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Knowing DSLR Mod Types...

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#176 asanmax

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Posted 15 November 2022 - 11:52 AM

Be very careful with buying cheap filters. They may even have proper coatings but there is such a thing as surface quality. It measures in the amount of small scratches and digs per surface area. A typical 'budget' filter has a  scratch/dig of around 80/60. A high quality filter goes down in the numbers to 20/10. Due to strict measures that have to be followed in production of high quality filters, they will never be cheap.


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#177 trambler58

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Posted 17 November 2022 - 02:15 PM

Be very careful with buying cheap filters. They may even have proper coatings but there is such a thing as surface quality. It measures in the amount of small scratches and digs per surface area. A typical 'budget' filter has a  scratch/dig of around 80/60. A high quality filter goes down in the numbers to 20/10. Due to strict measures that have to be followed in production of high quality filters, they will never be cheap.

Please tell me how it will be reflected in the pictures? I am currently using sony a7s with a 400-700nm aliexpress filter instead of the standard LPF-2. Here are some rav files with examples 

https://disk.yandex..../sHHwAgJ--ZuDcw

https://disk.yandex..../k8yZF4Fnju_4bA

https://disk.yandex..../DrOVBG93KZc64Q



#178 trambler58

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Posted 17 November 2022 - 02:26 PM

And like this, on the same 24mm lens, the stars are stretched at the corners of the frame, like sausages. Here I moved the sensor forward and removed the LPF-2, but leaving the LPF-1.

https://disk.yandex..../3qGLy9wl8xfO4A



#179 asanmax

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Posted 17 November 2022 - 09:17 PM

Please tell me how it will be reflected in the pictures? I am currently using sony a7s with a 400-700nm aliexpress filter instead of the standard LPF-2. Here are some rav files with examples 

https://disk.yandex..../sHHwAgJ--ZuDcw

https://disk.yandex..../k8yZF4Fnju_4bA

https://disk.yandex..../DrOVBG93KZc64Q

The images look like they have been compressed for some reason.

Anyway, the lower the filter surface quality the higher the scratch/dig count. So you can see those microscopic imperfections on the surface of the filter. You may not see them with the naked eye though. This will affect images with all sorts of spots and lines. This is of course not a big of an issue and flat frames should fix those spots. 

However there is another  more important aspect defining a filter quality - AR and transmission coatings. Poorly done coatings may cause UV and IR light to go through the filter causing star bloating and halos.

Poor AR coatings will most likely result in star halos.



#180 asanmax

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Posted 17 November 2022 - 09:23 PM

And like this, on the same 24mm lens, the stars are stretched at the corners of the frame, like sausages. Here I moved the sensor forward and removed the LPF-2, but leaving the LPF-1.

https://disk.yandex..../3qGLy9wl8xfO4A

Lenses are made with the sensor filter stack in mind because the light hits the sensor in the center and in the corners at different angles.

So when the filter stack changes, it affects how the light is refracted in the filters in the corners of the frame. That is why, when the filter stack becomes thinner, you see the elongated stars in the corners.

It is not recommended to use lenses with the focal length shorter than 35mm with the cameras with the LPF2 filter removed.

I should say, I have never seen a good 14mm lens. The corners is always a compromise when the lens is used fully open. I guess you wouldn't consider spending a ton of money buying a nice cine lens for astrophotography to just get nicer star shapes in the corners.



#181 trambler58

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Posted 18 November 2022 - 01:32 PM

The images look like they have been compressed for some reason.

This is a link to cloud storage, if interesting, you can download and open it in any convenient equal editor.

 

Lenses are made with the sensor filter stack in mind because the light hits the sensor in the center and in the corners at different angles.

So when the filter stack changes, it affects how the light is refracted in the filters in the corners of the frame. That is why, when the filter stack becomes thinner, you see the elongated stars in the corners.

It is not recommended to use lenses with the focal length shorter than 35mm with the cameras with the LPF2 filter removed.

I should say, I have never seen a good 14mm lens. The corners is always a compromise when the lens is used fully open. I guess you wouldn't consider spending a ton of money buying a nice cine lens for astrophotography to just get nicer star shapes in the corners.

I already understood about the thickness of the filters, that's why I installed LPF-2, bought on Aliexpress.



#182 Vito Pastorini

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Posted 03 July 2023 - 02:31 AM

hi guys, I have a couple of question for you and I think in this thread you can help me. I havent read all the pages but most of them. The think is someone is selling me a full spectrum Canon (im Nikon) with a 2" uv/ir cut filter that it has to be used as I have read. The thing is, i dont have a telescope yet, I only use lenses like my beloved rokinon 135 f2, tamron 150 600 and a sigma 70 300 apo. So, telescopes like zenithstar comes with a field flattener and filter drawer and they are build considering the distance to the sensor isnt it? but when you put a piece between the body an a regular lens, (im thinking on buying the canon filter drawer that i think is just for mirrorless camera becasue the sensor is closer to the bayonet, im just guessing) the result of that is the change on the focus distance, for example to be able to do macro (with macro extension tubes). I know this is particularly notorious in nikon cameras because the position of the sensor (hence my question, because i dont know many things about canon) and therfore you can use nikon lenses on canon but not the other way around.
so, the question is, may I or may I not use a filter drawer and stilll be able to reach infinity with a dslr and regular lenses (nikon with an adpater by the way 😬🫣). anyone know the anwser? thanks in advance.

ps: i know there are clip in filters that would fix my problem but right now I cant buy them.

thanks in advance

greetings from Chile.



#183 mmalik

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Posted 05 July 2023 - 02:41 AM

so, the question is, may I or may I not use a filter drawer and still be able to reach infinity with a dslr and regular lenses (Nikon with an adapter by the way ). anyone know the answer? thanks in advance.

 

ps: i know there are clip in filters that would fix my problem but right now I cant buy them.

 

First off, most confusing way to ask a question. Filter drawer with a lens doesn't seem like a good idea. One option would be to try what your concept is (which is hard to decipher for me) and go from there.

 

 

What do you mean when you say you can't buy clip filters; do you mean you can't afford them or are they not readily available?

 

 

You may also consider putting filter in front of the lens with step rings if at all possible. But then again how you would want to try such a solution if affordability/accessibility might be the issues.

 

 

All in all, a (very) confusing endeavor. Easiest & simplest may be to forego the whole idea and use a scope instead. Regards

 

 

.


Edited by mmalik, 05 July 2023 - 08:45 AM.


#184 AstroCorgis

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Posted 02 August 2023 - 05:02 AM

Hi all,

 

I am very new to AP, its fascinating to see what you can do to a DSLR to maximise performance, image quality and colour. I know modding DSLR is fun in its own right and it can be very rewarding to get better image out of gears you created. I would like to get into AP deeper in the future, on DSO especially, I am having fun with my DSLR and lens at the moment but would eventually like to get a refractor and new camera. However, I would like to ask, objectively speaking, is there any advantage to have modded DSLR compare to a dedicated AP camera, especially in the field of DSO? is it cheaper to mod for example, or is a DSLR sensor better than a similar priced astro-cam?

 

Cheers



#185 asanmax

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Posted 02 August 2023 - 11:45 AM

Hi all,

 

I am very new to AP, its fascinating to see what you can do to a DSLR to maximise performance, image quality and colour. I know modding DSLR is fun in its own right and it can be very rewarding to get better image out of gears you created. I would like to get into AP deeper in the future, on DSO especially, I am having fun with my DSLR and lens at the moment but would eventually like to get a refractor and new camera. However, I would like to ask, objectively speaking, is there any advantage to have modded DSLR compare to a dedicated AP camera, especially in the field of DSO? is it cheaper to mod for example, or is a DSLR sensor better than a similar priced astro-cam?

 

Cheers

Hello,

You can find some answers in the existing thread

https://www.cloudyni...meras-who-wins/

 

For the same price you can either get a big sensor DSLR or a tiny sensor cooled camera. Also, a cooled camera will produce less noisier images. However this is not an issue with the modern stacking and processing software.


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#186 mmalik

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Posted 02 August 2023 - 06:17 PM

However, I would like to ask, objectively speaking, is there any advantage to have modded DSLR compare to a dedicated AP camera, especially in the field of DSO? is it cheaper to mod for example, or is a DSLR sensor better than a similar priced astro-cam?

 
I could give you an answer first hand...
 
 
...since I am actually (currently) dealing with it. I am finding out the hard way after spending a lifetime with DSLRs/MILCs that dedicated monochrome is leaps and bounds ahead. Here is a fresh sample. Read more here....
 
 
CDK14/QHY600M

 

 

.

Attached Thumbnails

  • SNAPSHOT, 2023-08-01, 8x600R 12x600G 6x600B 6x0L, (Slot4 Slot5 Slot6), QHY600M_stacked_CRc.jpg

Edited by mmalik, 02 August 2023 - 08:29 PM.

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#187 mmalik

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Posted 03 August 2023 - 06:25 PM

Apples to apples comparison of sort...

 

 

Both captured with CDK14, an RGB (a7SIII cooled/modified) and an SHO (QHY600M)

 

 

.

Attached Thumbnails

  • NGC281-PacmanNebula_CDK14.jpg
  • SNAPSHOT, 2023-08-01, 8x600R 12x600G 6x600B 6x0L, (Slot4 Slot5 Slot6), QHY600M_stacked_CRc.jpg

Edited by mmalik, 03 August 2023 - 06:25 PM.

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#188 mmalik

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Posted 03 December 2023 - 06:53 PM

Useful info...
 

 


Are there comercially available IR filters that will restore standard performance to an astro modified camera? (Or a filtered lens, which might be better)

 

An Astronomik OWB filter or a X-NiteCC1 will do the trick.



#189 stevesanacore

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Posted 25 December 2023 - 03:25 PM

This is a timely subject for me. I can’t decide between going full mod on my A7R or buying a smaller format astro camera. I know there are advantages to both. Keep the samples coming!


Edited by stevesanacore, 25 December 2023 - 03:26 PM.


#190 mmalik

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Posted 25 December 2023 - 07:49 PM

This is a timely subject for me. I can’t decide between going full mod on my A7R or buying a smaller format astro camera. I know there are advantages to both. Keep the samples coming!

 

Get dedicated astro camera no IFs or BUTs for hard core DSO work; no harm having a modified MILC for some applications like galaxies, etc. I keep both on hand but use dedicated astro for the most part. In short, get both if you can, but start with dedicated and make it primary. Regards

 

 

 

My latest work here...; more here...


Edited by mmalik, 25 December 2023 - 07:51 PM.


#191 stevesanacore

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Posted 25 December 2023 - 08:22 PM

Thanks for the advice! Now just need to learn how to get rid of the clouds that have been here for months!

 

I am curious, what advantage is there using a modded MILC body for galaxies over an astro cam? Is it just sensor size? Is a OSC camera still that much better than a modded A7R? I know mono cameras are the best way to go, but I just don’t have the time for that now. Thank you!


Edited by stevesanacore, 26 December 2023 - 02:20 PM.

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#192 GTom

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Posted 26 February 2024 - 04:47 AM

Thanks for the advice! Now just need to learn how to get rid of the clouds that have been here for months!

 

I am curious, what advantage is there using a modded MILC body for galaxies over an astro cam? Is it just sensor size? Is a OSC camera still that much better than a modded A7R? I know mono cameras are the best way to go, but I just don’t have the time for that now. Thank you!

If the "galaxy" is M33 or M31 then yes, sensor size. Same goes for groups of galaxies. For the usual single-galaxy shot a cheap second hand camera does the job perfectly! Example: the entire Deer Lick group fits in the FOV of my 105/735 APO and the old ASI120mm I just bought for £50! Even that little guidecam is better for this purpose than a DSLR, adding a set of 1.25" filters (got my Baader LRGB kit for £110 also second hand) and an el-China filter wheel (~£50 on ebay) will keep you near DSLR budget.

 

I am still keeping my modded canon 6D though, for large things and travel astrophotography.


Edited by GTom, 26 February 2024 - 04:49 AM.



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