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How to replace IR-block filter on *ist D

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Vincenzo Miceli

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Folks,

I replaced the IR block filter of my *ist D to expand its spectral response to the far red and H-alpha line. This is very useful for astrophoto of emission nebulas.

I compiled all the info on the follwing web-page. Have a look if you are interested.

http://sites.google.com/site/vincenzomiceli/pentax--ist-d-ir-mod

Ciao,

Vincenzo
 
All this stuff is already out on the Internet if you look for it. Although for people who are not already DSLR astrophotgraphers on this forum it's nice that you have the info on here for others to use. Canons are easier to modify because you don't have to take as much of the camera apart like the *ist D to get to the chip. That and popularity are the reasons most early mod work was done for Canons, and then Nikons. I used to have a Hutech modded Canon 20D (Baader filter). But I didn't use it enough to justify keeping it. However I do have a spare *ist D that has a couple of minor issues that don't interfer with taking pictures I might want to mod myself. The Baader filter is good if you want to still use it for daytime photos, but for a dedicated astro camera a clear one is better for astro work (like the Canon 20Da).

Focusing aids are the key thing, with a well calibrated flip mirror being the best from my experience. Most other focus aids like a Kendrick mask, a Stilleto focuser, or a knife edge being second only because you can get still be off with those sometimes. Shutter control, either remote cable or by computer is needed also.
Plus a AC-DC powersupply to keep the power to the camera.

You can skip a lot of you want to do wide angle starfield imaging, but you need a sky tracking mount to take longer exposures. Or you can stack shorter ones using the freeware program Registax. Also free is astro imaging program IRIS, currently in version 5.57 has supported the *ist D since version 4.10. Has support for camera control also although I'm not sure if it covers all of them.
Kent Gittings
 
KentG said:
All this stuff is already out on the Internet if you look for it.
Although for people who are not already DSLR astrophotgraphers on
this forum it's nice that you have the info on here for others to
use.
Click to expand...
I'm not aware of any other place where *ist D mod is described. If you mean there are plenty of places describing the IR block filter, its drawbacks etc. then yes, but that's not what I wanted to document.
KentG said:
That and
popularity are the reasons most early mod work was done for Canons,
and then Nikons.
Click to expand...
Nikons are much less used than Canons for astrophoto, and the mod they receive is mostly the complete removal of the IR filter leaving the sensor unprotected. Canon is king in DSLR astro mods, by far.
KentG said:
Focusing aids are the key thing, with a well calibrated flip mirror
being the best from my experience. Most other focus aids like a
Kendrick mask, a Stilleto focuser, or a knife edge being second only
because you can get still be off with those sometimes. Shutter
control, either remote cable or by computer is needed also.
Click to expand...
I don't use any focus aid. I wrote an ASCOM driver for the Pentax so software like MaximDL and FocusMax see it as a regular astro camera and since I use a Robofocus system, focusing is all done automatically with high precision.

I guess I'll post some more details on my system sometime. It is based on a 400/2.8 (and dedicated 1.4x when necessary). Guiding is done with a Vixen short tele 80/400mm and a B&W CCD guider. Tracking, guiding and focusing is all controlled by software.

The reasons why you don't want to put just a clear glass in front of the sensor is to limit its spectral response. In fact if you are using a refractive optics the blu and red/infrared will focus at different planes giving bloated stars and loss of contrast (apochromatic optics are obviously much better than simple achromatic ones), so you will have to use other filters somewhere in the system to limit the spectrum. If you are using a mirror system or mostly mirror, then you chromatic aberration is much less and you can probably live with a filterless sensor.

Ciao,

Vincenzo
 
Hi Kent!
KentG said:
All this stuff is already out on the Internet if you look for it.
Click to expand...
But not for the *ist Dm AFAIK?
KentG said:
but
for a dedicated astro camera a clear one is better for astro work
(like the Canon 20Da).
Click to expand...
The 20Da did not have a clear filter.

Talking about the suitability of different brands and models, an important aspect seems to be amp-glow, which some models suffer from for long exposures.

Cheers
Jens

--

'Well, 'Zooming with your feet' is usually a stupid thing as zoom rings are designed for hands.' (Me, 2006)
My Homepage: http://www.JensRoesner.de
 
great, this is really helpfull..!!!

your AF adjust procedure looks like a trial and error for me. and to reopen + adjust the spacer again will take too much time.

are there any other way to calibrate AF, maybe some screws arrangement like on DS or under firmware ?
--
Long Live Pentax !!
Regards
---
BK
---
..MX is Beauty, KX is Reliability..
 
pb908 said:
great, this is really helpfull..!!!

your AF adjust procedure looks like a trial and error for me. and to
reopen + adjust the spacer again will take too much time.

are there any other way to calibrate AF, maybe some screws
arrangement like on DS or under firmware ?
--
Long Live Pentax !!
Regards
---
BK
---
..MX is Beauty, KX is Reliability..
Click to expand...
BK,

The procedure I gave is not trial and error as I calculated what the spoacer thickness is supposed to be with the apropriate formula. So if you put the Baader filter you alredy know what thickness you need to use, no trial, no error.

If you want your AF to be in agreement with your viewfinder then the spacer is the only way to adjust it.

If you want to only use the AF (viewfinder OOF) then you could adjust the three screws as in the DS (which I'm assuming are there), this really would be trial and error! I'm not aware of any firmware adjustment available for the *ist D.

Vincenzo
 
Even though I have no intention to modify my *istD in this fashion, I was most impressed by your fantastic craft, your great article and your illustrations. Thank you very much for this, Vincenzo!

Now I appreciate my two *istD bodies even more. :-)
 
I like the Robofocus system but don't currently use one. I do have a JMI SmartFocus system and focuser on my C-9.25 which is OK (cheaper but not as good). I've also used the Optec TCF on an APO refractor before.

I was just giving some info out for those who have not gone over the deep end in astro imaging yet. Most don't realize the amount of work to get real astrophotos. But they can get something with simpler equipment if they want to give it a try.

I started in 1963 with film using a Praktica 35mm astro camera, B&W film, and a Criterion RV-6. I did prime, eyepiece and afocal projection with that setup.
Kent Gittings
 
Zaldidun said:
Even though I have no intention to modify my *istD in this fashion, I
was most impressed by your fantastic craft, your great article and
your illustrations. Thank you very much for this, Vincenzo!

Now I appreciate my two *istD bodies even more. :-)
Click to expand...
You are welcome! I still have only two Pentax bodies and they are two *ist D.

Vincenzo
 
KentG said:
I like the Robofocus system but don't currently use one. I do have a
JMI SmartFocus system and focuser on my C-9.25 which is OK (cheaper
but not as good). I've also used the Optec TCF on an APO refractor
before.
I was just giving some info out for those who have not gone over the
deep end in astro imaging yet. Most don't realize the amount of work
to get real astrophotos. But they can get something with simpler
equipment if they want to give it a try.
I started in 1963 with film using a Praktica 35mm astro camera, B&W
film, and a Criterion RV-6. I did prime, eyepiece and afocal
projection with that setup.
Kent Gittings
Click to expand...
Thanks Kent, I have always used refractors and surprisingly enough, my first SLR was a Praktica MTL5 in the middle 80s :-)

Vincenzo
 
--
K20D+K10D+LBA=no$$$ but happy
Over 250K DSLR actions and counting
Remember: Too much Measurbating will make you go blind! :-p
 
Hi Flip!
flipflop said:
Actually, Jens, I get a broken link for the *ist-D instructions on
your modding page
( http://www.jr-worldwi.de/photo/Pentax_ist_DSIR.html ).
Click to expand...
Hm. Small "p" should work:
http://www.jr-worldwi.de/photo/pentax_ist_DSIR.html
flipflop said:
have the same problem? It would be nice to have it accessible again,
as I believe you detail adjusting focus through a special menu mode.
Click to expand...
Oh, I only mentioned it and didn't get it to work.
Maybe you were thinking of his page:
http://2k8.ch/xdeltax-alt/

Cheers
Jens

--

'Well, 'Zooming with your feet' is usually a stupid thing as zoom rings are designed for hands.' (Me, 2006)
My Homepage: http://www.JensRoesner.de
 
Hello Vincenzo,

That is an impressive piece of work.

I have tried using both the *ist-D and the K10D for AP with poor results - mostly because of Pattern Noise.

I have been considering buying a used Canon body after seeing what they are capable of.

Do you have a link to your astrophotos, or can you show some examples along with eposure and processing info? Before and after filter mod?

Regards,

Ron Moore
 
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