Reducer ?

[LaVey]

Not sure if this the right place to post this.. but its imaging related....

I bought one of these http://www.celestron.uk.com/catalogues/view_item.asp?ItemID=32895&CatalogueID=272&CategoryID=3875 for my meade lpi, it says x2 reducer but on a test on the double cluster (one small section of it) i get these results:

without the reducer:

with it:

sorry about the focus, my fingers were starting to frost up

anyway.. it looks as if there is no difference in the size of the images.. should this work with an LPI? I just figured it should.

[blinky]

In thoery it should work with the LPI. Where have you placed it? It should go at the end of the 1.25" adapter tube, the end furthest away from the sensor.

[Andrew*]

that's definitely giving you a wider field of view, but I don't think it's twice as big. Plus the quality seems to be very poor. To be quite honest I don't think this reducer will be any good. For just a little extra, the atik reducer, half way down the page, will give you excellent value for money and really does double your FOV.

HTH

Andrew

[Paxo]

Is it just me or does the shot with the reducer look more magnified than the one without (ie a more narrow field of view not a wider). Does the reducer have a lens element in it to cause the change to the light beam? if not surely moving the ccd sensor further away will cause magnification, or have I got this all wrong, and I await to be corrected.

Steve

[Sam]

I just layered both those images together and are they are exactly the same size.

Sam

[Andrew*]

yep, you're right there. I just noticed that there were more stars in the top half of the picture and assumed the FOV was bigger :oops:

how strange...

Andrew

[Kaptain Klevtsov]

It would appear that the focal reducer lens is missing from the adapter bit. All it seems to have done is change the focus position a bit. Very strange.

Kaptain Klevtsov

[Andrew*]

but it looks like there's a new optic in the light path because of that abberation which radiates from a centre point which is clearly not present in the first image:

also there is some chromatic abberation introduced - would these artefacts appear from a different focus position?

Andrew

[LaVey]

hmm... dunno if this helps any:

[blinky]

I am stumpted

[LaVey]

ok.. I think i have worked out why this does not work based on the things said here... let me know if this make sense..

the advert for this says

"The NexImage Reducer Lens replaces the 1.25" barrel and threads directly into the NexImage housing."

I screw the lens onto my existing 1.25" barrel as i cannot remove the 25mm stuby barrel of the LPI.. looking at the first image of the reducer the small lens is another 15mm down the lens.. so this would add around 40mm to it in front of the chip.... is it supposed to be super close? Its the only thin I can think of....

[iancandler]

I screw the lens onto my existing 1.25" barrel as i cannot remove the 25mm stuby barrel of the LPI

Thats the problem then.. it clearly states it should replace the current barrel.

I used a little antares .5x reducer.. cheap and worked a treat.. the bonus being that it just screwed onto the end of the LPI barrel like a filter.,