Meade DSI on Alt/Az?

[Johnboy2011]

What are your thoughts on the suitabilty of this?

I know alt/az is not the way forward for lx but as a novice I'd be more than happy to settle for reasonable quality images of the brighter galaxies or nebulae. I'm guessing I'd have to stick to lots of shorter exposures. (I don't have a wedge and opinion seems to suggest it may not be worth it)

I know I wouldn't get anywhere near the quality of the images on here but is this a good way to dip my toe into imaging?

Thanks,

John:D

[Si W]

Hi John

You can use Drizzle which is part of the Envisage Suite, this allows for long exposures using two guide stars on an Alt/Az Scope using Field De-Rotation software, but this is only compatible with Meade Scope's, as you have an LX90 you should have no problems . As far as image quality, you'll be surprised how good an image you will get.

http://www.meade.com/manuals/TelescopeManuals/dsi/DSI_III_manual.pdf

http://www.meade.com/autostar/update/drizzle_update.pdf

Simon

[Dave-Ryan]

Mark Sibole has been using a Meade LX200, Meade ETX-125, and the range of DSI camera's for years getting great results.

Take a look here.

[Si W]

And Steve Hamilton is another good example, He use's a Meade LX90 8" and an Meade LXD75 SN8 too, just proves what, with a bit of experience you can produce with the kit you've already got. Enjoy

http://www.meade.com/dsi_ii/stevehamilton/index.html

Simon

[collangm]

I too am interested in the Meade LX90 ACF SCT scope but was worried about comments relating to the mount and its limitations for astrophotography. The link to Steve P Hamiltons website was fantastic and certainly put my mind to rest.

Thanks,

Gary

[r3i]

You can do unguided short exposure alt-az imaging with an LX90 - that's how I started out. My results were somewhat woeful when compared with what others achieve, but encouraging enough for me to keep trying as I slowly accumulated kit that was more suited to the purpose.

The suitably of an LX90 for imaging was recently discussed here: http://stargazerslounge.com/beginners-help-advice/125613-meade-lx90-acf-8inch-uhtc.html#post1667070

However with reference to the above links from the Meade site: Just be careful that you are comparing apples with apples here. If you read the details under each of the images you will find that none of the images in the above 2 links were actually taken through an LX90 scope.

Furthermore, the pictures of both Mark & Steve with their gear clearly show them using their scopes with a wedge, i.e. in polar mode and not in Alt-Az mode.

Most of Mark Sibole's images were taken with another scope piggybacked onto an LX200 with the LX200 being used as an autoguider. Some were taken through the LX200 but remember that the LX200 mount is a significant improvement over the LX90 (hence the significant increase in cost) - stiffer forks, better gears etc.

Again, none of the images on Steve Hamilton's page were actually taken through an LX90 - some were taken with an ED80 APO piggybacked onto an LX90 being used as an autoguider. Others were taken using an LXD75 which is an EQ mount.

[Si W]

Sorry but i'm confused, yes the images are taken with the ED80 APO and autoguided with the LX90, i suspect using another DSI as the guide camera, optic's aside, if the reverse was true and the guide scope was the ED80, the tracking would be the same, would it ?, as everything is plugged in the same place it just the Guide camera thats changed position from the LX90 to the ED80

[r3i]

Sorry but i'm confused, yes the images are taken with the ED80 APO and autoguided with the LX90, i suspect using another DSI as the guide camera, optic's aside, if the reverse was true and the guide scope was the ED80, the tracking would be the same, would it ?, as everything is plugged in the same place it just the Guide camera thats changed position from the LX90 to the ED80

Not quite the same - you'd be going from imaging at 480mm/F6 whilst guiding at 2000mm to imaging at 2000mm/F10 whilst guiding at 480mm - much more of a challenge for the mount.

Anyway, I was assuming (rightly or wrongly) that the OP was starting off with a much more simple configuration, i.e. an LX90 on its own in alt-az mode with a single camera. No polar mount , no auto-guiding, very long focal length with a slow focal ratio - a completely different scenario from how the images on the Meade site were taken. Perhaps the OP can chime in to confirm or otherwise my assumptions.

[Johnboy2011]

Happy to chime in!!

Yes I'm thinking of imaging on alt/az with no wedge and therefore limited to very short exposures due to field rotation. From what I have read here the cost of the wedge isn't justified by it's performance? In fairness I really am not expecting the kind of quality in the images above, but if I could get even half way there I would be chuffed!

My thinking is if I could get half decent images for say a £200 outlay on a second hand Meade DSI then it would be worth it to see if I enjoy imaging. If I do then I would probably need to go a whole other route (GEM). Someone else suggested for the same sort of money I could go second hand dslr but the meade package does seem a bit more user fiendly.

It really all depends on what quality I could expect from DSI on an alt/az with no wedge.

Appriciate all input!

Thanks,

John

[RobH]

Yes, you can get results in alt/az unguided using a DSI.

That's how I started off in 2006.

I had an old 10 inch LX200 classic.

The LX90 is perfectly capable of doing the same thing as the difference in mount quality will only show up on longer guided exposures using a wedge.

I limited myself to 21 seconds maximum exposure, and shot lots of subs.

Not terribly impressive images when I look at them now, but a real thrill back then!

Much longer than 30s and your stars will get elongated due to field rotation. In certain parts of the sky, you can't go this long....I saw a graph regarding this once, with max exposure times, but can't remember where unfortnately.

Here's the Crab nebula done with that setup, at 2500mm FL.....my first attempt at LRGB processing, or processing of any kind in fact, so it could probably be better!

Cheers

Rob

[Johnboy2011]

Rob,

My heart just lifted! So you got that shot with just Meade DSI, no focal reducer, no wedge? If so that, I think, is all I am after for now!

Brilliant! Do you have any more from that type of set up I could see?

Thanks,

John

[Si W]

Rob

Did you ever try using Drizzle with the LX200, i tryed it a few times and managed to get exposers of 120 seconds without star trails in Alt/Az with an ETX 90 on the Ring Nebula ,this was before i got the LXD a couple of year ago.

[r3i]

John:

You should be able to get a decent DSI 2nd hand with a £200 budget. There's a healthy market for them so if you find that imaging isn't for you, then you could always resell it and you'll probably get most if not all of your money back. If you do find you enjoy the imaging and move onto bigger and better things, then the DSI makes a great guide camera - I've still got mine for that reason.

Si W: Nice M57! Below is one of my first efforts on M57 using a DSI1 OSC with an unguided alt-az LX90 8" at F10 from about 4 years ago. It certainly aint going to win any awards:o, but I have to agree with Rob, when you're new to the game any result is indeed a big thrill.

[RobH]

Great result Si, but looking closely you do have some trailing....mind you, it looks like you could have gone for about 60-70s without any at all, which is pretty good

At 2500mm FL, any trailing was obvious very quickly, so I found that shorter exposures, but a lot of them, worked very well for me. I think I used about 70 luminance for the crab, plus 30 or 40 each or RGB.

Drizzle is good for removing any field rotation between exposures, but can't remove it once it's on a sub.

John, I just had a look, but I don't have any older images on this computer, and I'm away from home until the start of next month, but remind me and I'll dig some out.

Cheers

Rob

[Si W]

Thanks Rob & r3i, that was my first decent image with the ETX90, i was well made up, only had the DSI 2 a couple of week when i took that image 2 years ago.

[jgs001]

You certainly can image in AltAz pretty well.. I started out this way.

You can get exposures up to 2 minutes if your target is low in the east or west, with the exposure time coming down to about 30 seconds as you get N/S or at the zenith. I can't find the graphs at the moment... but I have achieved this myself with a NexStar SLT, an ST80 and a Canon 450d. Based on the information I found at the time, focal length is not a factor in avoiding issues of field rotation in the image, however, as is always the case, as the focal length goes up, the accuracy of the tracking becomes more critical and the mount is taxed more.

DSS deals with any rotation between frames, and I'd think any stacking process would.

Even with the really short subs however, get enough of them ...

A couple of examples

M52 and the bubble neb (my camera is not modded for Ha sensitivity)

M31 - Please excuse the horrible vignette, it was before I discovered how to do flats with 1.25" fittings on an ST80... This was 2 minute subs.

[RobH]

Cracking images