Mandy D

1 minute ago, josefk said:

Check out the price of film and (if you can't do it yourself) developing and printing rather the price of kit if you want to talk yourself down 🙂

Oh, yes indeed! I used to have a darkroom, many, many yers ago, but sadly do not have the space for one today and my kit is long gone. I know how much of a dream it is, today and have no intnetions of pursuing it again, but that lovely camera did give me pause to think.

@Minhlead It's a great image, but where is the Earth?

Welcome to the 12 inch club. I got my 300PDS a couple of months ago and, so far, it has only been out once due to the terrible weather we are currently having. I'm sorry, I have no experience with the stuff you are asking about and all I can advise is to get your head around collimation, but I guess you knew that already. I've yet to use a coma corrector, but I have been advised that I will need one with my full frame camera. I've noticed that it does have better illumination across the entire field than my other scopes.

8 minutes ago, Mark2022 said:

Yes, I've recently been checking out the jet stream and the crap that came over from Canada with Storm Agnes. I lived in SE Asia for 10 years - wish I was back. They don't live under a jet stream!

You  say (as Mandy does)  that F15 is the right focal  ratio and that could be  correct but I don't have a  1.5x barlow and my best results are with the  2x. Then again, if that were  the  case,  how does the  14 year old achieve what he does with  a 3x barlow? 3.75 microns with an ASi 224 rather than  2.9 with the SVBony?

He has 3.75 μm pixels amd is at f/30 with a 6SE. He is pushing well beyond the resolution limit of his telescope. This is part of the reason his image is still not perfect. He should be at f/18.75 or thereabouts.

Just now, Mark2022 said:

Mandy, I am getting FAR more detail with the 2x barlow than what I get at prime focus F10 so I simply can't agree.

I've no doubt you are, but you will not, except, maybe, perhaps under truly exceptional seeing max out the benefits of 2x Barlow on an f/10 with 2.9 μm pixels. Physics is working against you, here. Scale your image to 75% and it will be closer to 1.5x Barlow and some of the blurriness will disappear. I doubt you have gained extra detail (byond a 1.5x Barlow) by using such a long focal length with that size pixels and that scope under the seeing you appear to have at your location. A 3x Barlow is simply going to give you a harder time focusing and controlling vibrations, etc. But, of course, this is my opinion only and you are free to go whatever way you like.

Native f/10 with 2x Barlow is effective f/20. For 2.9 μm pixels you should be running about f/15 max. With the 3x Barlow you will be at f/30. Nothing gained by doing that.

Just now, Mark2022 said:

I know this will sound odd  Mandy but I'm unsure which I prefer because with  the extra Gimp processing, I feel  it looks more and more like a coloured pencil drawing, if you see what I mean? Yes, there appears to be more "clarity" but I can achieve that with the wavelets and sharpening in Astrosurface or Registax but, again, it looks noisy and like a drawing. Compared to Kon's shots above (even with "bad seeing") it doesn't come close.

Yes, I do see what you mean and I did note that I was not doing a great job. However, I do think you are being too hard on your own image and not critical enough on your competitor's image, which I, personally, think has problems, too.

@Mark2022 I'm no expert on processing planetary images, but I think there is something odd about his processing. If you zoom in to 200%, there are rings outside of the planet and something doesn't quite look right. Your image, on the other hand, looks like it was taken under not-so-good skies in blurry old Britain, but if you push the sharpening a bit in GIMP and saturate the colours up a bit, it starts to look less blurry and less poor. I'm not saying I have done a good job, here, because I haven't but it certainly begins to look a bit more like Jupiter.

Have a look at what I did in GIMP to your image. Original on left.

4 minutes ago, pipnina said:

There is also a 3d printed medium format camera system if you wanted to only buy lenses and a film back haha.

But then, the lenses for MF cameras typically use leaf shutters which in some cases can require repair if not buying them refurbished.

I have given consideration to dropping the interchangeable lens Pi camera in one or these bodies and fitting a wide angle lens as a short telephoto for the smaller sensor, just to get the look and feel of such a camera, but it seems like sacrilege to "destroy" an iconic piece of kit like that.

Just now, pipnina said:

Depending on how much you spent on a MF camera back then, you might be disappointed at how cheap they are today if your aim is to avoid spending money haha.

If the page I saw was correct, that suggested a mamiya RB67 cost $2-3000 new in 1970, then its value has certainly plummeted as you can buy one today with a lens for about £500, less if you gamble on an ebay purchase, which might require repairs.

Yes! Thanks for that!

I also noticed that someone is doing / has done a Kickstarter for a digital back for medium format cameras with a price tag of $400. That just makes it worse! Although, I do love B&W film in medium format!

@pipnina Nice! You can watch that depth of field disappear, now! I loved shooting medium format many years ago, but it can be very challenging. I'm off to look up prices on your piece of gear now. Hopefully, that will put me off buying one.

@SkyPhil Sorry, that was all I'd got. I don't know the device you have, but hopefully, as we now have conversation going here, someone who knows more than us will see this and come along shortly with better answers.

11 minutes ago, GasGiant said:

Thank you folks.  

Im wondering if a DSLR mount will be better suited for me. Ive got an XT2 I could use.

 

Surely if the moon is nice and bright I can select a fast shutter speed, this would stop motion blur of the slow moving moon ??

 

Its all very complex 😬

It is really quite simple. You appear to be over-thinking things. A DSLR on a tripod or DSLR mounted on the focuser of a telescope via a T2 type nosepiece will enable you to take photos of the Moon and video footage. I shoot stills of the Moon at up to 2.7 metres focal length with a DSLR on my Dobsonian mounted Newt and my Skytee 2 tripod mounted RC6, with no problems and get superb results. The only thing I have to avoid is walking around when I am shooting high magnification video of the moon. I shoot at 1200 or 2400 mm FL and let the Moon float through the field of view. I determine it's direction by monitoring for a minute or so, then tilt the camera to match if I want to.

The Moon is extrmeley bright at -12.7 when full, so very fast shutter speeds can be used. At ISO-100 with a near full Moon and f/5.9 on my 8 inch, I might be using 1/400s, which is sufficient to freeze the motion. Always use a remote shutter release in Muppet (Mup) mode - this is where the camera lifts the mirror on the first press and takes the photo on the second. Wait 2 - 3 seconds after lifting the mirror to take the picture to ensure the camera is absolutely still. You can always up the ISO if shutter speeds are getting a bit long. With a 2x Barlow or focal extender, you will be down around 1/100s.

The Dobsonian mount is generally rock-steady, once locked on the azimuth and as long as you don't move around on the patio. I've shot video at 2.4 metres using my Dob and, as I said, you just keep still as any movement you make vibrates the telescope which will show in your video. You can edit out short bits of vibration quite easily in video editing software. I've cut out vans passing in front of my telescope when shooting the Sun across a road as it is setting. I never track for general lunar photography with a DSLR. I might do in the future as I go deeper, but that is sometthing to work up to. For now, I don't want the aggro and I don't think you do, either.

If your unit has an HDMI port and is running a version of Linux, connect a monitor and keyboard to it and in a terminal window type

ifconfig

It will scroll a list down the screen. Go through that list and find the IPV4 address in the form you expect.

11 hours ago, Ratlet said:

Back out again.  Managed to time it really well as io was just coming round the limb.  Started as a little wart and eventually got black between it and the planet.

Seeing was much better.  Oddly the BST's (8mm and 12mm) both performed better than the svbony 3-8mm.  Eventually settled on the 12mm with 2x Barlow.

The mobile phone adapter was very popular and we got some cracking images along with a really good video of Jupiter showing clear banding considering the setup.  

 

It just needs a bobble hat and a smiley face sticking on it!

4 minutes ago, Mr Spock said:

Concentr ic - concentr e - centr al - centr e. 'Center' is confusing for English speakers 

Definition of 'centric'

(ˈsɛntrɪk IPA Pronunciation Guide) or centrical
ADJECTIVE
1. being central or having a centre
2. relating to or originating at a nerve centre
3.  botany
a.  Also: concentric
(of vascular bundles) having one type of tissue completely surrounding the other
b. (of leaves, such as those of the onion) cylindrical

However, getting people to use English correctly is a pointless exercise, so I quit  

I have tagged FLO in an earlier post, in the hope that they can help fellow astronomers by also including the (more) British-English spelling in their website. As you know, this caused me problems when trying to follow your advice, but we have now resolved that.

Thank you. I am ordering the device from Flo.

17 minutes ago, Ricochet said:

I don’t think the name is derived from centre, but from concentric, with a standard -er suffix, as in a tool that makes the mirrors appear concentric, so Concenter is correct. Additionally, as it is a name, the spelling given by the manufacturer is correct in all countries. I certainly don’t change the spelling of my name if I cross the border from one country to another. 

It matters very little how the word was derived. The discussion came about because @Mr Spock gave me advice on collimating my telescope earlier in this thread and used the spelling concentre, which most of us assumed to be correct, because it is only logical that we Brits would spell such a word this way. Unfortunately, this caused significant confusion until someone else posted a link and the problem became apparent. It is not about what you or the manufacturer think is the correct spelling, it is about potential customers finding the desired product.

Yes, the manufacturer has the right to spell product names however they wish, but that does not automatically make it good practice or wise. You suggest that you would not change the spelling of your name when in a foreign country, but if your name were (let's say) Richard, the French would almost certainly spell it Ricard and, to your ears, mispronounce it. An even more extreme example is a certain diminutive of Amanda, rather than Mandy, which is Manda, but if that were your given name you might not want to use it in Russia! 🤣

@Captain Scarlet Thank you for linking me to this. It is going to be most useful. How is the rebuild of the OOUK 200mm coming along?

32 minutes ago, bosun21 said:

There’s 4 in stock at FLO 👍.

Yes, thank you. I already know this and am in the process of orerding one from them.. If you go back through the posts and also read the text in your screenshot you can spot where I, a Brit, was having difficulty. The product name has been Americanised and is probably something that @FLO should attend to if they wish to sell more of these things. The correct spelling, at least in the UK, is centre.

29 minutes ago, wimvb said:

Image quality-wise it can compete with telescopes that are in an entirely different price range. But I agree with you on the weight. I wouldn’t want to lift it every imaging night. If you can have it on a permanent site, I would absolutely recommend it. Otoh, the MN190 probably isn’t heavier than a 150mm APO. 😁

Skywatcher 150 ED APO Triplet: 14.52 kg

Skywatcher MN 190 OTA: 12.5 kg

That is going to do nothing. Your focuser intrudes more than that when it is wound fully inwards.

Fill the screw recesses with petroleum jelly. That will keep water out and is easy to remove.

@Captain Scarlet Yes, I guess you can, but I don't bother with flats for the Moon and the human eye does an amazing job of dealing with all sorts of optical problems. Whatever the case, if we have everything correct at the scope and camera levels, it is one thing less to worry about.

@Captain Scarlet Thank you. Yes, I understand the arrangement of the elements that should be achieved by perfect collimation. It is perfectly logical. Your description of the laser proces confirms this in my mind. I completely agree that the location of the secondary in space does not affect this element of collimation and now I understand the effect it has on the resultant image, thank you. So, for visual use the centring is not as important as for photographic, because for the latter an even illumination is of paramount importance.

Of course, due to perspective (the far edge being more distant) the secondary should not actually appear circular, but distorted by that perspective. But, as you note the shape is not terribly important and we could use a rectangular mirror here as long as it, at least, covers the section of the light cone at this interface. I think I have a much clearer understanding of what is going on from a practical point of view, now.

22 minutes ago, Space Hopper said:

You mean this.......?

https://www.firstlightoptics.com/other-collimation-tools/ts-concenter-2-adjustment-eyepiece-for-newtonian-telescopes.html

It appears @Mr Spock and myself are both British! I had not thought of using the American spelling for centre (AKA center).

Thank you!