East or West where 90sec could be done it may still be better to do 9 x 10sec say, and give DSS a better chance of using them ?

Blue star bloat in (who's was it ?) Achro,  wild idea = is there such a thing as a red & green pass filter ? a 2 position filter wheel with exposures made by red&green + blue.  Thus similar as the big long boys do R + G + B + luminance + whatever other channels they fancy   ok I'll get my coat

Nige - fingers and everyting xxed for your Mum, best wishes.

 

I hadn't realised that the Evo mount drive now included a worm gear, and it would be interesting to see how it performed in imaging. It's not sold separately however, though it can now be had with the Edge 'scope, so I guess that must say something about performance expectations.

The beefy mounts I referred to can be used in both altazimuth and equatorial mode, so there wouldn't need to be any extra work involved. Their software allows for that option as well. What we don't know about them though is how they perform in alt-az mode for AP, 'cos in general they are not used like that.

You are correct, in theory one can take say  3x30s subs or 9x10s subs instead of 1x90s, and there'd be more chance of getting an acceptable frame, except that each picture has an associated read noise so one ideally wants to minimise the number of subs. Conversely, I suppose, one might be able stack a greater proportion of frames, and also reduce the risk of saturating bright stars. But an hour or two's total exposure is a heck of a lot of 10s subs!

I think blue bloat reducing filters are available I believe, but I'd hesitate to guess what impact that would have on a full colour image.

Ian

[SilverAstro]

37 minutes ago, The Admiral said:

I hadn't realised that the Evo mount drive now included a worm gear,  I think so but best to check , my memory is not always reliable !

The beefy mounts I referred to can be used in both altazimuth and equatorial mode, so there wouldn't need to be any extra work involved. Yes, sorry, I was not clear, my brain cell had wandered to the other single purpose beefy but les expensive eq ones. I was also thinking that for the alt-az there seem to be two schools - those who swear that the mount needs to be carefully leveled and north pointed, and those who just plonk them down, so two software implementations ???perhaps,   maybe the go-to software in an eq may be the wrong sort and not tolerate a big tilt and plonk ! 

I think blue bloat reducing filters are available I believe,  hmm interesting, a blue cut filter presumably, so that would give a R+G image and then a B would need to be taken through a trueBlue filter and the two added in post proc. A lot of fiddling !

 

EDIT  Can regular eq mounts be sold to people living close to the north pole ? In which case one could be used in London with an appropriate tilt, the software would not know that you were lying when you said you were in Svalbaard or wherever ! Caveat, that will only work for geocentric coords, so the moon and close asteroids would not be tracked correctly (maybe not even the planets ? )

Edited July 13, 2016 by SilverAstro

[Nigel G]

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.

[Stub Mandrel]

14 minutes ago, Nigel G said:

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.

Put your mum first, but don't feel guilty about posting here - I know from experience it can be a big help to have a something to occupy you when you feel you should be 'doing something' to help but ether isn't anything you really can do.

[The Admiral]

I second that.

I wouldn't worry too much about the stoma, I gather people get on with them OK, and in any case, it does mean that there shouldn't be a recurrence as the badly affected part of the intestine will have been removed. So life might actually be easier.

I wish her a speedy recovery.

Ian

[The Admiral]

1 hour ago, SilverAstro said:

EDIT  Can regular eq mounts be sold to people living close to the north pole ? In which case one could be used in London with an appropriate tilt, the software would not know that you were lying when you said you were in Svalbaard or wherever ! Caveat, that will only work for geocentric coords, so the moon and close asteroids would not be tracked correctly (maybe not even the planets ? )

I think EQ mounts only offer a limited range of latitude adjustment. Goodness knows how they manage in high latitudes.

I've had a look on the FLO site and it looks as though the semi-APO correction filters don't impact the visible range too much. https://www.firstlightoptics.com/achromat-semi-apo-filters.html

Ian

[SilverAstro]

17 minutes ago, The Admiral said:

I think EQ mounts only offer a limited range of latitude adjustment.

Mechanically that is certainly true, bent bolts and all ! But if the software is capable of handling the spherical coordinate shift to working vertically at the pole then there is no reason (?) for it not to work in London if it were de-wedged and told a little white lie ! (In other words it would need to pretend to be working at the centre of the earth, ie. only good for geocentric not topocentric coords. ( good for stars,dso etc, not nearby solar system )  I think !!

 

[happy-kat]

Depends on how much movement you have in your focuser I thought you were out of any free length to be able to add a filter

[The Admiral]

5 minutes ago, happy-kat said:

Depends on how much movement you have in your focuser I thought you were out of any free length to be able to add a filter

I don't know if Nige meant a filter wheel, but otherwise don't they just screw into a fitting, and not add any depth?

Ian

[The Admiral]

25 minutes ago, SilverAstro said:

Mechanically that is certainly true, bent bolts and all ! But if the software is capable of handling the spherical coordinate shift to working vertically at the pole then there is no reason (?) for it not to work in London if it were de-wedged and told a little white lie ! (In other words it would need to pretend to be working at the centre of the earth, ie. only good for geocentric not topocentric coords. ( good for stars,dso etc, not nearby solar system )  I think !!

 

It's a thought, but I can't help feeling that would be too easy! I wonder if the calculations would become unbounded, like dividing by zero!

Ian

[Stub Mandrel]

Anyone who wo

29 minutes ago, SilverAstro said:

Mechanically that is certainly true, bent bolts and all ! But if the software is capable of handling the spherical coordinate shift to working vertically at the pole then there is no reason (?) for it not to work in London if it were de-wedged and told a little white lie ! (In other words it would need to pretend to be working at the centre of the earth, ie. only good for geocentric not topocentric coords. ( good for stars,dso etc, not nearby solar system )  I think !!

 

Absolutely true, if lat/long co-ordinates were that crucial, then you would need to input altitude as well! And recalculate to allow for the earth's oblate shape. Any error will be exactly the difference between a line through your position that's parallel to a line through the position in the handset. I can't see it making a problem for anything beyond Mars, even if you get the location 180 degrees out.

[happy-kat]

Mine fits on end I think, rather than inside. Perhaps it depends on how Nige attaches the camera, I use a t mount on my camera so any filter depth would not matter.

Startools does have capable CA removal functions Steve Nickolls on here uses to great effect, but I guess an image will never be as sharp as one without CA to remove but StarTools does really well. Would be interesting to see results used with a good camera lens. For me it is what I like about my little refractor is for viewing the stars are so pin point. 

[SilverAstro]

38 minutes ago, The Admiral said:

It's a thought, but I can't help feeling that would be too easy! I wonder if the calculations would become unbounded, like dividing by zero!

Yes, exactly my worry hence my "Can regular eq mounts be sold to people living close to the north pole ?"

I know there are general solutions to handle it, eg. in the case of star sensors on spacecraft, but I cant remember how (that wasnt my prime responsibility ) nor if it is implemented in these softwares. We need an experimenter

Side line : another thing, I've never been happy with German equatorials, too wobbly perched on top of tripods with their bearings way too close together on the shafts for stability,  but if one of those shafts is turned vertical(ish) then maybe not so bad ?

[Herzy]

I know this thread is supporting alt/az mounts and all but if you want to really get into serious imaging with a guider to image some of the best objects available an EQ mount will be needed. If you are going to go down that route you want to get a good one because your mount is the most important part. That can be VERY expensive. So just as a reminder this should be on your list. With an alt/az mount guiding is not really needed because of the rotation. An APO refractor will definitely help short-term but if you want to long-term improve to your astrophotography skills an EQ mount is the way to go. 

So that's long-term. If you want to best improve your results here and now a nice APO refractor would be good. An achromat refractor will be pretty good but eventually the CA will start to annoy you.

Hayden

Edited July 13, 2016 by Herzy

[Nigel G]

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.

[Nigel G]

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 ☺

[The Admiral]

46 minutes ago, Nigel G said:

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.

Good result.

You are best placed then, but in my experience it's sometimes good to be ignorant of what really goes on

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.

 

3 hours ago, SilverAstro said:

Side line : another thing, I've never been happy with German equatorials, too wobbly perched on top of tripods with their bearings way too close together on the shafts for stability,  but if one of those shafts is turned vertical(ish) then maybe not so bad ?

On a side note, I see iOptron have a range of what they call "Centre Balanced EQ mounts" (for example, http://www.ioptron.com/product-p/7102ec-hc.htm ), which I imagine are mechanically somewhat more stable than conventional GEMs.

Ian

[Stub Mandrel]

Not overly convinced there is an issue. Think of the overhung loads on a car wheel bearing which is of comparable size.

[madjock72]

1 hour ago, Nigel G said:

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 ☺

SHould put this into the DIY area mate. 

[happy-kat]

filter is an idea for bringing out nebula isn't it could use with your 150p?

[Nigel G]

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. 

[SilverAstro]

1 hour ago, Stub Mandrel said:

Not overly convinced there is an issue. Think of the overhung loads on a car wheel bearing which is of comparable size.

interesting that you should raise that - my first polar disc mount used a strut + wheel hub off a Ford Zodiac, amongst other bits and pieces !

But cars are not usually steered with arc second accuracy