6" sct and samsung scb400 for first video setup?

[mwainwright]

Hi there, ive reposted this from the equipment advice section..

im thinking about trying to put together a highly portable video astronomy kit.. 

I was originally thinking the nextar 6se, but having spoken to modern astronomy about it, apparently the mount isnt great, he suggested maybe the skywatcher130p goto as having a better mount and being g a faster scope being better for dso's.

however, I keep being drawn back to the sct as it is so compact.

how would the synscan az goto mount, a celestron c6 sct ota, and a focal reducer be rather than the nextar 6se? Compared to a smaller newtonian, I think as a newtonian it would have to be a 4" to rival the portability of the 6" sct?

bearing in mind the aim is really video astronomy on planets and dso's

im thinking of the Panasonic scb4000 for a camera. Which has a 512 sens up and 1/2" sensor.. I, hopimg this would give me good views of galaxies and nebulae through the slowish sct.

how does this sound?

My budget is about £1000, I realise I can get a bigger newt for the cash, but size is my limiting factor more than cost.

cheers,

mark 

[shirva]

hi mark

the best scope for video astronomy is the skywatcher ed80..cant see anybody argue with that..the scope is 80mm and will capture a fair bit of the sky and if you fit a focal reducer even better..

skywatcher az tracking mount is ideal..goto is the luxuary bit lol.

the scb400 is Samsung/haven't seen a Panasonic one with that model myself..good camera dragonman uses this camera and is an expert on it.doing a bit of juggling between second hand and new this would be within budget...davy

[HiloDon]

Hi Mark,

Welcome to the VA forum. I've been involved with VA for a couple of years now, so I'll share some of my experiences. I have a number of scopes ranging from a 50mm Orion mini refractor to an 8" Meade SCT. I use all for near real time EAA viewing. One scope I don't have and I think would be ideal for portable EAA is the Vixen 110 modified cassegrain. It includes a flip mirror that would come in handy for EAA. It weighs less than 5lbs. and has a nice focal length for the smaller video chips. You would still need some focal reduction, but not as much as the 6" SCT.

http://www.optcorp.com/vx-26052-vmc110l-4-3inch-f-9-4-modified-cassegrain-ota-with-finder.html

I started with a scb2000 camera. It does a fair job for beginning EAA, but falls short on dimmer DSO's. It also has to be modified by removing the IR filter. It's easy, but the camera does have to be disassembled. I suspect you will have to do the same with the 4000. The limited integration times on these video cams will have you wanting for more exposure pretty quickly.

My next camera was the SX Lodestar X2 mono. It has unlimited exposure capability and with the Lodestar Live software developed by Paul in the UK, it performs as a great NRTV setup. It has only one wire which connects to a lap top. If you want only to use a monitor, then the LS will not work. I was so pleased with the LSX2 that I bought the color version as well. Both have given me many hours of DSO viewing pleasure. The one drawback is that the LS does not have short duration exposure, so planetary and lunar viewing are not easy.

Here is a link to my gallery of captures, all taken with both versions of the Lodestar. The camera is more expensive than the scb4000, but not by much when you consider the addition things you will need with the Sammy. Nosepiece, cables and some remote control will be needed. The Lodestar is complete out of the box.

http://stargazerslounge.com/gallery/member/36930-hilodon/

My captures will also give you some idea of image scale of various DSO's using different focal lengths. The little 50mm mini is great for large nebulae. It works best with a narrow band Ha filter.

If you check some of the threads here on the VA forum, you will find a lot of discussion about the Lodestars. Nytecam is the LS guru, so please check out his website. He does an amazing job in light polluted London.

I don't have any experience with portable mounts, so perhaps someone else has some advice.

I hope this helps. If you have any questions, just post them here or you can PM me.

Don

[shirva]

hi again mark..depends on how portable do you want to go

I have done a portable array that can be very portable or intregrated into a bigger set up.

it comprises of three Samsung cameras with different focal lenses that transfers three video feed to a cctv dvr unit fixed into a b&q plastic tool box,in the lid of the tool box is a12v dc monitor and all the kit is run from a heavy duty golf cart deep cycle battery,the battery has a jumper cable so you can attatch it to a car battery or plug the extension into a car 12v adapter or even a jump pack,,i also have a lead that powers the eq3 pro mount and Samsung scb2000 camera..so my portable set up two box cams and an all sky cam and a cam mounted ed80 is very portable a laptop is also fitted into this system to make it a pretty neat unit..pictures on my forum link below.

[HiloDon]

Mark,

Here's a review of the Vixen 110. It looks interesting for EAA. I'm almost thinking of getting one myself. Would appreciate hearing from anyone who has experience with it.

http://stargazerslounge.com/topic/68419-vixen-vmc-110l-ota-review/

Don

[DoctorD]

Hi Mark

Have a look at my gallery - I use a 102MAK and a F3.3 SCT reducer to good effect with both the lodestar and the SDC435.

You could also consider the INED70 or similar with a suitable focal reducer (x0.6) - the problem with SCT or MAKs for video astronomy is that the focal ratio is too high.

I have used the Skywatcher on the synscan AZ mount - the accuracy of the mount made it difficult to get targets in the FoV with the MAK (even with the F3.3 focal reducer), however teh INED70 and a x0.6 focal reducer was much more forgiving. (`see my M42 images take with the Lodestar).

HTH

Paul

[mwainwright]

hey guys,  thanks a million, this is a lot of help, though the whole focal ratio is still a bit confusing to me.. 

just to get it clear in my head, 

the SCT`s have a high focal ratio, is this essentially just the fact that they have a narrow field of veiw compared to an equivalent newtonian or refractor? 

is the main reason an SCT is less suited to video astronomy purely because many DSO`s are too big to fit the image, or that not enough light falls on the sensor?  and the smaller DSO`s that do fit, are too dim anyway? 

i cant get my head around the brightness thing, if, hypothetically you had an SCT and a refractor of the same size mirror/lens, with the same FOV, they would have the same focal ratio?

is an 8" newtonian only a faster scope than an 8" sct because it has a wider FOV for the mirror diameter? 


i`m starting to rethink my setup a bit. 

ive spoken to two astronomy places about goto mounts, (lower end altaz mounts, i dont want all the weight associated with an equatorial) 

one seemed to suggest the skywatcher az goto is better than the nextar 6/8 mount, and the other said the exact opposite...    my suspicion is that the skywatcher is the less sturdy of the two. 

i was leaning to wards mounting something cheap and cheerful like an orion ST80 on a skywatcher altaz mount, but i also wanted tohe capacity to add a bigger scope (like a 6" sct) if i wanted more detailed views, so dont really want to underbuy the mount..  i want someting with a little futureproofness in it. 

the other guy i spoke to said i`d have no chance at getting images in a video camera with an orion st80 due to exposure times, but i dont think he was super familiar with the video astronomy side of things as he suggested i go to the regents park stargazing night and chat to a few people, which sounds like a good idea anyway.

any thoughts on here about AZ gotos and the orion st80? 

that vixen does look cool too, I`d be interested to see what kind of views it gets with a ccd cam. 

 

[mwainwright]

* i mean i was talking to people about lower end altaz GOTO mounts.    

[DoctorD]

Hi Mark

These video cameras have limited exposure time typically 10s to 20s, therefore we need the maximum possible light hitting the sensor.

Focal ration is a key factor here - SCT's typically have a high focal ratio due to their design limitations. The field of view is set by the focal length and the sensor size, the light hitting the sensor is set by the aperture, so scope with a 1m focal length will always give the same field of view regardless of aperture, however the bigger aperture will give a brighter image due to the shorter focal ratio.

Experience has shown that the SBC 2000 and SBC 4000 work well at F4 or there about for DSO work irrespective of aperture. We will not be pushing the limits of resolution with our low pixel count large pixel cameras.

The Skywatcher AZ mount is sold with a 127MAK (5") and this is considered to be the heaviest scope the mount can reasonably handle, I'm not sure a 6"SCT would be OK.

The 8" Celestron SE mount is more sturdy than the Skywatcher AZ.

The Synscan AZ and an ST80 would be a good starting point although I'd seriously consider an EQ3-2 with Synscan and a small refractor - but I understand you want light weight. For video you will only need rough polar alignment (don't be afraid of polar alignment, it's not that difficult for visual/video).

The SCB4000 has a noise reduction mode that effectively extends the exposure time, and drift will be seen as blurring of the image,  in AZ mode I was not able to use this successfully.

You might also want to consider the iOptron mounts and a small refractor.

Try using Stellarium to simulate the field of view at various focal lengths to get an idea of what DSO's will fit any given combination.

Hope this helps

Paul

[Martin Meredith]

Hi Mark

FOV is determined by focal length and sensor dimensions. For a given sensor, increasing focal length decreases your field of view and vice versa. For a given focal length, using a larger sensor provides a wider field of view, as you'd expect. This is irrespective of what type of scope you use, so a Newt with a focal length of 800mm will provide the same FOV as a refractor or SCT of the same focal length.

To be able to image/observe objects of a range of sizes you have a number of options. As an example, suppose you want to image a DSO like M31 that is too large for some hypothetical existing setup.

1. You could use a larger sensor. E.g., instead of my small sensor Lodestar I could use a DSLR camera with a significantly larger chip. So why don't I? In this case it comes down to sensitivity (and perhaps some practical matters like download times for large image files). The Lodestar is much more sensitive than my Canon 1100D. That means I can find fainter DSOs in the same exposure time. I could "improve" sensitivity by summing pixels in small regions but that reduces image resolution.

2. You could use a smaller focal length scope. Many people have several scopes, each suited to different purposes. A good set of scopes might have FLs of 350, 800 and perhaps 1500 mm. Don and others have shown great results too with shorter focal lengths provided by finderscopes -- great for large nebulae. The only disadvantage here is cost (and perhaps the hassle of changing setups or mounting several scopes).

3. You can decrease the effective FL of the scope you have using a focal reducer. There are limits, but reductions of around 30% are practical without too much image deterioration. Disadvantages: extra glass in the way of precious photons; some distortions. Dragon Man has some videos showing how you can turn binocular objectives into cheap focal reducers.

Going the other way (increasing focal length, perhaps for useable planetary images) can be achieved using a Barlow.

There are nuances to all of the above (e.g. fast versus slow; focusing; collimation…) and I hope others will chime in with their thoughts.

My own view is that option 2 is preferable in the long run as you're using your equipment at its sweet spot (no reducers/Barlows, most sensitive sensor) and has the advantage that it can be approached incrementally e.g. perhaps start out with a medium FL scope which is going to show some good detail on many DSOs, and then decide if you want to see wider views of nebulae/starfields. Given the sensor size of most cameras used for electronically-assisted viewing an 80mm f/5 scope i.e. 400 mm focal length will produce some excellent results on DSOs, globs, galaxy groups, dark nebulae… and you'll find there are plenty within reach once you start out in this game. I started out with a second hand 80mm f/6 achromat and have been very happy with the results apart from star bloat.

Your other issues of alt-az, mounting and brightness I'll leave for other posts unless someone beats me to it …   [EDIT: DoctorD did exactly that!]

cheers

Martin

the SCT`s have a high focal ratio, is this essentially just the fact that they have a narrow field of veiw compared to an equivalent newtonian or refractor? 

is the main reason an SCT is less suited to video astronomy purely because many DSO`s are too big to fit the image, or that not enough light falls on the sensor?  and the smaller DSO`s that do fit, are too dim anyway? 

i cant get my head around the brightness thing, if, hypothetically you had an SCT and a refractor of the same size mirror/lens, with the same FOV, they would have the same focal ratio?

is an 8" newtonian only a faster scope than an 8" sct because it has a wider FOV for the mirror diameter? 


i`m starting to rethink my setup a bit. 

ive spoken to two astronomy places about goto mounts, (lower end altaz mounts, i dont want all the weight associated with an equatorial) 

one seemed to suggest the skywatcher az goto is better than the nextar 6/8 mount, and the other said the exact opposite...    my suspicion is that the skywatcher is the less sturdy of the two. 

i was leaning to wards mounting something cheap and cheerful like an orion ST80 on a skywatcher altaz mount, but i also wanted tohe capacity to add a bigger scope (like a 6" sct) if i wanted more detailed views, so dont really want to underbuy the mount..  i want someting with a little futureproofness in it. 

the other guy i spoke to said i`d have no chance at getting images in a video camera with an orion st80 due to exposure times, but i dont think he was super familiar with the video astronomy side of things as he suggested i go to the regents park stargazing night and chat to a few people, which sounds like a good idea anyway.

any thoughts on here about AZ gotos and the orion st80? 

that vixen does look cool too, I`d be interested to see what kind of views it gets with a ccd cam. 

 

[HiloDon]

Hi Mark,

The Doctor has given you some sound advice. In addition I found a nice tutorial on telescope basics you might want to read.

http://starizona.com/acb/basics/equip_whichisbest.aspx

I don't think an SCT is less suited to VA than a refractor or Newt. Each has it's pros and cons. The SCT usually has a longer focal length and smaller FOV because of it's folded design which makes it more compact. It's usually slower around F10, but both the FL and speed can be compensated for with focal reduction. The SCT also has an advantage over a refractor for VA because the refractor has problems with focusing IR light with the visible spectrum. This causes star bloat which can degrade the image. I have used the ST80 with the Lodestar. It has a fairly wide FOV and because of the star bloat I use a narrow band Ha filter. It works well and I like the image quality better than an ed80 I have. You can see some of the ST80 captures in my gallery.

I have never had the chance to use a Newt, but from reading a lot, they are longer and heavier and appear to have problems with focusing if you use any focal reduction, although the focal reduction is less necessary because the speed is usually faster and FL shorter out of the box.

I think all three are suited for VA, but none can do all things.

Don

Edit: I see I was typing at the same time as Martin. He, as the Doctor did, has given excellent advice.

[mwainwright]

Great, thanks,ill mill over that, just downloaded stellarium.

those ioptron goto mounts look great. The cube pro also looks affordable, might tot up the cost of one of those plus 80mm refractor, seems like that might be a good starter kit, the gps in the mount appeals too. It says itll carry 5kg ota's would a 4.5kg c6 sct ( im just thinking ahead here) be pushing it? If I decided to get one of those later on.. I really only want one mount.. the 11kg carrying minitower2 is a bit out of my price range for the mount alone.

cheers,

mark

[Martin Meredith]

Hi Mark

You could also consider getting more out of your budget by buying second hand. I don't know if its still available but there's a barely-used colour Lodestar in the classified section at the moment. If you plan to observe via a laptop its a simple-to-use and yet highly sensitive solution. The software side for live viewing is just as important in making the most of the hardware, and as Don says LodestarLive by Paul is a really excellent and robust application. It has revolutionised my observing. With 80mm f/6 I can spot DSOs down to mag 15 and for the 200mm f/4 down to mag18+ with this camera.

Another thought: if you're after a really portable solution, the new Skywatcher Star Adventurer mount when coupled with a light refractor might be worth looking at (though lacking GOTO). I had a chance to look at one in the flesh last week and was impressed by the build quality for the price. I haven't heard much about them yet but its an option I'd like to explore myself for a travel setup at some point. For sub 1-min exposures I'd be interested to see what the tracking is like. It could probably hold the Orion ST80.

http://www.firstlightoptics.com/skywatcher-star-adventurer/skywatcher-star-adventurer-astronomy-bundle.html

cheers

Martin

[mwainwright]

hey, thanks for that..  that does look quite neat. i`ll add that to the consider list  

i`m erring away from goto now, as I want to be future proof, i`m starting to think i`ll start with something that i`ll always want to keep,  so keeping it simple with an ST80, and a basic, skywatcher AZ4 non motorised mount, nice and cheap, and I can build my video kit up around that, then if I feel like I need more, I can get a more serious telescope. 

"With 80mm f/6 I can spot DSOs down to mag 15 "

the lodestar does sound cool at that!   I`m guessing thats with relatively long integrations? thus needing the tracking mount?

cheers,

Mark 

[Martin Meredith]

Hi Mark

You definitely need tracking for DSOs so I'd suggest getting a tracking mount of some kind otherwise it will be an exercise in frustration. Goto is also really nice to have because you'd be surprised how difficult it is to find the small patch of sky that your scope/sensor combination allows for. The alternative is to star hop from nearby objects which can be done but don't forget you'll be doing it from the screen or video monitor and that isn't so quick as finding objects via the eyepiece. If your budget doesn't allow for a tracking/goto mount I'd suggest looking around for second hand items from reputable sellers (e.g. in SGL classified or astrobuysell). 

Yes, I typically use 30-60s exposures to get down to mag 15 in the 80mm. Here's a 60s shot with the Lodestar-C of the Abell 1656 galaxy cluster with galaxies marked, some with magnitudes. (Note also the star bloat you get from unfiltered achromatic refractors).

Electronically assisted observing is a huge amount of fun but there are some minimum requirements and for DSOs a tracking mount is one of them.

cheers

Martin

[mwainwright]

would a skywatcher supatrak be ok for VA with an ST80?      I could pick one of those up for just over £100 used from a glance at ebay, and then an orion st80, thats only £250 for the scope hardware.. 

cheers,

Mark

[mwainwright]

or - 

https://www.widescreen-centre.co.uk/Products/SKYHAWK-1145P_SynScan%E2%84%A2_AZ_.html


this looks like a nice compact and affordable setup.. 

[Dom543]

Hi Mark,

My air travel video setup is very similar to your thoughts. A C-6 SCT with an x0.33 focal reducer, flip mirror and a Samsung SCB-2000 security camera. All this on a Celestron SLT altaz mount, for which I made my own wooden legs. The only problem with the mount was that its tripod legs were too short and shaky. With the wooden replacement legs it's just fine and when folded, they perfectly fit in my suitcase. Please note that the SLT mount is substantially lighter and less expensive, than the SE mount.

I didn't go for the SCB-4000 primarily due to the higher cost but also because there isn't that much difference between a 6mm and 8mm sensor. The smaller sensor allows more aggressive focal reduction. And with that it yields the same field of view as the 8mm sensor does with a less aggressive focal reduction. A non-negligible additional benefit is that more focal reduction means faster overall optics and  hence shorter exposures.

I posted photos of my flip mirror and focal reducer on this forum a couple of months ago.

I have air travelled with this setup extensively within the continental US and also to places like Costa Rica or Hawaii. Here are the weights of the main components. C6 OTA = 8.4lbs,

SLT mount = 5.75lbs, tripod legs 4.5lbs.

More recently I have switched to using a color Lodestar x2c with LodestarLive software, when I am operating out of my home base and have AC power to use a computer. But when the computer is not an option, then I use the video setup with a 7" monitor.

Clear Skies!

--Dom

[DoctorD]

Hi Mark

I'm not sure the Skyhawk will acheive focuswith a camera - some.newtoinians have insufficient inward travel. FLO might be able.to advise - at native F5 it should be OK for vide astronomy use..

I agree with Dom, goto can e a great help as getting targets onto the sensor is not that easy.

You will need tracking, even for shorter exposures and definatley for 10s exposurese the SCB2000 is capable of.. The Syntrek mount should be OK and the ST80 is a good starting point.

HTH

Paul

[mwainwright]

Wah, dammit re. The focussing on the 1145p, I thought I'd got a winner there. And the compactness appealed...

maybe back to looking at an sct with reducer then, then I have the option of more detailed planetary views or deep sky with b the fr.

[mwainwright]

Dom, how do you find the c6 with fr on dso's?

how do you think the celestron 5se would fare if I could pick one up cheap, no point in paying the new price, as the 6 seems a better option at the price.

Re. The cams, what about the phil dyer cam? Thatdoes 20sec integrations I think?

cheers,

Mark

[mwainwright]

That vixen 110 is starting to look appealing again, though I read someone saying ot was quite dim visually, not sure how true it is.

specs wise it seems apoealing, at f9.4, as someone mentioned earlier, it should need less focal reduction than a c6, and it would go nicely on the sky watcher az goto..

[mwainwright]

-i think ive decided! 

for my total budget I worked out I can get the following, which I`ll work up to over time. 

a used celestron 5se for planetary/some deep sky with the 6.3 reducer, and orion shorttube80 for wider field, the phil dyer colour camera, a teleview 3x barlow, and a skywatcher AZ4 as a bonus for portable/manual sky browsing. 

reasoning behind this is as follows - 

the 5se is just the right physical size for me, I can keep it in my small room in london with no issue, it can be used table mount (i have a decent view of the sky from my rear window), its small enough to grab and go, and has a focal length which should be satisfying for the main things I can see from my north london yard..   planets.    and  is pretty, which means I can appreciate it when its couldy  

the ST80, seems to be a really well regarded and cheap little scope for DSO`s, should be small enough to mount on the celestron 5se goto mount. 

they both seem like fun scopes. and with both goto and a manual mount i should have a scope for every occasion, camping, hiking, garden parties etc. 

cheers,

Mark

[DoctorD]

Hi Mark

Looks like a good combination - the 5SE shouldn't disappoint on planets and the ST80 will be fine for DSO.

Let us know how you get on.

CS

Paul