Thalestris24

22 minutes ago, Zermelo said:

How's your Russian?

http://astro-talks.ru/forum/viewtopic.php?f=32&t=865

Thanks for that  

Only as good as Google translate, I'm afraid! It doesn't tell me much more than I already know. At a glance, doesn't do any comparisons - just the review. Does give a table of physical and optical properties which is useful  But I don't think I'm much the wiser. It's from 2012 so I don't know if the 27mm eyepiece has changed in any way since then?

Oh, I might be doing some imaging through it so the flat field is important. I see the Russians quote 22.5mm eye relief rather than 23mm but it's still at least 2mm longer than the BST  .

Cheers

Louise

16 minutes ago, vlaiv said:

That highly depends on telescope you'll be using them in.

In F/5 scope - you'll clearly see the difference between high and low end eyepiece. In F/12 - there will hardly be any difference if at all.

Outer field performance is usually compared. Most eyepieces have quite decent performance in the center, but outer part of the field starts to show aberrations like astigmatism and such - which blurs things in daytime use (and distorts stars in night time).

If you are worried about lateral color - some expensive and high end eyepieces also suffer from that. It is hard to get good lateral color performance in wide field eyepieces. That is something that might show up in daytime. Best cure - stick with eyepieces up to 60° or so.

What will be intended use for this eyepiece? In those focal lengths (25-30mm) Plossl eyepieces have enough eye relief and are excellent performers. For example Vixen NPL 30mm:

https://www.firstlightoptics.com/vixen-eyepieces/vixen-npl-eyepieces.html

has 50° AFOV and 24mm of eye relief.

If you really want wider FOV and decent eye relief, maybe this one:

https://www.firstlightoptics.com/explore-scientific-eyepieces/explore-scientific-62-series-ler-eyepieces.html

26mm focal length. It is said to be very good performer and it has max field stop for 1.25" barrel size.

 

Hi Vlaiv

Um, well if I told you the prime purpose was not for an astro telescope at all, someone might kick me out!

I was looking for >20mm eye relief - which is what the BST Starguider  25 has. The latter is the only Astro EP I've had any experience of (other than SW kit EPs). The BST has some distortion towards the edge of its field but it's acceptable. Colour is also good. Eye relief is ok - as mentioned, I could do with a couple of mm extra - but only if the image quality was as good as the Starguider, so it would be pretty much a straight swap. Hence I was looking at the EF 27 which is supposed to  have the extra 3mm eye relief.

Cheers

Louise

1 hour ago, Louis D said:

Here's a review of the Smart Astronomy 27mm EF Eyepiece which I believe is the same eyepiece.  Not quite as good as the 28mm Pentax XL, but not bad at all.

Thanks for the link. Shame they didn't give a little more performance detail or post some daytime phone photos (Perhaps I ask, or hope, for too much!).   Ironic there is an advert for the Paradigms/Starguiders on the same page... Anyone on here by any  chance actually have an EF 27 ?  I'm particularly interested in the actual eye relief, and any apparent colour aberrations (though it doesn't sound like there are any).  People always say things like you can't expect the performance of a 'low end' eyepiece (or whatever) to match a high end one, though they rarely describe the practical differences!  

Thanks

Louise

ps can anyone confirm if the bottom section (the 1.25" coupling) unscrews? I assume it does - but...

1 hour ago, Don Pensack said:

Bear in mind there is a difference in apparent field, the 27mm being 53° and the 25mm being 60°.

Hi thanks, I do know that. What I don't know, and would like to find out, is whether there is any difference in quality - sharpness, colour correction, contrast.

Cheers

Louise

Hi all

I don't think I've ever posted in this forum before! I was wondering about any comparisons between the above two EPs? I'm actually thinking more in terms of daytime / bright light use  but maybe astro also. I have some experience of a BST Starguider ED 25mm and it is excellent. But the EF 28mm apparently has an extra 3mm eye relief which might make it a tad more comfortable for me (with my glasses on). All the blurb on the EF 27 says it has  'excellent colour rendition' - not sure what that actually means, but I wonder if it's as good as the ED 25mm and welcome input from anyone who has used one .

Many thanks

Louise

57 minutes ago, CedricTheBrave said:

I used this guide to create an adaptor with a M43 x 0.75 to connect a Morpheus to my DSLR T thread adaptor.

very pleased with the result

Thanks for the info

 

Cool! Have you tried the Morpheus yet? I 3D printed an adapter for a BST Starguider 25mm to use as an imaging projection eyepiece on my microscope. There is some (barrel) distortion but quite a flat field. I may try it, or get another, for eyepiece projection on my refractor  Do post any images you get with your Morpheus  (ps I usually print astro bits in black.

Louise 

1 hour ago, tala said:

I'm trying to get M54 x 0.75 thread specs

All that I've found is the internal :

<MajorDia>54.000</MajorDia>
<PitchDia>53.671</PitchDia>
<MinorDia>53.378</MinorDia>

But I don't know what is the class or if it's even correct

 

 

Hi

If you can't wait, there's a calculator here: GewindetoleranzRechner ISO-Gewinde DIN 13 (iso-gewinde.at)

I found I had to do a little trial and error on my cheapo Ender 3 Pro  I don't think you need to worry about so many decimal places for an ordinary 3D print.

Louise

One of these would have just about done you though an heq5 pro would have been much better.

Louise

Even with a motor upgrade it won't take the weight of the 150pds. In general, a mount's payload for imaging is taken as ~half the quoted max value. Without a camera and accessories, the 150pds is already too heavy for it. With motors it might be ok to mount just the camera. Even so, you won't have a computer interface hence no goto or guiding capability.

Louise

1 hour ago, ShaunyC said:

Jst been and collected a new toy..... 

£250.. bought new last Feb still has years warrenty and even the receipt.. Looks mint

Well happy... 

😁😁😁😁😁😁😁😁😁

It's a manual mount....

Louise

16 minutes ago, ShaunyC said:

OK thank you I'll l add this to my list to look out for 👍 

So regards the pds for sale do you think its too close to rrp? Take away the mount/scope discrepancies.. I want to get shooting and can upgrade later if I go full flow at the hobby 👍

Well, why buy a second hand scope that you don't know much about, for £190 when you can get a brand new one for £229 with a warranty. Makes no sense to me! Get a new 72ED from Flo! Easy to handle, easy to guide. I mean you wouldn't buy an old Transit as a runaround town vehicle for two people when a Mini or a Fiesta would serve you better! With the wrong scope/mount combo you'll be wasting your time and money! Post a question on here in a separate thread - "should I get an old 150pds and an inadequate eq3-2 for imaging, or should I get an EQ3-Pro goto and a small ed frac?"

Louise

1 minute ago, ShaunyC said:

Lol... Snap, I just responded with msg about expanding search into fracs 👍

Edit: 120 startravel in particular I think

You don't want a Startravel - you want an ED Scope for imaging - a 72ED or 80ED

Louise

41 minutes ago, ShaunyC said:

Got the chance of a 2nd hand telescope.... 150pds £190 looks like new in the box with wrapping on still.. Got the black dovetail bar tho, does that just me its an old model? 

Can also supply eq3-2 mount £120 which he says used just waiting on pictures.... 

I know its not the best combination bit heavy bit flimsy but have seen decent pictures done with same set up.... 

My main query is, is £310 for both a little bit too much considering I can wait till mid February and get a new set for £70 more? 

Should I go for it or not!?!? 

Thanks

Shaun

You can get a brand new one for £229 from FLO - with warranty! The eq3-2 isn't a motorised/goto mount. I wouldn't bother with it. For imaging, even a eq3-pro goto is a bit weak for loading it with a 150pds plus bits. I've said before you'd be much better off with a small frac on a eq3-pro, for example.

Louise

1 hour ago, ShaunyC said:

Thank you for your comments.. 

I will try longer exp next time at 70mm, didn't cross my mind to see how long I could get before start trails.. 

I'm not sure I want to divulge into updating firmware with 'magic lantern', everything so far has been a learning curve even down to how to use Windows 10 on laptop, which I'm sure should be common knowledge 😂 I have found at wilko or argos they do a male to male 3.5 jack so will try that as a adpter.. Or will have to wait for another intervalometer.. 

Regarding flats.. On the video he dosent really say what settings you should be on iso, shutter... He mentions about getting histogram up and get the sign wave to the middle, couldn't how do you do that or is there just common settings to use?I'm gone change my screen display on phone get rid of the cracks and will try the t shirt idea... 

Just had a look for dslr controllers on google play where loads to choose from is there one people generally use? 

Also I take it you have to plug a lead in... Which will require a USB to USB adapter of some sort? Or is it wireless? Canon 600d to hewawi p20 pro(still runs android) 

Next time I will also drop the iso once I've found what I want to snap.. 

Thanks you for all your help

See here: DeepSkyStacker FAQ (free.fr)

Louise

Just now, tooth_dr said:

Glad to hear it worked!  Yes they were just to help screw it in and out. 

It's very satisfying when a thread works. It's very unsatisfying when a thread doesn't work!

Louise

On 11/12/2020 at 09:40, tooth_dr said:

It has been very reliable so far which is the main thing.

The print came out pretty well.  The bottom thread against the glass printed thicker at one point which I suspose was to be expected, so I trimmed this off with a stanley knife, and it has worked well.  I'll paint it matt black later.

It reduces the opening of the lens from 64mm to 45mm, to go from F2.8 to F4.0, which I've found gives me the best overall stars with the FF camera.

 

 

 

Hi again

I meant to ask what the cylindrical protrusions are for - just to provide some grip, maybe? I printed out a 58mm x 0.75 thread part this evening  It actually worked first time - miracles do happen! It's for part of a (focus rail) microscope illumination system (a work in progress  ). Microscopes can be as good a source of diy/3d projects as can astro gear! That reminds me - I must get back to the Lowspec spectrometer that I started over a year ago! I put it to one side - never a good idea, really. It's all built but needs some tweaks and commissioning, and maybe some reprinting of parts.

Louise

8 hours ago, AlexK said:

If you describe just one, I bet I could narrow it down to the filament issue 

By the way, is there a dedicated general 3D printing thread on the forum? So we could avoid hijacking this one chit-chatting around the subject?

Most of the problems I had were to do with the bed not being level, or not staying level. I realised after a while that the y-axis was loose... Tightened that up and improved things but still had problems. Upgraded the bed springs - big improvement, but still had some stability problems. My next hopeful is to add nuts to the loose bed screws. I'll be doing that soon. I'm only using the printer occasionally. Yes, there are filament issues but they aren't the main problem. I have a new reel of pva to put on. However, it will last me about a year. I suppose I really should take the reel off and put it in a sealed bag with some silica gel after using the printer.

I think I did start a 3d printer topic about 18 months? or so ago but it was just a topic in the diy astronomer thread. I'm sure there have been others.

Louise

7 minutes ago, tooth_dr said:

It’s printing away while I’m at work now.  So far so good 

You have a posh printer!

7 hours ago, AlexK said:

Exactly. The actual problem is not the printer but the filament. Even from the same vendor the same filament type may print different between batches. Add to that the hygroscopic nature of almost every filament, which means it may print different after a day of sitting open on the spool rollers. I would recommend simply learning your particular printer quirks (Ender-3 is a good modern enough choice for tinkering at home no doubt) and test-printing each new filament you get. With experience you will know at once how to adjust your model or slicer to fix any issues (or use them to your advantage). I'm personally never expecting my prints sub-millimeter perfect, thus keeping a toolset of precision woodworking chisels,  Dremel bits, and the fine soldering work heat gun at hand.

Hi

A lot of problems I've had the printer was definitely the problem. But yes, pla filament properties change over time mainly because of its hygroscopic nature. I first got the printer about 15 months ago and more or less went straight into using it to build a spectrometer. However, I really should have got more familiar with the printer first live and learn! Since then I've only used the printer sporadically and for making small parts. Any parts involving 0.75mm pitch threads are still a challenge!

Louise

i came across this thread calculator which might be generally useful: GewindetoleranzRechner ISO-Gewinde DIN 13 (iso-gewinde.at)

here is M72 x 0.75 I plugged in:

ThreadCalculater.pdf

It gives a male thread core diameter of 71.058mm - pretty much what I thought!  

Louise

6 minutes ago, tooth_dr said:

Louise

Thanks again, I now have it sorted.  My figures were correct, and the amendments I made in purple were incorrect.  What I did in the end was edit one of the existing Fusion360 thread files and just add my thread details into the existing ISO Metric profile (it went as far as M72x1.0) so now I have M72x0.75.  Now to try printing it tomorrow.

 

All the best

Adam.

 

 

Yeah, I was looking at M72 x 1.0mm on the grounds that the tolerances should be close (enough?). Looks like the base size should be 71mm or maybe a leetle bigger. Hope it prints out ok!

Louise

ps camera filters mostly have a 0.75mm pitch so there should be a spec somewhere...

Hiya

I take it you selected 'modeled' for the external thread? You could use the inspect -> measure in fusion to check the thread measurements. Also maybe try tweaking the values including reducing the base diameter (shouldn't actually be 72, I don't think..). Does what you've printed measure correct? 

We need a mechanical engineer's help here...

Louise

28 minutes ago, tooth_dr said:

I will do that too, will be easier to find it in the menus

 

Thanks again for your help Louise.

 

Adam.

I was just thinking I wasn't sure why the labels 'external' and 'internal' are used - 'male' and 'female' would do me!

Also re: tolerances doesn't necessarily take into account your 3d printer precision/variability/stability. I generally have to have several goes on my Ender 3D Pro to get a thread that fits properly, especially with 0.75 pitch (though 1mm pitch is usually ok). So that usually involves adjusting the tolerance values - trial and error! I'm currently trying to upgrade my printer somewhat and firm up the bed. I fitted upgrade springs which helped a lot. Hopefully, once I've made the further improvements it will be a more precise and reproducible printer. If you're fortunate enough to have a better printer, it may not be such a concern. I've looked at different models e.g. the Ender 5 Pro and the CR10S, but I'm not convinced either of them would definitely be better than I already have.

Louise

2 minutes ago, tooth_dr said:

-<ThreadSize>

<Size>49.0</Size>

-<Designation>

<ThreadDesignation>M49x0.75</ThreadDesignation>

<CTD>M49x0.75</CTD>

<Pitch>0.75</Pitch>

-<Thread>

<Gender>external</Gender>

<Class>6g</Class>

<MajorDia>48.908</MajorDia>

<PitchDia>49.4349</PitchDia>

<MinorDia>48.0415</MinorDia>

</Thread>

-<Thread>

<Gender>internal</Gender>

<Class>6H</Class>

<MajorDia>49.1291</MajorDia>

<PitchDia>48.5879</PitchDia>

<MinorDia>48.2831</MinorDia>

<TapDrill>49.25</TapDrill>

</Thread>

-<Thread>

<Gender>external</Gender>

<Class>4g6g</Class>

<MajorDia>48.908</MajorDia>

<PitchDia>48.4554</PitchDia>

<MinorDia>48.062</MinorDia>

</Thread>

</Designation>

</ThreadSize>

</ThreadType>

 

@Thalestris24 I've copied and pasted your and I think I've spotted the error in mine, I've highlighted it in purple.

 

<ThreadSize>

    <Size>72</Size>

    <Designation>

      <ThreadDesignation>2 inch filter thread</ThreadDesignation>

      <CTD>2 inch filter thread</CTD>

      <Pitch>0.75</Pitch>

      <Thread>

        <Gender>external</Gender>

        <Class>6g</Class>

        <MajorDia>71.908</MajorDia>

        <PitchDia>71.4409</PitchDia> this should be 72.4409mm i think.

        <MinorDia>71.0475</MinorDia>

      </Thread>

      <Thread>

        <Gender>internal</Gender>

        <Class>6H</Class>

        <MajorDia>72.1201</MajorDia>

        <PitchDia>71.5789</PitchDia>

        <MinorDia>71.2831</MinorDia>

        <TapDrill>71.25</TapDrill>

      </Thread>

      <Thread>

        <Gender>external</Gender>

        <Class>4g6g</Class>

        <MajorDia>71.908</MajorDia>

        <PitchDia>71.4594</PitchDia>

        <MinorDia>71.066</MinorDia>

      </Thread>

    </Designation>

</ThreadSize>

You should probably change the ThreadDesignation label also

Louise

Hi

Here is an example of adding an M49 thread which worked ok  Maybe you can just compare?

Louise

M49x75_Thread.xml