Astrophotography advice

[goldblade1983]

Hello!

I'm new here and relatively new to astronomy and astrophotography.

Got a new scope last year at seriously knock down price - LX90 8Inch GPS UHTC (£600! practically brand new!)

I have since deforked the LX90 onto NEQ6 pro using losmandy dovetail.

So my current set up can be summarised as:

LX90 8inch (UHTC - not the ACF one) - I have upgraded the focusser (with the EZ focuser thing)

Focal reducer (can't remember which one but the most used one)

Mounted on NEQ6 pro

Camera - Sony A300 (10 MP)

Webcam - Logitech something (3000?)

I have had some reasonable success with last year with unguided shots.  Been taking approx. 30 second subs and adding in darks.

So for this year I am looking to expand / upgrade (bit by bit over time!)

My current thoughts are:

1) I need to autoguide to get longer exposure times

2) F/10 is a pig but good for certain DSO and planetary with DSLR / webcam

3) I probably want to take some more wider fov shots (which also makes longer exposures easier)

So the way I see it at the moment (assuming I am not going to get a decent CCD until next year) I have two options:

1 ) (my preferred option if people think it will work).  Spend approx. £500 on an 80 apo (probably either Evostar 80ED or possibly 2nd hand ascension 80, or WO zenith 80) and piggyback this onto the LX90 using a rail on side of scope.  Also acquire a second hand planetary imager that can double up as a guider.  All in that would be approx. £700 by my reckoning.  Here's the deal though.  I am assuming (remember I am a novice and have never guided before ) that I would be able to shoot through LX90 and guide with planetary imager on 80ED or vice versa, guide through LX90 and shoot through 80ED.  I would also be able to shoot planets / moon with the lunar imager (unguided) through LX90. 

Will that work?

2nd option (not preferred at moment) - would be to refork the LX90. Sell it. Acquire apo refractor above and a guiding system and put on NEQ6.  Obvious downside to this is that I would lose the larger aperature for observing.  I ultimately aim to sell the LX90 and replace with a large 14" DOB but seems too much investment / hassle for me to do that at the moment.

What do you guys think?

Cheers

Brian

PS example of my astrophotography to date:

http://goldblade1983.myknowhowcloud.com/item/43f381d5bc70459ba4a94fa0cae02547  (press download)

[RT65CB-SWL]

Hi Brian / 'goldblade1983' and welcome to SGL.

Personally if it was me, I would stick with the first option. You may find it cheaper to purchase a focal reducer for your LX90. I think Meade & Celestron make an f10 'scope f6.3, or thereabouts. (I think Antares do one too). You will obviously need a guide scope, so the 80mm models you mentioned should be ideal.

I know someone who has attached a TeleVue Ranger to an LX, (though I cannot remember what model), and has great success with his setup.

Not being into 'serious' astro-photography' I hope this helps.

[IanL]

I was in a similar situation when I started AP (apart from dabbling with webcam planetary imaging).  Had my old LX10 which I deforked on to an NEQ6 and tried to guide using an ST80 with a QHY5 guide camera.  I've never had much success with that setup - guiding at 2 metres is hard enough (though might be easier with the reducer) but the real killer is mirror flop in the SCT - most subs end up with some trailing with a lucky few that are usuable (not great when F/10 is so slow to start with).

Not sure if your LX90 has a mirror lock - if it does then you might have more luck, but the LX10 doesn't and no easy way to DIY one on to it.  If it doesn't have a lock you will probably have issues whichever way round you image / guide since one set of optics will be moving relative to the other.

I got the ED80 (with 0.85x reducer) and that coupled with the ST80/QHY5 guiding rig works like a charm on the NEQ6 (ought to really given it is over-mounted).

Recently I got a cheap-ish OAG from eBay as this should work for the LX10 since the guiding and imaging are done through the same optics and thus mirror flop isn't a problem.  It seems OK but my QHY5 is not sensitive enough to get decent guide stars through the OAG so I haven't moved on much further.

I'm sure others have made this sort of thing work, but I haven't had much luck to date.

[wuthton]

Sorry, but I'd sell the LX90 and get a decent triplet.

Easier to guide, focus, less weight, faster. All round it would be just easier to learn imaging with.

[swag72]

I have just spent 7 months imaging with an SCT (C9.25) at f10. While it was doable, I was certainly pleased to see that I could produce an image from it. The short focal length refratcor is back on the mount now and it's a joy to use in comparison to the longer focal length. Guiding is spot on, data is coming in thick and fast, whereas at f10 it became a little of a chore, the focusing is easy. I've never experienced a direct comparison with a refractor before and now my eyes are opened. Long focal length imaging is hard, you really have to work for each any every sub.

I would say get a short focal length refractor - You will enjoy your imaging much more and it will be much more productive as well.

[ChrisLX200]

Well you can continue play with the LX90 and get the best from it you can, but I would not be spending more money trying to make it work for astrophotography, although I suppose a guider will be useful for whatever you end up with if you continue your imaging interest so that part won't be wasted, but any serious attempt with an SCT needs an OAG rather than a separate guide scope (too much going on in an SCT, too many things moving about - and at long focal lengths it's difficult to compensate for any other way). A lodestar X2 will work well with an OAG and later still work well with a guidescope. It is the most 'challenging' aspect of astro imaging - using a long focal length instrument with the necessary long exposures. It is not where I would choose to start for sure.

ChrisH

[goldblade1983]

Thanks for for responses.

I have a focal reducer for lx90. In terms of people saying not to image with the sct please note that I would be planning to also be imaging with the refractor on top and using the sct to guide. I suppose my main concern was not being able to guide successfully using the sct (thoughts please). Over time (probably next year) I would get another refractor to work in conjunction with the 80 and sell the lx90 and get a decent dob for visual.

In terms of mirror flop tthe lx90 doesn't have a mirror lock but I believe mirror flop with the 8 inch is minimal.

Any more thoughts?

Cheers

Brian

[goldblade1983]

A third option would be to get an 80 and 120 apo now piggy backed and sell the lx90 and settle for visual next year?

[goldblade1983]

Or... refork. Keep lx90 for visual as it's super quick to get aligned on the alt az mount and settle for unguided 80 apo for just now (or guided with basic guide scope).

Arch too many options!

[IanL]

Thanks for for responses.

I have a focal reducer for lx90. In terms of people saying not to image with the sct please note that I would be planning to also be imaging with the refractor on top and using the sct to guide. I suppose my main concern was not being able to guide successfully using the sct (thoughts please). Over time (probably next year) I would get another refractor to work in conjunction with the 80 and sell the lx90 and get a decent dob for visual.

In terms of mirror flop tthe lx90 doesn't have a mirror lock but I believe mirror flop with the 8 inch is minimal.

Any more thoughts?

Cheers

Brian

You can guide using the SCT - I even managed to convert the LX10's basic (for very basic values of basic) DC drive system to guide using an Arduino and relay shield - it just about worked to guide a DSLR with 80mm focal length camera lens piggy-backed on top.  It was a fun challenge since I had nothing better at the time.

I would absolutely not bet on the LX90's mirror flop being under control - if it is one of the types with no mirror lock I suspect that it will be the same mechanical design that the LX10 uses, as was the case for all the 8" Meade SCTs designed in that era (even the expensive LX200's, etc.)  They just made the OTAs on the same production line and then put them on cheaper or more expensive mounts depending on what you wanted.

If you guide using that you may well run in to problems - the mirror flop issue cuts both ways whether the SCT is the guider or the imager.  The saving grace as a guider might be if the focal length of the imaging scope is a lot shorter then any flop might be small enough to allow reasonable exposures without visible trailing, but it would be an expensive game of trial and error to find out for sure.  That's not meant to put you off, as you can see I have pushed the envelope in trying to make the best of what was available, but you need to go in to any purchase with your eyes open - a good doublet is not a bad addition to the imaging arsenal, but I think you should be prepared for a bit more expense to add a finder guider setup to the refractor if the SCT causes too many problems.

Would I trade in my SCT to stretch to a triplet though?  No way - it is a great lunar and planetary scope for visual and imaging purposes, and I've bagged a fair few DSOs visually too over the past 14 years I have owned it.

[goldblade1983]

What about this

http://www.astrobuysell.com/uk/propview.php?view=85612

£670 for ascension, auto guider and guide scope. Almost seems too goo to be true?

[goldblade1983]

Reforked the lx90 and so looking for equipment suggestions (say budget of 750) to get started. I'm thinking most likely to look at an 80 apo

[wuthton]

Reforked the lx90 and so looking for equipment suggestions (say budget of 750) to get started. I'm thinking most likely to look at an 80 apo

WO Gt81 hands down with that budget for me.

[wuthton]

You will need a flattener. The dedicated ff/fr will push it over budget.

If the budget is tight the Skywatcher flattener is excellent for the money.

[ollypenrice]

l think that the best of the small budget apos is the most obvious one, the E80 with focal reducer. WO are prettier but do they take better pictures? I've no reason to think so. It is all about controlling the blue channel and for some reason the ED80 is particularly good at this. You would need the reducer-flattener.

I'm glad you reforked the LX because you can use it for what it does well. I wish I'd done myself that because, quite honestly, it's a poor DS imaging scope. I never use it for that because I can out resolve it with a 140mm apo. I liked it in alt-az for visual though.

Olly

[wuthton]

l think that the best of the small budget apos is the most obvious one, the E80 with focal reducer. WO are prettier but do they take better pictures? I've no reason to think so. It is all about controlling the blue channel and for some reason the ED80 is particularly good at this. You would need the reducer-flattener.

I'm glad you reforked the LX because you can use it for what it does well. I wish I'd done myself that because, quite honestly, it's a poor DS imaging scope. I never use it for that because I can out resolve it with a 140mm apo. I liked it in alt-az for visual though.

Olly

Well I must say I'm surprised that you rate the ED80 over the GT81 but to the OP, Olly has much greater experience of using a wide range of equipment than I do.

[Earl]

id go with reduced ed80, st80 guide, getting both for £500 will take a bit of work though, but it is doable second hand, i think there is an orion one on ebay atm.

[kalasinman]

Just a thought...refork and sell, Buy an 8" f/5 newt,  a qhy5l-II, a set of screw in narrow band filters, and an Orion 50.--Jack

[goldblade1983]

Don't fancy the newt at moment - here's why.

As far as I understand when starting out with astrophotography better with guiding and wide field and an 8" newt wouldn't provide that. I had some success with LX90 on NEQ6 but I now appreciate how hard it can (and will) be to get decent shots.  Also having the LX90 on the forks is good for being a 'grab and go' (albeit a large one!) because it's very simple to set up - literally put up and aligned in 10 minutes.  Having a newt on the neq6 would mean that it would take longer if all I want to do is observe (I don't have a permanent set up - and decent dark sky is 30 min drive away).  

I think I'm fairly set on 80mm guided on neq6 for astrophotography for now unless anyone can tell me any reasons why it  shouldn't be.  Once I have a set up that works well (and after getting a ccd) would possibly (again with advice) seek to get perhaps a 120mm / or indeed a Newt for objects requiring a smaller fov.  

I'm interested in the debate on 80mm apo's.  Is the ED80 referred to by Olly the Orion one?  There's so many with similar names it's quite confusing!  More input please!

[kalasinman]

I believe I mentioned an f/5 newt, although in the same price range, f/4 is also common. A "fast" scope is a great advantage in astrophotography. Several members here have great success with them. There is the requirement for collumnization, but they have a faster cool down than a refractor also. CA is not an issue with newts, as it is with all refractors to an extent. I realize many members here prefer refractors. I just wanted to add some balance to the discussion. -Jack

[wuthton]

I believe I mentioned an f/5 newt, although in the same price range, f/4 is also common. A "fast" scope is a great advantage in astrophotography. Several members here have great success with them. There is the requirement for collumnization, but they have a faster cool down than a refractor also. CA is not an issue with newts, as it is with all refractors to an extent. I realize many members here prefer refractors. I just wanted to add some balance to the discussion. -Jack

The advantages of small refractors over reflectors for beginners are many and well discussed on here.

... and spiky stars!!!

[Earl]

I believe I mentioned an f/5 newt, although in the same price range, f/4 is also common. A "fast" scope is a great advantage in astrophotography. Several members here have great success with them. There is the requirement for collumnization, but they have a faster cool down than a refractor also. CA is not an issue with newts, as it is with all refractors to an extent. I realize many members here prefer refractors. I just wanted to add some balance to the discussion. -Jack

I agree that excellent results are doable from Newts Harry Page for example, but I only had to attach all my gear and click go, no tinkering other than basic setup was needed, that is not goign to happen with a newt even in the most experianced of hands there is still plenty to maintain to get the most out of its potential.

[kalasinman]

First I want to be clear, I'm not here to argue. As I said adding balance to the discussion, helping others, and maybe learning something along the way are my priorities.

Accepting the ease of setup of a frac as a given. Consider the cool down time, a newt could be collumnated in that time. Regardless of price (and it can be pretty high) CA can never be totally eliminated at all wavelengths from a frac from what I read. The inertial mass of a frac per aperture is much higher than a fast newt,  requiring more from the tracking system per aperture. There are more things which influence the astrophotograph than the scope and many of them cost money. An ED-80 costs $1405 plus shipping. I can buy a GSO 8" f/5 for $405 delivered here in Thailand. That's a huge difference in  photon capture. A thousand USD can buy a fair bit of kit. Diffraction spikes? Not all agree that they are bad, have even seen requests online for plugins that add them. Not my preference, just saying it's a matter of opinion. For myself, I'm thinking of replacing the spiders with a coated float glass plate to act as a secondary support for about $75 DIY.

Having said all of the above, I have nothing against any design of scope. I don't believe it's written in stone that one or the other has to be best. Different tools for different jobs and preferences, as I see it.

[swag72]

I think what people here are doing is offering their imaging advice (that was the OP) based on their own experience.

While it's not written in stone that one or the other scope is best, as far as imaging goes, it is certainly written in stone what is EASIEST. Again, most people on here are talking through experience.

[lensman57]

I believe I mentioned an f/5 newt, although in the same price range, f/4 is also common. A "fast" scope is a great advantage in astrophotography. Several members here have great success with them. There is the requirement for collumnization, but they have a faster cool down than a refractor also. CA is not an issue with newts, as it is with all refractors to an extent. I realize many members here prefer refractors. I just wanted to add some balance to the discussion. -Jack

One of the SGL members, Uranium 235, does amazing work with his 130PDS but according to himself it took over 6 months of work to get the scope to image well. I doubt if many people have either the time or the expertise to get the scope to an imaging stage. I for one have so far failed to get my Quattro 8s to perform well with either of my Atik cameras never mind a DSLR so I keep on using the APO quite often.

A.G