16 replies to this topic

[antarex]

Is it possible to use the 30mm Svbony SV165 teleguider with an asi224 camera, to do AP or EAA deep? I don't know so talking about using it as intended as a guide. 

Net of all the possible optical defects at the edges of the field. I was thinking of using it, to start without having a big budget.

Also, would it be possible to connect an off-axis guider? Or, would there be a risk of not being able to focus with the camera anymore?

 

Thanks.

 

[antarex]

Can anyone help me?

 

[MartinNI]

Up a bit and consider the Skywatcher Evoguide 50ED / DX ? The SV165 is just 30mm aperture. The Evoguide is a real scope, but of course you can use the SV165 as a guide scope when you upgrade to a bigger scope. I plan to test the SV165 as a guide scope. Focusing is not so pleasant.

[MartinNI]

Connecting an OAG to a very small scope could lead to problems both with focus and weigth. I tested the SV165 for a ’terrestial’ image check with a QHY 5III715C, and was able to get an image of distant trees, with quite a lot of focusing thread used, and the camera was also quite far back. I can’t say if you could focus with an OAG. Still, isn’t it better just to connect a camera and see how it works, without OAG and intended long exposure times ?

[antarex]

Connecting an OAG to a very small scope could lead to problems both with focus and weigth. I tested the SV165 for a ’terrestial’ image check with a QHY 5III715C, and was able to get an image of distant trees, with quite a lot of focusing thread used, and the camera was also quite far back. I can’t say if you could focus with an OAG. Still, isn’t it better just to connect a camera and see how it works, without OAG and intended long exposure times ?

In fact my fear with an OAG, would be related to the camera's focus. I would like to use the OAG to try to use the small telephoto, both as a guide and for shooting.

Surely before buying an OAG, I will try to connect the camera directly to the tube and surely there will be no backfocus problems.

Edited by antarex, 22 March 2025 - 03:19 AM.

[unimatrix0]

 

Svbony SV165

I had to look up what scope is this.  

 

So this is a 30 mm finder/ guider scope and I can already tell you that don't expect miracles, imaging through that thing. 

 

Also pointless to do any guiding, let alone attach an OAG to it.  You are at probably like 120-130mm focal length, guiding is optional, but again, it won't be the guiding that's gonna ruin your image, but the extremely cheap lens inside these mini scopes. These things barely qualify as lens if you ask me they probably cost like $5.00 to make.   I got an Askar mini triplet, but again, that's a 3 glass element scope and at 30mm it still very limited what I can do with it other than use it as a guider. 

Edited by unimatrix0, 22 March 2025 - 10:25 AM.

[antarex]

I did some tests with the 30mm svbony sv165, using the uv ir cut filter from svbony.
Basically, there is a chromatic aberration problem.
Basically, the stars tend to have a red halo around them, due to the blurry red channel.
Is there a way to correct it via software?

Edited by antarex, 01 April 2025 - 04:09 AM.

[MartinNI]

Hmm, a red halo sounds the color processing is a bit off, usually chromatic aberration gives blue halos, and those I have had besides the dreaded green tint from oversensitivity in the green channel. Anything can be done in the processing, but if you have the time it can be worth discovering processing tricks.

Edited by MartinNI, 01 April 2025 - 03:33 PM.

[antarex]

There are also red halos in the single shots.
For example, with which software could it be used?

[jml79]

There are a few tricks. First seperate the stars using Starnet or StarXterminator then a few options.

 

Expensive - In PI, separate the colour channels and use blur exterminator with different amounts of halo reduction to reduce the stars more in the offending channel. You might be able to do this using Siril and SETI Cosmic Clarity but I honestly have no idea.

 

Cheaper - Affinity has a tool that does pretty good identifying and desaturating red and blue CA in stars. I believe it's in the James Ritson AP add on but it has helped with some scopes that have longitudinal CA (red on one side of the stars and blue on the other). Unfortunately I am away from my processing computer so I can't look at the exact name of the tool.

 

Free - Using GIMP you should be able to mask the offending red and desaturate it or manipulate it. I know how to do this in photo shop and affinity but not in GIMP although I am sure it is possible.

Edited by jml79, 02 April 2025 - 07:24 AM.

[antarex]

There are a few tricks. First seperate the stars using Starnet or StarXterminator then a few options.

 

Expensive - In PI, separate the colour channels and use blur exterminator with different amounts of halo reduction to reduce the stars more in the offending channel. You might be able to do this using Siril and SETI Cosmic Clarity but I honestly have no idea.

 

Cheaper - Affinity has a tool that does pretty good identifying and desaturating red and blue CA in stars. I believe it's in the James Ritson AP add on but it has helped with some scopes that have longitudinal CA (red on one side of the stars and blue on the other). Unfortunately I am away from my processing computer so I can't look at the exact name of the tool.

 

Free - Using GIMP you should be able to mask the offending red and desaturate it or manipulate it. I know how to do this in photo shop and affinity but not in GIMP although I am sure it is possible.

Grazie per i consigli, sto facendo delle ricerche online su come operare con questi programmi, ma ancora non ho capito bene come devo operare.

[jml79]

Grazie per i consigli, sto facendo delle ricerche online su come operare con questi programmi, ma ancora non ho capito bene come devo operare.

Apparently I can read Italian. Who knew? I learned mostly from youtube and the forums here. What software do you already have and are you staying with free software or will you purchase software? That will help everyone narrow down how to do some more advanced techniques.

[antarex]

There are a few tricks. First seperate the stars using Starnet or StarXterminator then a few options.

 

Expensive - In PI, separate the colour channels and use blur exterminator with different amounts of halo reduction to reduce the stars more in the offending channel. You might be able to do this using Siril and SETI Cosmic Clarity but I honestly have no idea.

 

Cheaper - Affinity has a tool that does pretty good identifying and desaturating red and blue CA in stars. I believe it's in the James Ritson AP add on but it has helped with some scopes that have longitudinal CA (red on one side of the stars and blue on the other). Unfortunately I am away from my processing computer so I can't look at the exact name of the tool.

 

Free - Using GIMP you should be able to mask the offending red and desaturate it or manipulate it. I know how to do this in photo shop and affinity but not in GIMP although I am sure it is possible.

Thanks for the advice, I'm doing some research online on how to operate these programs, but I still don't understand how I should operate.

[antarex]

Apparently I can read Italian. Who knew? I learned mostly from youtube and the forums here. What software do you already have and are you staying with free software or will you purchase software? That will help everyone narrow down how to do some more advanced techniques.

Sorry! I made a mistake in copying/pasting the message! hahaha!

Anyway I have photoshop, I don't have other specific software like RC ASTRO or pixinsight

[jml79]

Sorry! I made a mistake in copying/pasting the message! hahaha!

Anyway I have photoshop, I don't have other specific software like RC ASTRO or pixinsight

No worries, I am fluent in French and know some Spanish and Latin so it wasn't too difficult. Once I was in Romania and trying to speak with a local, he tried Romanian which I do not speak, I answered in English which he didn't speak, he tried Romani (I think, I'd never heard it before) then I tried French and we settled on something resembling Italian and had a whole conversation. A little slow and pretty basic but a fun time either way. Obviously his Italian was far better than mine but I was able to use enough shared vocabulary and poorly conjugated verbs that he could understand.

[antarex]

What do you think, is it possible to do something with Photoshop?

[MartinNI]

Maybe it is better to have red halos than blue halos. I’m sorry but I use Pixinsight and am no expert on astroprocessing in Photoshop. But you could probably play with the red channel, somehow. Anyway, it may be that you should just use your SV165 to get as much total exposure as possible and be happy with the results.