QHY5L-II mono + Orion ST-80 Ext Tubes

[kkara4]

Well I spent 3 hours last night trying to bumble around with getting the QHY5L-II to:

1) Come to focus in the ST-80, despite a 2" extension tube
2) See anything on the screen (EZPlanetary which comes on the CD included), other than lots of horizontal polling lines, and a large fuzzy patch whenever aiming at a focusing target.

I did try using a streetlight across the road as a focusing target (approx 30m), maybe I should use something much further away. I only bought the basic package, so comes with a little screw on adapter for 1.25" filters, and an insertion stop, and some cables.

Can anybody provide advice on:

1) Actual settings to use so I can correctly expose for a common target, such as moon, normal night sky with moderate light pollution, distant tree in daylight, etc?

2) Software to use to test 1) above? Thinking of just using PHD2 directly, but no idea how the program works, does it give you an image preview, and can you adjust settings and the like? EZPlanetary just seems difficult, especially with half chinese manual included on CD.

3) Do I need more extension? I searched extensively before buying the extension tube thinking a 2" would be fine (this is what everyone seems to use, including with Orion SSAG package), and no info to the contrary when using a QHY5L-II. In fact I couldn't find much concrete information on using QHY5L-II with an ST-80, which was baffling since it seems to be a common setup.

4) depending on 3), how far into the extension tube should I insert the camera?

TIA!

[Amaranthus]

The moon is your best bet to find initial focus - you shouldn't need any further extension tube. Turn the gain right down to its minimum, and the exposure to 1-10 ms. Then mark the position for future reference!

[kkara4]

Thanks a lot Barry. I will give this a shot tonight. What should I set the gamma to? And use EZPlanetary or something else?

[Amaranthus]

Gamma shouldn't really matter, but when I'm trying to find focus I wind it back too. Gain is the key - it is your friend (e.g. when trying to find faint guide stars) or your enemy (when trying to find focus on a bright object!)

Capture software won't matter, but EZPlanetary is good for your cam. I use FireCapture, but I'm using an ASI120MM-S (which has the same chip as yours, incidentally).

[Amaranthus]

BTW kk, you are ultimately doomed to failure in guiding your SCT with an 80mm guidescope. Been there, done that, flexure will kill you :P

Take the path of the OAG...

[kkara4]

Haha, I took the advice of another member who has done it successfully with ~2000mm focal length.

The key is to bolt the dam thing down hard. Ill post a pic of the setup once I get it right. Far, far more solid than other setups ive seen using the ST-80. ill give it a go, already dropped the cash on it haha

[kkara4]

thanks a lot Barry, will give it a go tonight :)

[Amaranthus]

Have fun trying - you'll still give up on it. Trust me :D

[04Stefan07]

Hey mate.

I have the same camera as you. I tried using EZPlanetary which came with it and found it tricky to use and didn't like it at all. Thought I would try it even though I was using FireCapture.

FireCapture is 100 times better and has many features. Give that a go.

[kkara4]

haha, I hope I dont, and if it doesnt work Ill keep going with it till it does, provided it doesnt cost more than an OAG to get it there :P

plus high quality OAG is $$$ im guessing, so will see.

mistakes are made in life, cant get anywhere without making them. This member has done it and eliminated the flexure, and produced excellent images using very close to the same setup. I am still confident.

[kkara4]

Hello Stefan

Thanks a lot I will use FireCapture, many thanks!

[Camelopardalis]

Personally, I prefer EZPlanetary because it doesn't bog down my astro netbook. I don't feel the need to carry a powerhouse around with me when I'm imaging just because Java is poorly optimised :lol:

Just set the gain high.

QHY include a focal ring...so take the guide scope out and focus it on something (distance not that important) using an eyepiece of similar FOV. Then swap for the cam and slide in and out until you get focus. Then add the focal ring and tighten the screw so that the next time you put it in the diagonal or whatever you know where to find rough focus.
Then in the dark, focus on a bright enough star and use a bahtinov mask. Job done :thumbsup:

[kkara4]

dont have 1.25" eyepiece :(. so sticking eye into draw tube is my eyepiece atm :lol::rolleyes::shrug:

[kkara4]

well, some conclusions:

1) Firecapture seems to play much more nicely at the same settings of exposure gain and gamma as EZplanetary. Seems to be much more user friendly (thanks Stefan!)

2) 2" extension isnt enough. Drawtube fully racked out approx 2" + 2" extension and need another inch maybe, so second 2" tube ordered and on the way.

3) Gain 0, exposure about 6ms before i ran out of focus travel.

have to wait a bit longer for guiding :rolleyes:

[Amaranthus]

I'm amazed... Are you *sure*?

[kkara4]

Going to do a daylight test, but couldnt get the moon in focus.

Had the camera as far out as I possibly could in the extension tube, and draw tube fully in. watched live on the screen as i racked it out, and the moon got tighter and tighter but I ran out of travel! Another inch would have been it I reckon.

im wondering if people use lenses in front of their guide cameras when inserting them into their guidescopes? :shrug:

[kkara4]

Barry, just got the scope lined up to some trees about 700m away. Got the exposure settings right on firecapture, as I racked out maximum, i can now see very blurry outlines of trees moving in the wind on the screen. Managed to gain 1/2" by screwing on the 1.25" filter adapter, only made a slight difference. still need another inch I estimate.

Ill edit this post with some pictures to show how it looks in a few minutes

[Amaranthus]

Just as a sanity check, you did try starting fully racked out, and the gradually racking all the way in? The point of focus is *very* small so it's easy to skim past it.

You can also unscrew/detach the camera from the extension tube, hold it carefully by hand, and then move it backwards to check if 1/2" gives you the focus you think it will.

[gbeal]

I won't get into the guide-scope Vs OAG debate, each has their respective merits. Plus I currently use a guide-scope, but have in the past also used an OAG.

I'd run a few numbers though before making a broad statement about costs. What did the Orion ST80 cost? A decent OAG can be about the $100+ used, up to serious money.
If you are going to use an SCT, the OAG "might" be better.
Now you have the ST80, keep trying of course, but if you see an OAG in the Buy/Sell section, give it some thought.
Gary

[kkara4]

Barry, i managed to get a second person to help out, and it worked. Got focus about 1/2" before fully racked out, camera at very end of extension tube. You were quite right, very small depth of field, many times narrower than what I thought it would be! Thanks a lot for your help! :thanx:

So looks like a second tube would allow me to insert the camera at proper depth.

No way I would have got focus without the filter adapter threaded on it though!

[kkara4]

Very true, cheers Gary!

[kkara4]

so at the moment the sensor would actually be right around flush with the extension tube opening if I didnt use the filter attachment, and had the draw tube fully racked out for the in-focus point.

Extension tube ordered anyway, so will be perfect with a second one, then I can have the draw tube about half way along its travel, and the camera inserted into the extension tube properly :)

Settings of gain 25, exposure 0.5ms and gamma default for firecapture seem to be great for daytime use of dark coloured trees.

[Camelopardalis]

How are you connecting the guide cam to the ST80?

[kkara4]

Dunk, here is a picture. Excuse the books, jumper and various other unrelated stuff :P.

That picture is taken when cam was in focus, and you can see why I needed the 1.25" filter adapter threaded on (else there would be nothing to secure it in the extension tube).

[Camelopardalis]

Something's not right...although I can't tell what...a 1.25" visual shouldn't struggle to reach focus on an ST80...it's their territory!

Incidentally, when attempting to find an object to focus on, I use very high gain (like approaching 100) and 50ms or so exposure times.

[kkara4]

hmm, well I measured 400mm back from the front lens (roughly) and it coincides roughly at the camera sensor position shown in the picture.

but unless more people who know the ST80 well can provide some insight, have to deal with it :shrug::shrug:

[Camelopardalis]

Have you tried it with a diagonal?

[kkara4]

nah dont have one, and in any case that would extend it right about to where i have it in the picture i think.

i only bought the OTA