Do you think this may solve my focus problem?

[radioactive]

I have another thread running about a problem I have not being able to achieve a focus using an eyepiece whilst having the 6.3 FR then the JMI/WO motorised focuser and then with OR without a 2" diagonal "it matters not" I was unable to bring it into focus on any three of the EPs I tried the best out of focus view I managed to achieve was the C11 focuser wound completely anticlockwise and the jmi/wo most inwards which to me means I have used maximum IN focus if I am wrong please tell me as I think I may have the answer here on this link if I am wrong and you know it please shout loud and save me some more money I am getting a little fed up of buying stuff if its only causing me more grief so Maybe you will agree this method of reducing/flattening will be the better way to go as it does not extend the train at all

http://www.astrobuysell.com/uk/propview.php?view=17282

[Trevor]

Martyn

I think Roger used one of those or similar might be worth asking him.

With my C11 I have no problem getting focus with the reducer and Antares focuser fitted.

Trev

[Paxo]

Martyn,

Forgive my ignorance. With the additional focuser installed, what difference does the position of the primary mirror (i.e. the focus position), do you 'lock' the primary mirror down at an extreme or centre, or can this be adjusted to bring the external focus unit to an approximate focus. I am probably off the ball here but it was just a thought.

Steve.....

[Tiny]

Asking a stupid question. On which side of the diagonal do you fit the reducer.

The reason I ask is that the mob who built my camera also build reducers to fit them and give charts of their effect. These show that the amount of reduction the reducer achieves varies with the distance from the camera chip. In the case of mine the basic reducer screwed into camera gives 0.6 while sticking 20mm of connector between it and the chip gives 0.33. This my SCT can handle but moving the thing further away very quickly makes focusing impossible.

Knowing this I tried a .5 reducer in various positions and found that it had to be very close to the ccd or equivalent eyepiece and even a few mm of adjustment were the difference between achieving focus or not because increasing ccd/reducer distance caused reduction to change very rapidly - meaning the light path shortened a lot for a small reducer adjustment.

[Kaptain Klevtsov]

Martyn, I'm guessing here that you want to use an EP to aquire the target before sticking the camera on (otherwise you'd use a wider eyepiece, not the FR?) so the FR needs to be in place for both camera AND eyepiece. What I'd suggest trying is a Barlow lens (only with the EP) so that you can acheive visual focus and target aquisition prior to mounting the camera. The Barlow will need more out focus than without the Barlow so it might get you where you want to be. I think it has to be a "normal" Barlow as the Powermate types don't change the focus travel in the same way.

Kaptain Klevtsov

[radioactive]

Martyn,

Forgive my ignorance. With the additional focuser installed, what difference does the position of the primary mirror (i.e. the focus position), do you 'lock' the primary mirror down at an extreme or centre, or can this be adjusted to bring the external focus unit to an approximate focus. I am probably off the ball here but it was just a thought.

Steve.....

Steve I use the telescope focuser to get a reasonable focus then the motorised one for extremely fine focus Well that was the idea and it works without the FR added but of course that means I am restricted to imaging at F10 ish So in short I am still using the main focuser

Asking a stupid question. On which side of the diagonal do you fit the reducer.

The reason I ask is that the mob who built my camera also build reducers to fit them and give charts of their effect. These show that the amount of reduction the reducer achieves varies with the distance from the camera chip. In the case of mine the basic reducer screwed into camera gives 0.6 while sticking 20mm of connector between it and the chip gives 0.33. This my SCT can handle but moving the thing further away very quickly makes focusing impossible.

Knowing this I tried a .5 reducer in various positions and found that it had to be very close to the ccd or equivalent eyepiece and even a few mm of adjustment were the difference between achieving focus or not because increasing ccd/reducer distance caused reduction to change very rapidly - meaning the light path shortened a lot for a small reducer adjustment.

Tony Its not a stupid question at all I hope my answer is not also The only place the 6.3 focal Reducer will go because of its size is both before the diagonal but also before the motorised focuser because it matches the SCT thread

Martyn, I'm guessing here that you want to use an EP to aquire the target before sticking the camera on (otherwise you'd use a wider eyepiece, not the FR?) so the FR needs to be in place for both camera AND eyepiece. What I'd suggest trying is a Barlow lens (only with the EP) so that you can acheive visual focus and target aquisition prior to mounting the camera. The Barlow will need more out focus than without the Barlow so it might get you where you want to be. I think it has to be a "normal" Barlow as the Powermate types don't change the focus travel in the same way.

Kaptain Klevtsov

Yes you guessed correctly KK I was hopeful I could also use the C11 to Allign the scope at the start of the session but with it as I had it I could not even manage that :shock: I never had time to try a barlow before the clouds rolled in as quoted in my other thread it just I started this new thread because of the product I saw advertised so yes KK this may work don't know is the short answer its just that when I saw the Alan Gee reducer type and thought it may solve the problem I will investigate the barlow option later on weather permitting

thanks

[Paxo]

I have to admit Martyn that I have always bolted the camera directly to the focal reducer and have never placed a diagonal or other equipment in the way. I've always aligned first and then adjusted the optics afterwards for photography. My understanding of how these 'optical path adjusters' work is that the f6.3 version should work for visual and hence the use of a diagonal or similar should be permitted but FR to CCD/EP is critical, the further apart the less effect the on the scopes 'focal length' the reducer has and the greater vignetting effect it imparts (imagine the f/r turns parallel light rays into a cone whose end gets smaller the further away from the f/r you get). Do you notice whether this is te case?

[radioactive]

I have to admit Martyn that I have always bolted the camera directly to the focal reducer and have never placed a diagonal or other equipment in the way. I've always aligned first and then adjusted the optics afterwards for photography. My understanding of how these 'optical path adjusters' work is that the f6.3 version should work for visual and hence the use of a diagonal or similar should be permitted but FR to CCD/EP is critical, the further apart the less effect the on the scopes 'focal length' the reducer has and the greater vignetting effect it imparts (imagine the f/r turns parallel light rays into a cone whose end gets smaller the further away from the f/r you get). Do you notice whether this is te case?

Steve No I have not noticed albeit because I have not tried it yet the 2 DSOs I have taken images of the first one was using the C11 the Atik16IC with a 0.5 focal reducer put into the nosepiece the 2nd DSO I used it on the Antares Sentinal scope with an extender on to achieve focus and no focal reducer this time I cannot therefore give any further information on this

however I have decided to go ahead and get the Alan Gee internal FR after all so I hope when I get that it will sort out my issues I believe this item is very good in use with imaging through the SCT

pending

[Paxo]

Its interesting that Moonlite do a Crayford focuser for SCT's that is internally threaded within the barrel to take sct style focal reducers, probably doesn't solve your problem, but interesting all the same. Details at:

http://www.focuser.com/cgi-bin/dman.cgi?page=category&plugin=dstore.cgi&category=4

Good luck.....

Steve

[radioactive]

Steve yes that's quite an interesting link you know at times I think maybe I just do things the wrong way around perhaps it may be a good idea if we could have the experts not sure using that word is right but it just may be a good thing to get known working setups put on a sticky or something showing how you can set up your kit to use for imaging for my C11 I want to be able to use for visual as well as imaging and also using binoviwers as well when they turn up thats a whole other story but they are on their merry way yet again to me from Denkmeire USA what I know of them so far is they are addressed to Middlesex Leeds but as I say thats yet another Radioactive Saga :shock:

[Tinkerbell]

Lo Martyn

I had allready posted a reply in the other thread before reading this one

We had the same problem You are having but we managed by trial and error to get it sorted. :shock:

We added an SCT threaded 2" nosepiece to the reducer and then used an SCT threaded diagonal onto the reducer, then pushed the 2" nosepiece into the focuser and Robert is your aunties husband, so to speak. :hello1:

[radioactive]

Cheers for the reply Kev I will let you know how I get on using this Alan Gee FR. Re that 2" nosepiece is that like an OCS? I will have one of those come with my Binoviewers when they finally arrive here from the US that's another really long story I bore you with that one when I speak to you at Kielder I do have an sct type Diagonal too so options are opening up here for me now I am starting to accumulate more stuff than in Steptoes back yard here mate

[Tinkerbell]

Not exactly sure what an OCS is but this is the part I'm talking about < http://www.scopesnskies.com/images/bargains/large/IMG_2348.jpg > £12.00 from scopes n skies in the bargain section.

[radioactive]

think yes it will be pretty much the same thing I shall see when the Binoviewers turn up I know he has included one in with them here's a link explaining them its interesting reading at least if you scroll down a tad it seems to show something rather similar

http://www.handsonoptics.com/denkmeier_info.html

[Tiny]

Cheers for the reply Kev I will let you know how I get on using this Alan Gee FR. Re that 2" nosepiece is that like an OCS? I will have one of those come with my Binoviewers when they finally arrive here from the US that's another really long story I bore you with that one when I speak to you at Kielder I do have an sct type Diagonal too so options are opening up here for me now I am starting to accumulate more stuff than in Steptoes back yard here mate

So - when are you getting a flip mirror assembly to make up the set?

[iancandler]

I think I might be able to offer a solution that may work.. I have the ZS66 which is notorious for its lack of "intravel" I got around my probelms using the WO field flattner/reducer.

The way I see it is the focal reducer being on front of the diagonal is giving a too longer light path, with the WO reducer its not only sct thread but also comes with a 2" push fit adaptor..

SO you could connect the wo focuser direct to the rear of the scope, then change between using the diagonal and an eyepiece (parfocalised) to focus, then pop in the reducer that just so happens to terminate in a T thread, meaning you can connect it directly to the T ring on your camera.. it will give a shorter light path and should do the job..

If your round my way your welcome to pop up and try mine to see if it works with your OTA/focuser set up.

NB this is this reducer and is cheaper than the other option I think..

http://www.iankingimaging.com/show_products.php?category=65 the .8x zs66 one at £119

[radioactive]

Cheers for the reply Kev I will let you know how I get on using this Alan Gee FR. Re that 2" nosepiece is that like an OCS? I will have one of those come with my Binoviewers when they finally arrive here from the US that's another really long story I bore you with that one when I speak to you at Kielder I do have an sct type Diagonal too so options are opening up here for me now I am starting to accumulate more stuff than in Steptoes back yard here mate

So - when are you getting a flip mirror assembly to make up the set?

:shock: I got one a couple of weeks back!

[radioactive]

I think I might be able to offer a solution that may work.. I have the ZS66 which is notorious for its lack of "intravel" I got around my probelms using the WO field flattner/reducer.

The way I see it is the focal reducer being on front of the diagonal is giving a too longer light path, with the WO reducer its not only sct thread but also comes with a 2" push fit adaptor..

SO you could connect the wo focuser direct to the rear of the scope, then change between using the diagonal and an eyepiece (parfocalised) to focus, then pop in the reducer that just so happens to terminate in a T thread, meaning you can connect it directly to the T ring on your camera.. it will give a shorter light path and should do the job..

If your round my way your welcome to pop up and try mine to see if it works with your OTA/focuser set up.

NB this is this reducer and is cheaper than the other option I think..

http://www.iankingimaging.com/show_products.php?category=65 the .8x zs66 one at £119

ian thanks very much for your suggestion I have in fact sent off for the Alan Gee Flattener / Reducer today I hope to get it by the weeks end I think this will solve my problem too as it will not add any length to the train either thats the hopeful cure at any rate

[iancandler]

I think the key here lies in the reducer fitting AFTER the focuser.. I was thinking about light paths last night when it occoured to me that the reducer being before the focuser would affect the focal point and bring it forward.

[radioactive]

I think the key here lies in the reducer fitting AFTER the focuser.. I was thinking about light paths last night when it occoured to me that the reducer being before the focuser would affect the focal point and bring it forward.

Yes but the main focuser is still the proper one at the back of the SCT cell see picture how I had to set it up the FR has to screw on it that position and the other focuser is only meant for Fine focus only nothing else the telescope focuser should do the real work but has ran out of INfocus

[Trevor]

Martyn

Just a thought, have you added any rails to the scope? Maybe one of the screws is protruding inwards to far and stopping the full travel of the mirror.

[radioactive]

Martyn

Just a thought, have you added any rails to the scope? Maybe one of the screws is protruding inwards to far and stopping the full travel of the mirror.

Well yes at the top I put a rail on to accommodate having the ADM bar/rings for mounting the 80mm but I did not use very long fixings but I will check that out again at the rear end