FOV, DSLR, Question.

[K3ny0n]

Hello, Just a quick question on imaging with my DSLR, T ring adapter ect. My question is about the FOV, I took my first image of M45 last week and didn't get the full M45 in the shot. Is there a way to change the FOV with my setup? If you need any more info on my setup just let me know.

Thanks,

Rob.

[rfdesigner]

You'd need a focal reducer, problem is for a Newtonian they get fairly pricy.. The only one I can think of that will work properly on a Newt is the ASA one for about £500.

If you wanted a reducer for a Schmidt-Cass or a Refractor then there's some reasonable choice out there. If you wanted to zoom in then a barlow would do you fine.. and they're fairly cheap.

Your best bet is to fo a mosaic.

Derek

[JamesF]

This all comes down to image scale, which is entirely dependent on the focal length of your imaging system. If I'm remembering correctly the 200P has a focal length of 1200mm, which means that at the image plane there are just under 172 arcseconds per mm. If the 1000D has a sensor 22mm wide, that means you'll get a shade over one degree of sky on the sensor. If you want more then as Derek says, you need to reduce the focal length.

James

[K3ny0n]

Woah, £500 for a focal reducer. I don't think I could justify paying that at this point in my astronomy obsession.

So, there is no other way apart from a £500 item? Maybe keep my eye out for a second hand one.

Rob.

[VigdisVZ]

You could see if you could get a spare frac or smaller newtonian for this purpose otherwise. Some objects look better in weaker scopes, thats why I chose the 150PDS with 750mm focal length instead of a more powerful one.

Another option is to do mosaics, but thats pretty time consuming.

This is M45 through a vanilla 150PDS:

[rfdesigner]

I Know.. £500 woah!.. I would love to drop my 12" down to about f3.3 with one... that would almost let me do hand held!

You could by another scope with a shorter focal length, some thing like a 6" f5... more scopes is always a good idea .. would be cheaper than a focal reducer if all you want is more image scale

Derek

[K3ny0n]

Thanks for the replies, so for the price of a focal reducer for my scope I could get a something like a Startravel 150 which is a f/5 which is near on £500 then I would have a frac and reflector!

Rob.

[VigdisVZ]

Also keep in mind that a small frac can serve as a guide scope later.

[K3ny0n]

.. and it will be easier to transport for when I go to dark sites.

Rob.

[JamesF]

Thanks for the replies, so for the price of a focal reducer for my scope I could get a something like a Startravel 150 which is a f/5 which is near on £500 then I would have a frac and reflector!

Or you could get an ED80 which would kick the ST150 all over the pitch as far as astrophotography goes.

James

[K3ny0n]

Or you could get an ED80 which would kick the ST150 all over the pitch as far as astrophotography goes.

This one.. http://www.firstlightoptics.com/pro-series/skywatcher-evostar-80ed-ds-pro-ota.html if it is this one it's also a lot cheaper.

Rob.

[JamesF]

That is the very beastie I had in mind...

James

[K3ny0n]

Looks pretty cool.

Have you got one of there yourself?

Rob.

[JamesF]

Not that specific one, but I have one of the old "gold" models which I think is pretty much the same thing in different clothes waiting for me to get my obsy sorted.

James

[K3ny0n]

Very nice, what other equipment have you got for when your imaging?

Rob.

[tjensen]

what about doing a mosaic? take a couple of images and stitch them together (overlap by 40-50%). Cheaper than a new scope ... though maybe not as much fun

[IanL]

This one.. http://www.firstligh...ds-pro-ota.html if it is this one it's also a lot cheaper.

Just got this very item at the weekend from FLO as a birthday present from my dear wife, along with the Skywatcher 0.85x Focal Reducer (http://www.firstlightoptics.com/reducersflatteners/Skywatcher_Focal_Reducers-1.html) and the M48 -> Canon Adapter (http://www.firstlightoptics.com/reducersflatteners/sw_m48_adapter-1.html) to use with my Canon 500D. Mounted my ST80/QHY 5 guider setup on top and from the get-go I was getting perfect 10 minute exposures without even trying.

Wish I'd gone down this route sooner to be honest!

[K3ny0n]

That pretty much what I'm looking to do, ED80 as my imaging scope and the ST 80 as the guide or something similar.

Have you got any pictures of your setup Ian?

Rob.

[JamesF]

Very nice, what other equipment have you got for when your imaging?

A fair number of the bits in my sig For tedious reasons a fair bit of my kit is packed up at the moment, but I've not stopped picking up useful bits and pieces when they've come up second hand, so by the time I actually get the obsy finished I should have almost everything I need

James

[K3ny0n]

Thanks for that buddy, I shall have a look when I'm on the laptop, can't see them while on the mobile.

This is a quick joy down of a starting point.

ED 80 DS Pro

ST 80 Guide scope

QHY 5 Guide camera

I think I will stretch to a NEQ6 Pro

ADM Guide scope rings

Focal Reducer

Is the M48 ring adapter the same as the one I use when attaching my Canon to the 200p? Or is this something else I need?

Rob.

[VigdisVZ]

You will not regret the NEQ-6, best mount you can get in that price range. Never regretted getting it. Looking forward to hearing about your first light

[K3ny0n]

You will not regret the NEQ-6, best mount you can get in that price range. Never regretted getting it. Looking forward to hearing about your first light

I've tried imaging on my EQ5 with a 200p and I think I have totally been hooked on the imaging side of things. Can't wait to get the new gear, don't know when though.

Rob.

[IanL]

Have you got any pictures of your setup Ian?

Rob, setup below:

It is all mounted on my NEQ6 Pro. I reckon a HEQ5 would cope perfectly well with this load though. (I have an 8" SCT also, which defintely needs the NEQ6 for imaging purposes).

The ED80 is on the supplied tube rings and short Vixen dovetail that comes supplied with it. Using a stock DSLR that is more than adequate, but if you had a heavier camera or other gear I think you'd want a longer dovetail so you have more forward movement to balance the setup, and maybe go up to the Losmandy type. On top is the ST80, which is also in its own supplied tube rings. It is mounted on a long vixen dovetail bar which came in the box with the NEQ6.

The dovetail is bolted straight through in to the two camera piggy-back holes on top of the ED80 tube rings. This is not ideal since neither of the mated surfaces is flat (the camera holes have a raised lip around them and the lower side of the dovetail has a convex profile). This led to serious flexure and no amount of washers or tightening of bolts would fix it.

The solution was to use the four small holes at the far corners of the dovetail. I put small adjusting screws through them from upper to lower (i.e. the wrong way round). Normally these are used to correct cone error if you are using the full length of the dovetail. I could tighten these down on to the focuser and front lens castings which completely eliminated flexure. I was a little concerned it might push one or both ends of the ED80 out of alignment but doesn't appear to have caused any issues (I didn't tighten them that much).

I might look to change all the rings and the dovetails for something better later if I end up with a heavier camera (e.g. all-Losmandy and CNC rings).

The 0.85 focal reducer screws straight on to the end of the ED80 focuser and is locked in place with a ring. The M48 adaptor screws on to the end of the reducer and the camera just fits without any other rings or adaptors. The only thing I don't like is that the set-up is not easily rotatable. There are three tiny grub screws in the M48 ring which you loosen, and the two parts (front M48 screw, rear canon flange connector), can rotate one inside the other. It's not something you want to be doing in the dark, not least because the two parts will separate when you loosen the screws, camera hitting the floor moment, etc.

So basically whatever camera orientation you start with is what you are stuck with for the night. Of course you could rotate the ED80 OTA in the tube rings, but again not something I would want to be doing after I have set up for the night. The focuser can easily carry the Canon 500D (so 1100D's and the like should be no issue). If I had a heavy CCD I think I would replace it with a better after-market focuser that was rotatable.

The only other downsides I could see with the OTA-only purchase from FLO (rather than the full ED80 kit that most sell) are:

- No finder. Not strictly necessary with two wide-field OTAs like this, but would be handy; I had a lot of hassle getting aligned on Saturday, it was dark and I couldn't find my tripod alignment holes on the patio so struggled to get polar aligned (pretty much didn't in fact) and thus the star alignment process was also a nightmare using the camera. I didn't want to swap for an eyepiece (see below) so an aligned finder would have saved a lot of hassle. The problem is that both my ST80 and the ED80 have the Skywatcher finder shoe; I have two perfectly good Meade finders but cannot find an after market bracket to attach them and don't want to shell out 50 quid on yet another finder.

- The focuser is supplied with a 2" eyepiece holder with a pair of tiny/useless thumbscrews very similar to the ones on the ST80. Not something I'd want to trust with a big eyepiece and/or diagonal, and there is no 1.25" adapator (I think this stuff comes with the full kit). I could use my 2" Barlow with the lens removed as this has nice 2" and 1.25" compression ring holders if I want to do a bit of visual work, but would still have to battle the tiny thumbscrews to start off. Not a major problem for imaging as you just unscrew the eyepiece holder to attach the focal reducer.

If you were planning to use this scope for visual as well as imaging, either buy the kit not the OTA-only version, or budget for an upgraded focuser or maybe even the Equinox 80ED which is pretty much the same optics in a better tube and focuser package. Overall for imaging though, I have ended up with a relatively fast, flat-field scope and reducer for a fraction over £500 quid, so if imaging is your thing, get the OTA-only version and spend your savings on the flattener/reducer.

See here for my first light image; still a long way to go in terms of processing and other issues, but I was pretty pleased that after unboxing a new scope I had a clear night rather than rain. The secret appears to be that someone else bought it as a gift, whereas most people make the mistake of buying kit themselves, thus inducing a month or two of rain:

http://stargazerslou...ular-artefacts/

[IanL]

I think I will stretch to a NEQ6 Pro

ADM Guide scope rings

Rob,

Just catching up here

- As I said above, I reckon an ED80, piggy-back ST80 and a DSLR would be worth a shot on your EQ5. I don't have one myself so don't know if it would be stable enough for imaging, but my setup on the NEQ6 is definitely 'overmounted'. Works well though, I had basically no PA other than vaguely pointing north and up and swearing through the polarscope for a bit until I got fed up. Once on target I was getting good 10 minute guided subs without even trying, though field rotation would have become an issue if I wanted to go longer I expect.

- Guidescope rings can be a nightmare. I tried some cheap ones with my ST80 on the 8" SCT and it was a nightmare. The ADM ones may be better but it is a major source of flexure and best avoided if you can. Of course getting your guidescope and imaging scope aligned is handy, but with both being such short focal length and wide field, hardly essential (field rotation on really long subs could be an issue if not aligned, but I reckon flexure in guidescope rings would be more likely as a problem first).

If I was in your shoes I would stick with the EQ5 and solid rings for the guidescope (if you have them I assume?) and see how you go. If you need a better mount or want to try the guidescope rings, you can add them later but you may find you don't even need them.

Oh and one correction to my previous post. When I said "and the lower side of the dovetail has a convex profile" I acually meant concave profile. Not that it matters, the whole thing was rocking more than Elvis until I added the extra screws.

[K3ny0n]

Thanks for the reply Ian.

- As I said above, I reckon an ED80, piggy-back ST80 and a DSLR would be worth a shot on your EQ5. I don't have one myself so don't know if it would be stable enough for imaging

I think I might just go for the NEQ6 and sell the EQ5 then I wont be worrying about if it is stable enough.

I haven't currently got any solid rings, Do you think I should use what comes "in the box" with regards to piggy backing them and forget guide scope rings at this moment?

What guide camera are you using on your setup?

I like the idea of the Equinox 80 like you say a better tube and focusser, with only a 60-70 pound price differece. But just comes OTA only?

Would this be adequate setup to get me going:

ED80 DS PRO (the full kit)

ST80

A guide camera (maybe the GHY5)

Upgrade to the NEQ6 hopefully.

M48 Ring

Forget about the guidescope rings and piggy back them the same way you have?

0.85 focal reducer.

This is just a list so I can start to purchase them each month.

Anything else I have missed which will be essential?

Rob