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Posts posted by Uranium235

  1. 5 minutes ago, Davey-T said:

    And 14mm f2.8.



    That looks almost identical! :) You will notice that the three screws are not quite 120 degrees apart - one of them is offset by about 10deg, same as the 135mm.

    What it looks like is that the rear end of all the MF canon fit lenses are the same construction, just with different optics upfront (makes sense to keep production costs down).

  2. More on spacing... You can see the M48-T2 adaptor (plus delrin spacer) im using is roughly 8.5mm, and the distance from the camera T2 plate to the sensor is a whopping 35.5mm.



    Both add up to the magic number of 44mm, when setting up your spacings, dont forget to add distance when using filters.


    Astronomk: +0.33mm (may not need to bother)

    Badder: +0.66

    Astrodon: +1mm

    It might not seems much, but 1mm can put you well short of infinity focus. The camera im using has a mixture of Astrodon and Baader filters - slighly more complicated :D

  3. Okey doke, back in front of a proper keyboard now: :)

    As for the question of other lenses in the Samyang range, I have to stress that this mod is for manual lenses only - as the electronics invoved with an AF lens would simply get in the way.

    Now, looking a the bayonet for the 85mm Sammy - it looks like the mounting is suspiciously similar to the 135


    I suspect the 50 and 35mm manual lenses would follow suit. So if you already have one of those in your box then there may be a good chance it would work.

  4. 6 hours ago, Adam J said:

    I asked Uranium about this several months back and he said it was in the pipeline so glad to see this. The samyang 135mm is one possibility for my coming mobile setup. 

    I wonder if there is room for a filter draw and a filter adaptor...

    Great Idea. 

    More than enough room, you can use a standard thickness filter wheel which is usually about 21mm and still have room left for whatever adaptor and extension rings you need.

    Always better to space it just short to start, then add a delrin spacer or two in order to get it focusing as close to infinity as possible.

    I'm chuffed that one of my ideas actually turned out to be useful 😄

    I'm out working at the mo, but I'll fill in with more info when I get home. 

    • Like 1

  5. Its been a while, what with work, Christmas, and endless cloud getting in the way of things. But I've gotten a few images out of the modified lens now :)

    The only downside, this particular lens is not quite on par with the two Ive had previously - so Ive had to stop it down a bit. The following images are all fairly short runs, just over an hour for each, and absolutely no calibration:




    • Like 13

  6. 29 minutes ago, spikkyboy said:

    hi Matt, i have looked at the Samyang 135mm lens. around £400. I then found a zoom lens 50mm to 200mm. so will that give similar results to the 135mm or am i missing something? I know the sayang has superior umc coatings but wonder if the focal length is the main thing here? thanks.

    You very seldom get a flat field with a zoom lens, questionable levels of CA too. 

    Fixed, prime lenses are always better. 

    • Like 1

  7. 1 hour ago, Fieldsy said:

    I've looked at the compression ring but that seems out of stock , I've been told a twist lock is more secure but requires a extra 10mm in focus which I'm down to a few mm left and already poking into tube.

    Compression rings are a waste of time/money, and the clicklock eats up far too much backspace for it to be of any use to the imager.

    Two best ways are either screw fit, or three screws with a dovetailed 2"-T2 adaptor.

  8. 9 hours ago, 8472 said:

    Are there any owner's who know if the OTA will cover a full frame sensor without vignetting, coma and the like?


    Vignetting is pretty much unavoidable with the 130 (or pretty much every other telescope to some degree), depending on the size of the sensor. 

    Same goes for coma.... BUT .... that is what flats and coma correctors are for :D

    I got the KAF8300 sensor working with the 130, but only after a few modifications to the telescope. But if youre talking about full frame as in 35mm....lol.. no chance. There are very few astrographs that can cope with that (and the ones that do cost a mint).

  9. Things just got serious:


    Not sure how its going to cope @f2 as the QSI has 1.25" filters, wont know until I try it I guess.... but I've found the camera has a photo screw hole on the case, so ive just bolted it directly to the dovetail bar. The lens mod takes care of everything else, no need for further support :)  


    Actually, I can test the illumination/vignetting later tonight - I'll just set the lens to infinity and take a few flats, that should tell me roughly whats what.

    • Like 6

  10. 2 hours ago, StamosP said:

    During last month i tried to find a solution to modify the bayonette to a t2 male thread (i have a few ideas) but today i saw Rob's (i remember you from the legendary 130pds thread!) solution, very good indeed.

    Any info about this?

    Im just waiting for the dust to settle being as the SGL star party was cancelled. Then I'll ask FLO about getting a small production run sorted., maybe just kick off with 10 and see how we get on.

    • Like 1

  11. Oh ... no... I was hoping that this would be my only break in the run up to xmas :(  gutted....  Oh well, cant be helped I suppose!

    Safety first, even if it was open I suspect a number of the roads will be impassable as well - Ive already had a couple of dodgy moments on country roads here in Worcestershire, I waited for someone else to try and drive through the flooded bits first before trying (very carefully) with my little car 

    • Like 1
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