12 replies to this topic

[Eric Seavey]

Anyone know anything about the DayStar Filters 0.5x Imaging Focal Reducer? Has anyone used this for DSO?  Is this only good for solar imaging?

 

Thanks

[arkosg]

I’d have the same question!  Anyone try this on an SCT for DSO imaging, in particular?

 

Greg

[fabrizio76]

Hi all, late but finally somebody tried: me.

The purpose was to make a "cheap" but powerful astrograph. So I started from a 200 mm Newton in f4, plugged the daystar reducer to get down to f2, put it on a EXOS2 mount and imaged with an ASI183mc camera.

 

The 183 chip isn'd huge ($$$) so, the most comatose stars at the edges are not in the field of view. Where it matters, the image is not so bad. You barely need guiding cause it is a light bucket and you get lots of details. 

 

The daystar gives more reduction that other reducers/correctors of Newtons at half the price and unless you have a large chip sensor, you will be kind of fine with it.

[calypsob]

Hi all, late but finally somebody tried: me.
The purpose was to make a "cheap" but powerful astrograph. So I started from a 200 mm Newton in f4, plugged the daystar reducer to get down to f2, put it on a EXOS2 mount and imaged with an ASI183mc camera.

The 183 chip isn'd huge ($$$) so, the most comatose stars at the edges are not in the field of view. Where it matters, the image is not so bad. You barely need guiding cause it is a light bucket and you get lots of details.

The daystar gives more reduction that other reducers/correctors of Newtons at half the price and unless you have a large chip sensor, you will be kind of fine with it.

I saw this corrector recently, expensive for a reducer. I know its possible to even pair these with a coma correcter. Can you share the data you got with the 183 at f2?

[calypsob]

Anyone know anything about the DayStar Filters 0.5x Imaging Focal Reducer? Has anyone used this for DSO?  Is this only good for solar imaging?

 

Thanks

I know its a quadruplet, most .5x reducers are doublets.

[Eric Seavey]

Hi all, late but finally somebody tried: me.

The purpose was to make a "cheap" but powerful astrograph. So I started from a 200 mm Newton in f4, plugged the daystar reducer to get down to f2, put it on a EXOS2 mount and imaged with an ASI183mc camera.

 

The 183 chip isn'd huge ($$$) so, the most comatose stars at the edges are not in the field of view. Where it matters, the image is not so bad. You barely need guiding cause it is a light bucket and you get lots of details. 

 

The daystar gives more reduction that other reducers/correctors of Newtons at half the price and unless you have a large chip sensor, you will be kind of fine with it.

You managed to use this on a Newtonian, is interesting.... 

[fabrizio76]

Hi all, I got this image just tonight.

120 30 seconds subs unguided, gain 350 on the ASI 183c at -30 C with the Newton 200 mm f4 + daystar reducer and the Baader anti-pollution filter. I estimated that optically placing the reducer attached to the camera I effectively get a 0.6 reduction. I will try different distances to see how much more aberration I get at even lower reduction.

As you can see there is coma all around, but the image Is still reasonably pretty and the whole thing is a light bucket literally. In terms of brightness it's amazing.

The reducer/corrector that comes naturally from GSO for this Newton is around 800$ while the daystar reducer is aro 300 (don't remember exactly now). I may try to plug a coma corrector to it and see how things go. It is a 4 element optics. Spherical aberration is well corrected. Ultimately, if you plug in more glass and get rid of coma you basically get yourself a nice Schmidt camera. 

The whole point for me is this: if you do not have a large sensor, it is pointless to spend loads of cash to correct aberration all the way to the edges of the beam. 

 

Edited by fabrizio76, 15 January 2020 - 01:25 AM.

[calypsob]

Hi all, I got this image just tonight.

120 30 seconds subs unguided, gain 350 on the ASI 183c at -30 C with the Newton 200 mm f4 + daystar reducer and the Baader anti-pollution filter. I estimated that optically placing the reducer attached to the camera I effectively get a 0.6 reduction. I will try different distances to see how much more aberration I get at even lower reduction.

As you can see there is coma all around, but the image Is still reasonably pretty and the whole thing is a light bucket literally. In terms of brightness it's amazing.

The reducer/corrector that comes naturally from GSO for this Newton is around 800$ while the daystar reducer is aro 300 (don't remember exactly now). I may try to plug a coma corrector to it and see how things go. It is a 4 element optics. Spherical aberration is well corrected. Ultimately, if you plug in more glass and get rid of coma you basically get yourself a nice Schmidt camera. 

The whole point for me is this: if you do not have a large sensor, it is pointless to spend loads of cash to correct aberration all the way to the edges of the beam. 

 

Horsehead.jpg

that is indeed the advantage of small sensors, fast glass is more within reach.  Starizona makes a .4x reducer for sct's now that can cover small sensors as well.

 

This daystar reducer you have is unique in that it corrects spherically.  It looks to me like your scope is not holding collimation, either the secondary may be loose, or the mirror is sliding around in its cell or slop in the drawtube GSO newtonians need alot of fine tuning before they can reproduce nice round stars. 

 

thanks for sharing the data, I will be interested in seeing the data once collimation is dialed in.  Shooting at F2 fully corrected on a newtonian with a 1" sensor would be phenomenal.

 

this thread might help you decide on appropriate optical placement, again the daystar has a huge advantage over a normal doublet .5x reducer

it might be possible to avoid the CC all together

https://www.cloudyni...ucer-on-a-newt/

Edited by calypsob, 15 January 2020 - 01:05 PM.

[fabrizio76]

Sorry, I mistaken the brand of the Newton, although they are basically the same, I have a scope from TSOptics. It actually came in 3 days ago, so these are the very first shots I take with it. It may well be a bit uncollimated after traveling on a UPS track. I will do star collimation as soon as I have a good seeing. Before I used a skywatcher Evostar ED72 and I plugged the daystar to that as well. See result on Andromeda with the small sensor. I looked into the Starizona stuff, but I own a very old C8 that does not allow removal of the secondary mirror, so I couldn't use that. BTW, daystar + C8 very similar to what the usual Celestron 0.63x does.
As for where to place the reducer, I use some ray-tracing software (Zemax type of stuff) to decide distances and a bit of trial and error. By simulating the spots it seems to me that the distortions I have on my stars, especially at the border of the image, is coma rather than mis-collimation. I will check collimation anyway of course. Once I am sure about the scope I will run some tests at different distances. The daystar with a spacer between the reducer and camera can chop the focal of by as much as 0.3! On the APO that gives enormous stars at the edges, on the Newton, didn't try yet

 

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[Eric Seavey]

Still, it is interesting you are able to use a focal reducer on a Newtonian scope.  I once bought an inexpensive focal reducer from Orion for my MN190 to try out and it seemed that I would have to put the camera and FR deep inside the tube to reach focus.

[fabrizio76]

Actually, I just figured out that most of the distortion I get indeed comes from a misaligned secondary mirror. So, will fix it right away and than the daystar just works marvels! Even at a whopping f/1.2! And I do reach focus easily with the TSOpitcs tube

[calypsob]

And you are just using the daystar correct?

[fabrizio76]

Yes, only the daystar reducer