Pentax K-5 at iso 80 is changing AstroPhotography !

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6-7 years ago, Canon Eos 20d or 5d were fine tools for AstroPhoto,
but their huge amount of Electronic Noise from iso 100 to 400,
made the iso 1600 setting mandatory for AstroPhotography use !
(exept setting iso 800 during warm summer nights ?)
Taking Pattern Noise in account, the measured DR was no more than 9 EV
from iso 100 to 1600, so it was not a big problem using them at iso 1600 !
Exept the need of stacking 25-30 RAWs in DSS to get good results :
http://en.astronomike.net/m/6809.html

As there were no change in Canon's Electronic Noise levels at low iso setting :
http://forums.dpreview.com/forums/read.asp?forum=1032&message=35842756
I decided to change back to Pentax, and bought a K-5 and a "K" T2 adapter !

Now, the Pentax K-5 is playing in a very different world than the Eos :
= a total lack of Electronic Noise at iso 80 !
= a measured DR of about 14 EV at iso 80 !
+ at iso 80, the Pentax K-5 gives you very tiny RAWs of about 13-15 MB,
and you only need stacking from 3 to 5 RAWs in DSS to get good pictures :

http://www.chassimages.com/forum/index.php/topic,118675.msg2187995.html#msg2187995
(say 3 RAWs for big luminous Deep Sky Objects, else 5-6 RAWs !)
http://en.astronomike.net/m/134251.html

All photos presented here are taken at sea level, in a big city,
with such light pollution making any visual observation impossible !
I am very excited to bring my Pentax K-5 in the mountains,
where I could test its resistance at low temperatures !
and where, of course, i will get far better pictures !

You will certainly be very pleased by what you may achieve in a dark mountain sky. You may even push the ISOs a little higher. The following K5 image was obtained with a stack of eight 5 second exposures at ISO 12800 done with RegiStax. Taken from my balcony in the town of Geneva at the focus of a Takahashi FS 128 (1040mm/f8.1) apochromat. You should be able to do much better in the mountains.

Fantastic or should I say 'formidable';-)

Excellent work ! to reply one of yours questions in the french forum, there is an option in the K5 to change raw format from PEF to DNG
--
jpgoube

noel2 said:

... You may even push the ISOs a little higher. The following K5 image was obtained with a stack of eight 5 second exposures at ISO 12800 done with RegiStax...

Click to expand...

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yes, of course, you may !
but when shooting at iso 12800 instead of iso 80 :
-- DR is only half the iso 80 DR !
-- SNR is only half than the iso 80 value !!
-- RAW size is about twice the iso 80 RAW size !!!
-- you'll need stacking much more RAWs to get rid of Noise !!!! :O

mine is not very detailed, because shot very low vs horizon on 4.4.2011 22:30,

and at sea level + huge light pollution, but it's cleaner with wider DR than yours :

http://www.chassimages.com/forum/index.php/topic,118675.msg2195239.html#msg2195239

= only 3 PEF of 14 MB stacked with DSS 3.3.3 Beta 34 !

believe it, try yourself the iso 80 vs iso 12800 comparison !

you only need a WebCam with a Barlow on your finderscope,
and PHD AutoGuiding is free download and easy to install and use !

jeanphilippe Goube said:

Excellent work ! to reply one of yours questions in the french forum, there is an option in the K5 to change raw format from PEF to DNG

Click to expand...

thanks !
I finally found it in Pentax DCU4, but I don't need it anymore,
as DSS 3.3.3 Beta 34 now reads Pentax K-5's PEF files format !

geo444 said:

noel2 said:

... You may even push the ISOs a little higher. The following K5 image was obtained with a stack of eight 5 second exposures at ISO 12800 done with RegiStax...

Click to expand...

.

yes, of course, you may !
but when shooting at iso 12800 instead of iso 80 :
-- DR is only half the iso 80 DR !
-- SNR is only half than the iso 80 value !!
-- RAW size is about twice the iso 80 RAW size !!!
-- you'll need stacking much more RAWs to get rid of Noise !!!! :O

Click to expand...

Of course you will get better results with lower ISO ! - and above all better atmospheric conditions !

My point was that the K5 allows you to do decent astrophotography "even" at ISO 12800. That was impossible with the earlier sensors.

noel2 said:

Of course you will get better results with lower ISO ! - and above all better atmospheric conditions !

My point was that the K5 allows you to do decent astrophotography "even" at ISO 12800. That was impossible with the earlier sensors.

Click to expand...

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ok, sorry ! more than decent photography, event at iso 12800 :

http://www.chassimages.com/forum/index.php/topic,121744.msg2220158.html#msg2220158
... and even AstroPhotography, in case you bring just a simple tripod ?
you are absolutely right !!

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my first 10 min M51 shot, I missed to set my Pentax K-5 in RAW mode,
so I reduced it from 3 to 2 stars and uploaded it at imagehotel for download :
http://images.imagehotel.net/?7x61kj6z2s.jpg

imagehotel is fast but it's a 2 MB file !... here is a 150 KB version with Exif :
http://www.chassimages.com/forum/index.php/topic,118675.msg2235680.html#msg2235680

it's the first shot of this night and it's not sharp :
-- my Newton is still not at outdoor temperature and not perfectly collimated !
-- it's very difficult to achieve Perfect Focus with so Light Pollution !
however, stacking 3-5 PEF only, gives you a good picture :
+ there is no Pattern Noise at all, neither Amp Glow, nor Hot Pixels !!
+ despite the huge Light Pollution, SNR is not so bad ?

Note that there is No Dark Frames , Nor Bias Map subtracted here :
http://en.astronomike.net/m/134251.html
I just subtracted Flat Fields(2) from the 2 last Galaxies : M101 & M94
(M101 is blurred : my Newton totally misaligned !?!?)

Do I read that right that you are using the Vixen NA 120? Hmmmm.

I use a Borg 150ED, either at the native F6.7 (1000mm) or using the expensive ($995) 4 element (2 ED) FF/FR that makes is F4.1 (600mm). I have not upgraded to the K-5 yet but your results has me thinking I might want to do it sooner.
Kent Gittings

geo444 said:

jeanphilippe Goube said:

Excellent work ! to reply one of yours questions in the french forum, there is an option in the K5 to change raw format from PEF to DNG

Click to expand...

thanks !
I finally found it in Pentax DCU4, but I don't need it anymore,
as DSS 3.3.3 Beta 34 now reads Pentax K-5's PEF files format !

Click to expand...

First and most important...OUTSTANDING work I love astrophotography but have only ever shot the moon because I just don't need another hobby that I want to spend all my time with...hahaha...but seeing the sort of photos you all show makes me want to go outside right now and take a picture. I am not sure what to shoot but I want to shoot something...hahahaha...again amazing job and your happiness for it is very fun to read in your comments. Good for you my wacky friend in France or wherever you are.

ABout the DNG vs. PEF I do have a question. Most all info I have read about the debate over the two formats come to the same conclusion that there is no difference in normal photos. But in your astro shots, is there a compelling reason you prefer PEF over DNG? I ask because over time DNG is likely going to have a longer lifetime support in programs. Pentax's PEF is proprietary to Pentax and it's a good chance in a 10-20 years it it might not be possible to read the files anymore.

But your photos are really fun to see and I hope you come back and share more when you get some time at higher elevations. Heck I almost wanna pack my pickup, find a Celestron or whatever somewhere and head up to my old camping ground with an elevation of about 10,500ft (and we can drive up to it!!! ))

BTW, I only mention the Celestron because it's the only telescope I can think of because my college roommate had one. Sadly he lent it to his neighbor on year, my roommate was from Portland, Oregon here in the US, and the neighbor took it up to the mountains, set it up then went to sleep for a few hours before shooting time...it rained very heavily and the telescope was uncovered thus ruining that wonderful telescope. And this was back in the late 1970s or early 1980s...but had my roommate brought down a working telescope I might have actually learned a lot back then and today I could be doing something different...weird how life works.

Oh, any places where a person can look around to see the sort of lenses/telescopes that deliver nice images? Thanks!!

--
Real men shoot Pentax because we were born with our own Canons!!
{Ok...ok, some of use just shoot with a PnS but it always makes me happy! }

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first pictures, May 2011

• iso 80, 3 PEF = 12 minutes each :

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• iso 80, 5 PEF = 12 minutes each :

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• iso 80, 3 PEF = 10 minutes each :

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• other pictures :

http://en.astronomike.net/m/134251.html

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last pictures July 2011

• iso 80, 4 PEF = 12 minutes each :

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• iso 80, 5 PEF = 12 minutes each :

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• iso 80, 4 PEF = 12 minutes each :

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- No Dark Frames subtracted !

- No Bias Maps (Offset Frames) subtracted !

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thanks !

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first, thank you very much for your enthusiasm !

I shoot PEF because there is No obvious reason to convert them to DNG !?
and iso 80 tiny Astro PEFs are only from 13 up to 16 MB size !!

KentG said:

Do I read that right that you are using the Vixen NA 120? Hmmmm.

Click to expand...

I bought it 900€ and it's simply The Best Achromatic Refractor !
and perfectly usable with a Full Frame Camera mounted - No flattener needed :
http://en.astronomike.net/m/6809.html
http://en.astronomike.net/m/134251.html
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KentG said:

I have not upgraded to the K-5 yet but your results has me thinking I might want to do it sooner.

Click to expand...

to get a good iso 1600 Astro Picture, my Eos 20d or my Eos 5d needs :
30 Frames +15 Bias +15 Darks +3 Flats +3Dark-Flats = 66 x 15 MB = 1000 MB !

to get a good iso 80 Astro Picture, my Pentax K-5 needs :
5 Frames + 1 Flat-Frame = 6 x 15 MB = 90 MB !!!

Those are some great images. Does the GPS unit Pentax released seem like it will be useful? It seems to me that it would make it more accessible to more people.
--
http://wkoopmans.ca/notebook/

Excellent work ! Such results would have been unthinkable just a couple of years ago.

Geo, congrats on such nice astro photos :- )

• I enjoy pointing to the fact now and then that the K-5 ISO 80 tested out to be an actual measured ISO 70 by DXO Labs ;- )

geo444 said:

Now, the Pentax K-5 is playing in a very different world than the Eos :

Click to expand...

geo444 said:

= a total lack of Electronic Noise at iso 80 !
= a measured DR of about 14 EV at iso 80 !
+ at iso 80, the Pentax K-5 gives you very tiny RAWs of about 13-15 MB,
and you only need stacking from 3 to 5 RAWs in DSS to get good pictures :

Click to expand...

--

“At any given moment, there is a sort of all pervading orthodoxy, a general tacit
agreement not to discuss large and uncomfortable facts… Anyone who
challenges the prevailing orthodoxy finds himself silenced with surprising
effectiveness.” - George Orwell

say no more 80iso