Really dissapointed

[rocketandroll]

Hi folks

So, after some limited success catching a load of galaxies in Virgo last week with my 200mm f2.8 lens, I decided to have a stab at the area around M101 last night.

This time I thought I'd really do it right and actually captured over 2hrs of data, 40 mins of darks and 40 flats. Unfortunately, whispy high cloud passing through made half the subs unusable, the useable ones weren't really clear either tbh... in the end I have this... which is about an hour and five minutes worth of data:

m101-revised-stack-2drizzle-median-mod1 copy | Flickr - Photo Sharing!

For over an hour at f2.8 and ISO800 I am really dissapointed with the amount of noise and the pretty poor clarity of the image... it's far worse than the 30 min image I got from the Virgo cluster, and this time I was using an LP clip filter, which I didn't have before. I can only assume that's largely down to the haze?

Anyway... I have tried playing around with it in PS for a while but I'm just getting more and more frustrated with it as everything I do just makes it look worse.

I am kinda on the verge of actually stopping imaging for the time being until I can set aside the time to find somewhere online or somehow that I can learn proper image processing.

Oh, and sorry about the slightly oval stars in the bottom left corner.... I assume down to slight issues with my polar alignment.

Ben

[shaunster]

I dont know what you were expecting but it doesnt look that bad to me

This isnt exactly the best widefield target out there and your 100s subs are really short to be expecting any good detail in the galaxy

Haze has probably made it look worse yes if the individual subs were poor..

[antimorris]

You can't give up yet!!! Practice makes perfect, you just have to keep at it if you aren't happy with your current results. When I first started, not but a few years ago, I quickly realized that processing skills were a steep curve and can easily be the limiting factor so I found alot of files to practice on (some of my own, some from people on forums that would share, and some you can find on the web from sources like Hubble) and just practiced. Read online, books, and ask lots of questions and before you know it you will be happy you didn't throw in the towel.

I still occasionally have some data that I start working on that can get frustrating and I have to take a step back and reassess my processing steps.

Haze can definitely add alot of noise that wouldn't normally be there, so that indeed might be the big difference between your Virgo cluster and here. I had a bad haze problem when I shot the Cone Nebula and it took me a while to figure out why the subs were so noisy as I hadn't realized it was hazy at the time until I went back and looked at the wide-field shot I had taken of my setup and the sky and could see those high wispy clouds hiding high in the sky.

Would you be able to/want to post your raw files or your raw stack and provide a link so some of us here on the forum can have a go and if you like the efforts better than your result can give you step-by-steps?

[Cloudwatcher]

Try a 'de-magentarised' view............ any better?

[Earl]

Could you do a re-stack just using 20 Darks and 20 flats, also when i stretched the image there is a satellite trail in the top right corner.

[rocketandroll]

Cheers all

Sorry about the whinge, I think I was just having a bad day and was just getting frustrated with how poor the quality seemed to be in comparison with the last lot of stuff I did with this lens.

I did a few more stacks and found that one of the big problems was that I'd turned on 2Xdrizzle with the really bad one and that had made the noise MUCH worse. I did a few more stacks with different perameters and got it looking much closer to what I'd achieved before.

It's still not great, but I think the haze really didn't help much, probably not the best thing to try in poor conditions :-)

As for what I expected... to be honest, the galaxy came out pretty much as expected, at f2.8 100 second exposures are equivalent to about a 14minute exposure with a standard f7.5 refractor... so should be MORE than enough to get all the detail, the total stack is equivalent to 9hrs at f7.5 or so by my calculations so, again, should be more than enough to show 101 pretty well.

Anyway, here's a slightly cropped version of the latest stack after an hour or so playing in photoshop.

Still not great, but until I get my guiding set up and can do 5min+ exposures with the scope, this is probably about as good as I'll get on 101.

Ben

[Zakalwe]

M101 is very very faint, so you have set yourself a really hard target.

Your result is a good one...nice tight stars and good processing, so I wouldn't be de-motivated at all. Personally, (with my kit), I think that you need 4+ hours as a minimum on M101 to get any sort of detail.

An hour on M51 gets some nice detail and colours. An hour on M101 and you get a smudge that you have to tease out of the background.

Keep cracking at it...you clearly have the skill for it. But if you are a bit fed up, then maybe take a break for a few weeks and see if the urge returns?

[rocketandroll]

M101 is very very faint, so you have set yourself a really hard target.

Your result is a good one...nice tight stars and good processing, so I wouldn't be de-motivated at all. Personally, (with my kit), I think that you need 4+ hours as a minimum on M101 to get any sort of detail.

An hour on M51 gets some nice detail and colours. An hour on M101 and you get a smudge that you have to tease out of the background.

Keep cracking at it...you clearly have the skill for it. But if you are a bit fed up, then maybe take a break for a few weeks and see if the urge returns?

Cheers, yeah, I was just having a down day I think :-)

The urge is already back, I have secured a new site (on a famous local farm) to do some imaging next week so I'm gonna point the Meade at M81/82 for a couple of hours and try and get a nice quality shot of that pair.

As I said, at f2.8 you can get away with a lot... generally about 1/8th the time needed as with an f7.5 scope, that's the only reason I even tried M101 unguided :-)

Having done M51 with about an hour and 20 mins of data through the Meade... I was told early on that you need three times as much to get M101 because of it's low surface brightness. That's why I'm leaving off it as a target until I'm guiding later this year, then I'll do a full two night stint on it, try and get four hours or so of data with the focal reducer at f6... that should do it.

Cheers again all :-)

Ben

[Earl]

I think that is a very good result.

The reprocess has done the trick.

[Sparrow]

Stick at it Ben - I don't think there's anyone on this forum who hasn't had bad days - either due to equipment problems, software problems, or viewing conditions.

As others have said, M101 is not the easiest of targets - I'm collecting data for it at the moment and am aiming for about 4 hours of data - I've so far been thwarted by poor sky conditions. You may find teh Autumn a better time to image when there are larger and brighter objects on offer - M42 is always a good starting place (when it comes round again) and with a 200mm lense you should get a reasonable image in the FOV.

BTW - one thing I've found is that if I have the widest aperture on the lense it tends to be at the cost of sharpness - When I'm imaging through the lense rather than the scope, I actually close the aperture down by a stop or two - obviously it means longer subs or higher ISO, but the sharper image more than out weighs this.

Whatever you do, don't give up - sometimes it takes a while and experimentation to get good results. Also, sky conditions really do make all the difference.

Regards

John

[rocketandroll]

As others have said, M101 is not the easiest of targets - I'm collecting data for it at the moment and am aiming for about 4 hours of data - I've so far been thwarted by poor sky conditions. You may find teh Autumn a better time to image when there are larger and brighter objects on offer - M42 is always a good starting place (when it comes round again) and with a 200mm lense you should get a reasonable image in the FOV.

Cheers John

Yeah, this isn't the first target I've tried, did M42 to death back in March but have some 'interesting' plans for it when it's back up in the autumn... also very keen to try and get a nice widefield of M42 and the flame/horsehead in one shot with the 200mm.

Done a few galaxies now and globulars... I only tried 101 because I'd had some success with some smaller galaxies in virgo the week before through the lens and figured, seeing as 101 was so comparatively large and feint, it'd suit the f2.8 widefield approach.

Gonna leave it though for now and, as I said, wait till I have guiding and a week of good weather to do it justice through the scope.

And yes, a few have said the lens isn't at it's best at f2.8. Gonna try some more nebulae pics with it now, at f4 or so I think, see how much that improves things.

Ben