NGC 6604 Widefield

[sjastro]

Another image taken with a 300mm Pentax lens.

3 hrs Ha, 1 hr R, 1 hr G, 1 hr B ST-10XME.

High resolution here.
http://members.iinet.net.au/~sjastro/ngc6604c.html

Clear skies

Steven

[glenc (Glen)]

Thanks Steven.
The brightest part of this nebula is visible in a 16" with a UHC filter.

[MrB (Simon)]

Nice and sharp Steven!
Which flavour of the 300 have you got?
I picked up an SMC Pentax-A* 645 300/4 EDIF (Pentax ID's are so long!) a while back but I've been waiting 5 weeks now for an adaptor
Can't wait to test it out.

I also have an older 400/4 (can't afford the EDIF) which appears to be very sharp and flat with minimal lateral CA, but sadly oodles of axial CA so no good for OSC. Apparently excellent for NB tho I'm yet to test, my adaptor had much too long flange-focal distance and I couldn't focus on infinity. I'm currently reducing the adaptor length in my lathe a bit at a time and retesting, if only the rain and cloud would play nice.

Crappy phone pic:

[pfitzgerald (Paul)]

The nebula below the cluster NGC 6604 is called Gum 85 (Sh2-54). It is well worth imaging in its own right.

Due to Melbourne's rubbish weather this winter I haven't been able to have a decent go at it.

Very nicely done with your image Steven.

[Regulus (Trevor)]

Simon, what would the conversion factor be using the medium format lens on a APS-C camera?
Trevor

[MrB (Simon)]

Hi Trevor, do you mean like the 1.6x 'crop factor' often quoted for FF to APSc?
I've never really thought about the crop, I just think in focal lengths.

Have worked them out tho, keep in mind that FF and APSc are 3:2 aspect ratio and the 645 and 67 formats are 4:3 aspect so the 'crop' for the vertical works out higher than for the horizontal:
645: 2.5x hor. and 2.8x vert.
67: 3.23x hor. and 3.76x vert.

Crops would be even larger for the 8300 chips.

[RickS (Rick)]

Nice image, Steven, and a very nice FOV!

[sjastro]

Originally Posted by glenc

Thanks Steven.
The brightest part of this nebula is visible in a 16" with a UHC filter.

Thanks Glen

Originally Posted by MrB

Nice and sharp Steven!
Which flavour of the 300 have you got?
I picked up an SMC Pentax-A* 645 300/4 EDIF (Pentax ID's are so long!) a while back but I've been waiting 5 weeks now for an adaptor
Can't wait to test it out.

I also have an older 400/4 (can't afford the EDIF) which appears to be very sharp and flat with minimal lateral CA, but sadly oodles of axial CA so no good for OSC. Apparently excellent for NB tho I'm yet to test, my adaptor had much too long flange-focal distance and I couldn't focus on infinity. I'm currently reducing the adaptor length in my lathe a bit at a time and retesting, if only the rain and cloud would play nice.

Crappy phone pic:

Hello Simon.

I have the Pentax DA 300mmF4 EDIF SDM.

No problems reaching focus on the filter wheel of the ST-X10ME but attaching the lens presented some problems. Even though the filter wheel face has a Pentax mounting the attached lens was anything but secure.
I had to fit an O-ring to the lens to improve the interference fit and separately mount the lens to the base plate due to the weight of the lens.

Since the lens lacks an aperture ring a piece of plastic jammed into the adjustment lever kept the lens fully open during exposures.

Good luck with your activities.

Originally Posted by pfitzgerald

The nebula below the cluster NGC 6604 is called Gum 85 (Sh2-54). It is well worth imaging in its own right.

Due to Melbourne's rubbish weather this winter I haven't been able to have a decent go at it.

Very nicely done with your image Steven.

Thanks Paul.

Originally Posted by RickS

Nice image, Steven, and a very nice FOV!

Thank you Rick.

Clear skies

Steven

[atalas]

Nice shot Steven.

[sjastro]

Thanks Louie.

Steven

[Ross G]

Great looking photo Steve.

Love the colours and the widefield.

Ross.