Scope failings

[skywatcher1983]

I have a Celestron 6SE and saw mars for the first time last night. Like all the planets its a blurry blob in the 2.5mm eyepiece. I guess this is due to atmospheric haze but I'm not sure. Maybe the setup is still not quite there. Aligning the primary mirror has been a ongoing series of trial and errors. I feel that all scopes should have a simple and convenient way of precisely collimating without having to use a false star and looking concentric rings, better still an automatic mirror alignment system. Still, even if I keep fussing and continue tweaking the mirror, I think that's as good as it'll get with this type of scope. Seeing details on the moon and blurry planets is still cool but galaxies and nebulas? 

[starbob707]

Mars sucks right now. Never judge your scope by it. Collimating is quite easy. get a good laser.  Use a star to see how your optics are doing. Nice pin point stars is what I like. Plus you have a Celestron 6se'  their not going to be Takahashi perfect optics but should be decent enough  to have fun and see much.

[laudropb]

Do you mean a 25mm ep ? I think that perhaps you are not quite in focus. 

[rwilkey]

I think you are using too much magnificartion: 1500/2.5 = 600x.  Much too high for our thick atmosphere and the scope (max useful mag = 300x).  A 5mm will give you 300x but even so you would have to trek out to a dark sky spot to have any chance of acheiving this.  Clear skies!

Edited April 29, 2023 by rwilkey

[Elp]

2.5mm is a lot, I can barely use a 3.2 or anywhere near a 5, otherwise it'll be an out of focus blur.

Last time I looked at mars it was bright so a polarising filter can bring the brightness down, or use a Barlow and a low power eyepiece.

You shouldn't need to adjust the primary mirror, just the three screws on the secondary, try making and using a Duncan mask.

[niallk]

In addition to the other comments, cooling is key too along withcollimation, and I'm also in the habit of checking the jetstream forecast if thinking out viewing planets - seeing needs to be good.  The planets need to have reasonable altitude from your location.  Seeing due to thermals of concrete & rooftops you can strive to avoid by where you set up.  For the higher atmosphere, this link is useful - if you have seen it (or an equivalent):

https://www.netweather.tv/charts-and-data/jetstream

I don't even bother if the jet stream is overhead...

Edited April 29, 2023 by niallk

[mikeDnight]

Although Mars is tiny, too much magnification will kill detail. I'd suggest keeping it below 250X and study the image. I can still just see there are albedo markings visible at 128X, which to be honest is too low for meaningful observation, but 180X or 200X may be ok. Sharp is good, but once the view turns soft you know you've gone too far. Orange 21 and blue 80A filters may help bring out the darks and lights respectively. Theres also been some fast moving currents of air over the UK of late, so it may not all be down to your scope, although SCT's are very sensitive to even tiny amounts of internal heat.

Edited April 29, 2023 by mikeDnight

[dweller25]

@skywatcher1983

Collimation and cool down of your scope is critical to good planetary views.

However Mars is very small now so it’s not showing much detail.

[bosun21]

6 hours ago, skywatcher1983 said:

Aligning the primary mirror has been a ongoing series of trial and errors.

The primary mirror has no means of collimation by the user. I take it you are talking about the secondary mirror. As has been previously stated a 2.5mm is too much magnification for a long focal length scope such as yours. Replace it with a 25mm eyepiece and SLOWLY wind the focuser knob in the one direction and then the other until the target comes into focus. The focus travel on a SCT is considerable and the focus point can be missed if not paying attention. Good luck.

[skywatcher1983]

Nearly there, still needs a bit of fine collimation 

[StarDuke82]

9 hours ago, skywatcher1983 said:

Nearly there, still needs a bit of fine collimation 

Not entirely sure it needs collimation the focuser try fine tuning the focuser, barely turning it, I have Celestron 9.25 and the focuser is very sensitive the image can look soft and the I barely turn it almost feather light and it turns crisp and clear.  The only way you can truly tell if you are out of collimation is to focus on a bright star and defocus your scope and check the concentric pattern of the rings around the center, also is your star diagonal vertical (at a 90* angle to the scope) if your Star diagonal eyepiece isn’t positioned correctly it can give the impression that you are out of collimation when doing a star test and you can end up doing the opposite and move your scope out of collimation. I noticed this one night when I moved my star diagonal to the side to allow me to sit to the side of my scope and observe, even though I knew it was collimated when I did a star test in that position it showed that it was not but when I returned the diagonal to its original position it showed back in collimation.

[StarDuke82]

I will also note that a lot of the images the you see people post are edited to or stacked to bring out details as seeing through the atmosphere especially when there are high upper levels clouds or winds can soften the image. I will post a before and after shot of some lunar photos that I took recently so you can see what I am talking about one is a raw image the other has been edited to bring out more detail Basically the same photo except one has been enhanced by changing little details like contrast, shadow, sharpness; and still others Stack multiple images to get those crisp sharp images you see, now the question is how sharp is the image when you look through your scope ? Edited image is top image unedited image is the bottom one.

Edited May 1, 2023 by StarDuke82

[The60mmKid]

With all due respect: It isn't scope failings. It's inexperience. But that can be remedied with time by...

• learning about observing. Mars is a difficult target. The moon is a great starting point. Saturn and Jupiter are great, but we must wait for them to return. I suggest observing a few prominent double stars, open and globular clusters, and, if you're in a sufficiently dark location, brighter diffuse DSOs (i.e., galaxies, nebulae). The Astronomical League (one may Google it) has excellent observing lists for beginners, and you can combine those with a decent star chart (e.g., Pocket Sky Atlas).
• learning about atmospheric conditions and the implications for observing. As noted above, a 2.5mm eyepiece with a C6 yields 600x magnification. That's far too much unless you have a night of excellent seeing and a collimated and cooled telescope with enough aperture to provide such a magnification. With your (successfully collimated and cooled) C6, I suggest starting at a low magnification (using maybe a ~20-30mm eyepiece) and gradually increasing until you hit about 200x. If the conditions will support that, you can further increase. Too much magnification yields a dim, mushy image. If you need help figuring out eyepiece magnifications, this is a helpful tool: https://astronomy.tools/calculators/field_of_view/
• learning to collimate your scope, which you mentioned. Many "poorly performing" SCTs are actually poorly collimated. It's like tuning a guitar. It takes time to learn, but it gets easier after you've done it a few times. It's a rite of passage. Imagine an adept guitarist who can't tune the instrument... I recommend making yourself a simple diagram that shows the direction in which the concentric rings move when you tighten and loosen each screw. That makes collimation much easier.
• learning about thermal acclimation. If you take your SCT outside and use it immediately, the internal temperature will most likely be different from the ambient temperature. This creates air currents inside your telescope, which significantly degrade the image. The solution is to leave your telescope outside (if possible) for an hour or two before observing. Leave it in a shaded spot, pointed downward with the objective cap on and without the diagonal. This allows warm air to escape.

None of this is intended to dissuade you. On the contrary, it is meant as encouragement. The investment of time and care is part of what makes observing a beautiful craft. With time and care, one develops a relationship with the cosmos (and with one's equipment) that can be deeply fulfilling.

Keep at it.

Edited May 3, 2023 by The60mmKid

[The60mmKid]

13 minutes ago, The60mmKid said:

With all due respect: It isn't scope failings. It's inexperience. But that can be remedied with time by...

• learning about observing. Mars is a difficult target. The moon is a great starting point. Saturn and Jupiter are great, but we must wait for them to return. I suggest observing a few prominent double stars, open and globular clusters, and, if you're in a sufficiently dark location, brighter diffuse DSOs (i.e., galaxies, nebulae). The Astronomical League (one may Google it) has excellent observing lists for beginners, and you can combine those with a decent star chart (e.g., Pocket Sky Atlas).
• learning about atmospheric conditions and the implications for observing. As noted above, a 2.5mm eyepiece with a C6 yields 600x magnification. That's far too much unless you have a night of excellent seeing and a collimated and cooled telescope with enough aperture to provide such a magnification. With your (successfully collimated and cooled) C6, I suggest starting at a low magnification (using maybe a ~20-30mm eyepiece) and gradually increasing until you hit about 200x. If the conditions will support that, you can further increase. Too much magnification yields a dim, mushy image. If you need help figuring out eyepiece magnifications, this is a helpful tool: https://astronomy.tools/calculators/field_of_view/
• learning to collimate your scope, which you mentioned. Many "poorly performing" SCTs are actually poorly collimated. It's like tuning a guitar. It takes time to learn, but it gets easier after you've done it a few times. It's a rite of passage. Imagine an adept guitarist who can't tune the instrument... I recommend making yourself a simple diagram that shows the direction in which the concentric rings move when you tighten and loosen each screw. That makes collimation much easier.
• learning about thermal acclimation. If you take your SCT outside and use it immediately, the internal temperature will most likely be different from the ambient temperature. This creates air currents inside your telescope, which significantly degrade the image. The solution is to leave your telescope outside (if possible) for an hour or two before observing. Leave it in a shaded spot, pointed downward with the objective cap on and without the diagonal. This allows warm air to escape.

None of this is intended to dissuade you. On the contrary, it is meant as encouragement. The investment of time and care is part of what makes observing a beautiful craft. With time and care, one develops a relationship with the cosmos (and with one's equipment) that can be deeply fulfilling.

Keep at it.

(You could also just get a refractor and enjoy the lack of collimation, much easier/faster cooling, and wider range of practical magnifications 😇 But the other points would still apply.)

[Mr Spock]

As has been said, the 2.5mm eyepiece is too much for your scope - I don't even use those sorts of magnifications in the 15" Newt! My advice would be to get yourself a decent 7mm eyepiece and enjoy crisp views at x214. I use a 7mm Nirvana and it's the best £85 I've spent!

I used to own a C9.25 and there are a few thing that are essential with SCTs. First is collimation; even slightly out they underperform badly. Second is cool down time; SCTs need a long cool down time if they have been stored indoors - factor in at least 2 hours. Third, seeing conditions. I found the C9.25 was more susceptible to poor seeing than other scopes I've had, so be aware of that.