sky-watcher Problem with focusing

[Simone_DB]

20 hours ago, Denys said:

Oh, it's great that you can get the chance to try a modified camera. What is even better is that you can compare both cameras and check for yourself whether or not it is worth it.

Like I said, I have no experience with a modded DSLR, but if I had to make a wild guess I would say that it will give you better results for most DSOs. But you touch an interesting point about the reddish objects. For instance, I was checking for some pictures of Orion with modified DSLRs on astrobin and most of the images have a very strong reddish color (which I have to say, it’s not of my personal liking - but perhaps that can be treated in post-processing?). On the other hand, I once tried to capture the flame + horsehead nebula or the Rosetta nebula and didn’t have much of a success, and I think it’s probably due to the IR filter that is blocking most of the signal in these specific targets.

Anyhow, please let me know your thoughts on this once you get the chance to try the cameras.

Regards,

Denys

Hi! This evening there should be some clearing, at least until 10pm, so I could have a chance to get some pictures (but not with the modified camera that I'll borrow Monday). Probably I'll try to get a shot of the Pleiads, or some other DSO. Obviously if I succeed, I'll post the results! Have a nice weekend everyone 🙂

[Simone_DB]

Hi yesterday there were two main issues: a megawatt moonlight and scattered clouds. So I didn't shoot DSOs, but I tried to align the scope for exercise anyway, and something weird happened. The the only worthy pictures I took was the partially eclipsed moon. I attach a couple of pictures, one (made with the phone) that shows the moon rising behind the clouds, whose edges seemed lit as in daylight!. A very impressive sight! The others show two versions of the eclipsed moon and a "Halloween version" (with clouds).

The weird thing with alignement was that it seemed I made an acceptable work, as planets was more or less found by the scope. But when I tried to look for the moon, the scope pointed somewhere towards S instead of E, where the moon was rising. I couldn't get why. I used a 3-star alignement and maybe I made some mistake there.

Edited October 29, 2023 by Simone_DB

[Stu Wilson]

You need the critical 55mm spacing between your coma corrector and camera sensor.

[Simone_DB]

13 minutes ago, Stu Wilson said:

You need the critical 55mm spacing between your coma corrector and camera sensor.

Hi, I was told about this! Does it mean that I surely need a spacer, or maybe the distance could be already right? The camera is a reflex not a mirrorless. 

[Stu Wilson]

You need to know how far inside your camera the sensor sits from the front, then 55mm minus this size is the spacing you need to the coma corrector.

so for arguments sake your sensor is 15mm inside youll need a 40mm spacer.

 

HTH

[WolfieGlos]

On 27/10/2023 at 15:16, Simone_DB said:

About the modding of the camera, I have a collegue that own a Nikon D3100 which he removed the IR filter from, and he's not using it anymore, so I'll have a chance to make some practice with that! Buy the way, such a modding is suitable just for reddish objects, or is it good in general for DSOs?

Hi, welcome to SGL.

Regarding a modded DSLR, you can use it for any DSO’s. Essentially by removing the filter it will allow through circa 75% more of the red wavelength of light which is given off by emission nebula. If that light doesn’t exist on a broadband target (galaxy or reflection nebula; typically blue colours like M45 Pleiades), then the camera is still suitable. In fact, for galaxies which have some Ha emission , like M33 and M31, you will get both the galaxy and the red nebulas in one go 🙂

I’ve also used it for single shots of the Moon, but I had to correct the white balance in post. I’ve not tried planetary with a DSLR, so not sure on that.

Although UK based, this is where I got mine from last year and the website gives a good explanation and detail about astro modding, and what it does  http://www.astronomiser.co.uk/filters.htm . You do not want the full spectrum mod, but I asked him to buy a camera from MPB, mod it and I had it a week later. Top service. 

[Simone_DB]

1 hour ago, Stu Wilson said:

You need to know how far inside your camera the sensor sits from the front, then 55mm minus this size is the spacing you need to the coma corrector.

so for arguments sake your sensor is 15mm inside youll need a 40mm spacer.

 

HTH

Crystal clear, thanks! 👌

[Simone_DB]

45 minutes ago, WolfieGlos said:

Hi, welcome to SGL.

Regarding a modded DSLR, you can use it for any DSO’s. Essentially by removing the filter it will allow through circa 75% more of the red wavelength of light which is given off by emission nebula. If that light doesn’t exist on a broadband target (galaxy or reflection nebula; typically blue colours like M45 Pleiades), then the camera is still suitable. In fact, for galaxies which have some Ha emission , like M33 and M31, you will get both the galaxy and the red nebulas in one go 🙂

I’ve also used it for single shots of the Moon, but I had to correct the white balance in post. I’ve not tried planetary with a DSLR, so not sure on that.

Although UK based, this is where I got mine from last year and the website gives a good explanation and detail about astro modding, and what it does  http://www.astronomiser.co.uk/filters.htm . You do not want the full spectrum mod, but I asked him to buy a camera from MPB, mod it and I had it a week later. Top service. 

Hi, thanks a lot, those were very useful info! I hope I'll be able to take a picture of something colorful as soon as I can, you know, I'm still struggling with alignment 😋

[alacant]

4 hours ago, Simone_DB said:

I surely need a spacer, or maybe the distance could be already right?

No spacers needed. The required distance is correctly set simply by using the adapter which was linked in the earlier discussion:

 

Edited October 29, 2023 by alacant

[Simone_DB]

Thanks Alacant, I apologize, I got a lot of information I have to cope with, so sometimes something slips out of my mind. 😅