First light M42

[LamboDiabloSVTT]

I didn't see it mentioned yet, but a good tool to help you achieve sharp focus is a Bahtinov Mask. These help take the guess-work out of focusing, and they're pretty inexpensive.

[ollypenrice]

I'm pretty sure that the triangular stars are from pinched optics. It might be worth easing the lens cell a little. You probably rotate a lockring at the front but I can't be sure, then stand the tube vertically on a hard surface and tap it with your fingers for a while to settle the elements.

While an F5 refractor is a great idea if you are paying Takahashi prices it is, to be honest, the opposite of a good idea on a budget. This scope is about as imaging-unfriendly as it gets but you've done remarkably well. Yes indeed.

When you choose a scope don't just look at the numbers. You'll read that a fast F ratio is good - and it is. But it is also difficult to make (= expensive) and diffult to collimate, difficult to focus, difficult to keep orthogonal. When you compromise on budget you should also compromise on F ratio. Good F4 beats good F5. Cheap F5 beats cheap F4. That's the principle, at least.

No free lunches.

Olly

http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/22435624_WLMPTM#!i=2266922474&k=Sc3kgzc

[Magnus_e]

Well. I got a bit DIY modding hungry and wached the

"ST80 mods and tweaks"

Now the glass sides is darkended, and the fokuser has new litium grease and have been adjusted for better tention and less slop.

The optikal cell only got the retention ring tightened so i can hear a slight rattle if i shake the scope good. And i must mention that the

retention rin was verry tight when i took it apart. Also when i took the picture it vas sub zero C and very windy. I also remember that the

dew sheeld was loose due too the themperature beeng so low that the metal in the scope was contrakting "shrinking". Adding to the pinch theory.

I have toght about a bathinov mask and have downloaded and printed a vektor image from http://astrojargon.net/MaskGenerator.aspx

I currently do not have anything to make it from. I have assesed a old black mouse pad, but i think it will be to flimsy. What is the best matherial

to make one of? Should i just by some thick black cardboard from a "paper / book shop"?

Some modding pictures

[Magnus_e]

ollypenrice I do realiize as you say that this scope is not the best money kan buy, and maby not the best scope i could get for the money i used.. My plan and wishes is a 8" Newt and this is going to be my guidescope The budget part is just that i ran out of money

[happy-kat]

Look forward to seeing your next image. No more triangle stars :-)

[Magnus_e]

Just a fst question. What iso's is normal to shoot at?

When i have learned to use a camera with a lens i have alwais learned to shoot at the lovest possible iso.

But with a lens you can adjust the apperture wicth you cannot with a telescope. So i naturally thougth that when

i was using 9 min expotiures then if i went about 100 iso the image would bee sereously burnd out. Then earlier

in this thread someone mentioned that it was a good idea to shoot a couple frames at shorter shutter to blend

in to the stack and get the nessesarry dynamic range. The stacking proses also removes a lot of the noise assosiated

with higher iso's "if darks, bias and flats are provided". Then it's easy tho think that if i shot the frames at 400 or 800 iso

i would get more signal!

And again, its's not that easy. You normally don't shoot land pictures at ~10 min and you don't shoot your pictures on land

through the intire athmosphare, so then there is light pollution. If you look at the sub in this post http://stargazerslounge.com/topic/236667-first-light-m42/?p=2563822

then it's allredy brown at iso 100, so i'm guessing that iso 800 would look terrible, but then there is stacking and the possibillity

to ad frames with shorter exposure.

So before i'm trapped by an infinite loop i must ask, what are a good set of rules to follow when shooting the frames.

Shoud i just take som test and use some sense? Or are there some universial limits than can be of help to deside?

[Marky1973]

Magnus, I think you still have to adjust the ISO to the subject and the conditions, but you do use higher ISOs to pull out the detail you want with your longer exposures. I think the "catch-all" ISO for astro is 800 ISO, but people do go to 1600 and higher as they see fit. I tend to stay with 800 for 90% of what I am doing.

However, with Orion, for example, you may want to also take some shots with a lower ISO to capture the core ready for blending with the nebula. So I have been experimenting with 60-90 second subs on Orion at 800ISO to get the detail in the nebula. But I also took a set of 20 second lights at 400ISO to capture the brighter core without burning it out as it was in teh longer exposures at the higher ISO.

Just play around and see how you go - start at 800 and then take some at a higher and lower ISO to compare the changes - but 800 is definitely a good place to start!

[Magnus_e]

Hi Marky.

Thanks for that info. It seams that i proabably could have gotten more detail from my 1h+ exposure.

Just to ask. Should i be worried if a sub looks werry light? I guess if i follow your tips i would get a lot

of brightness / browness in the individual subs. As a beginner it's not easy to see / guess what are

noise ruined subs and what is just a lot of signal. Thinking about how my subs loocked and how

the stacked image looked, i probably could have had a lot brighter subs without the stack being

bright.

I guess it comes with praktice. Absolutely loocking forvard to learning the tips and tricks of the hobby

[happy-kat]

Check what the histogram is doing you don't want it either right to the left or right to the edge the other side I gather.

[Magnus_e]

So now as i'm not having clear skies i'm thinking about finishing my setup.

I do not have a battery for my mount. I have been looking at automobile shops and have found two batteries that can be a good choice in my price range.

One is a Silver-Calcium 55AH battery and the other is a 60AH Calcium-Calcium battery. The SC has 4 year warranty, and the CC has 3 years of warranty.

The appliances that will run on the battery will be the celestron avx, my laptop, probably my canon 550d with an adapter and i think i would get ~6+ hours of charge. I have looked at some deep cyckle batteries but they are to expencive. Both the silver and calcium-calsium batteries i'm considering is made to be used in boats or cars, but does not mention deep cyckle.

What kind of batteries is normally used for powering a astro rig? Does the contenders above seem reasonable?

I have also been up to no good and tried to make a bathinov mask. Long storry short the struts where to thin for my matherial an broke apart. I then started googelin and found a thread about the Y or Lorde mask. http://stargazerslounge.com/topic/140075-good-by-bahtinov-hello-the-lord-mask-amen/

After some reading it seamed like it is perfect for refractors, so i spent some time making one. It's cloudy so can't test it, but thougt i would ask how to use it?

I guess it can just bee used as is and checking in live view. I have notised that BYE has a bathinow choice for focusing. And have seen somthing about a bathinov grabber software. Does any of those assist in using a bathinov mask or are the bathinov grabber just a live view window, and the BYE bathinov focuser just a bathinov "simulation"? And is the Y mask similar enough to be used with bathinov software?

Just for fun, Here is some pictures of the mask

[happy-kat]

Once you have focused with the mask (need a fairly bright star I think, a planet would be nice and bright) you will need to remove it, does your mask come off?

[Magnus_e]

Yes. All of the black bits on the dew shield slide of.

It's just a strip of cardboard wrapped aaround the dewshield and with the Y taped in. I painted it with my blackboard paint, just to see how matte it was.

Glad i did not go strait to painting the inside of my scope with it, as the original paint is more matte. But more grey.

[Marky1973]

Hi Marky.

Thanks for that info. It seams that i proabably could have gotten more detail from my 1h+ exposure.

Just to ask. Should i be worried if a sub looks werry light? I guess if i follow your tips i would get a lot

of brightness / browness in the individual subs. As a beginner it's not easy to see / guess what are

noise ruined subs and what is just a lot of signal. Thinking about how my subs loocked and how

the stacked image looked, i probably could have had a lot brighter subs without the stack being

bright.

I guess it comes with praktice. Absolutely loocking forvard to learning the tips and tricks of the hobby

I don't think you should worry, if you take lots of subs and include the DARKS/BIAS/FLAT frames you should be okay. If you are worried that they are too light, maybe consider a light pollution filter? That should help darken the subs and allow you to take longer exposures.

[Magnus_e]

Ok. So something like this i guess http://www.astroshop.eu/broadband-filters/omegon-nebula-city-light-filter-1-25-/p,15629#tab_bar_1_select

How does it connect to the telescope setup? The only threaded part i have is where the 1.25" T-adapter screws on to the canon T-ring.

If it fits there, then it should fit on my setup.

Have seen people talking about these LP filters in other threads, and seams to do a lot of good.

[Magnus_e]

More light on M42

Last night there was clear skies and a new attempt on Orion nebula.

This time i used 10 min subs at iso 800. I did plan to take 8 of them, and 4 10 min at iso 100. Did plan to top it of with 4 3 min subs at iso 100 to get the detail in the centre. Things don't always go as planned, but i got 4 10 min subs at iso 800.

I was having truble geting PHD to calibrate. Got a "star did not move enough" error, but at the tird attempt with some blinde fiddeling with the settings it worked.

Also my celestron is chronically missing everything with about one hour in RA, witch makes it impossible to guess when it thinks its passing the meridian. Doing the meridian flip also gets more complicated when i have to slew manually to the target, and i can not find anything other than M42 cause i don't have any usable visual finderscope setup.

Guess i will figure these things out as i go along. Brobably gets easyer when spring comes and its not freezing.

So i made a stack in dss of the new subs. As i only managed to get 10 min iso 800 frames last night, the stack was burned out in the middle. Tried what i could, but didn't get it to an usable level. The end of the field of view has streaked stars, but think the stars that are more centered looks rounder. It is a 2x drizzle stack so the running man is right to the edge of the censor. Maby the tuneup made some improvements, but won't know before i get a better set of frames.

I also made a stack with the data from when i started this thread, combined with the subs from last night.

Let me know what you think. Seems to me that the new iso 800 frames gave me a lot more signal

First picture is just edited in dss and is only the subs from last night.

Second picture is edited in dss and ps and is all the subs i have on m42. In total 1h50m44s exposure