Zoom EP's and Planets

[Telescoop]

Hello, I was watching a video where someone was using a Nexstat 6se to film Jupiter, and while itbisbgood all Incould wonder is why it was so small in the view, if the person had a better Eyepiece, would Juliter have appeared bigger and/or clearer?, I am getting a 25mm with the 6SE, I am thinking of getting a 8-24 Zoom Lens would be a first good addition.. Any suggestions? Thanks! Heres the video with Jupiter and Saturn, it seems like it is a Wide mm eyepiece (I mean long focal mm length?)

[Moonshane]

This looks like a highly magnified view of Jupiter. I'd estimate it to be about 500-600x. You'd be lucky to use 250x visually in the UK on most nights. Imaging is very different to visual. That said, my visual images although smaller are much sharper and brighter than shown with a lot more detail.

[John]

I agree with Shane - that video shows Jupiter and Saturn quite a bit larger than it will appear through the eyepiece of your scope at it's top end magnification which will be around 250x. You might see a little more detail than the video is showing once you get used to observing these objects.

[RT65CB-SWL]

Hi again 'Telescoop'.

I am with 'Moonshane' & 'John' on this one. I personally would go for individual eyepieces rather than the 8-24mm zoom, or maybe a quality Barlow or PowerMate upto 2.5x

I do have and use a TeleVue 3-6mm Nagler zoom and the view I get of Jupiter & Saturn is 'sharper' than what is shown in the video, even in my light-polluted sky.

[ronin]

Unfortunately it is accurate to say ignore any video or image if you are thinking of visual observations.

A camera can/will have the gain turned up - your eyes are unable to do that.

As to the size, if you select and crop then the bit selected appears bigger.

Zooms are useful, they have improved a lot over the years, but you still need a good one.

Do not get hung up on magnification, for Saturn and Jupiter you want a good sharp clear image.

If they were imaging Saturn and producing a video then they will not be using an eyepiece.

The arrangement is scope to webcam - where the webcam is modified by having the lens in it removed.

The scope acts as the lens to form the image.

For a single "photograph" of Saturn/Jupiter you take a video of Saturn, say 60 seconds worth, then process the video frames in something like Registax.

The reality is that only the best 20% or so of the frames are actually used, then it is processed and sharpened and finally you get a good (hopefully) image of the planet.

It really is somewhat of a mistake to see a video or image and then expect the same visually.

Also owing to human nature the person may have tried 10 or 15 video's of Jupiter, they are not going to post the poor ones which effectively failed. All they are going to put up is the good/best one.

For your 6SE and visual suggest the 25mm it comes with, a 32mm for wider, and say around 12mm for Jupiter or Saturn. 15mm would be useful for when the 12mm doesn't work.

[jetstream]

I see Jupiter with much more detail too, about 300x is max for me here +/-. More contrast, colors and sharper etc, the 10mm BCO does a great job on this planet- near unbeatable for the price IMHO. 

[Telescoop]

Hi again 'Telescoop'.

I am with 'Moonshane' & 'John' on this one. I personally would go for individual eyepieces rather than the 8-24mm zoom, or maybe a quality Barlow or PowerMate upto 2.5x

I do have and use a TeleVue 3-6mm Nagler zoom and the view I get of Jupiter & Saturn is 'sharper' than what is shown in the video, even in my light-polluted sky.

(i never know if im supposed to write Above or Below the Quote!?!?)

Thanks, the Televues do look positively spectacular, But, are upwards of $500-700, the Agena Zoom lens I was looking at is only $60 and as they are Very proud of their products, it Has to be pretty good!. It is 8mm to 24mm and not only has smooth no click operation, and some way of maintaining constant focus between powers called 'Parfocal', but also a useful integrated T-Mount thread, that seems pretty relevant to what I'm hoping to attempt. (And endlessly useful for media production in general)

Perhaps it would help to understand I am truly just a beginner really, i'm a cancer Survivor adding a long time interest as a hobby to offset the awful frustration of cabin fever induced by 3 years at hospital followed by another 2 at home during chemo... I need an interest other than sitting indoors at my computer Animating every waking (non-sick) minute.. It will actually be my First Telescope though I have always had a HUGE interest in science, etc. I am sure I would love a 100 degree (tele) view but the 60 of the Agena seems not too shabby, especially with all the other considerations.. Add a $1.29 T Mount Adapter from eBay that goes from 37mm to 42mm and I could even hook up my Canon HD HV10 Camcorder with its pretty Excellent Still Camera (I know its not 'DSLR' ? But it does have great Canon Optics, programmable ISO and Shutter control, full focus control with infinty setting. So certainly worth a try.., The Agena Zoom would take a whole Middle Range of eyepieces out of the price equation, allowing me to spend More on an Ultra-Wide Close-up EP like a Meade 5 or 6mm alomg with a Wide EP like a 33mm and I would have only 3 favorite EPs that go all thw way from 5 to 33mm in Many Concenient Increments!

I could say; point with the Agena at 24mm, zoom in interactively to 8mm to find a spot of interest (all while recording DVD Video!), THEN put in an ultra wide angle 5.3 (or whatever would be appropriate for a Nexstar 6 SE) So it Really seems to have a place in a lot of different setups...

Also, while I have you, ;~) ... a lot of people have mentioned that the 6 SE (or even 8) SE wont do well with eyepieces that are too 'small', If you or anyone have advice about the most powerful eyepiece I could use with the Nexstar 6 SE I would apreciate it, My main interest is in viewing the Moon, seeing it as close in as possible, like In the Craters... I don't mind a bit of atmospheric interference.. Perhaps a 5.5mm or 6mm? I Know I can't do 2.3 or 4mm, etc with a Nexstar 6SE, but what is the real limit? It is listed as having 360x Mag, can I achieve that? I should probably say, that I got to look through my 70 year old Brothers Orion XT10 Dobsonian with a 5.3mm 'pinhole' Plossi type cheap Eyepiece with NO Barlow, I looked at the Moon and saw a Peak onside a Crater... Comfort, Atmosphere, it all fell away as I saw something so cool, I'm trying to recreate that essentially.. BTW it was also June in Missouri with 99% Humidity... Still the view was amazing to me!..

Last question, Would the 8 SE get me Enough Closer with More Detail on the Close Craters to Justify Cost, OR would the Increased Atmospheric Interference due to Increased Aperture size (along with the $400 price jump) start to kick in (at least where it comes to living mear a city) to make it a case of dimishing returns? Making the 6 SE a little more logical choice on my instance? (Interested in Moon, Live near City, Limited Budget)

All the advice is greatly appreciated!

[Dave In Vermont]

To find out what a eyepiece (EP) will magnify, you look at the Focal-Length (FL) of the telescope, which, as a 150mm (6") F10, works out to 1500mm: The aperture of the telescope is 150mm or 6 inches. F10 means the FL is 10X 150mm = 1,500mm. Now divide the FL of the EP into the FL: 6mm / 1500 = 250X. And 250X is about the highest magnification for a 150mm or 6" scope. This is going by the 50X per inch rule, which presumes perfect "seeing" conditions.

'Seeing' as it pertains to astronomy on Earth takes into account how clear the sky is. Not just by looking with your eyes, but one also needs to factor in where in the sky you are looking. The nearing you get to the horizon, the more atmosphere you are looking through. Is there turbulence in the upper-atmosphere? Is there smoke from fires? Is there any haze? All of these must be factored in. Sometimes the sky will look awful, and actually have good seeing. And the reverse is also true. You'll develop a sense about these things with experience.

I'll let someone else explain astrophotography. This is a massive study all on it's own. Certainly doable though. One caveat for you: No one telescope will be a great choice for everything. Each type of scope excells at certain tasks. I would suggest you get your scope first, but refrain from buying more eyepieces and such until you get a chance to aquaint yourself with it and the supplied EP's. If it was me who was in the market, I'd throw the extra $$$ to get the 8" - 200mm - model. An 8" scope is capable of bringing in enough of a range of objects as to be worth the extra money. An 8" can keep an observer busy for a lifetime. Literally.

I'm glad you're asking these things before taking the plunge. You came to the right place for answers! And we love questions.

Enjoy,

Dave

[Telescoop]

I agree with Shane - that video shows Jupiter and Saturn quite a bit larger than it will appear through the eyepiece of your scope at it's top end magnification which will be around 250x. You might see a little more detail than the video is showing once you get used to observing these objects.

Thanks, just as a sort of mind experiment, for now (I will try soon;) What would happen if I got Jupiter as Large as I can get it in Eyepiece (maybe using a 6mm on a Nexstar 6 SE?) then engage the 10x Optical Zoom of my HD camcorder, would it not get closer and bigger by 10 times? (There is 200x zoom on top of that but I know digital zoom is less than useless) That 10x Optical Zoom though, has me hoping it will be of use!

[Stu]

A few comments from me. The video shown is not stacked and processed, it's just the raw video at the eyepiece. I agree with previous comments that the view you will see at the eyepiece under good conditions will be far sharper and with more contrast. Colour is more dependent upon your eye's sensitivity I find but still quite likely on planets as they are bright.

Useful magnifications depend largely on the scope and more importantly seeing conditions. In the UK it is often difficult to get over x200 or x250, although it is certainly possible. In countries with more stable, dry atmospheres x300 or more is possible. You will only find out through experience.

The 6SE and 8SE are on computerised, tracking mounts, so once set up properly they will keep objects in the field of view. To a degree this reduces the need for ultra wide, expensive eyepieces, although something around 60 or 70 degrees would still be nice. The scopes also have a relatively long focal length at f10 which is good for easily achieving higher magnification with more comfortable, longer focal length eyepieces, and it also means it is less demanding. On those eyepieces ie you don't need top notch televues to achieve good results!

Aperture determines a number of things, but light gathering and resolution are amongst the most important. Given your desire to see the best views of planets and the moon, you will get better resolution and detail with the 8SE, so if you can handle this physically then I think it's worth going for.

In terms of using the camera to view, if you used a 6mm and got x338, you would get a large and probably blurry image. If you then magnify this further you will get a larger, blurrier image!!

Stick at realistic magnifications and you should get some nice results.

Cooling, collimation and seeing conditions are all important for the view you see, so these are worth understanding once you have your scope.

Good luck

Stu

[michael.h.f.wilkinson]

I have a Celestron GP-C8 (same optics as the 8SE), and focal-length-wise never use EPs shorter than 7mm on Jupiter and Saturn. I might use 5mm on the moon or Mars. The Nagler zoom is excellent but not really useful in a scope with a focal ratio of F/10 (like the 6SE and 8SE). I do have a 7.5-22.5 William Optics Zoom, which is pretty good, and I use it in my grab-and-go solar scope. It is not the match (detail wise) of a Pentax XW 7mm on planets, however. A good rule of thumb is to take the F-ratio of the scope (10 in this case) and use EPs of focal lengths between that value and half that value (so between 10 and 5mm) for planetary and lunar observing. Often, 10mm is the best you can do, and under good, steady skies, you might use 8 or 7mm, and only on bright, high contrast objects use 6mm or even 5mm. For nebulae and other DSOs, I use anything from 42mm to 12mm (single EPs rather than zoom)

[Highburymark]

Agree with what's been said. With 6 inch Celestron in the UK wouldn't normally go much under 10mm - 8mm under excellent conditions.

[LukeSkywatcher]

Id normally stick with 8mm on my 8se. On the very rare night of perfect conditions, i might kick the eyepiece up to 6mm.........mainly on the moon.

[bomberbaz]

Thanks, just as a sort of mind experiment, for now (I will try soon;) What would happen if I got Jupiter as Large as I can get it in Eyepiece (maybe using a 6mm on a Nexstar 6 SE?) then engage the 10x Optical Zoom of my HD camcorder, would it not get closer and bigger by 10 times? (There is 200x zoom on top of that but I know digital zoom is less than useless) That 10x Optical Zoom though, has me hoping it will be of use!

Although I have never tried this I imagine it will be a washed out blur, thats 2500X magnification you are talking about if I read you right.

[YKSE]

I agree with above comments about size and clarity of Jupiter. just want make an anology to camera pictures.

A picture taken by a camera with certain Megapix, you can enlarge it, but as you enlarge it, it gets blurrier, many details doesn't look as good as in original size.

Aperture of a telescope, design of a telescope, seeing conditions dictate how much magnification you can use(=best picure), if you go higher magnification, that's just the same thing as trying to enlarge a picture.

As to you question about a zoom, I think 8-24mm zoom a good idea, seeing changes during the night, you'll be easy to catch moments of good seeings with zoom than changing to other fix focal eyepieces. For your scope, a 5-3 Nagler zoom will mostly likely be waste of money.

[jetstream]

My zoom vote would go to the Baader MKIII and Yong makes a very good point about catching the seeing with one. I love zooms myself.

[Telescoop]

This looks like a highly magnified view of Jupiter. I'd estimate it to be about 500-600x. You'd be lucky to use 250x visually in the UK on most nights. Imaging is very different to visual. That said, my visual images although smaller are much sharper and brighter than shown with a lot more detail.

Sounds like yet another reason the 8" is better than the 6... It Doesn't seem much heavier either...

Thanks! Im SO close to purcase day. Next couple days I decide, Thanks for all the comments!

[Telescoop]

To find out what a eyepiece (EP) will magnify, you look at the Focal-Length (FL) of the telescope, which, as a 150mm (6") F10, works out to 1500mm: The aperture of the telescope is 150mm or 6 inches. F10 means the FL is 10X 150mm = 1,500mm. Now divide the FL of the EP into the FL: 6mm / 1500 = 250X. And 250X is about the highest magnification for a 150mm or 6" scope. This is going by the 50X per inch rule, which presumes perfect "seeing" conditions.

'Seeing' as it pertains to astronomy on Earth takes into account how clear the sky is. Not just by looking with your eyes, but one also needs to factor in where in the sky you are looking. The nearing you get to the horizon, the more atmosphere you are looking through. Is there turbulence in the upper-atmosphere? Is there smoke from fires? Is there any haze? All of these must be factored in. Sometimes the sky will look awful, and actually have good seeing. And the reverse is also true. You'll develop a sense about these things with experience.

I'll let someone else explain astrophotography. This is a massive study all on it's own. Certainly doable though. One caveat for you: No one telescope will be a great choice for everything. Each type of scope excells at certain tasks. I would suggest you get your scope first, but refrain from buying more eyepieces and such until you get a chance to aquaint yourself with it and the supplied EP's. If it was me who was in the market, I'd throw the extra $$$ to get the 8" - 200mm - model. An 8" scope is capable of bringing in enough of a range of objects as to be worth the extra money. An 8" can keep an observer busy for a lifetime. Literally.

I'm glad you're asking these things before taking the plunge. You came to the right place for answers! And we love questions.

Enjoy,

Dave

Thays great. Thanks, and thanks for the help in general. I think I have actually decided on a (drum roll please) used but new new looking Classic C8 with wedge amd a bunch of accessories. I would like the goto, ut perhaps I can add that later with a GEM or something if appropriate.. I ever had a telescope even though I always wanted one - Getting one that was out and around when I was ten makes me FEEL something that the new 8se doesnt.. Like, it was waiting for me, and though im 46 I still get to explore with it, now that I will really appreciate it and video/image it. Etc.. The price is right for ao many accessories (nice full solar filter, invertor, original 70's manuals,etc.) It has the lind of mount people say is better for imagery, and it has the Fork Design which I think looks lws like a toy than the SE's.. I'd rather have ine made in California than China as well. Do you think it would be possible to Update the Mount (or motors etc) to make it a goto? And / or, IF THE MOTORS BREAK AND it stops Tracking! Is it dead or fixable, (I think I mea. Replaceable not necessarily fixable although t is mechanical and im good at fixing things. Ill learn the maintain it. Clean and grease the gears, maybe I can get it to last another 10-20 years, ts lasted about 42 years if it is an early model, as I hope it is.. you I said it in 'public' my mind is apparently made up, I'm taking the chance on a used C8 superbundle to get an 8" with a wedge at a better price than a 6SE without.. I think id regret not taking the chance. Any tips to request safe shipping, swtting or toggles that steady it for travel? I have been practicing changing exposure and ISO setting on my old HD Canon HV 10 camcorder. LoL, Old telescope, Old Camera Old me! Thanks so much for the help!

HEY THERES NO ANNOYONG ADS AT THIS SITE!

[John]

I hope you enjoy your older C8 when you get it. As long as it's not one made in the run up to the return of Halley's Comet in 1986 it should be a good scope. I used to have a Celestron C8 from the early 1990's and that was very nice. It's only faults were more vibrations from the fork mount than I'd expected and that it had some mirror flop (common on older SCT's) which was annoying as the scope went out of collimation when it pointed at certain angles.

If your electronic skills are good GOTO modifications might be possible but I don't think you will find an off the shelf solution for these scopes now. Being in the USA you might have better access to experience in modifying the Celestron C8's than we do over here in the EU / UK.

You might see if there is a Yahoo group on the topic of C8 ownership and improvement. There are groups there on most things.

Rod Molise's website is a very good source of information on SCT's and Celestron SCT's in particular:

http://skywatch.brainiac.com/astroland/

His free guide to used CAT's is really worth downloading and reading

[RT65CB-SWL]

Thays great. Thanks, and thanks for the help in general. I think I have actually decided on a (drum roll please) used but new new looking Classic C8 with wedge amd a bunch of accessories. I would like the goto, ut perhaps I can add that later with a GEM or something if appropriate.. I ever had a telescope even though I always wanted one - Getting one that was out and around when I was ten makes me FEEL something that the new 8se doesnt.. Like, it was waiting for me, and though im 46 I still get to explore with it, now that I will really appreciate it and video/image it. Etc.. The price is right for ao many accessories (nice full solar filter, invertor, original 70's manuals,etc.) It has the lind of mount people say is better for imagery, and it has the Fork Design which I think looks lws like a toy than the SE's.. I'd rather have ine made in California than China as well. Do you think it would be possible to Update the Mount (or motors etc) to make it a goto? And / or, IF THE MOTORS BREAK AND it stops Tracking! Is it dead or fixable, (I think I mea. Replaceable not necessarily fixable although t is mechanical and im good at fixing things. Ill learn the maintain it. Clean and grease the gears, maybe I can get it to last another 10-20 years, ts lasted about 42 years if it is an early model, as I hope it is.. you I said it in 'public' my mind is apparently made up, I'm taking the chance on a used C8 superbundle to get an 8" with a wedge at a better price than a 6SE without.. I think id regret not taking the chance. Any tips to request safe shipping, swtting or toggles that steady it for travel? I have been practicing changing exposure and ISO setting on my old HD Canon HV 10 camcorder. LoL, Old telescope, Old Camera Old me! Thanks so much for the help!

HEY THERES NO ANNOYONG ADS AT THIS SITE!

Congratulations!

If it is the orange tube C8, then it is the one of the classic 'scopes that I wanted, (and the Questar 3.5)