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Need to get my subs above the 1 minute exposure time!!! HELP!!

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Rutgerbus

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Hi,

I'm running my astrophotography for a while now, but thus far, I was not able to get my single sub exposure time above 30sec. without startrails. Therefore, I had to crank up the ISO to get pinpoint stars, but also the noise increased dramatically)

Now, I think it is time that someone tells me how I can go up to the 1minute (or more ;-)) minute mark.

I have an GoTo version of the Meade LXD-75 mount....The mount itself comes with nice solid/rigid 2" stainless steel legs and feels pretty solid. It does not have a bubble level on top of the mount so I can't check if it's level or not. (Tried once with my smartphone and a bubble level app, but you need to calibrate that app as well and therefore is probably not accurate enough)

I already got some decent results with the method described above (short exposures, high ISO) but I want to do better.

I recently bought myself a LVI smartguider SG2 to guide my main scope but up to now I didn't got it running properly.

What I normally do is point my mount to polaris, but that is a rough polar alignment since I can't tell if the mount is horizontally. And I think that thats were my problem is...in the alignment procedure. Also, I can't loosen my telescope-unit anymore from my mount since the threaded rod which tightens the mount to the telescope-unit seems to be stuck as a rock.

Kind regards and hopefully you can help me to align my mount properly to polaris.
 
You could get a small stick-on bubble level like this one. Does your sighting scope that is used to align with Polaris have the outer ring? Polaris goes on the outer ring as it is approximately 0.75° off the rotational axis. And it has to be properly positioned on that ring according to your location and time.
 
Rutgerbus said:
Hi,

I'm running my astrophotography for a while now, but thus far, I was not able to get my single sub exposure time above 30sec. without startrails. Therefore, I had to crank up the ISO to get pinpoint stars, but also the noise increased dramatically)

Now, I think it is time that someone tells me how I can go up to the 1minute (or more ;-)) minute mark.

I have an GoTo version of the Meade LXD-75 mount....The mount itself comes with nice solid/rigid 2" stainless steel legs and feels pretty solid. It does not have a bubble level on top of the mount so I can't check if it's level or not. (Tried once with my smartphone and a bubble level app, but you need to calibrate that app as well and therefore is probably not accurate enough)

I already got some decent results with the method described above (short exposures, high ISO) but I want to do better.

I recently bought myself a LVI smartguider SG2 to guide my main scope but up to now I didn't got it running properly.

What I normally do is point my mount to polaris, but that is a rough polar alignment since I can't tell if the mount is horizontally. And I think that thats were my problem is...in the alignment procedure. Also, I can't loosen my telescope-unit anymore from my mount since the threaded rod which tightens the mount to the telescope-unit seems to be stuck as a rock.

Kind regards and hopefully you can help me to align my mount properly to polaris.

--
www.rutgerbus.nl
Photographic Moments
A photon only stops "existing" when it is captured by your sensor.
Click to expand...
You have a German type equatorial mount. They aren't that sensitive to leveling. But they are very sensitive to how well you are pointed at true north. I have the Celestron CG5 which your mount competes with. I have the scope that mounts inside the axis for proper aiming. It has a ring around the center which indicates the location of Polaris in its path around true north and it has to be adjusted to be right on that line. I use an App on my phone to identify where on that circle I should place Polaris.

One more thing, after aligning Polaris, rotate the scope back and forth, west to east and see how it behaves in its alignment that you just went through. It should not move. If it does, you are not aligned.
 
Hi Rutger,

You definitely should do a proper polar align of your mount. The polarscope helps but is not enough for a precise alignment required for long exposures. Having Goto will allow you to use software for that purpose. Read this: http://www.thewilmslowobservatory.org/polaralignmentsoftware.html

I've used Pempro 4-5 years ago to align my mount (Losmandy G11, Gemini) in the observatory and didn't have to do it again ever since. Exposures of fifteen, twenty minutes or even more are easy :)
 
Hummm, sorry, I think you don't have an observatory. If you have to align for each astrophotography session then things are not so easy but still probably the use of software is the best thing to do. As I align once for many years, I'll let others comment on one-session polar align.
 
Joao Vieira said:
Hummm, sorry, I think you don't have an observatory. If you have to align for each astrophotography session then things are not so easy but still probably the use of software is the best thing to do. As I align once for many years, I'll let others comment on one-session polar align.
Click to expand...
I don't have an observatory either.

But the key to a good session is indeed the polar alignment. I use the polar scope and get it as close as I can. And then swing the scope back and forth east to west several time and watch the polar scope. If I see Polaris deviating from the circle on the scope, I nudge it in the direction I think I need to go, and I do this a number of times.

I'm sure the SW method is vastly superior, but this is what I have to work with.

I haven't yet bought a tracking scope.

But I can maintain alignment for at least a few minutes.

Other tips:

I mark the spot where the tripod sits so when I set it up, it is already close.

I set up the scope prior to it being dark.

I start the polar alignment just as soon as I can see Polaris. And I can see Polaris thru the polar scope before I can see it without.

But where I often run into trouble is all the tree around my yard that block all the alignment stars I want to use.
 
Are using your camera/lens on the mount or trying to shoot through a telescope on the mount ?
I ask, because my SkyTracker allows me 3 min+ with no trailing at 100mm and lower.

If your shooting through a telescope on that mount, it's going to be very hard to get past 1 min w/o an autoguider.
 
Last edited:
JimH123 said:
Joao Vieira said:
Hummm, sorry, I think you don't have an observatory. If you have to align for each astrophotography session then things are not so easy but still probably the use of software is the best thing to do. As I align once for many years, I'll let others comment on one-session polar align.
Click to expand...
I don't have an observatory either.

But the key to a good session is indeed the polar alignment. I use the polar scope and get it as close as I can. And then swing the scope back and forth east to west several time and watch the polar scope. If I see Polaris deviating from the circle on the scope, I nudge it in the direction I think I need to go, and I do this a number of times.

I'm sure the SW method is vastly superior, but this is what I have to work with.

I haven't yet bought a tracking scope.

But I can maintain alignment for at least a few minutes.

Other tips:

I mark the spot where the tripod sits so when I set it up, it is already close.

I set up the scope prior to it being dark.

I start the polar alignment just as soon as I can see Polaris. And I can see Polaris thru the polar scope before I can see it without.

But where I often run into trouble is all the tree around my yard that block all the alignment stars I want to use.
Click to expand...
The things you describe above are mainly the things I also do before I start a session. The only difference I have is that my scope is in a grassy field and not on a concrete floor. So marking my spot will be a bit difficult.

I'm having this idea that I can try to hammer some steel pipes into the ground and level those with a bubble leveler so I can rest my tripod feet on the pipes

Well, seems that I just need to understand my polarfinder a bit more. ;-)
 
swimswithtrout said:
Are using your camera/lens on the mount or trying to shoot through a telescope on the mount ?
I ask, because my SkyTracker allows me 3 min+ with no trailing at 100mm and lower.

If your shooting through a telescope on that mount, it's going to be very hard to get past 1 min w/o an autoguider.
Click to expand...
I'm shooting through the scope at prime focus. And I do have a standalone autoguider (So PHD won't help here, although I just watched the Forest Tanaka movie about guiding, and that seemed pretty cool. He's using the BackyardEOS software for aligning the scope and PHD for guiding. But he's using a non-standalone guider.
 
This is how my view through Polar finder looks like>



0379385bb6744d99b4e11d0ba9abc4ce.jpg

I normally always put Polaris in the little circle by changing Alt & Azimut nobs...so basically it should be fine like this. I never check if Polaris is still in the circle after -lets say- half an hour.

--
www.rutgerbus.nl
Photographic Moments
A photon only stops "existing" when it is captured by your sensor.
 
autoguider.
 
ive heard only good things about phd guiding, have you tried that program?
 
Rutgerbus said:
Hi,

I'm running my astrophotography for a while now, but thus far, I was not able to get my single sub exposure time above 30sec. without startrails. Therefore, I had to crank up the ISO to get pinpoint stars, but also the noise increased dramatically)

Now, I think it is time that someone tells me how I can go up to the 1minute (or more ;-)) minute mark.

I have an GoTo version of the Meade LXD-75 mount....The mount itself comes with nice solid/rigid 2" stainless steel legs and feels pretty solid. It does not have a bubble level on top of the mount so I can't check if it's level or not. (Tried once with my smartphone and a bubble level app, but you need to calibrate that app as well and therefore is probably not accurate enough)

I already got some decent results with the method described above (short exposures, high ISO) but I want to do better.

I recently bought myself a LVI smartguider SG2 to guide my main scope but up to now I didn't got it running properly.

What I normally do is point my mount to polaris, but that is a rough polar alignment since I can't tell if the mount is horizontally. And I think that thats were my problem is...in the alignment procedure. Also, I can't loosen my telescope-unit anymore from my mount since the threaded rod which tightens the mount to the telescope-unit seems to be stuck as a rock.

Kind regards and hopefully you can help me to align my mount properly to polaris.
Click to expand...
 
Trollmannx said:
And another question - might it be time for a new mount? (just some wishful thinking here)...
Click to expand...
Yes, I was already thinking of buying the Celestron Advance VX mount, together with a faster Newt (8" f/4 for instance instead of my 6" f/5) and a decent dual speed focuser. I now have the original focuser which came with the Newt, and it is really bad for fine-focusing.

I don't know if I can use the LVI smartguider together with PHD since it is a standalone guider.

Probably, with the right cables I can attach it directly to my computer and use PHD and BackyardNikon (ssems to be a great set of software tools to work with)

In the most perfect case, I would like to have a static setup covered by an astroshed ;-).

But that's something for the (near) future ;-)
 
Rutgerbus said:
Trollmannx said:
And another question - might it be time for a new mount? (just some wishful thinking here)...
Click to expand...
Yes, I was already thinking of buying the Celestron Advance VX mount, together with a faster Newt (8" f/4 for instance instead of my 6" f/5) and a decent dual speed focuser. I now have the original focuser which came with the Newt, and it is really bad for fine-focusing.
Click to expand...
I settled for a Vixen SXP mount - this mount is super smooth when guided and have by far exeeded my expectations. Those round stars ALL the time. VIxen mounts might seem a bit expensive compared to some other mounts but they are not expensive considering what you get for the money. If into Vixen get amount from the new series as there are some quirky issues with someof the older mounts.

I am seriously bitten by the astronomy bug and having something that is fast and easy to set. Up, and that works and works and works is great (had a Losmandy mount but that one was a lemon and a stinker and my worst mount experience ever).
Rutgerbus said:
I don't know if I can use the LVI smartguider together with PHD since it is a standalone guider.
Click to expand...
The LVI is standalone and can NOT run PHD. Everything needed is integrated in the guider and all that is needed is the correct cable and a mount with a standard interface for guiders.
Rutgerbus said:
Probably, with the right cables I can attach it directly to my computer and use PHD and BackyardNikon (ssems to be a great set of software tools to work with)

In the most perfect case, I would like to have a static setup covered by an astroshed ;-).
Click to expand...
I have a small astroshed (made from lef over materials) and that have been a blessing. I am ready for flats and photography after a couple of minutes and I can finish a sesion litterally in five minutes after the last exposure.
Rutgerbus said:
But that's something for the (near) future ;-)
Click to expand...
Hope the future is bright! ;-)
Rutgerbus said:
--
www.rutgerbus.nl
Photographic Moments
A photon only stops "existing" when it is captured by your sensor.
Click to expand...
 
Many mounts were supplied with design features that were based on leveling a mount at some step in the process. But that is not a requirement for tracking, it's only a requirement for the particular parts that were supplied. For example, a reticle that it to be aligned to the earth's horizon (like iOptron's) as opposed to a different design that is aligned to stars near the pole (like Losmandy's).

You can free yourself from the manufacturer's setup instructions. Look up the drift method of alignment which works with any design of equatorial mount. Admittedly, it uses up time during your dark time that you would frankly rather use for imaging or collecting dark frames. But it gets more quickly with practice. pHD Guiding software includes software tools to assist with it. The upside is that it is pretty much as accurate as you want it to be, instead of how accurately a reticle happens to have been made.
 
just Tony said:
Many mounts were supplied with design features that were based on leveling a mount at some step in the process. But that is not a requirement for tracking, it's only a requirement for the particular parts that were supplied. For example, a reticle that it to be aligned to the earth's horizon (like iOptron's) as opposed to a different design that is aligned to stars near the pole (like Losmandy's).

You can free yourself from the manufacturer's setup instructions. Look up the drift method of alignment which works with any design of equatorial mount. Admittedly, it uses up time during your dark time that you would frankly rather use for imaging or collecting dark frames. But it gets more quickly with practice. pHD Guiding software includes software tools to assist with it. The upside is that it is pretty much as accurate as you want it to be, instead of how accurately a reticle happens to have been made.
Click to expand...
Actually, leveling is not required at all for this kind of mount. In the case of an alt-az type mount, it is mandatory. And the alt-az cannot track for very long any way due to field rotation that the German style equatorial mount does not suffer from.

The only benefit to leveling is when aiming the axis at true north. When not leveled, you can't just adjust up/down, left/right to aim it properly. Every adjustment is combination of both adjustments. But once aimed properly, the scope axis is parallel to the axis of rotation of the earth and that is all it needs.

The drift method is really good, but I haven't tried it yet. I do get good results swinging the scope east to west and back and watching how Polaris tracks on the etched circle in the alignment scope. It is quick and gets me close.
 
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