Where to place my IDAS LP filter ?

[kirkster501]

Hello, there are several places in my imaging train with the 2" threads where I could place my LP filter. Where is the optimal place please? As near as the camera as possible?

Warm regards, Steve

BTW - I have now owned this filter since 4th Jan and not had one single opportunity to use it yet !!

[steppenwolf]

Assuming that you have the SW FR/FR, I'd be tempted to buy the 2" nosepiece adapter and place the IDAS LP filter in the threads of the nodepiece.

[kirkster501]

Steve, I have exactly that adapter. That's what i will try then. That will mean the filter will be inserted into the focuser - in other words the filter will be the first thing the light hits after the objective. I was just wondering if the filter should come *after* the reducer? Will try both methods and report back

Rgds, Steve

[Gina]

I wouldn't have thought it would make any difference but I'm happy to be corrected if wrong.

[IanL]

I'm in the same position, having owned one since December 1st and only had one opportunity to try it out since, which was a failure due to other technical issues!

Currently I have it screwed in between the DSLR -> M42 adaptor and the SW focal reducer. There isn't anywhere else in my set up where it would fit as far as I can see. I don't think this is the ideal position, as I had understood it is better to put the filter as far away from the sensor as possible to avoid reflection problems. I'm not that keen on the idea of the push-fit nose-piece adaptor with the stock 80ED focuser, since it would rely on the rather poor-looking thumbscrews to hold it in place, whereas with my current set-up everything is screw fit and rock solid. (Downside being that I can't rotate the camera without disassembling the M42 adaptor, which is not a job to be done in the dark).

[kirkster501]

IanL. I have the stock focuser on my ED80. What I did was drill and tap another screw for it so there are now thumb screws at 120 degree points for firmer attachment. I must say though, I would prefer a screw in solution.

[kirkster501]

Also, in the case of the ED80 FR/FL, the location where you install the filter in the imaging train reverses the filter by 180 degrees.

This way where the "shiny" side of the IDAS is facing outward:

..or this way where the LP filter us between the flattener and the DSLR T ring and the "shiny" side is facing inward...

I will try both and see.

Rgds, Steve

[Gina]

I was told that it doesn't make any difference which way round filters are used - which I thought strange.

[kirkster501]

I was told that it doesn't make any difference which way round filters are used - which I thought strange.

Indeed. Most strange.....

[IanL]

You may well be right that I have it on backwards, I have been reading a bit more since I bought it and seems that it probably should be shiny side outwards. Trouble is there are no useful instructions in the box with the filter, which is a bit poor given the premium price. I was hoping to do a few tests by now to figure that one out, but not had any luck. Let us know how you get on.

Thanks for the tip about drilling the extra screw hole in the focuser - how did you do it? Hand drill or pillar drill? I am not super happy with the location of the IDAS anyway, the threads tend to lock as it is screwed in to the train and lacks surface to grip when you want to remove it. I have had to use a small rubber strap-wrench to remove it most recently. If it was in the end of the adaptor, the threads wouldn't be carrying any load so would not be likely to lock as much.

[RikM]

I put mine on the focuser end of the imaging train. (Filter first in lightpath) Though in my case it is on the end of a coma corrector rather than reducer.

[kirkster501]

Trouble is there are no useful instructions in the box with the filter, which is a bit poor given the premium price.

+1 tell me about it. VERY poor.

Thanks for the tip about drilling the extra screw hole in the focuser - how did you do it? Hand drill or pillar drill?

I unscrewed it then put it in a vice, drilled a 3mm hole (I think it was 3mm, would need to check) and then used a 4mm tap - Whitworth I think it was. A machine shop would do this for you for a fiver.

[IanL]

Aha, I found the document I was looking for, here (http://www.sciencecenter.net/hutech/idas/idas-lps.pdf).

Upshot is that when using with a telescope the orientation of the filter doesn't matter, it works just as well either way round. They do recommend keeping it as far away as possible from other optical elements if your scope is not fully multi-coated (probably a good idea even if it is). So it looks like there is no issue with putting it between the 0.85X reducer and the DSLR on my 80ED. Hoping for at least some clear skies on Saturday!

[Sp@ce_d]

Couple of things.. if you put the filter between the T mount & the reducer you loose the correct spacing distance sensor to reducer. The FLO adapter is the way to go to get the filter in the nosepiece. Then put one of these on the drawtube.. http://www.365astron...pes-p-1913.html

.. have them on all my scopes. They are solid, even clamping so you don't get issues with orthogonality if you tighten one screw too hard & makes it easy to rotate the camera for framing.

[IanL]

Thanks for that, looks like a good solution.

[kirkster501]

I had a 3.25>2" baader click lock on my CPC1100 which I sold. I agree they are very good indeed. I don't want to invest anymore on the stock focuser though since I will be getting a Feathertouch for my ED80. Is there a clock lock for that anyone know? I am well pleased with he click lock system.

[Nicho]

I have the Baader click lock on my ed80 it really does make a world of differnce . Well worth the buy if you cant afford a feathertouch focuser.

[IanL]

I have the Baader click lock on my ed80 it really does make a world of differnce . Well worth the buy if you cant afford a feathertouch focuser.

Seriously considering it as I don't think a new focuser is going to be a worthwhile investment with a relatively light DSLR. Don't feel like shelling out any more cash right now given that I got the ED80 on 1st Dec and that was the only day I have been able to image with it since due to the weather.

[kirkster501]

First time I used my IDAS filter tonight. Wait for it (drum roll etc) I got an hour, yes, an whole hour of clear skies before it clouded over again! This has been my first realistic opportunity to test this filter since I bought it on 4th January - the clouds where I live have been that bad of late.

I used this IDAS on Rossette nebula and all I can say is wow. Brilliantly effective - I was getting 6 minute guided subs in my semi-LP backyard no problem, no orange at all. The subs would have been washed out at 90 secs without this filter. Cannot wait to use it with more time. I reckon I could push my guided subs to longer but I think my modded DSLR will be too noisy much after 5 mins at ISO 800.

[K3ny0n]

Congratulations mate, I'm toying wether or not to get the camera mounted version as to getting the normal screw version. Glad you noticed the differences within just a short time frame, good to hear your happy with it.

Rob.