Couple of "shallow" images with the 200/2.8 at 2.8

[Psychobilly]

I have been using the reasonable weather to test out the techniques i plan to use with trhe modded 1000D and Canon 200/2.8L USM and IDAS P2 MFA filter working with a revised focusing technique which seems to allow you to use the lens at f2.8 and still get reasonably decent star shapes across the full APS-C sized sensor...

I am using the EQ3-Pro mount unguided PA'd with the Polarscope and Polarfinder app on the Android Smartphone , before manually starting sidereal tracking skip star alignment) and star hopping my way towards the targets with the help of the Sky and Telescope Pocket Star Atlas...

The camera is being run using APT from the Samnsung NC10 and Liveview x5 used with the softwares FWHM focus routine on a star on one of the 1/3rd points rather than centered...

I am shooting a mix of 30,60,120 and 180s subs and using Entropy Weighted stacking in DSS.. I don't shot darks - last night sensor temp was being reported as 22C - but do use flats and bias...

Just a couple or very quick roughs from last night about 1 1/2 hours worth of mixed length subs ISO800 at f2.8...

I should have had Herschels Garnet Star closer to the edge of the frame in this one..

And this is Sadr Region including the Butterfly & Crescent Nebulae

Thansk for looking...

Peter...

[Gina]

WOW!! There's a lot in there - great images

[Ags]

Very nice! I have to get back to collecting this kit... I have the camera and the S&T Pocket Atlas, so I am halfway there :-) I just need the mount and 200 F2.8.

I use the same focus technique with my ST80 - if I set focus using a centered star, the stars at the edges are shocking.

[ollypenrice]

Exciting stuff. What a magnificent FOV!

And a Welsh observatory is the first to see the summer this year! We have your rain, I might say, and we'd be rather glad if you'd be good enough to come and collect it...

Olly

[Uranium235]

Nice to see you posting some nebulas again Peter, top stuff.

I see your fetish for Cygnus hasnt wained

[Psychobilly]

Lol... no plans for guessing where I am imaging again tonight then...

I am planning on spending the whole night on Sadr again but at ISO400 Luckily i remembered this would need new flats and bias and I am shooting 15,30,60,120 and 180s unguided subs...

I an back in tourist mode with the 200/2.8 just getting a feel for it really before perhaps using it piggy-backed on the obs setup...

Although i do gave sone trips planned with the kit I am using now so just want to practice using it in its purest form...

Peter ..

[Ibbo!]

I think you like this area of the sky

Steve

[ollypenrice]

I think you like this area of the sky

Steve

And so he should! If you have the FOV it's pure gold.

Olly

[Ibbo!]

And so he should! If you have the FOV it's pure gold.

Olly

Yes I remember last years

are you going to add it all together?

Steve

[Psychobilly]

Perhaps next tine need to see how the 100/2.8 performs... see if tge same thirds focuding cab be applied to it... its not an L lens though just an EF macro but might be worth playing to see what it can do...

Yes i'm addicted to Cygnus... and like to use it to compare cameras and lenses...

2 1/2 hours of the shorter length sub in the bag now finishing of with 180s ones...

Should have enough of each length for entropy weighted to do its stuff...

I hopped again so there will be misalignment with last nights ISO800 data but might still be able to get the interesting stuff out...

Peter...

[angusb1]

Nice result Peter. I played around with the FWHM focus routine last time I was out and I like how it works. I think I'll give it a go the way you have here next time and see if I can improve my star shapes with the lens wide open.

[laser_jock99]

I'm interested in this focussing technique as I have a 300mm F2.8 APO lens that is 'fussy' to say the least. Up till now I have always focussed by centering on a bright star and using live view x10 to home in on focus. This as you say may leave the stars at the edge of field unacceptable. So you suggestion of moving away from the centre and foccusing from there might be worth a try. If you can work at F2.8 then it's certainly a fast system.

Do you think there would be any milage in trying to image the bright stars separately, say at f4 and introducing the 'sharp' star data as a separate layer- or would the 'non sharp' star layer be to difficult to subtract? Just thoughts.

[Psychobilly]

It came about after reading up on optimising the result across the whole field using a 0.63x reducer on an sct...

I suspect you might slightly compromise the centre of the field but gain a lot more from the edges and especially the corners... I think the starfield image shows the result better than the nebulae images...

When i get a chance I will do sort out done single sub 1:1 crops from that image...

Peter...