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Venus from 4.01.2017


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Venus has finally cleared the conifers at a high enough altitude to be imaged from my back garden. Not managed to capture any surface detail, but the phase is nicely visible.

C9.25/ASI120mm + x2.5 Powermate, IR Pro planet 807, no47 violet filter. 180secs, Stacked in A/S2, lightly sharpened in C/S2.

2017.01.07 5.30pm.png

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Venus has finally cleared the conifers at a high enough altitude to be imaged from my back garden. Not managed to capture any surface detail, but the phase is nicely visible. C9.25/ASI120mm + x2.

Sounds great on paper doesn't it. unfortunately I think it still cuts some UV I am sure i read Rik L on here say that somewhere ? look into that, see if you can find any info. looking so far for glass

You certainly don't see them 2nd hand very often!

Posted Images

1 minute ago, johnfosteruk said:

Very nice Pete, I think it's my imagination but do I see a very slight darkening at the limb as we look at the atmosphere side on?

That's some detail.

Not sure to be honest, maybe there is some subtle surface detail there.

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Just now, johnfosteruk said:

Either way it's one of the sharpest Venus I've seen mate.

Thank you very much. I think that is mostly down to the 807 Pro planet filter. I tried a IR/UV cut filter with the No47 violet, but the 807/No47 filter combo gave a much sharper, more stable view.

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It's the first time I have tried it, I was trying a few combinations of filters. I didn't think of that to be honest  :icon_scratch: you never stop learning, all I had on my mind was taming the seeing conditions. 

I will have to remember that next time,  especially considering that was the reason for using an I/R cut filter originally. 

What do you use Neil?

Edited by bunnygod1
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2 hours ago, bunnygod1 said:

It's the first time I have tried it, I was trying a few combinations of filters. I didn't think of that to be honest  :icon_scratch: you never stop learning, all I had on my mind was taming the seeing conditions. 

I will have to remember that next time,  especially considering that was the reason for using an I/R cut filter originally. 

What do you use Neil?

Its good to experiment Pete. Took me a while to figure what I think is happening, as its a unusual combo I hadn't  seen. Or read about. 

I could be wrong. But I think combining like this. would kill any UV detail flat. That combined with such a strong deep IR filter as the 807 is . I think,  swamping the W47 to the point where it effectively is hiding it.  For the most part what I think your getting here is a IR image. I am not certain of this. if any experts on this could clarify ?

If I am right,  You would have just as well used the IR on its own, and got more light into the camera. speeding up your frame rate.  It matters not.  I forget all number of things trust me.  I once put a clear filter on a colour camera for the moon and shot in colour instead of a UV IR cut. Your Venus is still a good IR image. 

What I am using at the moment for UV cloud, is a W47 with a  Altair IR only Block Filter.  But my first shots with this combo so far suggest I need to get either a BG 39 or BG40 and combine that with the W47. I think the IR only block filter I am using, Is still blocking some UV.  I think I can see subtle UV coming through. But its not optimal.

Don't forget I was spoiled from having a Schuler UV and Astrodon venus  Filters in the past. So always had strong UV clouds in my images. The W47 with pure IR block (BG39) can do well, I have seen some nice images. Its contrast will be less.  But is also much  cheaper than the Astrodon which is the best.  Even Barlow and SCT coatings can block UV not something you can do a lot about Though the barlow can be optimized. Recently I have seen some astounding detail being picked up in IR 1100 filter but with a 20" Scope. that's so far into the IR that it will be DARKKKKKKKKKKK  But wispy clouds all over the place in IR on some not all of he's images. I now have here a ZWO IR 850. which is quite deep into the IR but still might let some light through. Unlike  a IR 1100,  haven't used it yet.

Depends what you want Pete. But I reckon Looking at the quality of your Venus shots. I reckon if you combine a BG39 Or BG 40 with your W47 you should pick up UV cloud.

As your Venus images look tight enough. That's the important thing. If they are fuzz. There's little point. But yours are not

Think I am going to have to try and get one. Trouble is they have to be made. You cant get them on the high street. But they are not mega expensive. If your interested perhaps we could both look into it, and see what we find. BTW if you take IR 807 and separate W47 BG39 images they can be combined into a colour image with cloud features often showing

But one thing at a time if your interested

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Update do you have any old filters you don't use ? I just tried to dissemble a old filter using a Knife. I was surprised to find it unscrewed quite easily. Now I just need the glass. I am also wondering how much it would cost to build a equivalent of the old Schuler UV venus filter. I am looking into it

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1 hour ago, neil phillips said:

Update do you have any old filters you don't use ? I just tried to dissemble a old filter using a Knife. I was surprised to find it unscrewed quite easily. Now I just need the glass. I am also wondering how much it would cost to build a equivalent of the old Schuler UV venus filter. I am looking into it

I do have an old red/orange filter that is well up for destruction/conversion.  I would certainly be interested Neil.

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50 minutes ago, bunnygod1 said:

I should have been using my Astronomic IR block with the No47 filter, which is used for the "L" channel when RGB imaging. 

Sounds great on paper doesn't it. unfortunately I think it still cuts some UV I am sure i read Rik L on here say that somewhere ? look into that, see if you can find any info. looking so far for glass bg39 is coming up 25 mm wide My filter holder measures 28 mm it will fall straight through. I need 28 mill still looking around here.

what we want is a bit of this pete. But I don't know about you But I don't want to pay £200

venus astrodon.png

Edited by neil phillips
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I have had a look around for a few hours and only found 25mm diameter as well. I unscrewed the retaining ring on my old filter very easily, the minimum diameter of mine looks to be around 26mm.

I did see some interesting images on Emil Kraaikamp website http://www.astrokraai.nl/viewimages.php?category=4  Including an interesting animation in infrared light (>807nm)

 

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2 hours ago, neil phillips said:

Sounds great on paper doesn't it. unfortunately I think it still cuts some UV I am sure i read Rik L on here say that somewhere ? look into that, see if you can find any info. looking so far for glass bg39 is coming up 25 mm wide My filter holder measures 28 mm it will fall straight through. I need 28 mill still looking around here.

what we want is a bit of this pete. But I don't know about you But I don't want to pay £200

venus astrodon.png

You certainly don't see them 2nd hand very often!

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23 minutes ago, bunnygod1 said:

I have had a look around for a few hours and only found 25mm diameter as well. I unscrewed the retaining ring on my old filter very easily, the minimum diameter of mine looks to be around 26mm.

I did see some interesting images on Emil Kraaikamp website http://www.astrokraai.nl/viewimages.php?category=4  Including an interesting animation in infrared light (>807nm)

 

yeah its weird I don't get how they are not fitting, though do you think the 25 mm will work with your filter holder  yeah I know them images well pukka aint they

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I will take mine to work tomorrow and measure it accurately with a digital vernier, I think 25mm will probably fall through as well. I also thought about clamping a BG39 on top of the No47 violet filter, diameter permitting.  

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1 hour ago, neil phillips said:

yeah its weird I don't get how they are not fitting, though do you think the 25 mm will work with your filter holder  yeah I know them images well pukka aint they

I have just had a thought what if a washer was available which was the correct OD to fit inside the filter housing and also a small enough ID to act as a clamp with the retaining ring clamping down on it to retain the BG39 & No47 filter in the same housing.

I am pretty sure I might be able to get something close, it just needs to be thin, but strong enough to hold the filters in position.

Is this the type of filter you would source?

http://www.uqgoptics.com/catalogue/Filters/HOYA_FILTERS_-_INFRARED_TRANSMITTING.aspx?subCatOrCatName=hoya_filters_-_infrared_transmitting

 

Edited by bunnygod1
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7 hours ago, bunnygod1 said:

I have just had a thought what if a washer was available which was the correct OD to fit inside the filter housing and also a small enough ID to act as a clamp with the retaining ring clamping down on it to retain the BG39 & No47 filter in the same housing.

I am pretty sure I might be able to get something close, it just needs to be thin, but strong enough to hold the filters in position.

Is this the type of filter you would source?

http://www.uqgoptics.com/catalogue/Filters/HOYA_FILTERS_-_INFRARED_TRANSMITTING.aspx?subCatOrCatName=hoya_filters_-_infrared_transmitting

 

I thought of a similar idea Pete, but the thickness of the filter may play a part especially if you start adding extra thickness to the filter holder. Will depth of the holder be sufficient.  Actually I am unsure of the thickness question. The Wratten fiters I have here are 3 mill thickness as far as I can measure. Those are the types of companies and filters I have been looking at too. I am no expert in these matters my knowledge is limited.

This one looks good I think. if I can verify its ideal for the job. Look at the price Pete

https://www.thorlabs.com/thorproduct.cfm?partnumber=FGB39

Edited by neil phillips
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You get the feeling astronomy is not on the radar with a lot of this. This I found corresponds with the dimensions exactly of my current filter holder I have disassembled

But and its a interesting point. Where are there glass types that fit these what can only be described as  standard fittings for astronomy equipment ?

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p4045_Cell-for-1-25--filters-with-counter-ring--M28-5-filter-thread.html

I am going to contact a couple of places to find out how to bridge the gap with these questions, clearly we want either 28mill glass or holders from any company with 25 mill glass but with M28.5 threads. did you measure yours ?

Edited by neil phillips
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Yes I measured it. The ID is 27.9mm from the threaded part to the step, then it reduces to 25.9mm. I have 7mm of room for whatever glass I decide to fit. So I need something around 27.5mm in diameter.

I have also been looking around for a Venus filter, including a BG39 glass filter. I have come across this one Optolong Venus-U Filter 1.25" http://www.365astronomy.com/Optolong-Venus-U-Filter-1.25.html on Ebay for £99.  I posted a thread in the imaging discussion area, to see if anyone had any info.

Optolong-Venus-U-filter-transmission-curve.jpgofil-bp-fuv-2-3_2_1_3.jpg

 

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Yes that measurement comes close to what I need its tempting to get something suitable and be done with it. Though the more I learn the more interesting the subject becomes Like combining UG1 with BG39 for a Schuler venus filter, Hoya 360 and UG11 also transmit UV

looking at the graph there is a very small peak in IR around 890nm it looks negligible but I am uncertain. Not heard of this interesting find Pete

Edited by neil phillips
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Personally I am still going to figure the BG39 leak problem with W47 I have read some actually prefer this filter system as it lets more light through. So a ideal situation would be to have both A U Venus filter

W47 BG39 would be more useful under poorer seeing letting more light through, faster exposure and frame rate beating the seeing.

So are you thinking of trying the optolong

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Not sure to be honest, I am tempted. That said I think i need to get clear in my mind what I should be using with current equipment I have. 

I am guessing that my asi224mc is probably the best camera for capturing the UV part of the signal. This with the No47 & IR filter, or the U filter if I get one. 

Looking at chart for the Astronomic IR filter it looks to me that is going to be better than the "L" filter that comes with the type 2 RGB set. As it at least passes something in the 300-400 nm range, according to their data 30%

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