Jump to content

Narrowband

lensman57

Members
  • Posts

    4,234
  • Joined

  • Last visited

  • Days Won

    1

Posts posted by lensman57

  1. On 22/09/2019 at 21:30, Dave_D said:

    2nd print since i got the Mars... i wouldn't even know where to begin doing this on a FDM printer...

    still needs cleaning up and gluing once the tail is finished, but dayum...

    10" long (5 parts of the model done so far, 1 to go) cost about £3.50 in resin

     

    DSC_0098.JPG

    DSC_0099.JPG

    I have done this on my I3-M . Very difficult print for a FDM . A lot of delicate supports needed and the temp has to be spot on for the bridges and overhangs. Your result is very very smooth and nice. Well done.

  2. Just be careful with handling of the resin. These guys do print with incredible resolution and smoothness but I am not sure how permanent the prints are. Like the PLA that is beautiful to print but has no real use in the real world due to lack of strength.

  3. On 08/09/2019 at 09:27, mark81 said:

    Nice report there. I've often looked at the 80mm Opticrons as the 70mm were also great for the money.

    Was that session with a tripod or handheld.....or both. 

    I'd also be interested in how you get on with the 12x50s. I was close to getting a pair of 8x30 Pentax recently....

    Mark

    Sorry for the late reply. The binos were securely mounted on top of my Gitzo Studex ( a relic from my more serious photographic past ) and a Manfroto gearhead . LOL, the center pillar for the Gitzo alone costs 3x as much as the Opticrons. 

    • Like 1
  4. Well, last Saturday night the clouds broke around 8 pm and I managed to get the 20X80s out. Jupiter was the first target. Quite low now and just over the neighbors roof. The disc was lovely and six moons visible. The four Galilean ones in a straight line, two on each side with Jupiter  like a diamond in the middle and two others, one at 12 O'clock and the other at 7. It was a beautiful sight. Later on as my pupils fully dilated I could just make out the impression of a dark band north of the equator. I was in heaven.   I then turned to Mizar and the double with Alcor was nice but tonight a miracle happened. The Opticron managed to split the Mizar A and B with clear black space between them. I first thought that the moisture in the air was playing havoc with seeing as Mizar itself looked quite spiky but I just touched the focus, adjusted my eyes and there it was Mizar B. Dimmer than Mizar for sure but still bright. Andromeda Galaxy was the next target and it was easy to find it. A bight core, like a star, surrounded by ever decreasing in intensity of a nebula like cloud. As the last target I swung for M81. Very difficult to find even with a star map. I managed to see something with averted vision but I think for this one true dark sky and no LP is required. So far I have had two short sessions with the Opticron and I am very impressed with it. Considering the price I rate it as outstanding. It is by no means perfect but for what I paid for it from FLO it is punching well above its weight. I only wish that this new menace that is unnecessary security lighting around my house would go away. It has become a fashion to light up ones back garden as a football ground. One of the main reasons why I stopped deep sky imaging. Now I have a pair of Pentax 12x50 from FLO on the way, for wide viewing, and I ust pray that someone would turn those damned lights off.

    • Like 2
  5. I used to do deep sky imaging a few years back. My last image of M31 was in 2015. Increasing light pollution, increasingly bad weather, change of circumstances etc caused me to stop. A few weeks ago I took my 8X32 binos out for a change and enjoyed the wide field view of the sky. I decided to buy a new large bino. Today the Opticron Oregon 20X80 from FLO arrived. Guess what , the forecast for the weekend and most of next week is rain, strong wind and clouds. Manchester weather, luvely isn't it?

     

    A.G

  6. Thanks AG.  I have my dither set to 5, so I would assume that would be classed as extreme.  I usually set the delay to 5 seconds but may now increase that to 45s for the guiding to settle down??  I am not too sure of the theoretical resolution limit of my scope and camera combi though, Explore Scientific 102mm 714 FL APO and Canon 650D. 

    I believe the pixel dimension is about 3.2micron so at 714mm of FL you'd be imaging at approximately 0.9 arcsec/pixel, this itself is a slight oversampling and well over the UK seeing which restricts imaging to about 2 arcsec/pixel, however even if you do not get any benefit from drizzling on the resolution front it will do wonders for noise reduction and with a robust Sigma clipping algorithm during stacking a lot of the nasties will be removed. The ES 102 is a fine scope BTW.

    Regards,

    A.G

    • Like 1
  7. Thanks AG.  You say that the effective use of drizzle is subject to certain conditions re scale and subs.  What are those conditions so I know if they can be met or not?  Is it not right that If I am dithering my subs that I need to drizzle??

    As it was mentioned earlier effective drizzle is mandatory. Set the guide software to extreme dither ( you need this for a DSLR ) and give it a long settle time before exposure begins so the guiding settles to the normal rhythm. If the pixel sixes of your sensor are on the small size the drizzle may not be as effective as you are probably reaching the theoretical resolution limit of your scope and camera combination. The number of the subs need to be rather large, I 'd say upwards of 30 . In theory a minimum of 4 subs should be enough if the dithering could be absolutely repeatable from sub to sub  but this is beyond the mechanics of most hobby or even pro equipment, I believe Hubble space telescope is capable of doing this but I would not go to court with this one. In practical terms set your dithering to extreme and go for many subs as you could get. Hope this helps.

    Regards,

    A.G

    • Like 1
  8. I use an 18mp Canon 650D DSLR for my imaging and stack images using DSS.

    I have no issues stacking my images in DSS usually.  However, recently I have tried to stack using the x2 and x3 drizzle function.  DSS takes a while longer to process with these drizzle options and stacks all of my subs.  However, when the program moves to autosave the stacked result, DSS shows a yellow exclamation mark in a triangle and goes no further.  It gives no error message.

    Has anyone else had this issue and how did you resolve it?   Is the18mega pixel image too much for DSS to stack in drizzle mode?

    Hope you guys can help, thanks

    Julian

    DSS is still a 32 bit software and therefore its use of memory is rather limited. It was never really designed to handle huge DSLR file sizes so if the size of the file to drizzle is huge it will hang. The effective use of drizzle is also subject to certain conditions with regards to the scale and the number of subs. If these conditions are not met it only acts as a very laborious and inefficient resampling algorithm rather than fulfilling its function to recover detail in which case  one is better off using PS or other resampling software. If you have to use drizzle in DSS for whatever reason on a very large DSLR files then try and draw a ROI rectangle around the target ( the red rectangle  lines in the DSS ) and may just work.

    A.G

    • Like 1
  9. Hiya

    Ok. Yeah a budget essentials version maybe a tested reject or something... But still, might be worth going for. Nice to live near a showroom. You must have quite a collection of scopes now! The Ascension 80 looks nice on the Opticstar page, if a bit too expensive for me...

    Thanks

    Louise

    Hi Louise,

    The Opticsttar 80 ED doublet is a reasonable price and seems to have the same spec as the Equinox 80 but you do get the tube rings and bits and pieces with it. One of the members has one I think he goes by the name  Leemanley, perhaps you could drop him a line for info. The show room BTW will be closing shortly as they have taken over the distribution of the Meade telescopes so they have a bit of reorganising to do so it will be internet ordering for a while. I really do need to make better use of the ZS71 come to think of it.

    A.G

  10. Hiya

    Oh dear, I'm 'cross-threading' myself here... Started a separate one asking about the TS APO 90mm...  As mentioned at various places, I need something I can attach a filter wheel and dslr to... This is a headache with most flatteners/reducers.

    The TA APO 90 / Revelation has the advantage of being useable for imaging without a reducer though still needs a flattener of course. The Zenithstar 71 is also fast enough for doing that but is a little short. Still, I'll put it on the list! Do you still have the Ascension 80? I saw a couple of images you did with it - looked fine to me!

    Thanks

    Louise

    Hi Louise,

    Yes I still have the Ascension. It is really a great scope and with a 314L does not really need a flattner. I use a Televue TRF 2008 with it for anything larger. I live just down the road from OpticStar show room so I kind of hand picked it. It also came with a proper test certificate. It is no TAK FSQ but I am very happy with it for the price. The Explore Scientific ones are mainly the same scope but barebone wether they bother testing these before shipping is another matter.

    Regards,

    A.G

  11. Hi

    It's a little short and only has 35mm focuser travel and seems a bit 'non-standard'? It's a bit pricey... The Equinox is a bit pricey as well really, especially, as you say, with the flattener (+£170). Sigh. I've been pointed in the direction of the Explore Scientific triplet ED 80 Essential which is less than £500 incl shipping and has good reviews. There must be a crossover where there's a point that it doesn't make economical sense to pay more for a scope that's to be used with a dslr... The intention is to image with narrowband as I already have the filters but osc and LRGB are still an additional option. I might find that I have less lp looking to the west, away from the city, in which case non-narrowband would be much better than I get from my living room! It's like a lot of things - don't know until I try! I might simply postpone getting another scope and simply try out with my ST-80. It's pretty rubbish for imaging but will give me an idea what al fresco imaging would be like and the kind of images I could get looking West. More deep thought. Anyway, I still have to get a laptop and some other bits first... It all adds up!

    Thanks

    Louise

    Hi Louise,

    If u think that you'd be doing mostly Ha due to the LP then you may also consider the WO zenitstar 71, with the dedicated FF/FR it works out about £470.00 which is lot cheaper than the Star 71 and equinox 80, it is very small and light but  with the caveat that some samples are not so well corrected from some of the early reports. Mine seems to be fine and it had a very good review in the Sky at Night mag a while back. The ED 80 is fine but it is slow and it does need the 0.85 FF/FR which still makes a F6.4 scope @510mm of FL.

    A.G

    • Like 1
  12. The present specification say 102mm f/7 so not particularily an imaging scope. ES also says visula/imaging in equal amounts in the application summary.

    They all seem to have a 2" focuser and 2 draw tubes as standard.

    I cannot see a reason for so short a travel length, still think that an email or call to ES would be useful.

    Being honest they are a refractor I have looked at and would like to know the situation.

    If I go the the Astro show here in June I will certainly be taking a close look at them - curious now.

    Mine comes to focus with the diagonal with no problem, although I do not do much visual, so perhaps as you have suggested the OP should contact ES.

    A.G

  13. Forgive me - I was raised in SCT land where backfocus is something that is taken for granted...

    So I got my first refractor - a 102mm f6. I love the views, but I didn't realize how much fiddling around I have to do to get different EPs to come to focus. I put in a short focal length EP - I have to put in an extension tube to bring it to focus. I switch to a long focal length plossl - I have to take out the extension tube. I use this same EP with a 1.25 prism diagonal to control scatter, I have to put the extension tube back in. The scope actually came with two extensions tubes...

    Is this something I just have to expect to deal with when using most refractors, or are some refractors more prone to this than others? I don't see this kind of thing usually discussed in product descriptions, but if one scope said "can reach focus for most eyepieces without having to use extension tubes", I would consider that a huge plus... 

    Hi,

    This one is an Astrograph and a very good one at that, the short focus travel is to ensure that the combined weight of the CCD, the FW and the FF/FR  does not cause the focuser tube to sag or deflect under gravity. Short of using extension tubes the only other thing you can do is changing the focuser to a Feathertouch or something similar but would be expensive.

    Regards,

    A.G

  14. I think the open bottom design with these telescopes is to aid cooling, but with CCD imaging being more demanding and the likelyhood that you are chasing very dim targets means that the gradients caused by this design come into play when youre trying to sort out your nebulosity from your gradient(s).

    Good luck with the Quattro, it would be interesting to see whether you get a flat field out of the box (or with minumum tweaking).

    Thank you, as you mentioned the gradients started showing up once I got into the 1200s sub imaging. Hope this quattro fares better than the 150PDS, atleast the focuser seems to have been beefed up.

    Regards,

    A.G

  15. Ive been covering up my bottom (of the newt!) ever since I had the 130 (and the 150 previously). If you have enough ambient light at your imaging location, it will leak in through the bottom of the tube and give you a gradient. It seems all the PDS range have this "open bottom" design, but its easy enough to make a cover. A bit of circular card with notches cut out for access to the collimation screws, and just held on with a bit of tape - took all of 2min to make, saves much hassle.

    Edit: Same applies if you have a manual filter wheel - make a cover for it, or a drawstring bag.

    Thanks for your practical advice, the bottom cover is already prepared and yes while I was using a manual filter wheel I had the same problem and used to wrapp it up but nowadays I use an automated filter wheel so at least that side of the equation is covered. I am just a bit surprised that a range of scopes promoted and optimised for imaging should sufffer from light leaks where a simple plastic cover from the manufaturer would have helped to avoid all these problems. Now I have a Quattro 8s and the real fun begins.

    Regards,

    A.G

  16. Are you sure it's not light leaking through the viewfinder on the camera , it's a more common problem.

    There's a cover for it on the camera strap.

    It is not the viewfinder for sure, I was using an Atik428EX. I am now looking at the focuser too. I image from my back garden with street lights and the neighbours security lights causing havoc, so any llight leaks will show up on all the subs. I have wrapped the mirror end up with a black bin bag folded twice but it is an ungainly sight.

    A.G

  17. Hi,

    Just in case anyone is imaging using a 150PDS or anyother SW NEWT, I had noticed some strange gradients on my captures that I could not easily get rid of. I traced this to the light leaks from the rear mirror cell of the 150PDS and I am sure of this. One evening while leaving the camera to take darks indoors,  the background value of the darks showed an increasing level as the early hours of mornning  approached and the sky got lighter, now I have resorted to wrapping a black binbag around the rear of the scope untill a more satisfactory solution could be found. I may take the cell out and have a look at this at some stage. If this is a design fault then with regret these scopes are not fit for purpose but it is a little too late to do anything about this.

    Regards,

    A.G

  18. I only have a 70D DSLR at the moment, but I have managed to remove the IR filter on my old ESO 30D. I've read about CCDs, but wanted to wait until I had taken photos with the DSLR before I upgraded to something better.

    As for targets, I'd like to photograph galaxies, as there's something special about seeing pictures of them, but I also know that I tend to get carried away once I start something.

    Hi,

    If your imaging love is the Glaxies then to image these well you'd have to go deep and for this you need long FL, the popular choice is the SCTs with a 0.63 FF/FR to bring them to about F6.3 so for an 8" you'd be at about 50" of FL,  with the exception of M31 and M33 the rest of theses beauties are far too small to be imaged with short FL 80mm fracs. Something that you have to be aware of.

    A.G

  19. I am a bit of a pedant and have a habit of micro-analysing things I do to a level that is beyond the comprehension of my wife and family, which has meant that I've spent far too long on Google looking at options for novice to astrophotography (yes, I've got and read 'that' book). I recognise that the mount is the most important piece for imagery and I'm probably going to get a HEQ5; however,  I am still looking at suitable telescopes and would be grateful if someone could clarify whether it is worth spending a bit extra on a triplet. It is a bit extra to get a WO GT-81 or a SW Esprit 80ED over a , but as I'll be buying a mount, guide scope and a plethora of other items in the coming months, it isn't an excessive increase on the total cost. On the assumption that I'll continue with the hobby, and get carried away with it, is the triplet worth purchasing or a doublet?

    Regardless of the type of glass used, fast doublets and triplets have more CA than a scope of similar design and aperture but with a slower F ratio. It is not appropriate to compare these to each other. A good triplet will almost always outperform a doublet of the same aperture and F ratio. Televeue, Takahashi and a couple of other none mass produced brands have a reputation for quality and optical performance at a price of course.

    Regards,

    A.G

  20. For what it is worth (bearing in mind my newb status) - my experiences in using one.

    I was quite clear that I wanted decent RACI finderscope for my 6" reflector and I was quite impressed with it when it arrived - beautiful piece of kit!

    My problem was with focusing of the supplied 23mm eyepiece. It has a ring for focusing of the reticule and I have found that when reticule was sharp I was running out of focus range in the main helical focuser.

    It was OK when I tried it in daylight on distant objects, but at night when trying to focus at infinity the focuser was "bottoming out" and running out of adjustment.

    Altair Astro very quickly provided another eypiece to compare (thank you for great customer service!!), but I have found that there was no real difference between the two eyepieces.

    I could use/easily focus supplied 23mm illuminated eyepieces providing reticule was out of focus.

    I could easily use other 1.25" eyepieces with no problems in focusing.

    It seems to me that the scope tube would benefit from being shorter by a couple of mm.

    It maybe that it is as it is because of all the other options available for this scope (for use as a guide scope etc).

    Other thing that I have discovered was that for visual use (and that is what I do) 23mm eypiece giving x10 magnification was possibly not the best one. OK it is aimed at "...astro-imagers who want to centre an object more precisely in the camera field-of-view, yet the field of view is still very large...", but I found it was far better for my type of use with 32mm eyepiece (unfortunately not illuminated, but this may be another DIY project).

    I would love to hear opinions of other users, please.

    Hi,

    Sorry to hear you have such problems. I  bought a used one from a member of the forum  ( it is in mint condition )  a couple of weeks ago and I don't have your issues, but I found that once the illuminator was attached to the EP the resistance of the focuser on the supplied diagonal was not enough to keep the EP from rotating the focuser and it constantly goes out of focus. I may take the focuser out and apply much thicker grease to the barrel to resolve this annoying problem.  The other problem is that my finder guider came with a helical focuser for attaching a guide camera, the helical focuser is not a None Rotating type therefore as he focuser turns so does the guide camera and therefore the FOV, not a big problem but is shows that some corners have been cut to keep the cost down.

    Regards,

    A.G

  21. I have spent a few nights out withthe Synguider and I just cantget it working right. Perhaps someone on here has the answer for me :)

    I have a HEQ5 Pro, 80ED with a Canon 1000D. Stratravel 80 with a Synguider.

    The Synguider is focused correctly, lined up so that the hand control moves the star in line with one of the axis, I lock on a star, do Autocal, and as soon as it starts guiding, the star just flies off the bottom of the screen. Time and time again.

    I even halved the RA/DEC aggressiveness, as has been suggested in a number of threads, bu to no avail.

    HEQ5 is set to 0.5x for guiding.

    Has anyone had a fix for this, as I have seen a few others with the same issue.

    I gave up in frustration,and just did a pile of 2 min subs on Polar Alignment.

    Help!!!

    Thanks.

    Hi,

    If you  have managed 2 minutes subs unguided then your polar alignment is very good so there are no issues there, if the star is probably locked and there is drift then the most likely cause is differential flexure in your guide set up, have a good look at the way the guide scope is mounted and examine the integrity of the tube rings and the set up including the rubbish draw tube and the focuser mechanism of the ST80, the wiring loom, and the way the SynGuider is coupled to the focuser. It maynot be the answer in your but in most cases of bad guiding is the most likely cause.

    A.G

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.