191 replies to this topic

[mmalik]

For sake of completion, there is yet another permutation of 'NO' LPF where anti-aliasing (blurring) is essentially 'cancelled'. 5DS R has self-cancelling optical low-pass (anti-aliasing) filter. Regards

 

 

Edited by mmalik, 27 March 2015 - 03:51 AM.

[DaveN]

For sake of completion, there is yet another permutation of 'NO' LPF where anti-aliasing (blurring) is essentially 'cancelled'. 5DS R has self-cancelling optical low-pass (anti-aliasing) filter. Regards

 

 

 

 

Hi Mike

In plain English  ... what does this meant for its use as an astro camera ?

Is it going to perform well in the Ha range or am I still better off with a Nikon D810a ?

or for a cheaper option getting a 6D modded ?

 

Regards

Dave

[mmalik]

Anti-aliasing and Ha transmission are two different things. Cameras without anti-aliasing (a7R, D810, 5DS R) still block Ha and need to be modified for astro; exception of course is D810a which comes modified.

 

 

I am sure 5DS R will be good for astro once modified. Choice between all aliased ones (a7R, D810, 5DS R) is what you can afford, what pixel size suits you, etc.; they are all good astro cameras [once modified]. Regards

 

 

Edited by mmalik, 27 March 2015 - 09:58 AM.

[msalganik]

...ok but can the A7r be modified for enhanced Ha without making it a "full spectrum" camera or loosing AF? Essentially can you retain its usefulness as a daytime camera or is the only choice to modify it into a dedicated astro camera? 

[mmalik]

...can the A7r be modified for enhanced Ha without making it a "full spectrum" camera or loosing AF?

 

Short answer is 'yes'. Long answer is actually a question, "how feasible or amenable is it?"; answer is "not much". Given the design of Sony sensors/assemblies, it is more feasible to just remove Filter-2 in a7R than to replace it with a third party modified (enhanced Ha) filter.

 

 

That's what most folks do to a7R and that's what I recommend, i.e., removing Filter-2 and NOT replacing [which results in a full-spectrum mod in essence for a7R]. Note: This statement/conclusion is applicable to a7R only since other makes/models have their own ramifications!

 

 

Hope this helps. Regards

Edited by mmalik, 27 March 2015 - 12:23 PM.

[mmalik]

To complete the picture, a7II is another unique design; all Filter-1 and Filter-2 layers (three distinct layers visible...) are sandwiched into ONE.


What this all means is that 'Removed LPF-2' mod is NOT possible on a7II. Rather, most viable option for a7II is 'Full-Spectrum' mod. Regards

 



a7II 3-Layer Stack:

Edited by mmalik, 05 April 2015 - 11:38 AM.

[kalasinman]

The stack of filters and functions for a D5100/D7000 Nikon doesn't seem to be the same as the Canon models represented, or the A7s eitther. My understanding is that the piezo and the Ha filters are together in the front.

[mmalik]

Some filter choices for modified cameras; read more about filters here...
 
 
Note: 2" prime focus adapter shown is Sony Full Frame E-mount (SFFE) from TelescopeAdapters.com...

Edited by mmalik, 05 April 2015 - 11:55 AM.

[mmalik]

Useful quotes from Gary...
 

...full spectrum modification..., the sensor would need to be moved 0.46mm toward the lens

...when using the Astronomik MC Clear Glass replacement... the sensor needs only to be moved 0.15mm towards the lens

[mmalik]

With changing times, here is the revised list:
 

 

Mod Choices:

 

 

1. LPF-2 removed and replaced with a modified filter [stock LPF-1 AS-IS]

2. LPF-2 removed and NOT replaced [stock LPF-1 AS-IS] (My recommendation...)

3. LPF-2 removed and replaced with clear glass [stock LPF-1 AS-IS]
 
Note: This is 'old' thinner clear glass and is getting somewhat obsolete in favor of the 'new' #5 below


4. Both, LPF-2 and LPF-1 removed (full spectrum) [external UV/IR block required]
 
5. Both, LPF-2 and LPF-1 removed (full spectrum) and replaced with clear glass [external UV/IR block required]
 
Note: This is 'new' thicker clear glass than #3; its optical thickness is equivalent to combined two removed filters


6. LPF-2 removed and replaced with a modified filter & stock LPF-1 removed [this is quite rare and unorthodoxy]
 

 

 

Note: All options, except #4 and #5, 'may not' require external UV/IR block; additional UV/IR block can be added for refractive optics (to prevent star bloating). Light pollution suppression is something that can be used with any mod type


Note: Narrowband (NB) filter can be used with any mod type; 'NO' #4 or #5 external UV/IR block required if using a NB filter

 

 

IMPORTANT: Not all sensor designs allow for all mod choices. Sometimes for example LPF-1 and LPF-2 may be bonded together; in such cases full-spectrum mod may be the only option!

 

 

To conclude, remember this...

"Essene of any astro mod is to get rid of stock LPF-2"

Edited by mmalik, 29 October 2015 - 01:32 AM.

[AnakChan]

You may wanna add the mod to  "black out" of the clear glass filter bezel/edge to block out any IR that may coming from within the camera housing. I'm sure A7s wasn't the only camera having that IR LED for whatever purpose.

[DaveN]

Mike

 

thanks for your ongoing thread,  so much useful info for different brands and models

 

MY new Canon 700D arrived last Friday and have just been giving it a good standard photo hammering to make sure the camera is functioning OK before I mod it and void the warranty 

 

Your info and that of others elsewhere have encouraged me to get rid of LPF #2 to enhance the Ha sensitivity

I don't have any issue dealing with the electronics disassembly and reassembly, being in that field of work anyway

 

 

again, thanks for your excellent thread

 

Dave

[Cdnpilot]

Good thread - looking to mod a Nikon D300. Who is a good/best vendor to do this?

[Ketut]

 

Note: Narrowband (NB) filter can be used with any mod type; 'NO' #4 or #5 external UV/IR block required if using a NB filter

 

 

Could you please explain more details on this?

[mmalik]

Since NB is limited to a particular wavelength, it is not going to get affected by the other wavelengths. For example if you are using H-alpha 'pass' filter, it is not going to let IR or UV pass-through. Same for other NBs; list below.

 

 

And why modded camera let's NB especially H-alpha pass-through? Because stock camera blocks H-alpha. Hope this helps. Regards

• Hydrogen-beta (H-beta)............486.1 nm
• Oxygen-III (O-III)........................500.7 nm
• Hydrogen-alpha (H-alpha).........656.3 nm
• Nitrogen-II (N-II)..........................658.4 nm
• Sulfur-II (S-II)..............................672.4 nm

 

 

Edited by mmalik, 30 October 2015 - 11:02 PM.

[Edward Nash]

I have a T2i and i am going to do a full spectrum mod and remove both LPF-1 and LPF-2.

 

Question is do I need to reinstall the empty frame work?  or can i just remove the whole assembly,glass and all?

 

I see there is some cabling, I assume that need to be reattached so it does not error...

[mmalik]

It is good to keep the empty framing including piezo (...be it non-functional) to preserve the milieu around sensor and prevent any light leaks or reflections. Regards 

[mmalik]

A useful reference...
 

 

 

Sony's anchor points are mostly hard ones compared to spring mounts of Canon; easiest way to move the sensor forward in Sony is to remove the shims (with minor compensations if needed). I would 'not' suggest third party clear glass; do 'Removed LPF-2' mod or Full-spectrum mod. Read more here.... Regards


Note: I have done Sony mods of this kind, and post-mod auto-focus/infinity focus results have been excellent!

... the "Remove LPF-2" mod ... If you only use modern lenses with sufficient leeway around the infinity mark then a clear glass filter may not be required.

That sums it up quite well and seems what I have heard from folks on modded ones. This is also true for full-spectrum mod since that was the case with some of my mods for users. Regards

[mmalik]

A look at crop factor in terms of filter replacements where applicable...

 

Attached Thumbnails

• 

[mmalik]

Besides mod types, questions most frequently asked and their answers...

 

 

1. Is autofocus preserved after a mod? Yes (...for most cameras)

 

2. Is daytime use possible after a mod? Yes (...with appropriate filter and WB; read more here...)

 

 

Regards

[mmalik]

Another question more frequently asked is what filter to use with a modded camera, here are some general guidelines...

 

 

1. Use D1... with 'Removed LPF-2' mod for astro work

 

2. Use HEUIB-II... with 'Full Spectrum' mod for astro as well as for day time work

 

 

Regards

[mmalik]

From time to time this question re-surfaces as to which mod is better or recommended; below is a very useful post from Ralph that attests to my recommendation in the first post. Regards

 

There have been some questions here on Hutech filter-mods of the EOS 6D. I sent my new 6D to Hutech in February, 2013, to be filter-modded for astrophotography. I chose their (“Option T”, or “EOS 6T”).

Being new to all this and confused by the various options, I exchanged emails with at Ted at Hutech. His answers to my questions were prompt, but sometimes hard to understand. (Partly my ignorance of sensor construction and modding; partly, I think, a language issue.)

But this is my interpretation of what he told me then:

Option T (“for astrophotography”) involved:

• Removing LPF-2.
• Leaving in LPF-1.
• NOT adding any other filter.
• Adjusting the sensor position and “light path distance to make it exactly same as the original - 44.0mm”

As I tried to understand the options at the time (mostly as a new lurker to Cloudy Nights), there was a debate about whether any particular replacement filter had to be added, to fully block IR. (The debate seemed potentially confused by the fact that Canon’s sensor construction and filters had evolved over time, so that what was necessary for the earliest EOS models wasn’t necessarily needed for the newest ones.)

One of our exchanges (2/1/2013):

Q. Your website lists "EOS6T - Canon 6DH spectrum enhanced camera with built-in Canon UV/IR blocking filter." What is this built-in UV/IR blocking filter? Do you insert this in place of the Canon UV/IR filter?

Ted: We remove lowpass and color correction filter(#2) and remain using Canon-made UV/IR blocking filter(#1). Current Canon-made UV/IR blocking filter is well-made and works perfectly for astro. We used to replace #2 with our UV/IR blocking filter before since Canon filter was not good for astro.

Anyway these is no way you make mistake since there is only choice for astro. [Option T]

Ted

From this I concluded:

• In the past, LPF-1 wasn’t sufficient to block IR, but in the 6D it was.
• Another purpose of the debated replacement filter that some were adding (sometimes only clear glass) was to maintain the optical path for autofocus to still function - but the AF problem could be solved by adjusting the sensor position to maintain the “44.0 mm light path.”
• EOS dust removal will still work (because LPF-1 is still intact).
• Ted understood all this much better than I did (but perhaps wasn’t very fluent in English), and I should stop worrying about the details and just send him the freakin’ camera. (Which I did.)

I've been very happy with the result.

 

[t_image]

From time to time this question re-surfaces as to which mod is better or recommended; below is a very useful post from Ralph that attests to my recommendation in the first post. Regards

Wouldn't it be helpful and more specific to post a chart with common DSLRs and the options available to each of the cameras, with a recommendation for each?

since the post above shows differences in Canon models and filter #1?

With recent recommended terminology used as post #25 says:

LPF (low-pass filter) terminology is getting antiquated with new breed of DSLRs without LPFs (a7R, D810, D810a, etc.) I suggest we call LPF-1, 'Filter-1' and LPF-2 'Filter-2' and refer to their replacements as such;

 

and Ralph's point:

The debate seemed potentially confused by the fact that Canon’s sensor construction and filters had evolved over time, so that what was necessary for the earliest EOS models wasn’t necessarily needed for the newest ones.

 

 

ie:

                             filter 1 good for AP                             remove filter 2 only?             filter 1 and 2 bonded together             etc, etc.

Nikon models

xx

xx

xx

Canon models

xx

xx                                  no                                                        no

6D                                 yes                                                      yes

Sony models         

xx                                                                                              not possible                      yes, full mod needed

xx

xx

[Ketut]

 

 

Note: Narrowband (NB) filter can be used with any mod type; 'NO' #4 or #5 external UV/IR block required if using a NB filter

 

 

Could you please explain more details on this?

 

 

Since NB is limited to a particular wavelength, it is not going to get affected by the other wavelengths. For example if you are using H-alpha 'pass' filter, it is not going to let IR or UV pass-through. Same for other NBs; list below.

 

 

And why modded camera let's NB especially H-alpha pass-through? Because stock camera blocks H-alpha. Hope this helps. Regards

• Hydrogen-beta (H-beta)............486.1 nm
• Oxygen-III (O-III)........................500.7 nm
• Hydrogen-alpha (H-alpha).........656.3 nm
• Nitrogen-II (N-II)..........................658.4 nm
• Sulfur-II (S-II)..............................672.4 nm

 

 

 

My understanding, UV/IR block is NOT required if using a NB filter.

But, you said conversely: 'NO' #4 or #5 external UV/IR block required if using a NB filter.

Sorry for my stupidity, but could you please help me to make it clear? 

[mmalik]

In post #35... above since #4 & #5 are full-spectrum mods and if one were using a NB filter (H-alpha, etc.) then there really is no need to block UV/IR since NB is going to block UV/IR anyway.

 

 

So your understanding is correct and that's what I tried to say as well. My sentence is malformed a bit, sorry; I should have said 'NO' external UV/IR block required if using a NB filter in option #4 & #5. Hope this clarifies? Regards

 

 

Note: For accuracy, this is regarding options listed in post #35 above since options listed in post #1 are numbered bit differently