Uranium235

lol... 699 there but once it hits the UK - you can be sure it will be more   

However, all the test shots Ive seen are in narrowband - I need to see something in LRGB or OSC to see how it handles broadband imaging.

Hmmm... ive just come across this, astro stuff from Sharpstar occasionally pops up in my feed, which is usually ignored (until proven) - but this one caught my attention:

http://www.askarlens.com/index.php/wap/class1/179.html

Its a 200mm f4 lens, with inbuilt microfocuser (nice touch). And the test images ive seen so far are actually quite good in the corners - that might have something to do with it being f4... so it might not be suitable for someone looking for a photon hoover. And its got just 6 elements in three groups, not nearly as complex as some others (the Sammy 135 f2 has 11 elements in 6 groups!).... whether that is to its detrement.. I dont know. Its too new to comment until Ive seen more data.

Thats the trade off I suppose, swap a bit of speed for tight corners.

The price, I reckon it will be about 800 quid.

On 22/04/2020 at 20:52, Adreneline said:

You certainly want to achieve focus with the focus mark aligned somewhere in the base of the 'L'. The only way I have found to do this is to experiment with various spacer combinations to get the correct spacing. Nominally it should be 44mm but my experience is it is always more. You will find that even introducing a 0.2mm shim spacer will make a lot of difference to the focus position - it is very sensitive to getting the spacing correct, especially at f2.

 

100% correct on all counts! (apart from its 44.1mm but im just being pedantic...lol)

Dont forget, when you add a filter between the lens and the camera - you need to take into account the amount of spacing you need to add (not subtract).

Astronomik: Add 0.33mm

Baader: 0.66mm

Astrodon: 1mm

Yes, it does matter about adding the spacing when working with an f2 lens because the filter thickness can throw infinity focus out quite a bit.

If you have a mix of filter brands in your wheel, then you need to come to a compromise spacing.

5 hours ago, Fieldsy said:

How do you have your scopes rotated so the camera sits on top ,hangs on the side,or hangs underneath?

Thanks

This way up 

2 hours ago, ollypenrice said:

Rob, the mod is to the mount, not the camera. However, it seems that a Canon 200D in a 130P would be imaging at 1.17 arcsecs per pixel if I have that right. This would require a periodic error of 0.6 arcseconds over the duration of the sub. Is there is any experienced imager on this forum who would believe that? Such a claim is absurd. This mount modifier should stop talking about this scope or that and simply state the periodic error in arcseconds which he is prepared to guarantee. Bear in mind, Lucas Mesu claims 4 arcseconds peak to peak for his stunning 200 Mount. And let's have no talk of round stars! You'll get round stars as long as your tracking errors in RA and Dec are about the same but you'll still have lost resolution.

 

Ahh, my bad didnt see it was mount related - but even so trying to gain 4min+ just through modifications to a stock mount seems... optimistic at best.  You really have to shell out some cash if you want top notch unguided imaging.... if I remember rightly one of our (now sadly departed) members (Per) used to do everything unguided - but he had everything modelled right down to the finest detail. 

Quite right on the histogram, I personally leave a gap of 20 - as even though that "gap" looks like there is nothing in it - it can actually contain faint nebulosity or dust that would otherwise get clipped.

15 hours ago, Seleckta said:

I spoke to the chap at Dark Frame Optics who said, with their modifications, I could expect 5 minute + unguided with either my WO61 or a SW130pds. 

Hang on.... stop right there...lol.

No camera modification on Earth (apart from increasing the pixel size) can influence the maxiumum length of an unguided sub... that is determined by both the mount and the focal length of the optics. With a 130pds, you would be lucky to get 30s unguided without trailing (@ 1x1bin). You might be able to get longer unguided @650mm, but that takes a lot of fiddling.

Just wanted to clear up that bit of mis-information 

If you live in London, then its going to be narrowband imaging only im afraid (if you want any hope of a good image).

Keep the star adventurer, buy a fast lens (eg: like the samyang detailed above), a lightweight cooled CMOS camera + some filters. Should come to less than your budget.

Edit: Just need to add that your choice of camera needs to be mono

The SW 0.9x will be problematic when you point it at anything bright. Try taking an image of M45 with it and you will soon find out

Remember, the review posted earlier is based on using an F4 newt - which will always be next to impossible to get flat over a 22mm diagonal for your average imager. However when you apply something like the Baader to an f5 130pds, the results are much more consistent. Its entirely possible to (just about) get round stars over a KAF8300 using the Baader MkIII (example below)

A bit of late night Ha imaging    NGC6820

Just 90min, I'll pick this up again in a few weeks when I wont have to wait so late for it to clear the tree.

A bit of messing around for an hour last night (LRGB) :

On 13/05/2020 at 08:44, TheCounter said:

Hi everyone,

I'm reading this topic since a few months and I finally decided to join the discussion 

I have had a 130PDS for a few months now and did most of the modifications that were discussed here. But I always had a tilt anywhere in my system, so I eventually found out that the focuser was causing it.

So I bought a Monorail focuser from Teleskop-Service (here in germany), as they are pretty good for the money. Only problem is, there is no baseplate available to put it on the 130PDS. So in about 3 weeks I'll get a custom baseplate out of aluminum (that costs me about 130€) that I designed myself. If any of you want's to do the same, just tell me and I'll send you the CAD model / plans.

As soon as I get it, I'll post some pics of it here.

Anyway, apart from the tilt I'm quite happy with my 130PDS. I could take only 3 images with it for now, but I love them:

All images are taken with a QHY294c at standard gain 1087. I used no bias, but flat-darks instead. More details can be found at my astrobin account:

https://www.astrobin.com/users/TheCounter/

There is still much room for improvement

Greetings from germany

Kevin

Astonishing photos...

I had the same issue with a 200pds, great replacement focuser - rubbish baseplate. So I designed my own as you did, but I had it 3D printed instead.

When designing, have a think about how it will all attach to the tube. Might be worth uprating the bolts to M5, and where the nut goes on the inside - a flexible placstic washer or something simlilar to spead the contact area of the nut out a bit more (flat nut on a curved surface is never good).

5 hours ago, matt_baker said:

Also what's the best way to mitigate the red stars?

 

By killing all star colour in Ps:

Filter > Noise > Reduce noise

Strength: 10

Preserve detail: 10

Colour noise reduction: 10

Sharpening: 0

You can either apply that to the whole image, or on a star selection only.

On 28/04/2020 at 22:48, matt_baker said:

Do you have a before and after comparison with your flats? I'm considering doing this based on your idea and it looks cheap and effective, without spending £200 on a flatbox.

Would rather spend that money on going towards a mono cam rather than that

Here is the (stretched) master flat taken with that panel, looks fairly normal... apart from the excessive amount of motes...lol

10 hours ago, Stub Mandrel said:

I used to use a single sheet of A4, but discovered that flats with an uncovered board work just as well because it is so far out of focus.

 

Depends on whether your camera has a shutter or not. The QSI does (as is usual for KAF8300), so I usually give it at least 3 seconds per flat - hence the need to dim sufficiently

19 hours ago, Knight of Clear Skies said:

Excellent thanks, added to basket. Always good to have a recommendation rather than taking a punt.

When it turns up, you will notice it has a grid pattern on the illuminated side. That will disappear once you put a few sheets of A4 on it - you probably need about 3 or 4 sheets to dim it sufficiently enough for lum flats on its lowest setting. For narrowband just hit the power key once or twice to increase the brightness (you have three levels). It runs fine for ages from a small powerbank

On 03/05/2020 at 18:10, Knight of Clear Skies said:

Do you have a link to it please? I've always had trouble with flats but I've tried to use monitors and tablets.

This is it mate

https://www.amazon.co.uk/Portable-Adjustable-3-Levels-Brightness-Animation/dp/B07GSVB7RR

More than one way to skin a cat on this one, personally I would create a fake background (with fake noise) and bursh it in with a layer mask - blend mode ligthen (so the stars dont get touched). Takes practice, but it can rescue a project from the bin.

FYI, the lightbox I used was this - 14 quid from amazon:

I then created a protective cover and OTA attachment using the box it came in, and a bit of foam oh, plus 3 sheets of A4 to further dim and diffuse the light. The pic shown is with it on max brighness, I've only used the lowest setting so far on lum data. NB will probably require it to be kicked up a notch or two in brightness. Its amazing what you can do with a bit of glue and tape  

Probably needs a bit more tape around the edges, just to make it star party friendly.

Testing the new lightbox I built tonight, it seems to produce much better flats than a monitor - runs off usb power with variable brightness, which is great 

Just applied it to some M106 data I took a last week, which I didnt post here because the background was a bit blotchy. Flats from a different source seem to have cleared this up somewhat.

As promised Michael your colour data, plus my mono from the same subject (shot on Sunday evening):

Was the colour shot with a DSLR? Feels like it becuase I had to remove quite a bit of background blotches/noise.

Lockdown astrophotograhy

About 3 hours in 4min subs with the ASI178 Cool

Quick update on my quest to collimate via a camera.

Given up on the pinhole concept for now, as I spotted a super cheap 8mm CCTV lens (cs mount) that will work with either my QHY5 or 178mm camera. I can just pop that on and collimate / tinker until im blue in the face

Well, I gave it a go....

Good news: I got an image at the right distance from the pinhole.

Bad news: The image is not yet sharp enough to use, I was testing it on a barcode. Still too blurred, for macro (what this essentially is) the hole needs to be >tiny<

7 minutes ago, Davey-T said:

No idea, seem to recall from distant school days that pinhole cameras were something like f/50 ?

Long time ago so could be talking rubbish, and not for the first time 😂

Dave

Yeah, just looking ar a few examples done with a dslr. Its possible but to improve the sharpness I need to make the hole smaller. 

I will do a few experiments when I have a spare evening this week 

Patent pending....lol