Astronomy and DSLR Astrophotography Blog

The following, also very popular mount, is fork equatorial mount. As the name tells us it is one version of equatorial mounts which means that one of two axis is parallel to the Earth’s axis of rotation. In this way we avoid slewing at the both axis at the same time when capturing the astrophotos and simplicity almost always means less errors.

We find fork equatorial mounts mostly in observatories since they are more often made for bigger telescopes and not-portable. The exception here are two the biggest manufactures of astronomy equipment: Celestron and Meade. Meade’s the most popular telescope – LX200 – has this type of mount. Nevertheless, the most common use of fork equatorial mount is in smaller to mid-size observatories – mostly professional.

The fork equatorial mount exists in rough from two parts: the base and a fork. Fork is attached to the base and enables moving from East to West (R. A. axis) whereas telescope is attached in the middle of the fork and allows us to navigate from North to South (Declination axis). The main advantage of the fork equatorial mount is that it doesn’t require meridian flip – that problem occurs at german equatorial mount when is passes the meridian and has to go 360° around or it stops slewing.

To conclude, fork equatorial mounts are mostly used in the observatories, they costs much and are heavy, accurate and not-portable.

I have worked several times with fork eq. mount but I don’t like it at all! I have german equatorial at my home and it suits me the best! For everyone who needs portable and reliable mount I advise german equatorial.

Thanks for reading!

Image source: Wikipedia.org

equipment astronomy, astrophotography, earth, equatorial, equipment, fork, mount, tripod

There are several different types of equatorial mounts but surely the German Equatorial mounts are the most popular among amateur astrophotographers and astronomers. Let’s see why?

At German’s type of the mount we have two axis: one is parallel to the Earth’s rotate axis and another is rectangular to it. This is because when the mount is tracking there is no need to move both axis as the same time but just one. This makes those mounts so popular and useful because in theory you need just one motor to track the moving of the night sky. You also don’t get any other errors like field rotation or similar.

The axis which moves from east towards west is R. A. (Right Ascension) axis and the another one that enables us to move telescope from South to North is named Declination axis.

At this version of mount we need counterweights to balance the whole system. This procedure is very important to do it as precisely as possible because the better balanced mount slews better!

When setting-up we have to do everything in the right order to assure that in the end our mount tracks as precisely as possible:

1. Put the tripod to the flat and solid ground.
2. If you are using tripod make sure that the leg labelled with “N” (North) is positioned right to the North. Help yourself with a compass.
3. Attach the equatorial head to the tripod or pier.
4. If your mount has a polar finder check the time and a date, rotate the two wheels on the R. A. axis to the right date and time and check the position of Polaris (Northern Hemisphere) or the Southern Cross (Southern Hemisphere) in the polar scope and align the stars with the marked positions.
5. If necessary do a drift-align (the guide how to do it follows in the next posts).
6. Put a telescope on a mount.
7. Balance the whole system with counterweights and moving of the telescope tube.
8. Enjoy the good tracking!

That’s short review of the German equatorial mount. More read:

• http://en.wikipedia.org/wiki/Equatorial_mount
• http://starizona.com/acb/basics/equip_mounts_gem.aspx
• http://science.howstuffworks.com/telescope5.htm

Image source: http://www.company7.com/vixen/mounts/counterweights.html

Thanks for reading!

equipment astrophotography, earth, equipment, guide, mount, tripod, tutorial

As we all know, the sky above us is apparently moving. The sun, the moon and stars are travelling every day from east to the west. This fact is not very practical in astrophotography especially because for deep-sky imaging the long exposures are obligatory. That means if we just put the camera to the usual tripod and make a one minute lasting exposition then we get just the star trails. The following video demonstrates the virtual rotation of the southern sky. The Megellan’s Clouds are visible also:

I believe that everybody understands what I mean.

However, this daily ritual of our home planet is not very appropriate for astrophotography. We need special mounts with tracking which tracks with just the same speed as the sky is moving. The Earth rotates quite slow so the stepper motors must track really slow and smooth to assure enough good tracking. All the bearings and gearwheels must be made very precisely to avoid any unpredictable jumps and so on. It is extremely important that we have a stable tripod or pier otherwise everything is worthless.

In general we three different types of mount: Alt-azimuth mount, German equatorial mount and Fork equatorial mount. All three has their advantages and disadvantages and every single of them I will describe in the following posts.

Stay tuned!

equipment astrophotography, deep-sky, earth, equipment, mount, stars, tripod

I still remember my beginnings in astrophotography some years ago. I joined some astrophotography forums and admired the pictures some masters were taking. I didn’t have a telescope, a mount or any other equipment. I had just a Canon 3000N camera and kit lens.

Many of you would say that with this equipment astrophotograhy is just impossible. But this is not true! I have spent a lot of time capturing the moon with my very first telescope (60/700 Meade) and the star trails. The pictures was often useless but I have learned a lot for my progress.

I have been searching a lot to find the first picture of star trails I managed to take but I haven’t found it. So I can show you the one I have made 2 months ago:

Star trails @ Primož Cigler

For image like this you don’t need any special equipment. Almost every digital or analog camera for daylight photography is ok. Everything that is obligatory is a stable tripod where we attach the camera and remote control for expositions is useful too.

Analog cameras are more suitable for this type of astrophotography because they don’t have a digital noise. Exposition can last as long as we want and that don’t influence on image quality. We just set the length of exposition (usually between 30min and 3 hours), the field of camera (usually to the widest) and start the exposition. We generally use low ISO speed for capturing star trails – ISO100, ISO200, ISO400, rarely more. The length of exposition, ISO speed and aperture depend from the conditions, especially from light pollution. The more light pollution we have, lower ISO speed we should use and take shorter exposition.

If we use digital camera the process is little different. As I mentioned the digital cameras have a digital noise which grows as the length of exposure. To avoid this problem we take a set of continuous shots one after another where single show is long from 1 to 3 minutes. It’s important that between exposures in no more than 5 s of pause and that we don’t move the camera all the time during the exposures. At the end we also make a dark-frame (we cover the lens of the camera with a cap and make the “dark picture” just the same length and with the same settings as all the other pictures before), which we be needed after at processing.
If we done everything ok then processing is just the easiest part. We just download this software called Startrails and combine all the pictures. That’s all!

I hope that this article/post will help someone to start with astrophotography. Star trail can be really beautiful, just give them a chance!

astrophotography astrophotography, canon, equipment, images, landscape, stars, trails, tripod, tutorial

On many astrophotography and astronomy forums I notice that there are some beginners who would like to buy a new telescope and start with an astrophotography. They buy a reasonably good telescope, a mount for tracking, a camera but at the end there is no more money for a good tripod.

Tripod or pier is just one of the most basic parts of every astrophotography equipment. It’s just the base of our system. As I mentioned many people forget about it when they are buying a new scope and without it the whole equipment is unusable because it’s shaking and that’s very annoying at visual observation but impossible for astrophotography.

In general there are two options how to ground out setup:

• Tripod
  

  Aluminium tripod from Vixen

  It’s the most common holder of our astrophotography equipment. Tripod sometimes comes together with the mount or the whole telescope but these tripods are not good every time. It may happen that we are going to attach more heavy equipment to our telescope (eyepieces, guidescope, camera) which causes that the default tripod is not enough strong anymore. In this case we have to change out tripod with the new one.A lot of manufactures produce tripods nowadays. We have to be careful when we are buying a new one, because they are not all the same. We have to know for what we are going to use it – astrophotography or visual astronnomy observations. If we are planning to use it for astrophotography then a tripod should have 20-30% more weight capacity then we are going to put on – just for any case! That’s because in astrophotography (expecially in deep-sky imaging) long-lasting exposures are necessary and every single shake during the min lasting exposure makes it crap. So think twice when you will be in doubts to save some money!
  The last but not the least thing to mention here is that wooden tripods are usualy better because wood reduces all the minimum shakes that occurs when we are walking around the telescope. And naturally, they are also more expensive!

• Pier
  That’s the second option we have. We use piers mostly in observatories. They are better because they are cheper variant but on the other hand we cannot just pick them up and go to the holidays. Another advantage is that they are fixed on the same position all the time and when we make accurate polar alignment of our mount there is no need to realign it every time we start the observation or astrophotography.

So, that’s all about our base of the whole system for astrophotography. I hope that you found this article interesting and useful.

astrophotography, equipment astronomy, astrophotography, equipment, tripod