SpaceCat Eta

[Peter Ward]

More fun with the Canon EOS Ra, but this time married to a WO SpaceCat 51 lens.

I found extending the exposure time while shooting from the Sydney 'burbs did little in picking up the faint stuff, and really only picked up the glowing urban sky with more zeal.... but again am surprised what you can get without a dark site.

As a grab and go, I really like this combo. Tack sharp stars and nice wide field. I sense a country road trip will be in order soon

The link is here

[LewisM]

Tack sharp? No, it looks rather soft to me Peter. Quite soft in fact - I guess hand-focused? Plus the red glow is intriguing in places.

Not a jibe, just a genuine observation I am seeing in a LOT of Redcat images.

[multiweb (Marc)]

Nice widefield. Should come really handy for the road for sure. Hours of fun.

[Peter Ward]

Originally Posted by multiweb

Nice widefield. Should come really handy for the road for sure. Hours of fun.

Ta Marc...that's the plan

Originally Posted by LewisM

Tack sharp? No, it looks rather soft to me Peter. Quite soft in fact - I guess hand-focused? Plus the red glow is intriguing in places.

Not a jibe, just a genuine observation I am seeing in a LOT of Redcat images.

Nah, while I appreciate the frank and fearless feedback, looks way sharper to me than any standard camera lenses I've used to date....including some $7-10k Canon L-glass.

That said, not a show stopper image for sure....this rig needs a dark site and at least five minute subs to pull in the faint stuff.

There is an interesting blocking filter (?) reflection that is indeed red, that the camera itself I suspect generates. Attached is a 200% enlarged crop of said red doughnut near one of the brighter stars. While I don't find it objectionable, I'm not totally sure of its cause.

[topheart]

Hi Peter,
Looks great for what it is. You seem to have gradient removal down pat with PI's DBE.
Cheers,
Tim

[Paul Haese]

Moving into wide field now Peter. The composition looks interesting albeit orientated towards terrestrial rule of threes. I imaging you might be able to get some quite interesting looking wide fields with this kit if you took it out under dark skies.

[LewisM]

Originally Posted by Peter Ward

Nah, while I appreciate the frank and fearless feedback, looks way sharper to me than any standard camera lenses I've used to date....including some $7-10k Canon L-glass.

Learned it from a pro . Definitely better than any camera lens images I have seen too.

Originally Posted by Peter Ward

That said, not a show stopper image for for sure....this rig needs a dark site and at least five minute subs to pull in the faint stuff.

There is an interesting blocking filter (?) reflection that is indeed red, that the camera itself I suspect generates. Attached is a 200% enlarged crop of said red doughnut near one of the brighter stars. While I don't find it objectionable, I'm not totally sure of its cause.

The red cast-offs did attract my attention immediately.

I take it this isn't motor-focused as yet? A simple cogged belt drive on the helical would be easy enough to fabri-cobble.

[gregbradley]

A nice flat field and round stars corner to corner which is rare for lens full frame longer focal length. A reasonable amount of detail for a lens image.

I may end up getting my EOS R modded as I have wanted to have a full frame modded digital camera for a while now. Its just a bit too good for regular photography to do that even though I have a Sony A7riii as well.

But I am tempted especially with Milky Way season coming up.

The red halo is odd but probably easy enough to process out so long as it not too common. Like you said its probably some reflection artefact from the modded filter.

I was using 5 minute ISO640 for deep sky objects at a dark site which seemed to work well.
EOS R sweet spot for ISO is higher than the Sony's, around 1600 or so. ISO2500 is game for urban imaging.

Greg.

[AnakChan (Sean)]

Originally Posted by gregbradley

A nice flat field and round stars corner to corner which is rare for lens full frame longer focal length. A reasonable amount of detail for a lens image.

I may end up getting my EOS R modded as I have wanted to have a full frame modded digital camera for a while now. Its just a bit too good for regular photography to do that even though I have a Sony A7riii as well.

But I am tempted especially with Milky Way season coming up.

The red halo is odd but probably easy enough to process out so long as it not too common. Like you said its probably some reflection artefact from the modded filter.

I was using 5 minute ISO640 for deep sky objects at a dark site which seemed to work well.
EOS R sweet spot for ISO is higher than the Sony's, around 1600 or so. ISO2500 is game for urban imaging.

Greg.

The image is 75% cropped so that's why possibly it's round stars edge-to-edge.

Nice image and good work by Peter.

[JA]

Originally Posted by LewisM

Tack sharp? No, it looks rather soft to me Peter. Quite soft in fact - I guess hand-focused? Plus the red glow is intriguing in places.

Not a jibe, just a genuine observation I am seeing in a LOT of Redcat images.

Hi L,

It's potentially a lot sharper (some 3x sharper/higher res) than what can be seen in the web image Peter linked to, since

1. the original photographed image scale was something around 4.4 arcseconds/pixel (based on the 250mm focal length of the Redcat optic on Full-Frame, roughly 8.24 degrees wide over the 6720 pixels of the Canon EOS Ra sensor), versus

2. the displayed web image scale of around 12.8 arcseconds/pixel (based on an image estimated at around 6.85 degrees wide [vide Stelllarium comparison] over the 1920 pixels width of the web image posted)

Best
JA

[gregbradley]

Originally Posted by AnakChan

The image is 75% cropped so that's why possibly it's round stars edge-to-edge.

Nice image and good work by Peter.

Perhaps. My copy has some weakness in the outer 10% or so. Not real bad but you want it as good as you can get it.

The newer version has a tilt/tip adapter which I got for my Redcat 51. So its a matter of taking the time to adjust the minor tilt/tip that may be present.

I have yet to do that but I suppose it may be possible during the day with the right type of object photographed to show corner reproduction of pinpoint light sources.

I wouldn't see it as a defect because you have to correct for tilt with almost any scope and camera.

Greg.

[Peter Ward]

Originally Posted by gregbradley

.....

I wouldn't see it as a defect because you have to correct for tilt with almost any scope and camera.

Greg.

I've found not T-adapters are created equal. Many have a little slack that would be evident as slight tilt, hence not a fault of the lens or camera.

WO Copper-T's while not inexpensive (About $A150 landed) and Baaders seem to be the best for the precision of their fit.

[gregbradley]

Originally Posted by Peter Ward

I've found not T-adapters are created equal. Many have a little slack that would be evident as slight tilt, hence not a fault of the lens or camera.

WO Copper-T's while not inexpensive (About $A150 landed) and Baaders seem to be the best for the precision of their fit.

Yes I got the copper Canon adapter. Its an amazing piece of gear.

Greg.