First photo from 140mm, F6.5 Apo Triplet!

[Watcher3]

An early production 140mm, F6.5 Triplet has been fast-tracked for visual testing using an improvised wooden OTA. With functioning optics, the temptation for the builder to try some astrophotography was clearly too much despite the fact that he was located in a light-polluted city.

So, with a ZWO ASI2600 color camera and Optolong L-Pro light pollution filter in place, the scope was turned toward M31 and with remarkable results given the circumstances.

• Scope:- iStar D140mm, F6.5 Apo Triplet
  
• Accessories:- Apex ED-L 0.65x Reducer/Flattener
  
• Effective F-Ratio:- 4.2
  
• Geographic location:- Tucson
  
• Date:- (11th Oct 2020)
  
• Exposure:- 60 x 60 seconds, stacked.
  

Well, I'm impressed. Now think.... properly constructed and aligned tube assembly combined with a nice dark site away from city lights.

Hey Ales, we are going to see some really outstanding images from this setup and I can't wait!


Cheers all, Watcher2

[Ales - iStar Optical]

Yes, the lens was slightly tilted, not mounted perfectly square due to the crude setup, but that will be taken care of soon as we are planning on introducing a completely CNC machined OTAs with tube rings and 2.5” large format MoonLite focuses with dual accessory bracket. A complete package for estimated $4495!

[Ted White]

I have just received one of the 140mm APO's and I am busy building what I am calling The "Ideal" Astrograph. You can follow my progress at seriousastronomy.com/the-ideal-astrograph-project/

I will try to post more details here as I go along.

Cheers,

Ted White

[GrahamP]

Nov 3, 2020 1:45:55 GMT -5 Ted White said:

I have just received one of the 140mm APO's and I am busy building what I am calling The "Ideal" Astrograph. You can follow my progress at seriousastronomy.com/the-ideal-astrograph-project/

I will try to post more details here as I go along.

Cheers,

Ted White

Hello Ted,

a mighty big welcome!

thanks for sharing your build URL. I have read that through and found it most interesting. Can I get a better resolution image of your traces on the last page? Like to see it close up.

cheers ... Graham.P

[jamesling1000]

Hi Ted..

Welcome to Istarscopeclub, and your review of this new APO 140 triplet will give readers like us to know the quality that Istar-optical is providing to this market..

Please keep us posted on your progress...

Regards

James Ling

[Ted White]

Hi All,

Thanks for the welcome!

I tried to post an enlarged copy of the wire frame drawing but I don't know how to do it on this forum.

Any suggestion?

Cheers,

Ted

[Ted White]

Just tried adding a couple of attachments!

Ted

Attachments:

[Ted White]

I forgot to mention, I've made major updates to the site!

Ted

[GrahamP]

Nov 5, 2020 20:50:53 GMT -5 Ted White said:

Just tried adding a couple of attachments!

Ted

Hi Ted,

cheers, that's better!

BTW, the forum is set to maximum available attachment size and quantity (up to 2MB per attachment, and 5 attachments per post).

So you could ramp up the resolution on your images quite a lot (your line drawing is only 21K)

Regards... Graham.P

[Ted White]

Hi Graham,

Unfortunately, that's the size my CAD program exports as a PNG file.  I have tried other formats and get the same result.  It seems to only export images at the screen resolution.  I can zoom in on specific areas and export that part which would better detail if there is an area you are specifically interested in.  And, of course, those two images are assemblies of many individual parts and I can produce images of those at bigger scale if you like.

I noticed that there is a topic on DIY refractor building.  Would this discussion be better held there?

Cheers,

Ted

[GrahamP]

Nov 5, 2020 20:53:34 GMT -5 Ted White said:

I forgot to mention, I've made major updates to the site!

Ted

Thanks Ted,

had a look. Thanks for explaining auto-collimation. Haven't heard of it before, and will use it to check my lens.

cheers ... Graham

[Ted White]

Here is my first light image with the 140mm with the Apex reducer.



The camera was a SBIG STF-8300M with Astrodon LRGB filters.  The processing was done in PixInsight.  It's a stack of only 5, 200 second luminance frames with 5 or 6 each 100 second RGB.  I had some trouble with my guiding setup and wound up rejecting two thirds of the frames I took.  It was the first good night in weeks so I am afraid I rushed things a bit and used a temporary guide scope mount and forgot to increase the guide output in EQMOD to compensate for the much shorter focal length.  But damn!  Not too bad at all.  It's definitely a keeper!

There is virtually no tilt in the system but it does have a small amount of field curvature, about 7% according to CCD Inspector using a uniform star field in the Milky Way.  I checked the focuser alignment with a laser and it's pretty much bang on.  I am hoping to adjust out the field curvature but I need to first get some advice from Starizona.

Cheers,
Ted


I will be posting more details on the construction process on my blog shortly

[GrahamP]

Hi Ted,

that is incredible! Thanks for sharing.

Graham