New member in northeast US

[richard]

I've been doing CCD imaging for some time with SCT's and smaller refractors for a while now. I started visual observing and a little film imaging in the late '70's, it's amazing how far things have changed since then.

This past fall I bought an 8" Istar (white tube f/6 model I believe built in 2015, with a moonlight focuser) from a fellow astronomer who had to part with it due to limitations on observing where he lives. My interest is primarily DSO imaging where color correction is less of an issue. After setting up the scope on my AP-1200 and taking a few 10 minute shots of some of my favorite Messier objects I'd like to say I'm extremely impressed and pleased! This scope is a real keeper. My friends are very impressed to even one who owns all AP scopes.

I'd like to post one or two of my first light images to Istar where can I email them to? I can't upload attachments to this site using the Desktop version and my file is 130KB so I put my M27 shot in as the avatar photo, it's 10 min with an STF-8300 camera.

Richard

[nobody]

Jan 29, 2017 13:33:33 GMT -5 richard said:

I've been doing CCD imaging for some time with SCT's and smaller refractors for a while now. I started visual observing and a little film imaging in the late '70's, it's amazing how far things have changed since then.

This past fall I bought an 8" Istar (white tube f/6 model I believe built in 2015, with a moonlight focuser) from a fellow astronomer who had to part with it due to limitations on observing where he lives. My interest is primarily DSO imaging where color correction is less of an issue. After setting up the scope on my AP-1200 and taking a few 10 minute shots of some of my favorite Messier objects I'd like to say I'm extremely impressed and pleased! This scope is a real keeper. My friends are very impressed to even one who owns all AP scopes.

I'd like to post one or two of my first light images to Istar where can I email them to? I can't upload attachments to this site using the Desktop version and my file is 130KB so I put my M27 shot in as the avatar photo, it's 10 min with an STF-8300 camera.

Richard

Hi Richard

A most impressive  avatar! Congratulations.

You can certainly add images directly to your posts.
You should see a row of symbols above the text composing box.
7th from the right is a tiny 'landscape' in a frame.
This is used to post images hosted elsewhere.

Top right, above the symbol bar is Add Attachment.
Click on this and follow the instructions.

Remember to place your cursor where you want the image to appear.
Otherwise it should appear at the end of your post.

Image size should be kept modest to avoid forcing the post frame to expand and stretch the text.
Normally I'd suggest that anyone posting images on forums Previews their Post.
But Preview has never worked for me. I just get javascript:void(0);

[richard]

I've posted two of my first light shots here, they are M13 and M27 both 10 min subs with the 8" f/6 Istar and an STF-8300C camera.

www.astrobin.com/full/283444/0/

www.astrobin.com/full/283443/0/

Thanks for looking!

Richard

[tjn58]

Richard, very nice photographs - thanks for sharing. What mount are you using to accomplish this with such a large scope?

Keep them coming!


Thanks, Tom

[richard]

Thanks Tom!

I'm using an AP-1200 mount and the camera is an SBIG STF-8300C.

I found the scope to be very front heavy so I've mounted a Megrez 110 on it towards the rear, it's good for very wide fields. I've got two 50mm scopes, one on each side of the focuser, one is a Finder the other is for guiding.

It would be nice to have some kind of counterweight ring to put on the back. I'm considering trying to order another set of rings so I can rig something up, but it does work well with the Megrez on it the way it is now

Richard

[nobody]

I would recommend your idea of adding a weight eternally to an extra tube ring.
I made a doughnut ring to go inside the focuser of my nose heavy 6" f/8.
It made the balance point just right but added considerably to the OTA's weight to be carried in and out!
 
An internal weight might also affect the OTA's internal thermal "seeing."
Since the internal metal ring might takes a long time to cool being protected by the tube.
The image passes right through the weight so it more likely to be affected than an external weight.
The external weight is out of the light path and exposed to the night air for cooling.
One advantage is that the radial balance is not changed by a doughnut ring.

It would need some quick release mechanism for an outside weight to be truly practical.
Fiddling in the dark with a heavy weight on an OTA which wants to move about is no fun.
The tube is also badly out of balance until the extra weight is added.
Would you have to slide the OTA up through the rings after adding the weight?
Unless you have a solid pier you could tip the whole instrument over.
Not to mention the OTA's weight, variable friction in the rings.
Then there's the potential damage to the OTA's external finish.

Muscle builder's ankle weights with Velcro fastening have also been tried.
Might need an XXXXXXL ankle size to strap around an 8" refractor tube!
It must be 110% safe or you are waiting for a disaster to happen in the dark.
Broken toes if the weight falls off! With a cartwheeling OTA to follow!
Hard hat and steel capped safety boots?

Seriously though:
I know I'm talking the problem to death but it needs careful consideration before proceeding.

[richard]

Thanks for the reply!

First of all, I place the mounting plate that has the tube rings on my mount first and open the rings facing north/south, then I place the OTA into the rings. I find this to be a much easier and safer way to mount the OTA. I'm used to mounting a C-11 with two dovetail plates on it which is about 30lbs, so this is not so different, just more bulky. I recommend having two dovetail plates on the rings for stability.

Balancing is the tricky part, I'd like to emphasize that I'm always holding the OTA at the bottom because it will try to move! For safely, I keep the OTA pointing north when loosening the rings to adjust the OTA position. Then I tighten and move it east or west to check the balance. It may take longer but it's safer as long as you are always holding the scope from the bottom.

I think a second pair of rings with two shorter dovetail plates would be best for a rear weight assembly. Then one can bolt some smaller weights to both plates and have them sit side by side. It would be easy to add to the back after the OTA is mounted before balancing thus reducing the difficulty of mounting the scope.

Richard

[richard]

Here's the Veil Nebula same type of 10 min sub. I have considerable light pollution where I am even with an Hutech IDAS LPR-V3 filter but the Istar really performs even under those conditions 

www.astrobin.com/full/283502/0/

Richard

[richard]

Ok, busy night. It's raining so no observing this evening. I wanted to mention that I tried using a Telescop Service 2.5" flatenner visually on my Istar. While I will say it works, I didn't see a noticeable difference. I haven't tried it photographically because I don't have a rotator and the threads end up in an odd position for me. This is just a flatener, at f/6 I'm not looking for reducing the focal ratio. All the photos I posted are without the flatener.

Richard