Canon 600D / Heritage 130P, can't sort this out!

[zgoro]

Hi guys, I'd love to have some help before I end up tossing money without a practical reason!

I have an AZ-GTi / Heritage 130p tube connected to a Canon 600D by a T-ring adapter: 

 

The issue here is that I can't see any stars at all! The live preview is practically pitch black even at 400 ISO, whilst I see nice and bigger stars with my 10/25mm oculars!

Upon seeing the raw and adjust it, I did actually see a few stars but at 100% resolution the rarely are above 1 pixel: 

 

My Galaxy S8 on top of 25mm eyepiece does a much better job!

What should I do to at least image the same quality / size of the stars I see through my telescope eyepiece?

Thank you pals!

 

-Andrea 

[wxsatuser]

Are you sure it's coming to focus?

Sounds like the one pixel stars are just that, pixels, hot or stuck ones.

You could bump up the ISO, 1600 should show stars if you can reach focus.

[CraigT82]

The screen is pitch black because you're not in focus with the camera.

You will need to collapse the tube a couple of inches to get the DSLR to focus.

[Aramcheck]

I'm not sure which scope the "AZ-GTi / Heritage 130p" description refers to. If the tube length is 650mm then I would have thought it should be possible to achieve focus, but the draw tube will have to extend into the OTA by several cm. I use a "130pds" with a DLSR & that requires winding the drawtube into the OTA by a long way in order to get focus.

Try getting the camera to focus in the daytime on a distant object on the horizon.

If the OTA tube length is longer - i.e. 900mm then, I don't think it will be possible to do prime focus photography. Also - if the scope is this one: https://www.firstlightoptics.com/sky-watcher-az-gti-wifi/sky-watcher-explorer-130ps-az-gti.html then the mount won't be suitable for DSO's which require long exposures, and you should also check that it is capable of carrying the extra weight of the DLSR.

Cheers
Ivor

[Waldemar]

You will need a 130PDS, for they have a longer backfocus that will work with a DSRL, which has a backfocus of ± 44mm.
With the 130P your only option is to shorten the tube, so the distance between main and secondary mirror will be shorter.
In fact there is only one way to do that, which is to move the main mirror up. The distance needed will be app. 1½" , but for the exact number you will need to do some measuring, or ask people on this forum that already did it. (you are not the only one...)

The second option is to buy a dedicated camera with shorter backfocus...

[Waldemar]

Sorry, I crossed Ivor's input, who seems to know more about it then I do...

[Cornelius Varley]

16 minutes ago, Aramcheck said:

I'm not sure which scope the "AZ-GTi / Heritage 130p" description refers to. If the tube length is 650mm then I would have thought it should be possible to achieve focus, but the draw tube will have to extend into the OTA by several cm. I use a "130pds" with a DLSR & that requires winding the drawtube into the OTA by a long way in order to get focus.

Try getting the camera to focus in the daytime on a distant object on the horizon.

If the OTA tube length is longer - i.e. 900mm then, I don't think it will be possible to do prime focus photography. Also - if the scope is this one: https://www.firstlightoptics.com/sky-watcher-az-gti-wifi/sky-watcher-explorer-130ps-az-gti.html then the mount won't be suitable for DSO's which require long exposures, and you should also check that it is capable of carrying the extra weight of the DLSR.

Cheers
Ivor

The Heritage 130P is a flextube  dobsonian telescope, 650mm fl 130mm aperture. and uses the same optics as the standard 130/650 but in a collapsible tube. Just like a lot of reflectors you can't achieve focus with a camera without some sort of modification. In this case not extending the tube fully should solve that. The main concern I have is that the focuser mount may not be strong enough to support a heavy camera body, it is just a bracket holding the helical focuser (not a rack and pinion). The AZ-GTi mount has an alternative firmware that allows it to be used in an equatorial mode so allowing longer exposures.

[Ricochet]

I agree with @Cornelius Varley. The heavy, expensive camera on the end of the cheap, plastic focuser is a concern. I am not an imager but my suggestion would be to:

1. Buy the book Making Every Photon Count
2. Buy a wedge for the AZ GTi, and upgrade the firmware to enable EQ mode.
3. Remove the Heritage 130p from the equation and mount the camera directly to the AZ GTi, using whatever lenses you already own for it.

[Bagginsies]

I have a Celestron 130 SLT which doesn't have enough 'in' focus, but it is achievable with a barlow lens. I also use Iso 6400 and the lowest shutter speed (30) in video mode on a Canon 60D until I get it focused on a star. I then put it into bulb mode at Iso 1600, for my 1-2 minute exposures. Without the barlow I cannot get focus.

[zgoro]

Thank you guys! This hobby is very challenging for total rookies, but after seeing Orion nebula with my telescope I couldn't stop thinking about imaging some of this immense and beautiful universe!

But I digress, regaring your suggestions:

3 hours ago, Bagginsies said:

I have a Celestron 130 SLT which doesn't have enough 'in' focus, but it is achievable with a barlow lens. I also use Iso 6400 and the lowest shutter speed (30) in video mode on a Canon 60D until I get it focused on a star. I then put it into bulb mode at Iso 1600, for my 1-2 minute exposures. Without the barlow I cannot get focus.

Do you have any pics to share? Close in-stars or nebulae would be fantastic!

Following your suggestion, I'd need to buy an adapter to put inside a barlow lens eyepiece (which magnification?) to connect it between T-ring and telescope, right? Do you have any cheap model to suggest?

 

4 hours ago, Ricochet said:

I agree with @Cornelius Varley. The heavy, expensive camera on the end of the cheap, plastic focuser is a concern. I am not an imager but my suggestion would be to:

1. Buy a wedge for the AZ GTi, and upgrade the firmware to enable EQ mode.

Yes I have updated it, but I need the EQ mount + wedge, do you have anything cheap to reccomend?

 

Thanks!

-Andrea

 

[Bagginsies]

I have a few pic's on here in various posts, but most are on @photoncass if you have Instagram. 

I use a 2" barlow that is x2, but it is what you call non-telecentric. This means the closer I have it to the sensor on the camera, the less it multiply's the focal length.  I also use a set of adaptors. This allows me to get enough 'in' focus. 

This sounds complicated, but to start with a standard barlow lens for your eyepiece size (not sure what it would be on yours? 2" or 1.25") should work fine (maybe see if you could borrow one before spending out any money?). The top of the forum has a link to the FLO webpage shop. You can find various ones on there.

Do bear in mind that using a barlow will slow your telescope down and mean that you need to do longer exposures or higher iso. To get real 'prime' astrophotography, it is best to get a scope designed with astrophotography in mind. I was looking at moving my mirror closer, but I would probably break something LOL I am looking at a PDS or Comet Hunter next.

Below is my barlow setup. I have a Canon t-ring adaptor, an svbony converter (eBay), an additional svbony extender (eBay) and the barlow lens itself taken off a revelationsastro kit. By attaching the barlow to the one converter I get about x1.5 magnification which allows me to fit the moon in shot. If I am imaging galaxies etc I use the second extender and get true x2 magnification.

I also recently cleaned my mirrors and then took a picture of Capella with a bahtinov mask showing good focus (see bottom image)

 

 

Edited April 26, 2020 by Bagginsies