Light pollution filter, which for use with unmodded Canon 5D?

[milan]

Ive had a look through the thread on here but am none the wiser (cant see anything for a Canon 5D), having just ordered a QHY5 and guidescope i thought it may be prudent to order a LPF as anything longer than a 30sec exposure i get lovely David Dickison orange images (Plenty of sodium lights nearby )

Setup is a WO Megrez 90 with a 0.8 Field flattener straight into my Canon 5D, how/what LPF should i be looking at?

[Rossco72]

If there is nowhere on the imaging train to screw on a filter then it's going to be difficult.

I have a 5D and the chip size means that clip filters are out, you would need a 2" filter and with the field flattener that could prove tricky.

If you can attach a filter to the flattener then a CLS filter is a good general purpose filter to reduce the effect of street lighting and "skyglow"

[milan]

Like you i came to the conclusion clip in filters were out, but thats as far as i had got. Does anyone know of a potential solution?

[Carbon Brush]

Just to add to my support for the CLS filter. I have two Canon 1000D. One unmodded for 'family snapshot' use and one with the internal IR/red cut filter removed, and a CLS clip in added. The difference is amazing. One is unusable for sky pictures despite my half decent sky and the other literally switches off the sodium light. Maybe an email to the filter manufacturer would help? I'm sure you aren't the only person with this problem and maybe the solution hasn't got through to the dealers yet? Just a thought.

[Rossco72]

The problem is the full size 35mm chip in the 5D, there isn't a clip filter which can cover the full chip area.

[davew]

If the field flattener has the 2" drawer tube fitting then a filter screwed on the nose ?

If not then maybe a T filter and a thin EOS T ring. Don't know where you get them ( Thin T ring ) but I've read some one talking about them.

Dave.

[Carbon Brush]

This extract taken from the Atronomik web site may be useful....

The filter is available in the following sizes

• Mounted filter in 1,25" cell (M28,5mm x 0,5mm), 57,98€*
  
• Mounted filter in 2" cell (M48,5mm x 0,75mm), 133,61€*
  
• Mounted filter in T2 cell (M42mm x 0,75mm), 100,00€*
  
• Mounted filter in SC cell (2" x 24Tpi), 133,61€*
  
• Mounted filter in EOS-Clip cell, 108,40€*
  
• Unmounted filter with 50mm diameter, 133,61€*
  
• Unmounted filter with 38mm diameter, 91,60€*
  
• Unmounted filter with 36mm diameter, 83,19€*
  
• Unmounted filter with 31mm diameter, 66,39€*
  
• Unmounted filter 50mm x 50mm square, 175,63€*
  
• Filters with custom diameters are available upon request
  

* suggested net retail price

[simon84]

I'd go for a 2" filter on the end of the nosepiece.

Your best options filter wise are either the CLS CCD from Astronomik or the IDAS P2 from Hutech.

The CLS CCD is the second item down on this page, Astronomik filters @ Modern Astronomy and the IDAS P2 is available from here, Hutech IDAS 2" Nebelfilter LPS-P2 für Deep Sky Fotografie - Teleskop-Express: Astro-Shop + Fotografie + Naturbeobachtung

I dont think you would want to change the T ring as you might muck up the spacing between the sensor and the flattener.

The CLS CCD filter is good but has reports of being a bit too agressive whereas the IDAS P2 allows in some other wavelengths. I've attached some curves that show you what they can do. The first one is the CLS CCD.

Edit: Just had a look at the WO 0.8 reducer and it says it has a 2" push fit nosepiece, I imagine there is a good chance that the inside of that nosepiece is threaded for 2" filters.

[milan]

Thanks! will have a look tonight and report back

[Psychobilly]

I use 2" Hutech IDAS P2 on the front of the WO Flattner...

I Also use the Astronomik CLS-CCD but personally prefer the results from the IDAS under the light polution levels i have at home..

The CLS-CCD cuts out more... but for me the IDAS cuts out enough and gives more "color" due to its narrower "targetted" cut off bands...

Peter...

[milan]

Peter, thanks for this! when you say on the front you mean the end that goes inside the scope?

Is it an import job as noted by SlySi84?

[Psychobilly]

yes it should scre into the front of the flattener...

[milan]

Just got home and can see now, your right the nose piece has an internal thread. Great stuff, looks like this is the way forward.

Thanks all, invaluable information as always.