skymax 127 32mm super plossl or 40mm?

[Space Cowboy]

I'm torn between purchasing a 32 mm super plossl or a 40mm super pl for my skymax 127 az GOTO. The 25mm i have wont cover the inacurracy of the goto. I need a wider field of view. I've been told the 32mm would be best but also that the 40mm has a wider field of view...rather confused. Is there someone out there using a mak 127 who could advice me on which would be best please :-) At the moment i'm struggling to pick up any DSOs.

Also could anyone suggest how i can improve the accuracy of the goto. I use it with a mains power adapter so weak batteries are not an issue. Viewing the spotter scope as a dart board the goto is not even hitting the 25. Is a bullseye too much to expect?

[FLO]

The 32mm is best.

When the eyepiece focal length is greater than about 24mm the 1.25" barrel starts to intrude into the FOV. For this reason the 40mm will show you almost exactly the same area of sky as the 32mm.

This FOV diagram shows it clearly:

HTH

[ringz]

The 32mm is what you need. The 40mm shows exactly the same field because it has a narrower apparent field of view.

Here's a quote from the Televue website:

The 32mm Plossl has the same true field as the 40mm, but higher magnification, while the latter has very long eye-relief for spectacle wearers. Both these eyepieces deliver maximum field for the 1 ¼ inch format.

I hope this helps and you don't waste your cash, like I did, on a 40mm

--

Martyn.

[Nina]

Hi i am new to this and i am hopeing you can help me. I have a skymax 127 goto az and i am out every night when the skys are clear to try and line up two stars i find the first star sometimes it is the brightest and sometimes one of 2 stars. but when it comes to the second star my telescope wont go right round to the second star and so never get to set my scope up i just cant figure out what i am doing wrong. tHANKS nINA

[Space Cowboy]

The 32mm is best.

When the eyepiece focal length is greater than about 24mm the 1.25" barrel starts to intrude into the FOV. For this reason the 40mm will show you almost exactly the same area of sky as the 32mm.

This FOV diagram shows it clearly:

HTH

Thanks Steve! Very clear explanation :-)

[Space Cowboy]

The 32mm is what you need. The 40mm shows exactly the same field because it has a narrower apparent field of view.

Here's a quote from the Televue website:

The 32mm Plossl has the same true field as the 40mm, but higher magnification, while the latter has very long eye-relief for spectacle wearers. Both these eyepieces deliver maximum field for the 1 ¼ inch format.

I hope this helps and you don't waste your cash, like I did, on a 40mm

--

Martyn.

Thanks Martyn! Now i'm wondering if i should go for the 40mm as i wear specs and can't use them with my other eyepieces. I'm sure i'm missing out using my inferior eyeballs!

[FLO]

I would have thought both the 32 and 40mm would have ample eye-relief (ask your supplier whether they will swap the 32mm for a 40mm if necessary).

Also, a widefield (68-degree) 24mm will cover almost exactly the same area of sky as the 32mm Plossl.

Another chart, this time with a Skymax 127 and your existing 25mm Plossl for reference:

HTH

[Space Cowboy]

I would have thought both the 32 and 40mm would have ample eye-relief (ask your supplier whether they will swap the 32mm for a 40mm if necessary).

Also, a widefield (68-degree) 24mm will cover almost exactly the same area of sky as the 32mm Plossl.

Another chart, this time with a Skymax 127 and your existing 25mm Plossl for reference:

HTH

That is such a brilliant graphic! I've heard First Light Optics are pretty good so i shall be purchasing a 32mm from them

[FLO]

Thank-you, though credit for the graphic belongs to Starry Night PRO, I just entered the figures

[sxinias]

Telescopes Using the SkyWatcher SynScan Alt/Az GOTO Mount and Tripod

I have noticed several owners of SkyWatcher Telescopes that use the SynScan Alt/Az Mount and tripod are having some problems with GOTO accuracy. I have a SkyWatcher SynScan Alt/Az GOTO Mount and Tripod with a Celestron C6S SCT mounted on it. My scope exceeds the maximum size and is at the maximum weight recommended for the mount. My goto accuracy is 100% so far DSOs, Saturn, Moon & Stars (25mm eyepiece; f=1500 f/10 telescope). However, on my first night using the mount, my accuracy was ZERO PERCENT, all misses with not even one close to. Here is what I’ve learned about the mount and what I did to get it working properly.

First, consider your telescope as a system (telescope, mount, tripod, manual, and observer). Any one of these system components can introduce an error impacting upon GOTO accuracy.

The weakest link in the SkyWatcher SynScan Alt/Az GOTO system is the tripod. The tripod is very flexible and is the source of nearly all goto error in the system.

The first thing you want to do is stiffen the tripod. The following actions typically are sufficient to stiffen the tripod and minimize the error it introduces:

• Firmly tighten the nut and bolt on each tripod leg hinge.
  
• Firmly tighten the nuts and bolts on the folding cross brace hinges and leg brackets. The tripod will still be able to collapse and fold up so don’t worry about that.
  
• Always insert the accessory tray on the cross brace and rotate it until it clicks in place.
  
• Do not extend the tripod legs 100 percent. This is scope dependent and you will need to experiment with your scope. The larger and heavier the scope, the less you can extend the tripod legs. I have a 150mm 5 kg scope, the maximum aperture and weight for the mount, and can not extend the tripod’s legs more than about 15 cm).
  

The second source of error is the manual which attempts to simplify the process too much and ends up not being as clear as it should be.

• step 1 of the instructions reads “make sure the mount is level with the ground.” What SkyWatcher really means is make sure the vertical axis of the tripod is orthogonal to the plane of the earth. The tripod has a bubble level. Verify that yours is accurate. If your bubble level is accurate, then adjust the tripod legs until the bubble is in the center of the level. If the bubble level is not accurate, then use a carpenter’s level and make sure the top of the tripod is level in two directions 90 degrees apart from each other.
  
• Step 2 of the instructions tell you to point the telescope to one or a group of visible bright stars in the sky. This really means point your scope in the direction the stars, not at the stars. The telescope should be parallel to the plane of the earth. Unlike all other goto systems that I am aware of, the telescope can be pointed at any direction of the compass for the start position. All that matters is that it is parallel to the ground. There are certain features in the firmware programming that work best if instead of pointing the telescope in the direction of a group of stars, you point it toward true north. I always position my scope pointing toward true north before I power up. The reason that SkyWatcher says point the scope in the direction of a bright star is to quicken the alignment process if you choose that particular bright star as your first alignment star. (More on how to make your telescope level to the ground later on.)
  
• Step 3 mentions autotracking and multifunction telescopes. Your SynScan Alt/Az GOTO telescope is an autotracking telescope. It does not have an on/off switch. You power it up by pluging in the power cord. While not a source of error, step 3 is a big “got ya.” (More on this later on.)
  
• The remaining steps are fairly clear. You will need to enter the time and date. You can get an accurate time from the internet. You will need to know your longitutde and latitude. This too is available from the internet. I use Google Earth. Other sources are maps, etc. For the time, latitude, and longitude you don’t have to be exact but the more accurate you are, the better.
  

The SkyWatcher SynScan Alt/Az GOTO Mount has two star alignment options; both are a two star alignment process. The mount does not have a single star or three star alignment routine.

If you are not familiar with the names of stars, use the Brightest Star Alignment process. Look around the sky and pick out the brightest star you can see that is not directly overhead or near the horizon and does not have any other real bright stars nearby. Note which direction of sky it is located. e.g., north, northeast, east, southeast, south, southwest, west, northwest. Choose the brightest star alignment process and tell the hand controller which part of the sky your target star is located. Follow the directions.

If you are familiar with the names of stars, use the two star alignment process. It is straight forward.

There is another process to use if you do not know the names of stars. This process requires that when you power up the telescope that you have it level and pointing toward true north (it dose not have to be exact but the closer the better). After powering up, choose the two star alignment process. The SynScan controller will provide you a list of stars. Select one. The controller will then give the coordinates for the star (use the scroll keys to get the display in Alt/Az readings). Wright down or memorize the coordinates and the star’s name. Press the escape key to exit the setup menu then select the utility menu. On the utility menu select “show position.” Now use the hand controller direction keys to slew your telescope in both altitude and azimuth until the readings match the coordinates of the star you selected in the alignment process. Your telescope should be pointing in the general direction of a very bright star. That star is the one you selected earlier and now you know its name. Now hit the escape key and go back to the set up menu, toggle down to star align, select two star align, then select your star. Now follow the directions on the handset. For your second star, the mount will automatically slew toward it. The second star will be the brightest one near where your scope is pointing. Wait until the hand controller beeps letting you know that it has stopped moving, center it and the alignment process is over.

Items I said that I would discuss later

• Power plug issues. The mount comes with a battery pack holding 8 AA batteries. The power cord is unusual in that it has a locking nut on it. Make sure that you tighten this locking nut as firm as you possibly can. The power cord will drag on the mount’s surface as it moves in the azimuth direction and can easily break contact meaning you loose everything and have to start all over again entering the time, date, and doing the alignment process. After the third time in one night, you’ll probably pack up with bad thoughts about SkyWatcher. If you are using a power pack or an AC adapter, your cord will not have a locking nut. My best advice is to use some duct tape to hold the plug in place. Right angle plugs tend to disconnect easier than straight ones do. I use an automotive power pack for my scope. I removed the power cable from my Skywatcher battery pack and spliced it to the end of my automotive power pack cord using an inline on/off switch to do the splice. Next, I used needle nose pliers to tighten the power plug nut as tight as I possibly could. It is essentially locked in place and I never remove it. I also now have a power switch for my mount.
  
• Level the scope. Make sure your tripod is orthogonal to the plane of the earth. When you power up, the mount will initialize with the telescope at zero degrees altitude and zero degrees azimuth regardless of where the scope is pointing. Before powering up point the telescope toward true north if you want your initial azimuth settings synchronized with true north being zero degrees (required if you want to use the star identification routine I mentioned earlier). The telescope is attached to the altitude axis. The altitude axis has a clutch and when the mount is not powered, you can manually move the telescope in the altitude direction. DON’T unless you know for sure this is OK to do. (I have sent an inquiry to SkyWatcher asking if manually moving the scope in the altitude direction will damage the clutch, but have not heard back from them.) Instead, power up your scope and use the direction keys to lower the scope until the index indicator on the altitude arm points to zero then remove power from your mount. When you power back up, zero degrees altitude will also be level. You may have to enter setup and adjust your slew limits to do this.
  
• Beginners often do not properly center alignment stars. Start with a low power eyepiece 25 or 30 mm. After you get the star in view, center it as best you can. Switch to a higher power eyepiece around 10 to 12 mm. Center the star as best you can then defocus the star until it almost fills the eyepiece. Now center the defocused star. After a little practice, this method will produce alignment star centering just as good as a cross hair eyepiece does.
  
• When going to an object, have a low power eyepiece in your scope, 25mm or 30 mm. With the scopes that fit on the mount, anything bigger than around 30 mm will most likely not increase your field of view and may exceed the scope’s capabilities making viewing though it tedious.
  
• The SkyWatcher SynScan Alt/Az GOTO Telescope hand controller does not have a time chip nor does it have an auxiliary red LED lamp that most hand controllers have. This means you will need to enter the time and date when you power up. To do this you will need a watch synchronized with GMT and a way to read the watch at night. Without these two items, you are dead in the water.
  

Joe

Sxinias Greece

Meade DS2090AT Refractor

Meade 2045 LX3 SCT

Celestron C6S SCT

Meade DS2000 GOTO Mount

Celestron CG5/iOtron GOTO Mount

SkyWatcher SynScan Alt/Az GOTO Mount

[Space Cowboy]

Brilliant info Joe! I've printed it off and will be using it as my new GOTO manual! Many thanks :-)

Stuart.

[AztecastroMcJ]

I'm torn between purchasing a 32 mm super plossl or a 40mm super pl for my skymax 127 az GOTO. The 25mm i have wont cover the inacurracy of the goto. I need a wider field of view. I've been told the 32mm would be best but also that the 40mm has a wider field of view...rather confused. Is there someone out there using a mak 127 who could advice me on which would be best please :-) At the moment i'm struggling to pick up any DSOs.

im going to add 32mm (x47mag)or maybe 31mm(x48mag) very soon 2

also thinking of adding 0.5 focal reducer to reduce 11.8 factor ratio to 5.9 and lower mag to 23.5xmag or 24xmag with above EP's

which should improve it for DSO also able to use with 25mm for 30xMag

did u buy anything else with ur 32mm??

regards James

[AztecastroMcJ]

The 32mm is best.

When the eyepiece focal length is greater than about 24mm the 1.25" barrel starts to intrude into the FOV. For this reason the 40mm will show you almost exactly the same area of sky as the 32mm.

This FOV diagram shows it clearly:

HTH

hi there do u have FOV diagram for 32mm and 31mm as got same scope and thinking of adding

also if possible could u show another FOV diagram using them both with a 0.5 focal reducer

much appreciated James

[AztecastroMcJ]

Brilliant info Joe! I've printed it off and will be using it as my new GOTO manual! Many thanks :-)

Stuart.

me 2 thanks alot Joe very good detailed info:hello2:

noticed a few things myself

b4 connecting powertank to mount i carefully used knife to slightly prize apart the 2 pins where power plugs fits seems to hold in place really well

also on my synscan handset in Set-up mode menu under tracking i have Stop Tracking option in tracking menu alongwith sidereal lunar,and solar rates

also when using brightest star align u can use 3star alignment (well planet n 2 stars) if u choose area of sky with visible planet like jupiter (SE direction)after choosing jupiter from choices it gives u , u then have to choose further 2 stars to finish alignment

thanks again for advice Joe which i will definetly B using !

James