astrophotography need help. just begun astrophotography and have a few doubts.

[dwayne dias]

Hie all.

 

I currently have an 8" GSO reflector newtonian(1200mm focal length, f/6 focal ratio) and i have spent a year observing and manually tracking planets and deep space objects.

I recently purchased a nikon d5500, a t ring, uhc broadband filter and a 32mm telephoto projection superview eyepiece. I have a few doubts though.

I connect my eyepiece to my dslr directly using the t ring. As this eyepiece doesnt need and extra adaptors. I recently calculated the amount of time a star or deep space object would take to go out of my FOV. It takes about 4.8 mins. So what if i take 8 to 15 sec exposures with manual tracking?? Will there be any very visible srar trails in my image...?? I will be stacking 500 to 600 light frames along with dark frames in DSS and edit it in lightroom. And use a shutter remote to take exposures without shake...is this possible...???

 

Can someone please help me out with this..???

[pipnina]

9 minutes ago, dwayne dias said:

Hie all.

 

I currently have an 8" GSO reflector newtonian(1200mm focal length, f/6 focal ratio) and i have spent a year observing and manually tracking planets and deep space objects.

I recently purchased a nikon d5500, a t ring, uhc broadband filter and a 32mm telephoto projection superview eyepiece. I have a few doubts though.

I connect my eyepiece to my dslr directly using the t ring. As this eyepiece doesnt need and extra adaptors. I recently calculated the amount of time a star or deep space object would take to go out of my FOV. It takes about 4.8 mins. So what if i take 8 to 15 sec exposures with manual tracking?? Will there be any very visible srar trails in my image...?? I will be stacking 500 to 600 light frames along with dark frames in DSS and edit it in lightroom. And use a shutter remote to take exposures without shake...is this possible...???

 

Can someone please help me out with this..???

A non-motorized mount won't be any good for deep sky photographs. But a D5500 and manual mount will do fine for planets if you put it in video mode. Though you'll likely need a barlow / powermate. Set the DSLR to the highest frame rate it can do and the shortest exposure you can get away with.

To do deep sky, you want the telescope to be on an equatorial mount preferably. But even an ALT/AZ can be suitable for shorter exposure lengths if it is tracking.

[Galactic Wanderer]

4 minutes ago, pipnina said:

A non-motorized mount won't be any good for deep sky photographs. But a D5500 and manual mount will do fine for planets if you put it in video mode. Though you'll likely need a barlow / powermate. Set the DSLR to the highest frame rate it can do and the shortest exposure you can get away with.

To do deep sky, you want the telescope to be on an equatorial mount preferably. But even an ALT/AZ can be suitable for shorter exposure lengths if it is tracking.

Yes you need a driven equatorial mount to take photos. However I have taken a few photos with an a altaz mount even though thay are not as good. I took them with a  Celestron CPC and I stacked them in deep sky stacker. A single image of m42 and a stacked image of m42 with an altaz mount!

 

IMG_0181 (2) (1).TIF

[dwayne dias]

Buying a mount is going to take me two years till i get that kinda funds. I am in my final year of mechanical engineering. And have planned to make a mount with a friend. Which one would be better...??? A german equatorial or a fork equatorial mount.??? I know this sounds kinda stupid but its the only way out for me buying one willbcose me more than 3000$ here in india. Which is a huge amount.

[pipnina]

51 minutes ago, dwayne dias said:

Buying a mount is going to take me two years till i get that kinda funds. I am in my final year of mechanical engineering. And have planned to make a mount with a friend. Which one would be better...??? A german equatorial or a fork equatorial mount.??? I know this sounds kinda stupid but its the only way out for me buying one willbcose me more than 3000$ here in india. Which is a huge amount.

Hmmm. I heard of someone making an image of M31 which looked ok out of like 500 1 second exposures. You could give it a go, but don't expect impressive results.

I think a fork mount might be better for a DIY build but I'm not entirely sure... Maybe someone else will come along who can help you with that one. (Or you could make another post in the DIY section) I think both mounts, made properly, will be just as good as each other.

[hjw]

Hi Dwayne and welcome to the forum. Your problem is that you have a heavy scope with a longish focal length. The longer the focal length the better your tracking has to be. With your scope I doubt a HEQ5 or equivalent would be enough. Building your own mount is an interesting idea but my guess would be that when you finish it will be more expensive than buying a mount from the shelf. You will want the ability to guide shortly after you start taking images.

Now to the alternative. Start your imaging career with much shorter focal length. I just obtained one of my best pictures with a 50mm (!) lens.

Many DSOs are really BIG and you don't need the large focal length anyway. Keep the scope for visual purposes until you can afford a suitable mount. By then you will have learnt all there is to know about imaging, stacking and post processing and you will get the best from your telescope.

Good luck

HJ

[dwayne dias]

@hjw

Building a mount will anyay take me two years or more. And i will b building a heavy duty mount. Even the stand will b an extremely sturdy one. I have already spent a year manually tracking a few deep space objects and planets. Unfortunately i do not have a smaller scope and will have to make do with the 8" newtonian that i have. But im sure u get pretty brilliant imaging through this scope too. Yes but with tracking.

[Galactic Wanderer]

8 hours ago, pipnina said:

Hmmm. I heard of someone making an image of M31 which looked ok out of like 500 1 second exposures. You could give it a go, but don't expect impressive results.

I think a fork mount might be better for a DIY build but I'm not entirely sure... Maybe someone else will come along who can help you with that one. (Or you could make another post in the DIY section) I think both mounts, made properly, will be just as good as each other.

300 1 sec exposures is not the same as 1 5 minute exposure, each subexposure needs to get well above the background sky level. It  The least you need is about 15 secs, especially as I see Dwayne(?) that you live in Mumbai (light polluted area).

[dwayne dias]

My place is at the far outskirts of mumbai touching the sea. There are no mich lights out here and galaxies which are of 11 magnitude are easitly spotted. With ease. M94, whirlpool galaxy and other deep sky nebulas are very clear. Skies out here are star studded. So its not an issue for me.

[dwayne dias]

It takes about 5 to 6 mins for an object to move out of my eyepieces FOV. So if skies are clear how long exposures can i take..?? Still 1 sec..??? Or can i do a bit longer exposures...??

Below are unprocessed raw images of the milky way from my roof top. Have a look at it. It was really dark on this day when i got this shot. I used the kit lens and a simple mini tripod.

[happy-kat]

What about building an equatorial platform instead to sit your dob on (assuming you GSO in mounted on a dob base).

[dwayne dias]

Ummm... didnt khink about this yet..

Thanx kat. But can this b used for deep space long exposure photography..??? Can it be motorised or computerised and do u know anyone who has used or made this kinda mount...????

Would b really nice to know this.

[pipnina]

1 hour ago, dwayne dias said:

Ummm... didnt khink about this yet..

Thanx kat. But can this b used for deep space long exposure photography..??? Can it be motorised or computerised and do u know anyone who has used or made this kinda mount...????

Would b really nice to know this.

An EQ platform could be motorised or even computerised with some more work. Wouldn't be as good as one of the sold products but it would likely be substantially cheaper.

In terms of exposure you can get with your setup... Try taking 5, 10, 20 and 30 second exposures and see when the star trails get unacceptably long. 

[Galactic Wanderer]

10 minutes ago, pipnina said:

An EQ platform could be motorised or even computerised with some more work. Wouldn't be as good as one of the sold products but it would likely be substantially cheaper.

In terms of exposure you can get with your setup... Try taking 5, 10, 20 and 30 second exposures and see when the star trails get unacceptably long. 

Yes,  any exposures over 25 secs, trails become obvious. As I said you can take images with your altaz mount which are much shorter exposures. Also, consider getting a remote shutter cable release. You set your exposure time and how many photos you want to take. It also stops any nudging that your finger makes when pressing the shutter release.

[happy-kat]

There are several project guides on building your own motorized equatorial platform on the internet.

[dwayne dias]

Thanx folks. 

 

I spent some time searching the net. And i am surprised. U do get dual axis motorised mounts where the RA and the declination axis can b controlled. A tracking time of 80 mins can b easily attained. So longer exposures are possibel. I also got in touch with a few manufacturers. And the platforms cost about 450$ for a kit. Includes hand controles to maintain diff speeds. These mounts can be used for fainter deep sky objects. 

[Astrosurf]

I don't know what your budget is now or if you can get this in India, but this is a nice little mount and will take small refactors. A good tripod is necessary plus a ball-head joint:

https://www.firstlightoptics.com/skywatcher-star-adventurer/skywatcher-star-adventurer-astronomy-bundle.html

Some people have built barn door mounts:

https://en.wikipedia.org/wiki/Barn_door_tracker

There are tutorials on the Web.

Good luck!

Alexxx

[Stub Mandrel]

I understand that in the old days people use to make barn door supports for dobsonian mounts and drive them with a piece of studding/allthread attached to a low-geared motor with variable speed control. Probably tricky to get the speed dead right (it will always be a compromise beyond a couple of  minutes anyway - do the trig!)

[pipnina]

1 minute ago, Stub Mandrel said:

I understand that in the old days people use to make barn door supports for dobsonian mounts and drive them with a piece of studding/allthread attached to a low-geared motor with variable speed control. Probably tricky to get the speed dead right (it will always be a compromise beyond a couple of  minutes anyway - do the trig!)

If you use a voltage regulator and a high-power eyepiece, you could get it pretty accurate. But it would still not go past 5 minutes probably.

[Galactic Wanderer]

As Alex said, the star adventurer might be a good option.

[dwayne dias]

I still think that the dob platform is something that fots onto my bidget and its simple to build. And if im stuck up somewhere i can just buy it. Plus it doesnt take much time to set up unlike an eq5 or eq6 go to mount. You can still take stunning deep sky shots using theount. Which sounds good enough. A normal eq mount will cost me 3000$ or more. Where as a dob platform is just about 450 to 550$. So i might just settle down with it.

[Mick J]

And just to give you a bit more to think about dwayne dias (what a great name, I can see the Goan bit but dwayne, so cool), hope you don't mind the comment.  have you seen any of the 'lucky' imaging threads that are popping up on the web just lately,  the newer cmos cameras that are used for planetary, seems they may be useful for short exposure deepsky images, lots of subs almost like video, stacked, much easier on the tracking. I think over the next year we will see more and more of them. Good luck with this, it cannot be easy getting kit in India.

[Galactic Wanderer]

1 hour ago, dwayne dias said:

I still think that the dob platform is something that fots onto my bidget and its simple to build. And if im stuck up somewhere i can just buy it. Plus it doesnt take much time to set up unlike an eq5 or eq6 go to mount. You can still take stunning deep sky shots using theount. Which sounds good enough. A normal eq mount will cost me 3000$ or more. Where as a dob platform is just about 450 to 550$. So i might just settle down with it.

Sorry what currency are you in?

[Galactic Wanderer]

8 hours ago, dwayne dias said:

It takes about 5 to 6 mins for an object to move out of my eyepieces FOV. So if skies are clear how long exposures can i take..?? Still 1 sec..??? Or can i do a bit longer exposures...??

Below are unprocessed raw images of the milky way from my roof top. Have a look at it. It was really dark on this day when i got this shot. I used the kit lens and a simple mini tripod.

it depends what eyepieces you used. The longer the mm of the eyepiece, the longer it takes to get out of the FOV. With photography you have to think about star trailing. Trailing becomes evident after about 30 secs.

Nice images there, what exposure time were they?

[dwayne dias]

Galatic wanderer

Theae were 30 exposures. The first one was at iso1600  and the pther one was about iso800.  And my currency is the INR...the indian rupee... stands pretty much mo where..but i gotta love with that.