NexStar 5SE & 6SE queries
Posted 10 October 2012 - 11:28 AM
I appreciate that there isn't a single telescope 'for all occasions' but I'd like to be able to use it for visual work & to dabble in a bit of imaging (especially Jupiter & the Orion Nebula), which I'm very fond of). Is the 6SE worth the extra £190?
Apologies in advance if these are stipid questions, or have been asked elsewhere, but I'd be very grateful for any advice on the following:
i) Why is that most people only appear to image Jupiter etc using a webcam, rather than using a single camera exposure? I've managed to get a (very basic) image using only a 300mm lens & even captured 3 of the moons, so I assume that via a 5-6 inch telescope the image would be a lot more impressive? I understand the benefit of long exposures/stacking for DSOs, but Jupiter is very bright!
ii) If single exposure photography isn't suitable for Jupiter, has anyone tried to use HD video, rather than a webcam? (my 550d has this option, although I haven't ever used it). Are Registax etc capable of stacking HD images?
iii) If you use something like Registax, can it cope with multiple photos, as my 550d creates photos of 6-8mb, and is there a realistic minimum RAM requirement for it to run? Is 3GB sufficient?
Thanks for your help, Robin
Posted 10 October 2012 - 01:10 PM
If you look down the NexStar list you will find recent responses to your inquiry comparing 5SE and 6SE scopes. Your post suggests that astrophotography ranks high on your list of uses for the scope. If so, I suggest you consider a C6-SGT rather than 6SE. The german-equitorial mount is much more appropriate for photography.
Posted 10 October 2012 - 01:36 PM
As for the webcam - this is a technique also known as "Lucky Imaging". At the high magnifications needed for planets, seeing is a big problem and blurs the image like looking through the hot air above a campfire. This blurring changes by the second, and will sometimes clear up for very brief periods of time. If you take a long enough video, you can get "lucky" and capture many of these moments of clarity.
The stacking software then combines the best of the images, throwing out the most blurred ones, and creates an image with much better sharpness and detail than can be gotten from any single image.
Posted 10 October 2012 - 02:29 PM
Welcome to CN and to this forum !
I don't know with any certainty, but I see no reason why, if your 550D possesses video capabilty, it should not do the same job as a webcam.
Such obviously depends in what format your HD video will download its frames and at what frame rate(s) it operates.
If for example it is capable of downloading in fits format and at a frame rate somewhere between 5 and 30 frames per second, then I see no reason why these should be incompatible with Registax.
Posted 10 October 2012 - 03:48 PM
I really like the 6SE, but if it's not suitable I might need to have a re-think. I'm signed up to an Astrophotography course this weekend and I'm hoping that this will help. There's so much to learn and I've found it difficult knowing where to start!
Dan - thanks for the explanation regarding the benefits of using a webcam, I hadn't realised that the image clarity could vary so quickly. My EOS has an option to take multiple photos in few seconds, so it might give that a go at some point in the future and see if I can 'get lucky'!
Thanks again for all of your help, and if anyone has any photos of Jupiter taken with a 6SE & a 550d I'd be very grateful if you could post them
Posted 10 October 2012 - 07:23 PM
Posted 10 October 2012 - 09:07 PM
My EOS has an option to take multiple photos in few seconds, so it might give that a go at some point in the future and see if I can 'get lucky'!
Well, you really want to get tons of images to stack them using software. Normally, people will take several minutes of video and get thousands of images to start with. The stacking software automatically grades the images as to quality level and lets you pick a threshold for how many you want to use - say the top 20% best images. It then stacks those to bring out the most detail and reduce the noise. Once that's done, the software provide sophisticated sharpening algorithms like wavelets to enhance the detail.
But for this to be effective, you need thousands of frames, not just the few you get with burst photo mode. Plus, with the still image mode, you'll get far more resolution in each image than you need for the amount of detail available through the scope. You'll end up increasing your processing time dramatically for no increase in image quality.
There's several ways you can take use your DSLR instead of a webcam. One is to use the HD movie mode you mentioned. That should work fine. There is also a free application called movrec that is available for Mac or Windows that records what you see on the live view screen. Or you can get BackyardEOS which does the same thing in addition to offering lots of features for DSO photography as well. I use BackyardEOS and highly recommend it.
Posted 11 October 2012 - 06:30 AM
Venus, Mars, Jupiter, Saturn, Uranus,and Neptune.
Some were taken a couple of months or years apart and show how the size changes depending upon distance.
These are all at the same image scale, taken through my NexStar 6 SE with a Meade LPI "webcam".
Posted 20 November 2012 - 03:57 PM
Well, following a month of serious deliberating I finally took the plunge and ordered the 5SE last night. I was going to buy the 6SE but it had been out of stock for a couple of weeks at my local distributor and took this as a sign!
Actually, I checked again today and the 6SE was back in stock....I think that the term I'm after is 'Doh'!
Anyway, I'm collecting it tomorrow & I'm soooo excited!! I've already got the adapter for my EOS 550d, so all I need now is a dewshield, powertank, some spare lenses and maybe a webcam but they can wait until next month.
Thanks again to everyone for your advice, I'll let you know how I get on. It might be a while though as it hasn't stopped raining here for the last 24 hours......
Posted 21 November 2012 - 12:34 PM
I'd be tempted to suggest when picking the 5SE up that as you haven't even opened the box, can you upgrade immediately?
I have the feeling that if you "flash the cash", they'll sort it out for you.
The 6SE has a steadier mound, a wider database of objects and, of course, that valuable extra aperture.
Posted 21 November 2012 - 05:13 PM
I collected it this afternoon & my initial impressions are very positive; it seems well built (apart from the red-dot sight) and the software is intuitive. After 30 minutes I had it tracking the moon, and then had a very brief glimpse of Jupiter before they dissapeared under dense cloud.
My only dissapointment was the magnification from the standard 25mm Eyepiece; Jupiter was a bright dot with 3 smaller dots around it! The manual states that the maximum theoretical maximum is 300x... I was debating getting a 6mm as this would give 208x but would appreciate any advice on this. I'm particulary interested in viewing Jupiter & Saturn, & wear glasses, which I assume will complicate things!
Posted 21 November 2012 - 06:40 PM
... a wider database of objects and ...
I don't think that's the case these days. I believe that all the alt az mounted Celestron scopes (with the exception of the GT models) are using the same firmware and hardware for the hand controller.
And from some earlier postings here it appears that even the GT scopes can be firmware upgraded to the regular NXS4.xx releases which gains you the full 40,000+ object data bases.
Posted 21 November 2012 - 07:37 PM
I'd go slow on getting that 6mm., if you have to observe with glasses. I believe a better approach would be to get a 2x or 3x barlow In conjunction with an EP in the 12mm range. That way you have better eye relief than with the 6mm and you get the power that you're looking for.
Posted 21 November 2012 - 08:43 PM
A very warm welcome to CN and to this forum !
Please don't be attracted to claims of high magnification especially in small to medium aperture 'scopes. They may be attainable but believe me, so rarely, that I would not waste any hard earned cash on the excessively short focal length eyepieces necessary to reach them !
Indeed I was using a 6mm on my Nexstar 8i tube tonight, purely to check its collimation, but for all practical viewing purposes, its focal length is too short even for this 'scopes 8" aperture.
It is true that these very short focal length EPs might exceed all expectations once every ten years or thereabouts when that superbly clear and atmospherically stable night comes around, but for all other occasions, I would advise you to look for something with a little longer focal length like perhaps an 8mm, 9mm or 10mm.
If you're not too familar with observing as yet, you'll soon appreciate, I'm sure, that the best views, (and I have to generalise here), are in fact obtained via EPs of medium to low magnification.
If you're interested, the Baader Hyperion Zoom EP, (at ca. $290), offes an "all-in-one" comprehensive range of focal lengths, (24mm, 20mm, 16mm, 12mm and 8mm), in one single unit which might well suit your 5SE.
Just a thought,
Posted 21 November 2012 - 11:57 PM
I could not agree more than what Tel has said about High magnification however I still think that if you get a 2X Barlow and use it with your 25mm that's like getting a 12.5mm EP with the eye relief of the 25mm. Sorry that I didn't warn you about High Magnification and the difficulty of getting good images with them in my previous post.
Posted 22 November 2012 - 07:01 AM
I use an 8mm X 24mm zoom as my main eyepiece so I second Tel's recommendation.
You might try observing without your glass's. I wear them on a permanent basis, but take them off at the eyepiece. I have never experienced any ill effects, even though I can barely see without them. I just bring the object to sharp focus and observe. I have tried observing with them on but have given up. The view is so much better, for me anyway, with them off.
I hang my glass's around my neck on a lanyard when at the eyepiece.
Enjoy your new scope.
Posted 22 November 2012 - 10:09 AM
I think the 5SE is a great choice as a scope to start with. Just my opinion, but since I own a 5SE and an 8SE, I think it fits better into a future lineup of scopes than a 6SE.
Most people end up with more than one scope. If, down the road, you decide to move up to an 8SE, the 5SE is different enough to warrant keeping as a travel scope. To me, the 6SE and 8SE are closer in capabilities and size and there's not enough difference between the two to make me want to keep a 6 if I have an 8.
One nice feature you may not know about these scopes is that they can operate as a table top model, without the tripod - assuming you have a reasonably stable surface to put it on. This makes it even more portable if you can leave the tripod at home. The 8SE will theoretically work in this mode too, but it's pretty top heavy and I'd worry about tipping it.
As for eyepieces, I'd start with something in the 10-13mm range. I have a 13mm Baader Hyperion and it is my most used eyepiece. Your maximum magnification will usually be limited by atmospheric seeing conditions rather than the scope's capabilities. Most any night I can get to 150x (13mm EP). A little less than half the nights I can use my 8mm EP to get to about 250x. Only on rare nights of perfect seeing, maybe 2-3 nights a year, can I use my scope's full magnification capabilities with a 5mm EP.
Posted 22 November 2012 - 01:43 PM
Next questions if you don’t mind:
i) I’ve purchased the Celestron T-adapter & the T-ring and I was wondering what the best method for attaching everything together? As far as I can tell you can either slot them into the star diagonal (after removing the eyepiece obviously) or remove the diagonal & attach it directly to the back of the telescope. I’ve been trawling the internet for answers and getting rather confused!
ii) What sort of magnification will this be approximately? I initially thought that the adapter would use the eyepiece somehow, but it does seem to fit within it!!
Posted 22 November 2012 - 03:08 PM
i) Directly to the back of the scope. The T-Adapter has SCT threads on one side, these attach directly to the back of the scope or to an f6.3 Reducer corrector (which makes the scope faster). The T-Ring should be a model that matches your DSLR.
ii) With the C5 and your camera you effectively have a 1250mm f10 telephoto lens (or a 788mm f6.3 with the reducer/corrector in place). "Magnification" will depend on the sensor size in your DSLR. If you want to try out some examples of how things will look size wise download CCDcalc and select your scope and camera from the lists (or create a new entry for you camera but you'll need some very specific numbers about the sensor in your camera (# of pixels and their size).
1250mm is not really long enough for work on the planets. For that, you'll need a 2 or 3X barlow and a different adapter. Your setup will work well on the moon and sun (with proper filter). At f6.3 or faster you can also start to take a few shots of the brightest DSOs (like M42 for example).
Posted 24 November 2012 - 05:27 AM
Second (pre-First Light!) report:
The forecast looked good, but early last evening the sky was covered in a thin veil of cloud, which was a little dissapointing to say the least. However, I could see the moon & decided to have another go at getting used to the set-up & tracking. I used the solar-system align & it seems to work really well.
First discovery is that I need to invest in a powertank; I'm currently using 8 x 2450mah rechargables & they died really fast. I managed to attach my EOS 550d via the eyepiece, but the lack of power stopped me after I'd only taken a couple of test shots. Even though the moon was covered I'm really impressed by the detail, this definately has potential!!
I tried again a couple of hours later, following a partial re-charge, and although the moon was still covered, Jupiter was totally clear. The view was far more impressive than my first attempt and although it was only 50x I could make out two faint bands!! I couldn't get an image on my live-view, but I guess I need to play with the focus? I found that I had to move the adjuster quite a distance anti-clockwise to get the moon in focus; do I keep going for a more distant object?
I'll post some photos as soon as I get some decent results
Posted 24 November 2012 - 10:31 AM
The problem with rechargeables is that they are usually Nickel Metal Hydride or NiMH. This means that each cell is 1.2v instead of the normal 1.5v of a non-rechargeable alkaline battery. When you string 8 of them together, you only get 10 volts instead of the needed 12 volts. They will work for a little while, but they quickly drop below the voltage needed to power the mount.
A power tank is a popular choice because they are available everywhere, are reasonably priced, and usually have the needed cigarette lighter jack built in. But they are heavy, and you have the issue of the cord wrapping around the base during use.
Another option is to get a 10-cell NiMH battery pack that rides on the base of the mount. With 10 cells instead of 8, you do get the 12v that the mount wants and they work quite well. They're much lighter than a power tank and you eliminate the cord wrap issue because the battery pack moves with the mount. The only downside is you have to wire up a connector yourself. Here's my setup:
I got the battery and charger at:
Mine lasts 4-5 hours powering the scope and 2 dew heater straps.
ii) What sort of magnification will this be approximately? I initially thought that the adapter would use the eyepiece somehow, but it does seem to fit within it!!
There's three kinds of AP (astrophotography): afocal, eyepiece projection (EPP), and prime focus. Afocal is where you just hold your camera up to an eyepiece and snap away. In this case both the camera's lens and the eyepiece are in place and both affect the magnification. However, since these optical systems were not designed to work together, the results are pot luck.
In EPP, you remove the camera's lens but you leave the eyepiece in place. In this case, the EP projects the image directly onto the camera's sensor. The EP does contribute to magnification and changing EPs will change the image size. This setup requires some way to mount the camera to the EP. There are some EP's like the Baader Hyperions that are designed specifically for this purpose. They have a thread around the eye lens so you can screw on an adapter that mates to a T-thread which then connect to your camera. EPP is much better than Afocal but still, the EPs are designed to work with your eye, not with a flat sensor. They often curve the field somewhat and usually do not provide as good a result as with prime focus.
Prime focus is using the scope without an eyepiece or a camera lens, to project the image directly onto the sensor. This provides the best quality image, but of course it limits you to one image size. You can use barlows and focal reducers to change the image size, and they will do a better job than an eyepiece because they are simpler designs and tend to leave the image cleaner and the focal plane flatter.
Focal reducers can be pretty easy to use because they screw right onto the back of and SCT. You then jus use an SCT-to-Tthread adapter on the back of the focal reducer and a T-ring on your camera, and you're good to go.
Barlows are a little trickier because you don't find them with an SCT thread. To allow the use of a barlow, you have to get to a 2" eyepiece sized tube so you can use a standard 2" barlow in it. So the chain of adapters you need is:
SCT > 2" visual back > 2" Barlow > 2" nosepiece-to-Tthread adapter > T-ring > camera
Posted 24 November 2012 - 03:32 PM
SCT > 2" visual back > 2" Barlow > 2" nosepiece-to-Tthread adapter > T-ring > camera"
I use a Tele Vue Powermate that has an adapter that threads to the lens part of the barlow and has a T-thread for the camera. Works great in the 2" diagonal.
Posted 24 November 2012 - 07:02 PM
Yep. Although, having a 2" diagonal is like having a 2" visual back. Both serve the purpose of converting the SCT thread to a 2" barrel receptacle. I like to avoid using a diagonal for AP because it seems to attract more dirt and dust particles than other other piece of optics I own. Never could understand why, but when I clean my optics, it's always quite dirty. Plus, attaching directly to the back of the SCT eliminates the mirror as a potential source of misalignment.
Since your Powermate has a T-thread on top, it sounds like it eliminates the need for the 2" nosepiece-to-Thread adapter. That's handy!
Posted 26 November 2012 - 01:38 PM
Link below to my flickr account, if the attachment didn't work:
This is fun
Posted 26 November 2012 - 05:09 PM
Prime focus or afocal? Single frame, stacked or mosaic?
Any details would be welcome.