Extended Dew Shield or Heater for Bresser Messier AR-152/S

[SnakeyJ]

As we had a nice giberous moon last night, I decided to get the AR-152/S out and find out just how bad the CA was on a nice bright moon. I was very pleasently surprised - though only took the magnification up to x95 with the 8mm - there was a very thin and faint violet arc at the edge of the moon, but not visible on surface detail and the view was pin sharp with excellent contrast.

Pleased with this first go - I shot an 8 panel mosaic of the moon which came up very well despite some small but noticeable dust smotes on the sensor. I shall post the result up in lunar imaging later once I get a chance to crop all the edges nicely. Very pleased with this for a first attempt with this scope - I tried a much larger mosaic at x3 with about 30 panels, but the seeing was not quite up to this despite trying the IR-PASS filter.

Then at midnight I switched over to Saturn and got a couple of 1200 frame runs, but the seeing was very poor and Saturn was becomming dimmer and very difficult to focus - I then realised that I was dewing up very badly and had to bring the frac in and swap over to the newt. Sadly the seeing never really improved enough and I gave up at about 01:30hrs.

Given the low elevation of Saturn, I hadn't been too worried about things dewing up even considering the rather small dew shield that comes with this model - which is the same as the Meade AR6.

I took the dew shield off this morning to allow things to dry out properly and look at the options for putting a dew heater band - though looking at the construction I'm not sure a standard dew heater tape will do this easilly.

Any suggestions for warming the relevant bits here, or perhaps I should go for an aftermarket or original extended dew shield? The existing one is 206mm dia x 175mm long - guess I'd be wanting something at least twice 300mm.

[RichieP]

I have had the same problem with the AR5. The supplied dewshields are much too short. Astrozap make rigid replacement dewshields for the AR5 and AR6. FLO seem to be the official distributors of Astrozap products but don't seem to be able to get hold of them (I contacted them several times but got no response).

I use an Astrozap flexible shield instead, wrapping it around the original shield.

[SnakeyJ]

Thanks Ritchie - I'll have a look around and see if I can find the Astrozap dew shields. The scope is 1020mm long from diagonal to lens cap, so although it would be very nice and look 'the biz' to have a proper rigid dew shield the flexible removable one may be more practicle and pragmatic..

[John]

Telescope House used to list replacement dew shields for the AR5 LXD75 and AR6 in their "end of line" section. I used one on my AR6 and it was around 4 inches longer than the standard one. Currently they show the smaller one only though but it might be worth a call:

http://www.telescope...e_Products.html

Alternatively I've seen really long ones imported from the USA or folks using the wrap around dew shields for a 6" mak / SCT. Or DIY with a camping mat !

[SnakeyJ]

Thanks John Ill give them a shout.

[celkins]

As we had a nice giberous moon last night, I decided to get the AR-152/S out and find out just how bad the CA was on a nice bright moon. I was very pleasently surprised - though only took the magnification up to x95 with the 8mm - there was a very thin and faint violet arc at the edge of the moon, but not visible on surface detail and the view was pin sharp with excellent contrast.

Pleased with this first go - I shot an 8 panel mosaic of the moon which came up very well despite some small but noticeable dust smotes on the sensor. I shall post the result up in lunar imaging later once I get a chance to crop all the edges nicely. Very pleased with this for a first attempt with this scope - I tried a much larger mosaic at x3 with about 30 panels, but the seeing was not quite up to this despite trying the IR-PASS filter.

Then at midnight I switched over to Saturn and got a couple of 1200 frame runs, but the seeing was very poor and Saturn was becomming dimmer and very difficult to focus - I then realised that I was dewing up very badly and had to bring the frac in and swap over to the newt. Sadly the seeing never really improved enough and I gave up at about 01:30hrs.

Given the low elevation of Saturn, I hadn't been too worried about things dewing up even considering the rather small dew shield that comes with this model - which is the same as the Meade AR6.

I took the dew shield off this morning to allow things to dry out properly and look at the options for putting a dew heater band - though looking at the construction I'm not sure a standard dew heater tape will do this easilly.

Any suggestions for warming the relevant bits here, or perhaps I should go for an aftermarket or original extended dew shield? The existing one is 206mm dia x 175mm long - guess I'd be wanting something at least twice 300mm.

I wrap an 8" 'scope dew heater around the base of the black step-up section, reasoning that it's thermally quite close to the lens cell, and it wraps twice - my dew shield is held on with what looks a bit like Velcro from the front; not managed to get it off, yet.

I've had success with a camping mat extension too.

Nice to hear of another R152s owner - for a while, I thought I was alone.

[SnakeyJ]

I wrap an 8" 'scope dew heater around the base of the black step-up section, reasoning that it's thermally quite close to the lens cell, and it wraps twice - my dew shield is held on with what looks a bit like Velcro from the front; not managed to get it off, yet.

I've had success with a camping mat extension too.

Nice to hear of another R152s owner - for a while, I thought I was alone.

Thanks Celkins,

I was thinking the plastic would be too far back and insulating - also there seems to be an air gap around the objective lens cell (though I haven't looked too closely yet as a bit scared to start poking around in here!). But I do have a tape for my SW200P (which I've never had cause to use to date), so think I will try the experiment on this. There is a lot of glass open to the elements here, so I feel it probably will need a little of both heat and dew shield extension. I'll also flock the inside of the fitted dew shield to help reduce stray light (every little bit 'elps).

Nice also to hear I'm not alone with this bad boy - although I've only had limited use so far (and still haven't posted a proper first light), I'm really looking to pushing this once I get my 2" diagonal for the widefield visual (the supplied 1.25" diagonal is a bit of chocolate fireguard and displays a lot of flex under the load of filterwheel and camera (not helped by my cooler). I'm also hoping to do some narrowband imaging once I get a proper CCD and guiding solution nailed - light grasp, focal ratio and some inbuilt field flattening should prove quite a useful combination on larger targets.

If you've done any imaging with this I'd be very interested to hear how its performed.

Jake

[celkins]

Thanks Celkins,

I was thinking the plastic would be too far back and insulating - also there seems to be an air gap around the objective lens cell (though I haven't looked too closely yet as a bit scared to start poking around in here!).

I'd looked at this, too, but the dew shield appears to be specifically insulated by the 'Velcro' so this was as close as I could get to the lens cell - at least it's heating the main tube - and it's worked for me

But I do have a tape for my SW200P (which I've never had cause to use to date), so think I will try the experiment on this. There is a lot of glass open to the elements here, so I feel it probably will need a little of both heat and dew shield extension.

I think that's the best option.

I'll also flock the inside of the fitted dew shield to help reduce stray light (every little bit 'elps).

I did mine with a strip of Protostar Flockboard - didn't even need to glue it.

Nice also to hear I'm not alone with this bad boy - although I've only had limited use so far (and still haven't posted a proper first light), I'm really looking to pushing this once I get my 2" diagonal for the widefield visual (the supplied 1.25" diagonal is a bit of chocolate fireguard and displays a lot of flex under the load of filterwheel and camera (not helped by my cooler). I'm also hoping to do some narrowband imaging once I get a proper CCD and guiding solution nailed - light grasp, focal ratio and some inbuilt field flattening should prove quite a useful combination on larger targets.

I've finally (thanks to John at JTechDesign) got a Baader ClickLock installed onto mine, but have managed a few decent shots through it to date. Discarded the supplied diagonal almost immediately, and replaced with a Revelation quartz one, but always go straight through for AP, anyway.

If you've done any imaging with this I'd be very interested to hear how its performed.

Jake

You'll find my attempts at http://univac.homeunix.org/ and follow the gallery links to sky and astro - not very many, but clear nights always seem to come when I'm at the wrong end of the country. Now I've got it on a mount that can really cope, I'm pretty happy.

Carl

[SnakeyJ]

Thanks Carl,

Re the dew shield - mine is on felt pads not velcro. It actually came off by accident on my first go with the scope when I removed the dust cover, but goes on and off with a little gentle rotation now. I think the dust cover had become stuck due to a long period of not being used by the previous owner.

I flocked the SW200P with the standard DC-Fix, though not entirely happy as it does shed amount of fibres - so will use protostar board/material in future.

Re the diagonal I have a barely s/h Meade 5000 diag which should arrive sometime next week - though this will really be for visual for the wide angle 24mm and 32mm EPs. Looking forward to trying these out as I've had them unused for 4-5 weeks! If I'd brought new the Baader Click lock diag would be the weapon of choice - very well reviewed and you don't see many come up s/h which tells a storey.

Imaging wise I'm confined to planetary and perhaps solar until I can get a proper camera, but should happen later this year!

Some very nice images with the Star Shoot 2, M42, M3 and 13 come out very nicely and a very nice resolution/wide field with the R152S and Orion SS2 - my favourite there though is the LEO triplet which looks stunning. Liked all the diving shots to - I never did any Underwater photography/imaging, but plenty of diving through the army and BSAC - not as widely travelled, but did a couple of nice trips around Cyprus, Adriatic/Croatia and Sharm. Budget wise its one hobby at a time now due to having a young family - so my bikes have been sold and my fins hung up for the time being

Thanks again for the tips and info on this - I'll keep a keen eye out for future posts/images.

Jake

[sbooder]

Hi Jake,

                I have the 1200 f7.9 version of this scope on order and wondered if you have tried to source a Crayford that would fit these scopes and have you had any luck?

[SnakeyJ]

The dew band is easy - I wrapped the astrozap one I have for my 200p, this went around the base of the dewshield almost twice - ran it at full power and it did the job quite well, though best on from start as it takes a good while to conduct through. You could put a smaller tape around the cell, inside the dew shield which would be more efficient.

I'm a bit stuck with my focuser as th rear two elements of this design are mounted in a one piece 3" focuser. However, the R&P is nicely made and well worth seeing how you get on with it. I did replace the standard 2" screw adaptor with a much nicer compression fitting from teleskop service.

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[sbooder]

The dew band is easy - I wrapped the astrozap one I have for my 200p, this went around the base of the dewshield almost twice - ran it at full power and it did the job quite well, though best on from start as it takes a good while to conduct through. You could put a smaller tape around the cell, inside the dew shield which would be more efficient.

I'm a bit stuck with my focuser as th rear two elements of this design are mounted in a one piece 3" focuser. However, the R&P is nicely made and well worth seeing how you get on with it. I did replace the standard 2" screw adaptor with a much nicer compression fitting from teleskop service.

typed on my mobile with Tapatalk

When you say elements, you not talking glass elements here are you?  Are you talking about the focuser being one piece from the tube end to the focuser travel tube?

[SnakeyJ]

Yes, the near petzval has two doublets. The rear doublet cell is fixed to the focuser, though not certain it travels with the draw tube. I did e-mail ES re a replacement focuser, but got a reply saying theirs was not suitable for this reason. I'll look and see if I can find this.

typed on my mobile with Tapatalk

[SnakeyJ]

Might be worth an enquiry about the Baader steeltrack for yours though.

typed on my mobile with Tapatalk

[SnakeyJ]

Just looked out the e-mail response from ES below:

-------- Original message --------
From: Tassilo Bohm | Explore Scientific GmbH <tassilo.bohm@explorescientific.de> 
Date: 
To: Jake Gully 
Subject: WG: Fwd: Contact Us Form-Explore Scientific Store Submitted [T-UAPK9DKC3W-74] 

 

Dear mr Gully,

thank you very much for your mail. Do you have a problem with the 4"-focusser that is attached to the telescope? Changing the focusser doesn´t make sense: the Bresser Messer AR-150S is a four-lens system - similar to a Petzval-achromat. The two lenses that form the rear objective are attached to the focusser - the telescope would not work if you remove them. A 2" focusser would also not work with your telescope - at f/5 there would be severe vignetting.
If you have a problem with the focuser, please contact the Bresser representative in UK:

Telescope House
Unit 1 Starborough Farm, Starborough Road, Marsh Green
TN85RB Edenbridge, Kent
Tel.: +44-1342-837 098
sales(at)meade.uk.com
www.telescopehouse.com

[sbooder]

Looks like Bresser have to do some catching up with the desires of the AA comunity and start producing these fracs with Crayfords.  I am not sure that mine will have the elements at the end?  I have been doing some research on the Meade model that is the same scope and from the schimatic I downloaded it is very traditional.

And judging by this review on Cloudy Nights it is possible to change focuser.

[SnakeyJ]

Looks like Bresser have to do some catching up with the desires of the AA comunity and start producing these fracs with Crayfords.  I am not sure that mine will have the elements at the end?  I have been doing some research on the Meade model that is the same scope and from the schimatic I downloaded it is very traditional.

And judging by this review on Cloudy Nights it is possible to change focuser.

Yep it was this article that originally prompted my e-mail to ES - good review and beside the easier to change focuser, the AR-6 also has a better longer dew shield.    Note in the review picture - this is how I have mounted the dew tape on mine.

On further reading the extended dew shield was an after market replacement - The Astrozap solid AR-6 dewshield