Jump to content

Banner.jpg.b83b14cd4142fe10848741bb2a14c66b.jpg

ST80 Mods for Imaging

Gina

By Gina
in DIY Astronomer

Recommended Posts

Gina

Gina

Posted
  • Author
Posted

The remote focussing system is now working fully and properly.  The focus steps seem about right for both the Esprit and ST80 which are all I'm concerned about ATM.  I have set up on my usual daytime target of the top of a tree on the far hill.  Focussed both scopes and aligned the ST80 to the Esprit as closely as I can with the crude adjustment method I have at present.

460EX cameras on both scopes.  FW with Astrodon 5nm Ha filter on Esprit and Baader 6.5nm OIII filter on ST80.

Here are screenshots taken of the TeamViewer image from each scope with the Reticle turned on.

Esprit 80ED Pro

post-13131-0-15658900-1416836885.jpg

ST80

post-13131-0-62113800-1416837151.jpg

Link to comment
Share on other sites
  • Replies 209
  • Created
  • Last Reply
johnrt

johnrt

Posted
Posted

Huge difference in the sharpness and contrast of the 2 images there, if they are both 100% in focus you can see where you money goes buying better quality optics. Be interesting to see how this will work out on some astro targets Gina.

My hat is off to you for your continued ingenuity, you come up with things other people wouldn't dream of :)

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

Thank you John :)

I'm not sure the ST80 was perfectly focussed - I was in a bit of a rush as I was going out.  Anyway, if it's clear tonight I shall be able to tell with the FWHM values.  I would certainly be amazed if the ST80 came anywhere near the Esprit for quality :D

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

All set up for an imaging run :)  Adjusted focus for both scopes on Auriga Alpha then slewed to IC1805 Heart Nebula.  Set up PHD and guiding fine and now running concurrent imaging on both cameras unbinned and 5m subs.

I was able to get FWHM values of under 2 on both scopes unbinned.  Seeing appears very good tonight :)  So the ST80 is doing as well as the Esprit in the centre of the field but the real test is on a star field comparing stars around the periphery.

Link to comment
Share on other sites
ollypenrice

ollypenrice

Posted
Posted

OK, so nobody will be surprised that the Esprit is sharper. It is. The question, though, is In which wavelength does the object present the fewest resolvable details? Give this wavelength to the ST80. For instance, you are shooting M31 in an amateur telescope. Try as you might, you are not going to find much to resolve in M31 in Ha. It is beyond the range of small scopes to do so so don't bust a gut. You are going to get a load of blobs from HII regions and be very glad of them, but you are not going to find a Horsehead in M31.

I don't do narrowband other than to add to natural colour images so I can't comment beyond a hunch, but my hunch would be to start with SII in ST80. I doubt that this will be a controvertial suggestion!!

Olly

Link to comment
Share on other sites
Thalestris24

Thalestris24

Posted
Posted

Good job, Gina!

I posted a 2min dslr/ST-80 sub here: http://stargazerslounge.com/topic/229919-on-the-issue-of-light-pollution/page-2

Ignoring the dreadful lp, it would be interesting to compare my awful field curvature with what you might get with your ST-80, though I imagine they'd be similar... I don't think it's worth trying to add a ff.

Louise

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

OK, so nobody will be surprised that the Esprit is sharper. It is. The question, though, is In which wavelength does the object present the fewest resolvable details? Give this wavelength to the ST80. For instance, you are shooting M31 in an amateur telescope. Try as you might, you are not going to find much to resolve in M31 in Ha. It is beyond the range of small scopes to do so so don't bust a gut. You are going to get a load of blobs from HII regions and be very glad of them, but you are not going to find a Horsehead in M31.

I don't do narrowband other than to add to natural colour images so I can't comment beyond a hunch, but my hunch would be to start with SII in ST80. I doubt that this will be a controvertial suggestion!!

Olly

I'm not really expecting very much from using the ST80 for OIII although the above results look pretty good to me.  Thing is I'm using a fairly small imaging sensor in the 460EX - 12.5mm x 10mm.

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

Good job, Gina!

I posted a 2min dslr/ST-80 sub here: http://stargazerslounge.com/topic/229919-on-the-issue-of-light-pollution/page-2

Ignoring the dreadful lp, it would be interesting to compare my awful field curvature with what you might get with your ST-80, though I imagine they'd be similar... I don't think it's worth trying to add a ff.

Louise

A DSLR has a much bigger sensor than the Atik 460EX so you wiull be much more prone to field curvature.

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

Here is a 10m OIII sub binned 2x2 from the ST80 resized to 1200x960 pixels and saved as PNG for upload here.

post-13131-0-36851700-1416863010_thumb.p

For comparison here is the Ha from the Esprit also 10m binned 2x2 resized etc. for upload.  With a lower stretch.

post-13131-0-01783900-1416863508_thumb.p

Of course comparing Ha and OIII with the same exposures is hardly a fair way of comparing scopes and puts the ST80 at a disadvantage from the outset.  Unfortunately I haven't got two filters the same.  It wouldn't be fair even to compare with my two OIII filters since one is Astrodon 3nm and the other a Baader 6.5nm.

I have now set Artemis Capture on the 460EX on the ST80 to run 20m subs

Link to comment
Share on other sites
Thalestris24

Thalestris24

Posted
Posted

A DSLR has a much bigger sensor than the Atik 460EX so you wiull be much more prone to field curvature.

Yeah, though the 1100d image can be cropped to the same size as the 460ex which is about 60%ish the number of pixels of the 1100d, tho the 460ex has slightly smaller pixels.

A very quick and rough crop and adjustment:

post-33532-0-01110600-1416864333_thumb.j

Comparable?

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

Yeah, though the 1100d image can be cropped to the same size as the 460ex which is about 60%ish the number of pixels of the 1100d, tho the 460ex has slightly smaller pixels.

A very quick and rough crop and adjustment:

attachicon.gifL_2014-11-22_19-36-17_0011_ISO800_120s__20C_crop.jpg

Comparable?

Yes, I think it is :) 

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

Fancied a chang of DSO so I've moved over to the Pacman.  Checking star intensities I found 5m for Ha and 10m for OIII took the brightest stars just below saturation.  So I'm doing a run with these settings.  Here are single subs slightly stretched in Photoshop and resized to 1200x960px.  I might even be able to get a proper imaging run tonight on a new target for me :)

Ha
post-13131-0-72529600-1416872225_thumb.p

OIII

post-13131-0-06104100-1416872272_thumb.p

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

Here is a processed image of the Pacman from last night.

35m total Ha with Esprit 80ED and 25m total OIII with ST80 - all binned 2x2.  I thought I had more OIII but somehow didn't :(  Considering the small amount of data I'm pretty pleased with this image.

Captured with Artemis Capture - Stacked with DSS and stretched in Photoshop - Aligned with RegiStar - Combined as HOO in Photoshop with further processing and cropped to improve appearance.  No resizing so this is pixel for pixel -  saved in PNG format.

post-13131-0-26123000-1416921613_thumb.p

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

Found more OIII from after I had centred the object but there was only one Ha sub centred (bit of a messup there :()  So this is 7x5m Ha and 4x10m OIII.  Processing as above.  This is flipped to be the right way round - north is up.

Still needs much more data though.  Next clear night I may devote the whole time to the Pacman.  And start with the object correctly positioned in the frame.  But last night was really only testing the ST80 to see if it was going to be useful and I believe I have shown that it is so...

Test Successful :)

post-13131-0-21324700-1416925064_thumb.p

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

Love reading this thread

Why does the ST80 pick up more stars is it the filter being used?

The other scope pics up more nebulosity it looks to my inexperienced eyes.

Yes, I think it's the filter - the OIII filter is a Baader 6.5nm.  For a proper imaging run I shall put my Astrodon 3nm OIII filter on the ST80.  The 3nm OIII filter is a much better match for the 5nm Ha for the stars.  The nebulosity contains much more Ha than OIII.

Link to comment
Share on other sites
Gina

Gina

Posted
  • Author
Posted

Thanks Chris :) 

I agree - I could try putting the Astrodon Ha filter on the ST80 and use the Astrodon OIII on the Esprit.  Or I could just swap over the filters I used last night but I would prefer to use the Astrodon 3nm OIII as it's definitely a better filter than the Baader 6.5nm OIII and I think using the Baader would be wasting good imaging time.

Link to comment
Share on other sites
Chris

Chris

Posted
Posted

Sounds like a briliiant plan to me :) 

I've been coming down with the mono imaging bug recently, despite the weather! all these interesting threads don't help! :D

I'd have to do it on the cheap though with an Atik16ic on my WO66  f/5.9 388mm FL.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.