refractor choice

garymck (Gary) · #1 17-11-2009, 10:52 PM

Hi,
tonight I *^*&^ my back trying to lift my newt/eq6 into position for the first clear night of imaging in a while. I'm over it. Now I'd like to replace the newt with a small easily moved refractor. It will be used pretty much strictly for imaging with my QHY8. The problem with the low end 80mm's seems to be that on an APS sized chip field curvature shows up, which means you have to crop the pic. Is there a field corrector (and/or reducer) that will work effectively with either an ed80, ed100 or WO zenithstar 80 11 ed (good price at the moment direct from WO), and result in NO need to crop pics? I know I want champagne performance on a beer budget, but I don't want to have to take pain killers every time I image!!! and I'm poor... The WO reducer correctors seem to have very patchy performance according to what I have been able to find. I did see the corrector tests here, but I wouldn't call any of the results spectacularly good. What about the latest incarnation of the P-Flat4? Feel free to berate me if I'm being unrealistic...

cheers
Gary

leon · #2 18-11-2009, 01:42 AM

Gary Mate, you seem a bit stressed, looking at the way you have written your post for answers to your question.

It is hard to read and really know what you want.

have another go mate.

Leon

troypiggo (Troy) · #3 18-11-2009, 05:40 AM

I have the gold SkyWatcher ED80 and a DSLR (similar sensor size to QHY8). Frustrated with the curvature/eggy stars as you mention, I've bought the WO Flattener IV. Did some initial testing here the other night, but will be giving it a bit more of a serious workout this weekend. I'll certainly be posting results somewhere here, because if it doesn't work I'll be ropable, but if it does work I'll be ecstatic.

gbeal · #4 18-11-2009, 06:32 AM

Gary, Leon is on the money. Sit tight for a while.
If you are looking at an 80mm refractor, then most, if not all, need some form of assistance to give a flat field. This is no biggie, and even the champagne units require them.
Suggest you see what others are using and replicate that. In my case I had a nice Lomo/TMB 80mm apo, and used the Baader MPCC. Now I have the FLT132 and it has a dedicated flattener, and it works, contrary to some of the other W/O flatteners.
Decided your budget, and go from there.
Gary

Kal (Andrew) · #5 18-11-2009, 07:33 AM

What budget for refractor + flattener are you looking at Gary?

garymck (Gary) · #6 18-11-2009, 08:02 AM

Hi Guys,
thanks for the gentle answers. I was a little stressed when I wrote it - major spasms in back and the pain killers hadn't yet kicked in. I've decided that moving an 8" newt eq6 is too much for my back. I now want to purchase a small refractor/corrector combo with a well corrected field that will be a lot easier to set up.

What I want is an 80mm class refractor. Budget is limited, say $1000 for scope and corrector. This is fairly limiting I know. I already have a baader MPCC (for use on my newt) if that helps. Has anyone found a combo in the low end area that works without cropping the image on a QHY8?

I had looked around, and found that there aren't that many options in my budget. If I had $3k life would be a lot easier, but funds are extremely limited as I am in the prosess of setting up a business.

There is obviously the ED80, and the WO Zenithstar 80 11 ED. Both of these require a field flattener. After searching I could find no definitive answers on what flatteners work without cropping. I had read the test here on IIS, but found even the best of the tested items to be a bit wanting. I guess I'm used to a great results with my corrected newt. The new WO P-Flat4 looks interesting, but have not yet seen real tests of the current (third?) version.

Troy, I am awaiting your test results with baited breath, an ED80/P-Flat 4 is in my budget......

Hope this all now makes sense,

cheers
Gary

troypiggo (Troy) · #7 18-11-2009, 08:07 AM

FWIW I tried the MPCC on my ED80 because I had read others trying it and got good results. I didn't, hence the WO FF IV currently.

Kal (Andrew) · #8 18-11-2009, 11:49 AM

A flattener that might work well with the scope you are looking at is the Astro-Tech 2" 0x Field Flattener.

A post about the performance of this flattener with an F6.25 80mm scope can be seen in this cloudynights thread.

At US$150 it could be worth considering.

pmrid (Peter) · #9 18-11-2009, 12:03 PM

Hey Gary, if you're looking at buying a modest-sized APO, why not have a look at the North Group 127mm ones that many of us ave imported direct from China. Terrific optically and great value at about A$1250-1300 imported and delivered.
Peter

allan gould · #10 18-11-2009, 04:18 PM

Quote:

Originally Posted by pmrid

Hey Gary, if you're looking at buying a modest-sized APO, why not have a look at the North Group 127mm ones that many of us ave imported direct from China. Terrific optically and great value at about A$1250-1300 imported and delivered.
Peter

Gary
The 127mm ED Apo is a heavy beast - about the same as your 8". I would consider its stable mate the 80mm Meade ED Apo (same manufacturer). Ive tested one of these and they are really brilliant. far better correction in my opinion than the WO or SW brands. Coupled with the Astro-Tec 2" flattener you would be right in there even using a DSLR or QHY8 camera.
Regards, Allan

garymck (Gary) · #11 18-11-2009, 06:24 PM

Thanks Allan,
I thought that the ed127 was pretty heavy. It seems that there are no low end comb inations that actually work. I've just heard back from WO, and they say " FlatIV was tested with M90, FLT98, FLT110 and FLT132. WE recommend to use it with WO FLT triplets telescopes." For the Zenithstar 80, they say reducer 11 or 3, but having looked at the results with these which were not wholly satisfactory, I think I'll have to forget the low end thing and sell some stuff to fund a more expensive purchase. Perhaps something like a 77mm Borg, which "just works"....

cheers
Gary

En1gma (Robert) · #12 18-11-2009, 09:34 PM

I use an ED 100 with a Meade 6.3 Flattener/reducer. This is tied up to a DSLR camera with very little vignetting and not as much curvature. Cheap option

Here is a 30second unedited image.
http://users.tpg.com.au/en1gma83/_DSC0081.jpg

garymck (Gary) · #13 18-11-2009, 11:48 PM

That looks very promising, what spacing do you use?

cheers
Gary

[QUOTE=En1gma;524013]I use an ED 100 with a Meade 6.3 Flattener/reducer. This is tied up to a DSLR camera with very little vignetting

En1gma (Robert) · #14 19-11-2009, 11:56 AM

Howdy,

I will measure up tonight and post a pic. Although with my current setup I had to change the focuser as the stock one would not focus (in focus)

I was acually suprised on the results myself as I did not know if the 6.3 was going to work with very little info on the net

rob

edit: as for cost, I paid 800 for the scope and 189 for the reducer/adapter

garymck (Gary) · #15 19-11-2009, 04:02 PM

This is really interesting, as your results look as good or better than anything I've seen with other scopes. Could be the perfect combination of visual and imaging (even though imaging is my priority)

cheers
gary

Quote:

Originally Posted by En1gma

Howdy,

I will measure up tonight and post a pic. Although with my current setup I had to change the focuser as the stock one would not focus (in focus)

I was acually suprised on the results myself as I did not know if the 6.3 was going to work with very little info on the net

rob

edit: as for cost, I paid 800 for the scope and 189 for the reducer/adapter

En1gma (Robert) · #16 19-11-2009, 07:50 PM

Hey Gary,

Here are a couple of photos of the setup.

Centre of reducer/flattener to sensor is ~ 100-110mm. Recommended distance for this reducer is 105mm so it seems I have just got it spot on.

Rob
http://users.tpg.com.au/en1gma83/photo1.jpg
http://users.tpg.com.au/en1gma83/photo.jpg

garymck (Gary) · #17 19-11-2009, 11:33 PM

Thanks Rob,

vital info, I will check everything out

cheers
Gary

Quote:

Originally Posted by En1gma

Hey Gary,

Here are a couple of photos of the setup.

Centre of reducer/flattener to sensor is ~ 100-110mm. Recommended distance for this reducer is 105mm so it seems I have just got it spot on.

Rob
http://users.tpg.com.au/en1gma83/photo1.jpg
http://users.tpg.com.au/en1gma83/photo.jpg