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DSLR - Rear filter removal "advice please"


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Good morning everyone  :)

I am taking delivery today of an astro modified Canon 60D that appeared for sale on another forum with the following modification originally performed by Andy at Astronomiser:

“Rear Filter Removal with Sensor Repositioning Modification”

I visited the Astronomiser homepage to try and better understand exactly what this modification entailed, if an additional piece of glass was added (possibly not) and the "possibility of star bloating".

While I do understand that this filter partly removes UV/IR and colour correction, with the first filter still in place I am wondering if I still require an additional filter within the imaging train to help overcome "muddy images". Then apply a custom white balance - appreciate the raw image will be ok but I will be doing "live streaming" so want to try and keep the image close to normal. My imaging train consists of the camera, nosepiece with an Ikharos field flattener (ideal for crop sensors, not so for full frame), coupled to a SkyWatcher Equinox ED120. I did read the star bloating may or may not appear and is dependent on the quality of ED glass.


With just a single filter replacement, would I be looking at a CLS option or a CLS-CCD or indeed something entirely different again.  I have no intention of using EF-S lenses so will be considering a clip-in filter solution.

Main reason for selecting this camera is for the "movie crop mode" for planetary imaging and only 3 of the Canon camera's offer this.

I did try to email andy@astonomiser but the email was returned undelivered with a "mailbox full" message and I am not sure if he monitors SGL. I was set to proceed with a brilliant online dealer that I previously bought a full frame 6D from but the 60D just appeared out of nowhere and the cheaper option might mean the "bank of wife" may still allow me to retire next year  ;)

Many thanks for your help.

A very Happy New Year and I hope it is a better one for all of us.

Steve


 

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Hi,

With the rear filter removed, and the front one still in place, you will NOT need another UV/IR cut filter, as the one left in the camera does a very good job of this, hence why it’s left in, the rear filter also cuts some UV/IR but also much of the Ha, hence why it’s removed....so for LP the cheaper CLS is all that’s needed.....the repositioning of the sensor is to enable autofocus to still work when using a camera lens, so you can use in this manner, it’s to counteract the loss of the thin filter....HTH... 👍🏼

Edited by Stuart1971
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Oh, and to take a custom white balance image, put the CLS in the camera and take an image of a piece of neutral grey photographic card, on a bright day with the sun behind you, and make sure it fills the frame, then set this as the custom white balance....this works very well, some people say to use white card, but I found neutral grey much better and it’s also recommended in many places... 👍🏼

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Stuart, that is brilliant, thank you so much for your help. I actually have a set of cards and have done a custom WB on my Canon 6D (from Juan)  which is coupled directly to a WO ZS73 through a full frame field flattener (works perfectly).  Stuart, thanks for your suggestion of the normal CLS filter (ie not the CLS-CCD). Should the CLS suffice completely or are there other options I might consider ... duobanded or would that be overkill.  The one that comes to mind is the Optolong L Pro.

Really appreciate your fast answer, thanks again and a very Happy New Year  :)

Steve

Edited by stevebb
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49 minutes ago, stevebb said:

Stuart, that is brilliant, thank you so much for your help. I actually have a set of cards and have done a custom WB on my Canon 6D (from Juan)  which is coupled directly to a WO ZS73 through a full frame field flattener (works perfectly).  Stuart, thanks for your suggestion of the normal CLS filter (ie not the CLS-CCD). Should the CLS suffice completely or are there other options I might consider ... duobanded or would that be overkill.  The one that comes to mind is the Optolong L Pro.

Really appreciate your fast answer, thanks again and a very Happy New Year  :)

Steve

Your welcome....

As for the filter, the CLS should be fine, but will depend on your skies where you live and where they are on the bottle scale....the more LP the stronger the filter you will need.....

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