MartinFransson

Pokey pokey!

Keepin' the flag flying for the 130:

On a side note, its quite interesting what you get when you type "130pds" into Google and click the images tab a lot more astro images than there used to be!

That's a real beauty! Looking forward to testing my recently bought 150PDS, even if I'm disqualified from this thread

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Hi,

I was out last night giving my new 130PDS its first light, using my unmodded Canon 700D. Had a few problems stacking (discussed in another thread) but have come up with some pleasing images. This is nowhere near the limit of what DSLRs can do, but it's not bad for a comparative beginner with his first newt.

You'll get pinpoint stars ok as long as your polar alignment and guiding are good, and you use a coma corrector. I used the SW own make 0.9 one, which takes the scope to F4.5. For guiding I got an adaptor from Modern Astronomy which allows one to use, in my case, an Orion Starshoot autoguider with a standard SW 9x50 finderscope with excellent results.

Anyway, here are my first light results from last night:

Wow! That looks great!!

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My latest project is a section of the Elephant Trunk Nebula.

Currently at 41x600s frames of just HA, all with the moon in the sky (only time it seems to be clear round here).

ElephantTrunkWip.jpg

Just a quick process to see how its going

I've dropped down from my usual 15 minute subs as I found I was dropping to many subs for the small amount of semi-darkness we are getting at the moment.

As a result I haven't had to remove any subs due to guiding errors for this image which makes me a happy bunny

Awesome! Is that a scaled down version of the entire image or a 100% crop? Looks good either way

When you say sharpness, thats a bit of an open question because the there are quite a few things that contribute to the sharpness/contrast of an image, examples being:

1) Resolution: This is determined by the cameras pixel size, and the focal length and resolving power of the telescope. Its unlikely that you will find a pixel size small enough to oversample the 130, most DSLRs will yield roughly the same results.

2) Good data: That is data taken with good guiding and conditions (no clouds, no moon), long subs.

3) Processing: A fair amount of the contrast and sharpness is won back at this stage. You cant expect a newt to be as contrasty as a frac (eg: an 80ED), but where is does win out is with the depth of the data you have from running at f5 (can therefore stand up to more processing).

4) Collimation: Better the collimation, better the image

Yes you need a coma corrector if youre going to do anything serious with it, but when you ask for pinpoint stars - that wll be down to you and how you handle the telescope (ie: collimation etc). Its perfectly feasable to get a good field without much effort, but if youre asking for 100% perfect in each corner of a big chip (what I call "the last 1%") - thats a bit more difficult.... it depends on how demanding you want to be.

Thanks for a good answer! Knowing myself - I'm pretty darn demanding. Today I use a Canon EF 300/4L IS, which is in essence a 75mm f/4 triplet with a built in field flattener On a good day (seeing, turbulence etc) it gives me really sharp stars.

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Loving this thread! [emoji4] Haven't read all of it but could someone post a single frame (or stacked) from a DSLR so I could see what kind of sharpness I can expect with the 130PDS? Crops are OK as well. Can I expect pinpoint stars when viewed at 100% ?

I assume a coma corrector must be used and tracking (guiding) spot on.

In short, what is the maximum sharpness possible with this scope?

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