The Astro-Imaging Thread

[munlander1]

Partly cloudy tonight!  what do you guys think about photographing M81?

[munlander1]

Oh, @NSEP when are you going to post your telescope info?

[_Augustus_]

Played around more with AutoStakkert and got these:

[NSEP]

6 hours ago, munlander1 said:

Oh, @NSEP when are you going to post your telescope info?

Whoopsees! I forgot, i will do it when im not busy and stressy.

[Green Baron]

7 hours ago, munlander1 said:

Partly cloudy tonight!  what do you guys think about photographing M81?

Its on my list.

[kurja]

On 4/23/2017 at 3:36 AM, munlander1 said:

Partly cloudy tonight!  what do you guys think about photographing M81?

Conveniently high elevation this time of  year, many bright(ish) objects in the area, m81 and 82 show detail even on small telescopes - nice for a hobbyist. A 300mm fl camera lens even without active guiding reveals many galaxies.

A plate solved & labeled picture from last year (with 300mm camera lens):

Edited April 24, 2017 by kurja

[Green Baron]

Bode's alone is a little too small for the fov of my telescope/camera without reducer (1.3°*1.0°). But the couple M81/M82 will fit nicely.

@munlander1: Calculate the field of view of your scope/camera combination. Image size of the scope is a function of focal length, while the size of the chip determines how wide an angle of that image it actually sees. The size of the pixels determine the resolution (together with the scope's resolution and the the seeing conditions of course). A quick search will show you the formulas.

You might discover that with 1m focal length and an aps-c chip you might have something in the range of 1.6°*1.3° (not calculated just pi*windowframe !). It seems like the grid in the overview is 1° wide (?), so you can estimate of what you'll see with your scope/camera combination.

 

[_Augustus_]

2080 fork and Bob's Knobs arrived today.

Expecting the wedge and tripod to come before Friday.

[Green Baron]

Looks sturdy.

Am curious, since i do not have any experience with an alt/az mount. Do you plan long term exposures ? If so how do you plan to cope with the rotation of the field ? Do you plan to put some sort of equatorial wedge (German "Polhöhenwiege", took me 3 min to find the translation :-)) under it ?

 

Edited April 25, 2017 by Green Baron

[_Augustus_]

2 hours ago, Green Baron said:

Looks sturdy.

Am curious, since i do not have any experience with an alt/az mount. Do you plan long term exposures ? If so how do you plan to cope with the rotation of the field ? Do you plan to put some sort of equatorial wedge (German "Polhöhenwiege", took me 3 min to find the translation :-)) under it ?

 

It's not on an alt-az mount; it's an equatorial fork - wedge arrives soon. 

[Epox75]

On 4/24/2017 at 10:14 PM, _Augustus_ said:

2080 fork and Bob's Knobs arrived today.

Expecting the wedge and tripod to come before Friday.

Keep it covered!

[Epox75]

I ordered an ASI1600MM-Cool, an electronic filter wheel, a focal reducer/flat field, a finder to attach my planetary cam for guidance. Finally, after 4 years of dreaming about it, I will do some serious (hopefully) deep sky imaging. Next dream: build a little observatory in my garden

Edited April 26, 2017 by Epox75

[Green Baron]

A wise decision !

Spoiler

Here's my stuff, ready since February, with an atik 383l monochrome, but only a manual filterdrawer. That is my sacrifice to the financial depertment. I got me a ccd because it has 16bit dynamic range instead of 12 (16 times as much), 2lv higher sensitivity (compared to my dslr), and much less read out noise.

And the first try with good old Sword of Orion:

Processing is still very rudimentary, many artifacts, satellites, spikes from moisture on one of the surfaces. Next time it'll be much better !

 

 

[_Augustus_]

6 hours ago, Epox75 said:

Keep it covered!

It came with a dust cap, but it's warped and hard to get on/off. I use the shower cap on the left.

Tripod arrived yesterday and the wedge will be here in a couple of hours.

Edited April 26, 2017 by _Augustus_

[_Augustus_]

So apparently the two pieces of the wedge itself don't fit together. I don't know how exactly that's possible, but it happened. The top part is around 1/10" too wide to fit the bottom part.

And the wedge doesn't fit the threaded rod in the tripod.

And the wedge didn't come with the screws for attaching the scope.

[Epox75]

7 hours ago, _Augustus_ said:

So apparently the two pieces of the wedge itself don't fit together. I don't know how exactly that's possible, but it happened. The top part is around 1/10" too wide to fit the bottom part.

And the wedge doesn't fit the threaded rod in the tripod.

And the wedge didn't come with the screws for attaching the scope.

Sorry to hear that, I hope you can return it. Anyway if I will ever find myself in need of a wedge I would probably download a design and get it done by a carpenter/blacksmith. Prices are just insane for two metal plates and some screws.

http://www.skymtn.com/mapug-astronomy/MAPUG/WedgeDesign/Wedge_Design.htm 

[_Augustus_]

11 minutes ago, Epox75 said:

Sorry to hear that, I hope you can return it. Anyway if I will ever find myself in need of a wedge I would probably download a design and get it done by a carpenter/blacksmith. Prices are just insane for two metal plates and some screws.

http://www.skymtn.com/mapug-astronomy/MAPUG/WedgeDesign/Wedge_Design.htm 

I want it to look good and original. It's going to be at a booth at NEAF next year!

Going to try and return the wedge and buy one from another dude (whom I've bought from before and actually knows what he's doing).

Edited April 26, 2017 by _Augustus_

[MaxPeck]

I don't understand why anyone would do this. Using an alt-az (even a fork) with a field rotator or wedge introduces so many potential failure points into your imaging session. I mean, a good polar alignment will take you a good half hour or more with an equatorial mount, let alone a wedge, and then to introduce the possibility of misalignment or other mechanical issues into the mix... it makes me shudder. 

Totally worth the money for a good GEM or CEM with ST-4 and serial ports.  

[_Augustus_]

1 minute ago, MaxPeck said:

I don't understand why anyone would do this. Using an alt-az (even a fork) with a field rotator or wedge introduces so many potential failure points into your imaging session. I mean, a good polar alignment will take you a good half hour or more with an equatorial mount, let alone a wedge, and then to introduce the possibility of misalignment or other mechanical issues into the mix... it makes me shudder. 

Totally worth the money for a good GEM or CEM with ST-4 and serial ports.  

I can't afford even a used CG-5. I'm going to start with piggyback photos guided through the main scope, and eventually I'm going to get an f/6.3 reducer and finish my homemade guidescope, which will allow me to shoot at prime focus.

How does a wedge introduce errors? Plenty of good photos were made with fork-mounted SCTs back in the '80s, before ST-4 ports and autoguiding, before Polemaster, etc.

[MaxPeck]

12 minutes ago, _Augustus_ said:

I can't afford even a used CG-5. I'm going to start with piggyback photos guided through the main scope, and eventually I'm going to get an f/6.3 reducer and finish my homemade guidescope, which will allow me to shoot at prime focus.

How does a wedge introduce errors? Plenty of good photos were made with fork-mounted SCTs back in the '80s, before ST-4 ports and autoguiding, before Polemaster, etc.

A wedge is one more mechanical piece, and many of them are of dubious quality, as you found out.  Instead of rotating along a central axis like an EQ mount does, you're tilting the whole shebang, and polar alignment, as you will learn, is very unforgiving.  If price is your issue, I recommend checking out iOptron - I had a SmartEQ Pro and now I have a CEM25... you could probably get both of them together for less than what you'd pay for a CG-5 or VX mount.  The CEM25 has a 29 lbs payload, and the SmartEQ has an 11 lb payload, but is very forgiving and lightweight.  (No, I don't get kickbacks, I'm just a fan of iOptron stuff).  The CEM25 takes a pretty steady hand to use, so it's not for the faint of heart or easily frustrated, but once you get the hang of it, it's one of the best mount designs I've ever seen, and I've been doing amateur astronomy for quite a few years.  

Yeah, they took pretty good photos back in the 80s, but everyone doing serious astrophotography was on a GEM mount. Forks and Alt/Az mounts are okay for momentary visual work, but they don't track well since they want to go horizontal and vertical and the celestial dome doesn't work that way.  Almost everyone I know who uses a fork does so out of curiosity or amusement, but when it's time for the camera, out comes the EQ mount.

I don't mean to discourage you, you have to work with the tools you have on hand.  But I would definitely take a gander at what iOptron offers and consider putting an EQ mount on your Xmas list.

Edited April 27, 2017 by MaxPeck

[Green Baron]

Well, in principle i agree that an eq mount can't be replaced by anything else except a bigger eq mount. So be prepared that pointy stars can be a problem with your setup because you can only roughly adjust it to your latitude and stability might be an issue as well because there is no counterweight.

But now we have to find a solution for the wedge prroblem. [joke]Maybe the other guy that just bought a wig welding machine to build the "rocket to beat all other rockets" can weld you one ?[/joke]. You have the two parts and need to connect them together with a hinge, right ? You need to change or drill new bore holes to fasten one plate to the tripod and the other to the bottom of mount, correct ? Missing screws cost a few bucks if they are not very special. Also you need something to fix it to an angle, a rail with a clamping screw, may on both sides.

So, if your plan b doesn't work, post photos of the messed up wedge and we try to find a solution until your purse permits an eq mount with a polar viewfinder ...

 

Edited April 27, 2017 by Green Baron

[YNM]

On 4/25/2017 at 2:58 PM, Green Baron said:

Am curious, since i do not have any experience with an alt/az mount. Do you plan long term exposures ? If so how do you plan to cope with the rotation of the field ? Do you plan to put some sort of equatorial wedge (German "Polhöhenwiege", took me 3 min to find the translation :-)) under it ?

If it's motorized and computerized, it'll work its way. Most things with motors and computers nowadays is alt-az.

Also, I kind of question the stability of equatorial fork...

Edited April 27, 2017 by YNM

[Green Baron]

46 minutes ago, YNM said:

If it's motorized and computerized, it'll work its way. Most things with motors and computers nowadays is alt-az.

 

If only it was that easy :-)

Alt/az cannot be used for photography without solving the problem of rotation of the field. All computers in the world, on mars, europa and titan cannot solve that edit: without the aid of a non-trivial mechanical contraption called a field-derotator. You need a fairly exact polar alignment to get the circles the stars will describe during 24h as small as possible.

That's what in this case the wedge is for, to tilt the whole load so that the former alt/az-axises are transformed into an eq coordinate system, so that the az simultes rigth ascension and alt the declination. (I always have my problem imagining this, so i hope it isn't the other way round.)

Even a polar finder can only offer a coarse alignment. For more sophistication see Scheiner (pron. "Shiner") method. Because we won't scheiner our contraptions each time we set them up we use auto-guiders for the mobile equipment. Still a coarse polar alignment is necessary because stars will be slightly prolonged even during 2min exposures and short focal lengths (like 1m).

 

Edited April 27, 2017 by Green Baron

[_Augustus_]

9 hours ago, MaxPeck said:

A wedge is one more mechanical piece, and many of them are of dubious quality, as you found out.  Instead of rotating along a central axis like an EQ mount does, you're tilting the whole shebang, and polar alignment, as you will learn, is very unforgiving.  If price is your issue, I recommend checking out iOptron - I had a SmartEQ Pro and now I have a CEM25... you could probably get both of them together for less than what you'd pay for a CG-5 or VX mount.  The CEM25 has a 29 lbs payload, and the SmartEQ has an 11 lb payload, but is very forgiving and lightweight.  (No, I don't get kickbacks, I'm just a fan of iOptron stuff).  The CEM25 takes a pretty steady hand to use, so it's not for the faint of heart or easily frustrated, but once you get the hang of it, it's one of the best mount designs I've ever seen, and I've been doing amateur astronomy for quite a few years.  

Yeah, they took pretty good photos back in the 80s, but everyone doing serious astrophotography was on a GEM mount. Forks and Alt/Az mounts are okay for momentary visual work, but they don't track well since they want to go horizontal and vertical and the celestial dome doesn't work that way.  Almost everyone I know who uses a fork does so out of curiosity or amusement, but when it's time for the camera, out comes the EQ mount.

I don't mean to discourage you, you have to work with the tools you have on hand.  But I would definitely take a gander at what iOptron offers and consider putting an EQ mount on your Xmas list.

I also got the OTA for $100, and the cheapest way to mount it was to get the fork.

Christmas gifts this year will probably be an ASI224MC and some Explore Scientific eyepieces. If I make enough money to buy the 224 myself, I'll consider replacing its spot on the list with a used equatorial mount (my parents are happy to buy gifts off eBay!)

3 hours ago, Green Baron said:

Well, in principle i agree that an eq mount can't be replaced by anything else except a bigger eq mount. So be prepared that pointy stars can be a problem with your setup because you can only roughly adjust it to your latitude and stability might be an issue as well because there is no counterweight.

But now we have to find a solution for the wedge prroblem. [joke]Maybe the other guy that just bought a wig welding machine to build the "rocket to beat all other rockets" can weld you one ?[/joke]. You have the two parts and need to connect them together with a hinge, right ? You need to change or drill new bore holes to fasten one plate to the tripod and the other to the bottom of mount, correct ? Missing screws cost a few bucks if they are not very special. Also you need something to fix it to an angle, a rail with a clamping screw, may on both sides.

So, if your plan b doesn't work, post photos of the messed up wedge and we try to find a solution until your purse permits an eq mount with a polar viewfinder ...

 

I'm returning the wedge. The top part is around 1/4" wider than the bottom part - no way to fix that.

Edited April 27, 2017 by _Augustus_

[Green Baron]

The cam you have in mind seems to be fine for ir. You've shown already a nice Jupiter Image with your dobson (?) so i am sure you'll be fine with the setup for planetary imaging. A pity that people have problems manufacturing such simple parts as a wedge ...

By the way, i hope i don't bore you, know this ? I mean, if a self made one doesn't fit you can only blame yourself, which leaves open the opportunity of doing it better ;-) Version 1.0 with fixed inclination, version 2.0 with a variable one (long screw with thread in a fixed nut). And left/right fine adjustment (V 2.1) :-)