RGB widefield from Crago - Pentax 200mm

multiweb (Marc) · #1 29-06-2011, 06:09 PM

Here's one I've just finished processing. Approx 40x2min with my 200mm F4 lens one stop down. A lot of star bloat so I'm getting a step down ring to fit a UV/IR filter or some kind of Nebula filter to stop that. It was a pain to process in the blues and greens as a result. Red was tight enough.

Here's one big one here [4MB] . The field is approx 8x8 degrees.

Looking forward to do some more from Ilford this week-end.

I've just received my new 100mm F2.8 lens and it has a 49mm pentax UV/IR cut in the front

Ross G · #2 29-06-2011, 08:34 PM

Great shot Marc.

Sharp and so much detail.

The lens gives you an excellent FOV.

See you in Wiruna.

Thanks.

Ross.

Hagar (Doug) · #3 29-06-2011, 08:50 PM

Very nice Marc. May take a while to settle in to this wide a field when processing it but it looks good so far. Stars don't look to bad.
A lot of wide field imagers seem to bloat up the brighter stars and blur them a bit to lift the image and give it some punch.
Nice and sharp without blurring the background.

Well done.

multiweb (Marc) · #4 29-06-2011, 09:12 PM

Quote:

Originally Posted by Ross G

Great shot Marc.

Sharp and so much detail.

The lens gives you an excellent FOV.

See you in Wiruna.

Thanks.

Ross.

Thanks Ross - see you there.

BTW I got a 50mm F/1.7 and 28mm F/2.8 too.

Quote:

Originally Posted by Hagar

Very nice Marc. May take a while to settle in to this wide a field when processing it but it looks good so far. Stars don't look to bad.
A lot of wide field imagers seem to bloat up the brighter stars and blur them a bit to lift the image and give it some punch.
Nice and sharp without blurring the background.

Well done.

Thanks Doug.

Definitely a different way of processing. Getting around it now. Another thing to learn but it's fun. And easy to capture.

jjjnettie (Jeanette) · #5 29-06-2011, 09:23 PM

Wide Field rules!!
It's nice for a change isn't it. Low stress imaging.

Dennis · #6 29-06-2011, 09:49 PM

Wow Marc- you don’t hang around do you, already putting the Pentax 200mm F4 to work! That is a very nice shot – the 4 Meg image is an absolute ripper!

Cheers

Dennis

desler · #7 29-06-2011, 10:00 PM

I quite agree with everyone Marc. Nice, very nice! and the learning curve continues!

Darren

Ross G · #8 30-06-2011, 06:43 AM

Wow Marc!

A 50mm and a 28mm. There is no stopping you now.

You've got all FOVs covered. You are going to need a 2nd and maybe 3rd camera!

The quality (...and quantity..) of your work will be amazing. I am looking forward to it.

I have been experimenting this week with the 50mm lens. I am finding I like it even more then the 135mm.

Good luck.

Ross.

gbeal · #9 30-06-2011, 07:13 AM

Again with the #8 wire technology, I used to tape a 1.25" IR/UV filter into the rear of the Pentax 55/4 (67 lens) I used, the rear opening and element were close to the 1.25" size, and the IR/UV cleaned up the bloat a bit.
Gary

multiweb (Marc) · #10 30-06-2011, 08:24 AM

Quote:

Originally Posted by jjjnettie

Wide Field rules!!
It's nice for a change isn't it. Low stress imaging.

Thanks JJJ.

Sure is.

Nothing else to do with the seeing of late.

Quote:

Originally Posted by Dennis

Wow Marc- you don’t hang around do you, already putting the Pentax 200mm F4 to work! That is a very nice shot – the 4 Meg image is an absolute ripper!
Cheers
Dennis

Thanks a lot Dennis. Glad you like dit.

This is a bit new to me and I wasn't sure about posting it.

Quote:

Originally Posted by desler

I quite agree with everyone Marc. Nice, very nice! and the learning curve continues!
Darren

Thanks for the kind words Darren.

Quote:

Originally Posted by Ross G

Wow Marc!
A 50mm and a 28mm. There is no stopping you now.
You've got all FOVs covered. You are going to need a 2nd and maybe 3rd camera!
The quality (...and quantity..) of your work will be amazing. I am looking forward to it.
I have been experimenting this week with the 50mm lens. I am finding I like it even more then the 135mm.
Good luck.
Ross.

No camera for me for a while. My next one will be definitely a mono.

Quote:

Originally Posted by gbeal

Again with the #8 wire technology, I used to tape a 1.25" IR/UV filter into the rear of the Pentax 55/4 (67 lens) I used, the rear opening and element were close to the 1.25" size, and the IR/UV cleaned up the bloat a bit.
Gary

Thanks Gary. I was wondering if star bloat was caused by internal reflections or just focusing different wavelength in different locations like chromatic aberration. That's why I thought I'd but the filters before the wole lens assembly.

In NB I did put the Ha/Sii/Oiii filters at the back with no issues at all. No internal reflections and no star bloat which goes inline with what you're saying. Here's 3 channels on the same area I did earlier still to blend. It looks very different in RGB though that's why I went to a dark site to test. I hope to get a lot of data this week-end and test further.

strongmanmike (Michael) · #11 30-06-2011, 12:17 PM

Looks ok Marc.

Have you posted that combined SIIHaOIII on 6188 already, I can't remember? It looks good too.

Mike

multiweb (Marc) · #12 30-06-2011, 12:56 PM

Quote:

Originally Posted by strongmanmike

Looks ok Marc.

Have you posted that combined SIIHaOIII on 6188 already, I can't remember? It looks good too.

Mike

Thanks mate. Nah... I haven't processed it yet. Still collecting data and I was trying to get RGB stars before combining but that last outing at Crago didn't go to well. I ran out of power at 22:00 [low voltage] and spent the night looking up at a blazing, still, milkyway.

Hopefuly I bag a load from Wiruna. Living tomorrow morning.

Paul Haese · #13 30-06-2011, 12:57 PM

Looks very good Marc. I like the dark dust knots and the hints of hydrogen surrounding these areas.

multiweb (Marc) · #14 30-06-2011, 01:15 PM

Quote:

Originally Posted by Paul Haese

Looks very good Marc. I like the dark dust knots and the hints of hydrogen surrounding these areas.

Thanks Paul.

The plan is to go deeper once I have those stars under control. 200mm is the sweet spot I reckon for that kind of imaging. Nice FOV and image scale.

Tom Davis (Tom) · #15 30-06-2011, 01:25 PM

Nice one! There is lots of stiff in that frame!!

Tom

ving (David) · #16 30-06-2011, 01:43 PM

nice... whats it a widefield of?

multiweb (Marc) · #17 30-06-2011, 02:28 PM

Quote:

Originally Posted by Tom Davis

Nice one! There is lots of stiff in that frame!!

Tom

Thanks for that Tom.

Quote:

Originally Posted by ving

nice... whats it a widefield of?

Thanks David.

It's NGC6188 at 2o'clock from the center. At the bottom left you start seeing the nebulosity associated with the prawn nebula IC4628. With the 100mm I should bridge the gap between those two and frame them nicely. Still experimenting a lot. The only thing I don't have to worry about is guiding.

.. which is refreshing.

gregbradley · #18 30-06-2011, 05:48 PM

That looks good Marc. Are these Pentax 67 lenses or some other format?

Good tip about the UV/IR cut filter. I have a Pentax 55 F4 so I'll do that.

This is the perfect time of year to be doing lens widefield shots.

Greg.

multiweb (Marc) · #19 30-06-2011, 06:20 PM

Quote:

Originally Posted by gregbradley

That looks good Marc. Are these Pentax 67 lenses or some other format?

Good tip about the UV/IR cut filter. I have a Pentax 55 F4 so I'll do that.

This is the perfect time of year to be doing lens widefield shots.

Greg.

Thanks mate. Yeah the milkyway's right up. Can't miss it

The lenses are M prime series: SMC Pentax-M.
I now have 200mm F4, 100mm F1.7, 50mm F2 in the post and biding on a 28mm F2.8.

The 200mm has a great flat field even fully open. Haven't tried the 100mm yet. They're all use a K-mount and similar so I can use them exactly the same way with my QHY8 adaptor.