Jump to content

sgl_imaging_challenge_banner_31.thumb.jpg.b7a41d6a0fa4e315f57ea3e240acf140.jpg

Altair Lightwave 0.8x reducer with Evostar 80ED (& Equinox)


Recommended Posts

Altair Astro has an inexpensive 0.8x reducer for refractors, but I had never seen any actual results with it, at least not with my SkyWatcher refractors (Evostar 80ED and Equinox 80ED), so I thought I'd get one and see. Turns out it works well with the Evostar, even giving you some advantages over the expensive matched 0.85x reducer, and it is not bad even at the corners of an APS-C sensor:

EvAltComp.jpg

So people who can't afford the SW 0.85x should perhaps consider it.

It wasn't such a good match for the Equinox unfortunately. For more details and comparison with the TeleVue TRF-2008, you can read my blog post.

  • Like 2
Link to post
Share on other sites
3 hours ago, ecuador said:

Altair Astro has an inexpensive 0.8x reducer for refractors, but I had never seen any actual results with it, at least not with my SkyWatcher refractors (Evostar 80ED and Equinox 80ED),

 

 

Totally agree with your thoughts :) here's my review of the Altiar 0.8 with the ED80 from a few years back, I'm a big advocate of them :)

http://www.insideastronomy.com/index.php?/topic/530-altair-lightwave-08-reducer-mini-review/

Edited by Chris Lock
  • Like 1
Link to post
Share on other sites
2 hours ago, Chris Lock said:

Totally agree with your thoughts :) here's my review of the Altiar 0.8 with the ED80 from a few years back, I'm a big advocate of them :)

http://www.insideastronomy.com/index.php?/topic/530-altair-lightwave-08-reducer-mini-review/

Ah, nice. I didn't come across your review because I was searching for results with the Equinox, for which I really wanted it. But, yeah, we agree on the Evostar, great bargain this reducer ;) 

  • Like 1
Link to post
Share on other sites
5 hours ago, ecuador said:

Ah, nice. I didn't come across your review because I was searching for results with the Equinox, for which I really wanted it. But, yeah, we agree on the Evostar, great bargain this reducer ;) 

Yeah I think the Equinox at f6 is a bit fast for it, but It definitely did the trick with the Equinox ED120 I had @f/7.5.

 I've been meaning to pick another up for my ED100 f/9 which already has a fairly flat field but could do with speeding up a bit for when I fancy taking some pics. It will be interesting to see how they do with this scope.

The 0.6 also works very well with RC scope by the way :)

Link to post
Share on other sites
3 hours ago, Glimpse111 said:

So what works best for Equinox 80 ?

The TRF-2008 works reasonably well for such a curved field (I have images in that blog post), but if you can find something better or cheaper do tell! ;)

  • Like 1
Link to post
Share on other sites
5 hours ago, Chris Lock said:

Yeah I think the Equinox at f6 is a bit fast for it, but It definitely did the trick with the Equinox ED120 I had @f/7.5.

 I've been meaning to pick another up for my ED100 f/9 which already has a fairly flat field but could do with speeding up a bit for when I fancy taking some pics. It will be interesting to see how they do with this scope.

The 0.6 also works very well with RC scope by the way :)

Do you know how well matched the 0.6 is with the ED100 f/9? The FoV would then be similar to ED80 with the matched 0.85x reducer, but faster.

ED80 with 0.85x = 510mm FL, f/6.375

ED100 with 0.6x = 540mm FL, f/5.4

Link to post
Share on other sites
6 hours ago, Bagnaj97 said:

Do you know how well matched the 0.6 is with the ED100 f/9? The FoV would then be similar to ED80 with the matched 0.85x reducer, but faster.

ED80 with 0.85x = 510mm FL, f/6.375

ED100 with 0.6x = 540mm FL, f/5.4

I haven't tried the 0.6x personally, but from what I read, if you have a largish sensor like a crop DSLR, then the vignetting will be severe. Also I wouldn't expect a sharp field far from the center. For small sensors though it might work.

Link to post
Share on other sites
7 hours ago, iwols said:

daft question but do these improved speeds have the same effect with the dedicated  atik ccd cameras

The faster F ratio would effect any image capturing medium, film / digital

If you were taking photos of a given exposure time of say 6 minutes with a F7.5

with a quicker system, say f6.25 you would get roughly the same image brightness

with 5 minutes, at f5 four minutes ,  these are only rough estimates for the explanation

and not actual figures.

 

Link to post
Share on other sites
2 hours ago, ultranova said:

The faster F ratio would effect any image capturing medium, film / digital

If you were taking photos of a given exposure time of say 6 minutes with a F7.5

with a quicker system, say f6.25 you would get roughly the same image brightness

with 5 minutes, at f5 four minutes ,  these are only rough estimates for the explanation

and not actual figures.

 

Actually the f-ratio is logarithmic. In your example, if you need a 6 minute exposure at f/7.5 for a specific signal/pixel value, you only need 4.16 minutes at f/6.25, or, if you use the 0.8x reducer to go to f/6, just 3.84 minutes. You get the same light concentrated on a smaller, so more signal/pixel, less object size in pixels. 

Oh, and f/5 would be 2.66 minutes - f/5 is more than twice as fast as f/7.5 ;)

Edited by ecuador
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By cwinstone
      Hello, does anyone know if my imaging train looks correct, and if it does, why am i still getting these coma errors?
      Could it be incorrect backfocus? Searching the internet makes me think my dslr is 44mm, adding the t ring (even tried a 1mm spacer too) gets me to the required 55mm (assuming that's correct)
      I have no idea how to solve this and i feel like I'm just throwing money down the drain fighting this in vien. Help would be much appreciated.
      Skywacher Evostar 72ed
      Reducer rotator for 72ed (needs this for extra distance to achieve focus, the reducer and adapter alone doesn't allow for enough outwards travel)
      Reducer/corrector for ed72
      Canon eos 650d


    • By SStanford
      Hi all,
      With the ongoing stock shortage it's going to be sometime before I get my hands on my desired scope for my ideal setup.
      I'd like to make the most of my current scope until stocks replenish and so I have a few questions about Flatteners and Reducers.
      I currently have a Celestron Inspire 100az (details here), a Canon 450D and a EQ3 Pro (synscan).
      As I understand, the 660mm focal length makes the scopes FOV too narrow for a mount such as the EQ3. Am I able to add a reducer to bring the focal length down to a level that would be suitable for this mount?
      If so, can someone provide some guidance as to which reducer would be the right choice?
      This brings me onto my next problem; I can achieve focus with my Canon 450D DSLR in the Celestron 100AZ but by only using the supplied diagonal (here) and my 2x Barlow (here).        
      I have tried using the 68mm extension tube that came with the T-ring and adaptor (here), inserting this directly into the scope but cannot achieve focus at all. In addition to a reducer, what else do i need to add to the OTA to get focussed?
      S.
    • By Gwil
      Hi Everyone,
      I've just bought a Skywatcher Evostar 72ed but can't get hold of the sky-watcher .85x reducer/flattener or the OVL versions in these current times.
      Can anyone suggest any alternatives to the above?
      Many thanks 
      John (UK)
       
    • By Rchurt
      Hello,
       
      I recently purchased my first telescope and camera, and now I want to make sure I have the correct Barlow or reducer to couple them together to achieve Nyquist sampling on the camera (or slight over-sampling). In case it’s important, I’m interested in planetary imaging—in theory that shouldn’t matter for this sampling question, but maybe there are other considerations to take into account.
       
      I used this calculator (https://astronomy.tools/calculators/ccd_suitability) and plugged in my info:
      Telescope: Celestron 8 SE
      Camera: ZWO ASI462MC
      Seeing: experimented with this one, but would like to get optics that allow for poor or very poor
      Binning: prefer 1x1 to preserve spatial resolution, but could consider higher if SNR is a problem
       
      I’ve seen on several forum posts that people often use a 2x Barlow to couple the two. However, according to this calculator, that will always lead to over-sampling. If anything, it says I should use no intermediate optics or even a reducer.
       
      So my questions are:
       
      Binning: Will I be able to see anything with 1x1 binning, or should I expect to need to bin to collect enough light?
       
      Is there some other consideration that’s more important here than achieving correct sampling? It seems like most others are over-sampling, and perhaps there’s a good reason for this. If so, is there another formula that would let me determine the appropriate optics to buy?
       
      Thanks in advance for any help!
    • By AstroRuz
      Used Altair Lightwave flattener, 0.8x Works well with f5.5-f8 refractors. Bit of marring as expected on the nosecone but optics in A1 condition. Includes postage £50



×
×
  • 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.