First light: Samyang 135mm f/2 and ASI1600mm Pro

[RickS]

Still some work to do on spacing and tilt but not a bad result for 30x30s red, 30x30s green and 30x30s blue (gain 200) on a moonlit night from a heavily light polluted back yard. Lens wide open at f/2 and an IDAS filter on the front. Mount was a Star Adventurer (unguided for the moment.) Quick & dirty processing with PixInsight 1.8.5.

I have an hour of Ha and an hour of Oiii to play with next...

Cheers,
Rick.

[Atmos]

What are the Star shapes like at F/2?

It’s looking pretty good so far Rick!

[RickS]

Thanks, Colin. The stars are still not as good as I'd like in the corners at 1:1 but I'm getting incremental improvements playing with thin spacers. I plan to change to new filters so I'm not putting too much more effort into sorting out the spacing for now because it will change...



Thanks, Glen. It's a wonderfully portable system. I just pick it up and carry it out onto our deck, do a quick polar alignment and I'm ready to go.

I did some subs with and without the IDAS and it does make quite a difference to the contrast. Unfortunately, it also added some strange blobs which I think must have been reflections of Saturn (which I have edited out). I believe the filter rejects spectral lines from Mercury and Sodium lights. Not sure what they use on the busways these days.

[Dennis]

Very impressive results Rick, and what a portable and quick to set up system.:)

Did you encounter any flexure issues with the deck as the support structure?

Cheers

Dennis

[RickS]

Thanks, Dennis! It's so much less hassle than the AP900 and one of the big scopes so I hope to get a lot more use out of it, especially during summer when good weather is so rare and fleeting.

I have assumed that since I'm imaging at around 6 arcsec/pixel that I can largely ignore that the scope is three floors in the air (and generally pointing over the roof to our kitchen and living room.) So far that assumption seems OK. I focus using a small ROI at greater than 1:1. I should try walking around while I do it to see how much wobble I get. I do walk softly whenever I approach the tripod just in case :)

[peter_4059]

That is looking good Rick. Do you find the gaffer tape boots induce low vibrations when walking around the mount? Might be worth trialing duct tape to see if it is any better?

Pete.

[RickS]

Thanks, Peter. With the warmer weather I've been wearing tapeless flip flops with integrated bottle openers. I don't know if they are better from a vibration POV but at least I can open a beer with them :thumbsup:

[peter_4059]

Haha...Wish I could find the "like" button.

[Ryderscope]

A great configuration and first light Rick.

[RobF]

Looking good Rick. Maybe you should be putting a reducer on the FSQ and trying in between wide-field with that too? :)

[RickS]

Thanks, Rodney.



Ta, Rob. I have a few plans. Might end up with at least a couple of wide field systems imaging in parallel. Would be nice to have a combination effectively running at f/1 or less :lol:

[SimmoW]

Nice start Rick, joining the club eh? It's a refreshing change. Great lens that seems, well the DSW boys get great results at least!

[cometcatcher]

Well if you can take a shot like that in moonlight and LP from your place, the sky is yours! That wide lens will be great for close passing comets (when we get one).

[ozstronomer]

Great image Rick, looks like that combo will give some nice results

How does the Samyang compare to the Zeiss?

[gregbradley]

A very good first light Rick. I would prefer the image the other way up though.

Widefield imaging is a lot of fun and opens up larger patterns than our normal view.

The Samyang 135 F2 has a good reputation.

Greg.

[willik]

Very nice image Rick your images always look good
Martin

[LewisM]

Time to sell all that Astrophysics junk now Rick...:lol:

[RickS]

Yeah, thought I'd give it a go after playing around with my D800 at Astrofest, Simon. It's nice to get (relatively) quick results.



Thanks, Kevin. I haven't imaged a comet before but that sounds like a lot of fun!



Ta, Geoff. The focus isn't quite as smooth but the Samyang seems to be a great lens, especially for the price.



Thanks, Greg. It was a test shot with no real thought given to composition... but I should have known better :)



Thanks, Martin.



I might keep it just in case I get sick of wide field, Lewis :lol:

[multiweb]

Not bad at all. You're well on your way with your milkyway mega mosaic project. ;)

[RickS]

Thanks, Marc. That could keep me occupied for a long time!

[RobC]

Impressive and well done Rick. When are you mounting the 1600 on your 140 ?

Cheers Rob

[RickS]

Thanks, Rob. Might try it on the Ceravolo at f/9 and do lucky imaging of small, bright things one of these days...

Cheers,
Rick.

[LewisM]

Darn it, I was hoping to get a bargain...

[OneCosmos]

Rick, you need to buy an SDM and a pair of denk binos :)

[Retrograde]

Great first light Rick. looking forward to seeing what you can produce with this combo. :)

I have this lens for my DSLR. It works really well but I tend to get flaring around bright stars.

[RickS]

Maybe if I ever need a kidney, Lewis :lol:



I'm happy to look through an SDM or two every year at Astrofest, Chris :)



Thanks, Pete. I have seen some halos in blue and Oiii but I'm assuming that's the filters. Bright stars, and ever Saturn haven't come out too badly so far.

[Atmos]

Given the playing you've done with spacing Rick, when you were achieving infinity focus at lets say, 10m, did you need to increase or decrease spacing?

I have a Zeiss 135mm that I've used with a QHY163M and I can focus but it isn't quite at the correct spacing so I was curious as to whether I needed to increase or decrease where I am at.

[RickS]

Hi Colin,

Increasing the spacing pushes the focal point further towards infinity on the lens scale for all the lenses I have tested. I'm working on the assumption that I'll get the flattest field when the lens scale matches the actual distance and that seems mostly correct. Adding filters seems to complicate things. Spacing that works well for the Ha filter doesn't always do so well with the other filters. Things get tricky at the focal ratios where I have been playing!

Cheers,
Rick.

[Atmos]

Thanks Rick. I think I have another 0.5-2mm that I need to add then. I'm pretty close but I'd like to get it as close as possible. As my Astrodons are all 3mm thick I wouldn't have thought that different filters would cause issues. I have done some RGB imaging and my only "issue" seemed to be blue bloat at F/4... Along with tilt caused by my mounting :lol:

Might get a clear night on Wednesday night to do some playing.

[RickS]

I'm using Baader filters that are purportedly all 2mm thick but I'm not sure that's the only consideration. Purportedly "parfocal" filters never focus at the same place for me and I have found the differences are quite large in fast systems.

Good luck with the playing!

[RickS]

Here's 108 minutes of Ha (30 sec subs) of the region containing M17, M16 and NGC6604/SH2-54. Bigger version: https://www.astrobin.com/full/368424/0/?nc=user

It's a bit like the exact opposite of what Mike & Trish do :lol:

Cheers,
Rick.

[Camelopardalis]

Nice one Rick :thumbsup:

I’ve tried RGB from “the Far East” with all its streetlights and found it a bit lacklustre...at the sluggish f/5.5 :sadeyes: will have to look into the IDAS.

Should be a ripper out at a dark site...

[RickS]

Thanks, Dunk. I don't plan to do much RGB imaging from home but it's good to know that it isn't completely impossible. I am really looking forward to the next opportunity for some dark sky imaging time.

[gregbradley]

That looks promising. I am fan of lens imaging and that's a very modern setup you have there.

Dipping your toe in short exposure multiple subs stacking eh?

The results show.

Greg.

[RickS]

Hi Greg,

Thanks, I thought I'd try something altogether new for me. So far it has been quite challenging but I think there's a big payoff if I can get it all working well. I have some large targets and also some very faint ones in mind...

Cheers,
Rick.

[multiweb]

Nice! Love Ha with lenses. Good res on that one :thumbsup:

[strongmanmike]

Things are looking good so far Rick, looking forward to watching your new journey with this system :thumbsup:

What processing software will you be using :question:......

:P

[topheart]

That is very wide and very good Rick!!
Cheers,
Tim

[RickS]

Thanks, Marc!



Ta, Mike. Perhaps PixInsight? :lol:



Thanks, Tim.

[Ross G]

A great looking widefield Rick.


I have been experimenting with Nikon 180mm and 300 mm lenses with the asi1600 and getting mixed results.
The quality of the lens to camera adapter seems to be the biggest problem.


Looking forward to more photos.


Good luck.
Ross.

[RickS]

Thanks, Ross! I agree. Getting a solid connection to the lens with exact spacing and minimal tilt is quite a challenge.