QHY8 Gurus in here

[toryglen-boy]

Hi guys

Ok i picked up my QHY8 yesterday, a big thanks to mtodman who was very helpful regarding getting it going! Am wading through the mire that is the very begginers end, of a steep learning curve, and i have a few questions for the experts.

1. Is the camera meant to get as hot as it does? it feels really quite warm to the touch, all over front and back

2. How do i know if the cooling is working? how can i check the temp?

3. is there a correct procedure for switching it off? i dont want the TEC to turn off, and for all that heat to go straight to the sensor

4. Can someone please demystify taking flats with this, and a good method for doing so, infact, if anyone can point me at any good begineers tutorials, that would be better.


thanks

:)

[multiweb]

1_ Yep. it's normal.
2_ It get's hot on the outside. You'd need to install a DIY temp sensor.
3_ Just common sense - don't induce any thermal shock by opening the freezing camera straight away and putting it into a hot environment. Usually switch it off. As sson as you see water droplets on the cold finger you're good to go.
4_ Best and easiest way in an EL sheet. Aim for 9000-10000 ADU in the brightest part of the bayer matrix.

[toryglen-boy]

thats what i mean Marc, point 4 you made could have been in double dutch!! can you explain it any simpler?

thanks

:)

[dpastern]

agreed, lost me as well!

Dave

[allan gould]

It was all double-dutch to me to start off. Read the Nebulosity manual (free) and it explains the whole shebang. I made a light box with the assistance of Peter_4059 (thanks Peter) and made my flats using this. Ive included one of my recent flats made in nebulosity. If you run pix maths over it you will see it had a pix 0f ~9200 max. This is what I aimed for according to Marc and it worked brilliantly resolving the vignetting and small dust spots. Took Bias frames which you also need to determine the gain and offset to use (again see nebulosity manual). For the QHY8 I would get Nebulosity as it makes image aquisition very easy.
Regards, Allan

[DavidU]

El sheet = electro luminecence sheet
http://www.elec2go.com.au/prod10.htm

[multiweb]

Oops - sorry guys. :doh: Got carried away :whistle: Here's what works for me.
An EL (Electro Luminescent sheet) is great coz it's small/compact and you can shoot your flats under controlled conditions anywhere anytime. Don't have to wait for twilight (evening or morning).

When you shoot a flat, let's say 1s You get a big bright spot in the center dimming towards the edges with the occasional black dust spots there and there. If you use nebulosity do a preview then roll your mouse over the brightest part of the frame and note the ADU value for the pixels you roll over (bottom right in the status bar). Aim for 9000 approx.
When you've determined your ex time, shoot 40 of them and stack them into one master flat. To learn about calibration frames you'll need to do a bit of reading. There are tutorials on this site in the resources section.

[dpastern]

Is this what you're referring to Allan?

http://www.stark-labs.com/downloads_files/Nebulosity2Docs.pdf

Dave

[toryglen-boy]

whats a good gain, and offset?

[allan gould]

Yes - and the gain and off set determination is explaned in there as well.
I use 1% gain and 65 offset as determined from my bias frames of ~0.001 sec, however each camera is an individual and you need to determine whats best for yours.
Allan

Edit:- I forgot to mention, once you have determined your flats for an imaging session you dont chance camera orientation, focus, etc or you have to do new flats for that setup. They are easy to so once you get the hang of it. B dont do what I did and have the scope pointing up with the ligh box balancing on top. Got messed up with the power lead and it came off and hit me on the head. Ouch.

[dpastern]

More to read, doh! Thanks Allan.

Dave

[multiweb]

Depends on your camera. But I use Gain 1 Offset 60 for everything (RGB, Narrowband). With this camera there is absolutely no point pushing the gain. I use 1 but you could use 0. I only use 1 because it gets written into the FITS header and CCDStack chucks a BF if the gain is 0 in the file. Other than that Craig S. says Offset 110 works fine. In my case I try to get the background ADU to 900 or 1000ADU max. Offset 110 gives me too bright backgrounds. But hey, that's my cam. Experiment with yours.

[toryglen-boy]

ok, now this is a FAR steeper learning curve than i thought ...

my flats come out in negative, white background with a dark splodge in the middle, and after trying an image of NGC 6357 (as its the redest thing i have ever seen) it came out blue! as did the Horsehead last night ...

:question:

[toryglen-boy]

ok, M8 and M16 have came out blue, and TBH i dont see an advantage with this over a DSLR, although maybe thats just me. the bit rate of the image looks indentical.

I wanted this to be a hobby, not something thats unfathomable and makes me pull my hair out !!

will give this a couple of days, then if still no joy, put it up for sale.

:confused2:

[TheDecepticon]

Ha ha! :rofl:I tried to do 6357 last night also, with my QHY8 that arrived Thursday from Gama. Great service and expedient delivery!:thumbsup:
I have had all the trouble in the world doing the flats until I contacted a more experienced imager. I had an ok colour to the nebula, but I had red rings around the edges of my image. I too thought that the transition from DSLR to QHY8 was gonna be easy,:lol: WRONG:lol:! What software are you using to capture & stack your files?:question:

[marki]

Duncan, what format are you saving the images in and what software are you using? If you are saving in FIT's format the image will be grey scale. When you convert to colour the result may depend on your software settings. For example I use MaximDL and in the convert to colour window I can choose a lot of different camera models. If I choose some of the canon options it delivers images from mild red to over the top red. If I choose SBIG every thing is blue on the same image. Be patient the learning curve is not that steep. It won't be long before you will see the difference cooling makes.

Mark

[toryglen-boy]

Exactly

I am using MaximDL 5, and DSS. I have worked out the colour thing, i had to set the X and Y offset when debayering. Any advice on flats would be good mate, mine are currently white, with a black splodge in the middle ...

Here is my first attempts ...

[toryglen-boy]

I hear you mate, i have had all sorts of obstacles. first off was getting the MPCC at exactly the right spot, although i am still convinced its not right, secondly was getting the focus sorted, and as you can see thats still not right. third, i am starting to realise that to get the accuracy that i want, i will need a better mount than an EQ6.

as for converting to colour, i am going to the option called "convert to RGB" and just checking the offsets.



hmm !


:question:

[marki]

Have you read this?

http://www.iceinspace.com.au/forum/showthread.php?t=50012

Black splog??? The camera is not icing up is it? Usually the centre will be best illuminated with vignetting toward the outsides depending on your scope.

Mark

[marki]

If you look to the right next to the offsets there is a drop down menu that lets you select camera type, it sets the offsets for you.

Mark

[toryglen-boy]

Thanks for that Marki, the trouble is, even that thread talks about stuff that i dont understand, the camera isnt icing up, as the images taken with it look ok, but my flats appear to be in negative.

:question:

[Tandum]

I've been capturing with maxim and stacking with deep sky stacker. You can select QHY8 FITS files in DSS under settings RAW/FITS.

[marki]

Duncan, I use a light box I made up and shoot about 40 x 2 second exposures with the light on (light flats) and 40 x 2 second shoots with the light off (dark flats). These are then calibrated in maximdl to make a master (process tab --> make master frames). As others have said you can go to town trying to find the best value for your camera.


Mark

[toryglen-boy]

ok then, so a lightbox is the way forward?

i am sure i will crack it, its just at this stage, i dont see much difference between this and the Canon 1000D !!

[marki]

I edited below. To make master frames in MaximDL 5, process tab --> make master frames. Fill in the fields and it will do it for you. The biggest difference is noise or lack of it. Once you get the hang of it it will make your processing easier.

Mark

[toryglen-boy]

thanks for all your advice so for Marki

Should flats be applied before debayering?

:question:

[TheDecepticon]

I ended up pointing my scope towards the window this afternoon and doing flats that way. The window has a heavy lace curtain over it and while it is reasonably bright, it is quite diffuse. I then used Nebulosity 1 to take the flats and used the pixel info dialouge box to tell me the the maximum exposure time. I ended up with 1 second flats at about 11000adu. I am using Deep Sky Stacker and you just chuck in all your files and give it 5 or 10mins and it does the lot for you. As long as all your images are the same size in height and width, it shouldn't be a drama. In the panel on the left in Deep Sky Stacker towards the bottom is a title of RAW/Fits. Hit this and then the fits tab, select the "treat all monochrome...." and underneath is a drop down box to select your camera for colourization. I use the AHD option just below this also.
In MaxIm, I select generic for clouring, it is reasonably accurate.
Good luck.

[marki]

Yes mate, all calibration is done to the monochrome image before debayering or stacking as it will not work properly. Each sub has to be calibrated individually before debayering or stacking. This can be automated in Maxim to remove some of the grunt work. There is a tutorial on the maxim website under calibration.

http://www.cyanogen.com/maxim_tut.php

Mark

[multiweb]

That's because you didn't subtract the bias prior to divide the flat into your light subs so you're over correcting. You need to calibrate your frames prior to do anything else. That is debayering & aligning.

[multiweb]

Hi Duncan so I don't confuse the issue, here's a generic flow that you can refine - should be a good starting point for you:

1_ Take 40 flats at 9000ADU and stack them into one master.
2_ Take 40 bias and stack them into one master.
3_ Calibrate all your light frames (subs)
4_ Save them into a "calibrated" directory
5_ Debayer all your subs into a Red, Green & Blue directory (separate channels)
6_ Select the best sub in each channel to register to and align.
7_ Do your data rejection, stack to mean. Build the three color masters (save as FITS).
8_ Create you color by combining the masters (save as FITS).
9_ DDP/Deconv then save as a scaled TIFF.
10_ Season to taste in Photoshop.

[multiweb]

This can happen during calibration when you subtract the bias and end up with a negative ADU in the dark areas. All you need to do is a pixel math on your subs to add the negative offset. Aim for 100ADU overall then resave your file as a 16bits FITS, DDP again and you'll be back in business. No fringing or funky colors anymore :)

[toryglen-boy]

Some good advice there fella, although i think i need to go back to school, as i got lost from point one onwards !!

;)

[multiweb]

No doubt there's a fair bit of reading but IMHO understanding calibration frames is critical and is going to make your life sooo much easier. There's a lot of litterature about it. Doesn't matter what program you use, the concepts are the same. :)

[marki]

Thats interesting Marc, I only ever use bias frames when building a master dark. Have never tried it on the flats, will have to give it a go. Perhaps what you are doing is similar to what I do with dark flats??? I take a series of light flats and a series of dark flats then combine to make a master flat.

Mark

[dpastern]

Plus 1!!!

Dave

[multiweb]

Yes it's the same thing because your dark already contains the bias needed to scale the flat prior to divide. If your bias subtract your flats prior to stacking them then you don't need to do that.

[Tandum]

All this has got me totally confussed. I just treat the the QHY8 as a 16bit DSLR, which it is. That means it can take longer exposures without saturating star colour and since it's cooled, darks are not as important. As for subtracting this bias file from that flat file etc etc , I wouldn't know how to do it, nor does the software I use. I just load everthing into DSS as I was doing with the canon, tell DSS it's a QHY8 and go. I must admit I've only shot a handful of images with it but I've never had a problem either.

[multiweb]

Whether it's a QHY8 or a DSLR the process is the same. I did follow the same procedure when imaging with my Pentax *istD. Calibration is something that helps getting the most out of your hard earned data. Bit of reading goes a long way. I used DSS in the past and it confused the hell out of things because I didn't understand how it worked or how I could control things. To me it's a black box. You shove a lot of subs, flats and darks and you get something on the other end. Sometime it works, sometime it doesn't. CCDStack was a giant leap because it forces you to understand what you're doing, not just pushing buttons.

[Tandum]

Then you are looking for something more than me. I always remember that I first plugged my camera into the scope cos I couldn;t see anything in an eyepiece. A camera was the only way to see the objects, so I'm not after an apod, just a better view. I've used almost all the software available to stack/combine except ccdstack and they are all black box, as you call it. I don't see your images being any better than someone using maxim or dss or anything else, so your controlling what is happening makes it better thoery is crap. Sounds like reteric from an air buss driver to me.

[multiweb]

:rofl:

:lol: You're some piece of work dude! :nerd: Duncan's original query was about "demistifying flats" and the thread is about understanding calibration and other techniques with the QHY8. If you're not interested have a look at another thread instead of posting negative comments. I just share information based on my experience and "what works for me" in order to help others. It's not about who thinks he's right or better or as good as the others. That is your view only. We're all having fun taking pictures and showing them off. No more no less. BTW if you are chasing an APOD you'd better brush up on your spelling for the editorial. IMHO. :thumbsup:

[mtodman]

Hi Duncan,
I've just added to my website a brief description on how I captured flats for the QHY8 using MaximDL. It seemed to work well for me. Perhaps it could help.
http://www.astroromp.com/astronomy/shooting_flat_frames.htm

I'll try and work on a more comprehensive description in the coming days that covers how I processed the images using calibration frames.
Matt

[toryglen-boy]

Matt, you've been an absolute saint through this, and i think your work is done !!

thanks heaps mate, its appreciated

:)

PS. after i got back, i had terrible sunburn on my head and arms ...

[DavidU]

How's it going Duncan? Still tearing your hair out?
Or are you getting a handle on it.

[toryglen-boy]

Hey Dave, thanks for your concern! still tearing my hair out. There are a few things that throw me, namely the terms used, and the procedure. i have taken a few pics, but TBH, i cant see much difference between the QHY8 and my Canon, i got the CCD for two reasons, cooling with longer subs, and a great colour bit depth, although i am yet to see this in my images, but thats no reflaction on the equipment, merely me being a n00b.

I almost gave up imaging with the Canon, as i found that difficult, although i got there in the end, i am sure i will get there with this to, although the learnign curve is VERY steep.

do you know, do you have to keep the IR nosepiece on? or can you put anything you want on there? i took it off, and just used a camera adapter, with the MPCC attached.

:)

[multiweb]

Got to be careful if you remove the nose piece. The camera will ice-up real quick if there is moist air inside. I currently use a MPCC with the nosepiece glass off but I blow dry the air in the camera and adapter prior to assemble. It works fine for me.

[toryglen-boy]

Thanks for that Marc. i was putting the CCD and MPCC in a clear plastic bag, filling the bag with warm air from a hairdryer, and throwing a few bags of silica gel in there, and then assembling the whole lot, with the bag tied shut

:)

[multiweb]

That'll work nicely although you don't have to go to that extreme unless you do this outdors, then yes the bag trick is good.

I usually assemble indoors. Hold the camera without the nose piece face down then blow air up in it (warm - not hot). Do the same for the spacer and MPCC in the cavity then quickly assemble them.

One thing I did too was to tape all around the body of the QHY8 with black electrical tape to "seal" it. Both from light leaks and air. Also siliconed around the power/USB plugs. I also recently got some silica gel strips from Theo to stick on the walls of the spacer but I haven't had any problem so I didn't use them as yet.

One thing to keep in mind is the orientation of your camera too. If it points down the cold air will fall on to any glass surface at some point and you will fog up. So just look for that when you choose your target to image or side of the meridian.

Learnt that the hard way when shooting flats with my 67mm pentax lens and I sat the QHY8 face down on my EL sheet :P First two 0.5s flats were fine. Took less than a second to fogup the lens.

[toryglen-boy]

Marc, how do you attach the MPCC? i think i have my spacing correct with the rings etc, but i cant be sure.

i am pretty certain its sitting at 55mm away from the CCD, although i have to remove the IR Nosepiece to do this.

;)

[multiweb]

Ha... that's another one I got stuck on for months. :lol: I ended up getting a custom spacer done from http://www.tan14.com/gears.htm. On my 5" newt I need 53.5mm. On the ED80 closer to 56mm. So I have a telescopic adapter that gives me nearl20mm travel on each side. I posted a pic to this reply.

The nose piece is approx 13mm, the sensor plane is approx 6mm from the outside face of the camera so you already have 19mm there minus 55mm that gives you approx 36mm for the spacer on top of the nose piece.

You will find that keeping the nose piece with the MPCC gives you terrible results on bright stars. Light bounces like crazy and you get secondary reflections everywhere.

[pmrid]

Do you mind explaining how you arrived at the figures mentioned - 53.5 and 56 mm? Is it just trial and error or is there a formula?

Also, with the adjudtment rings, did you buy them as a set from Peter Tan or did he have them made up to your design and specifications? Obviously, the idea strikes me as a good one - using the final threaded adjuster with the little lock ring. If someone isn't making this as a set they probably should.
Peter.

[multiweb]

Yes Peter, trial and error. I took pictures of Alpha Crux centered on the CCD chip and run the subs through CCD Inspector measuring the spacer with an digital caliper.



I originally bought the solid spacer he sells for the QHY8, But I couldn't shorten it. I did some test by moving the spacer away and I was over correcting so I figured I had to shorten the distance and in order to do that I needed a shorter spacer. I wasn't ready to stuff around with different lengths rings so I worked out this spacer and send him the drawing see if he could do it and it worked a treat. :thumbsup:

I googled all over the place for one and nobody made any. I was really surprised because to me it's just common sense to have an adjustable spacer for field flateners or coma correctors rather than fixed length rings. :shrug:

[allan gould]

Nice solution for the adjustment rings. I should state here that instead of an MPCC I use the Lumicon field flattener which is a 2" screw in optic. See here http://www.telescopes.com/telescope-accessories/general-accessories/2inchthreadinfocalreducer.cfm. In conjunction with the Lumicon low profile 2" adapter http://www.lumicon.com/telescope-accessories.php?iid=LA1080&cid=33&in=2in+Male+-+T-Thread+Male+Prime+Focus+Adapter+Low +Profile&hn or here http://www.myastroshop.com.au/products/cam-adapt.asp 3/4 down the page. The adapter screws into the filter holder of the QHY8 and then the FF screws into that. Simple and a flat field over the entire chip. It gives me better correction than the meade f6.3 focal reducer/FF.

[TheDecepticon]

I couldn't find it in here, but did I read some where about reflections pertaining to the filter glass in the noise piece of the QHY8? If I want to do RGB with the camera, do I need to use the UV/IR glass or can I take it out and just use the extension on the front of the nose piece with out the UV/IR glass and the MPCC? If I'm using a reflector, how does this affect my images in respect to star bloat/bleeding, UV or IR saturation? I have a 1.25 inch filter wheel that I'm gonna use(loss of field, vignetting, etc all understood already) with Ha, OIII & SII filters, so I don't need UV/IR for those, do I? Would it pay to use my 1.25" UV/IR filter in the filter wheel to capture a bit of RGB to go with my narrow band images?:shrug:
This is a great thread for the QHY8. Maybe we should make it a sticky, moderators?:hi:

[DavidU]

I 2nd that. Excellent stuff.

[Gama]

You need a IR block for the color chip, as IR will bloat your stars because it will pass thru the filters you place in line (Unless they themselves have IR Blcok).
Leave the IR block in line.

Theo

[multiweb]

I have a null adaptor which is a nosepiece without any glass. If you use any nosepiece with the MPCC you will get bright secondary reflections on bright stars. Not too bad on the UV/IR but a shocker with the clear one. For example you won't be able to image the HH or the pleiades without reflections but a lot of other targets won't be affected, like diffuse nebulae (i.e tarantula, eta carina, etc...)

When doing narrow band there is no need to have extra glass in the optical train. Just your NB filter and the MPCC on top of the null adaptor.

[toryglen-boy]

Yo Marc, i was under the impression that you couldnt do NB imaging with an OSC Camera, and if you wanted to image at different wavelengths, then you had to do this via mono and a filter, isnt this the case?

:question:

[TheDecepticon]

Ok, so we have an opposite here.:confused2: When you image without a glass in the noise piece Marc, how do you control the IR bloat of the stars Gama talks about? This sort of answers my own question, which is to use my Astronomic IR filter in the wheel for RGB shots.:) Ha, SII & OIII should supress the IR, at least I've never used them with my Meade DSI Pro II, but that is a mono camera.

[multiweb]

Nope. The QHY8 works fine for NB pics. I posted a lot of NB shots on these forums done with the QHY8 and NB filters. Ha & Sii go into the red pixels so you debayer and keep the red only (monochrome image). Oiii goes in the blue and the green and you do the same.



I wouldn't know about a filter wheel as I never used one but the reflections I was having were happening between the CCD and the MPCC. That's why I got rid of any extra glass in that area. I now put any filters before the MPCC, so that's the first glass the light hits. Whether it's a Ha, Sii, Oiii, or the UV/IR filter.

[marki]

I imagine SII data would take a while to collect with a OSC. Is that the case Marc?

Mark

[Hagar]

Hi Fellas, I have been watching this thread with interest. I don't use a newtonian so really have not been able to add anything to the discussion about the MPCC spacing and configuration but I maybe can add a few things now that narrow band imaging has come into the arena....
The QHY8 is very capable in recording NB images. Two methods I have used which seem to be quite reasonable are:
1. Capture using 2x2 binning as the images captured don't make use of the bayer matrix and images captured are mono only and can be stacked and compiled as if it was a truely mono camera.

2. Capture the images as if normal RGB with the NB filter fitted. Depending on the software you use and how narrow the filters band is you will in most cases be able to reduce your image to a luminance only image which contains almost all light which passes the filter again as a mono image. In the case of my capture software (Nebulosity2) it has a menu item under the image menu Keep Lum and discard colour. Again the images can be stacked,colourised and combined to produce very acceptable NB images.

Although the OSC camera is not as sensitive as a mono camera good results can be achieved with NB images without talking very extended image capture sessions compared to the mono camera.
I have tried a lot of capture software and still maintain that nebulosity is one of the best and easiest capture programs available at a reasonable price. It also has a lot of neat little features built in to the processing routines. Well worth having a look at it.

Good luck Fellas. Look forward to seeing some great images.

[allan gould]

Hagar
Really interesting message and has made me was it to NB imaging at one stage. And I agree with you that Nebulosity is the easiest program for capturing. Realy like it.
Allan

[multiweb]

It does indeed. But there's not much of it to start with I was told so that would be true for any camera including mono :shrug: . Although the QHY8 QE is not as good in the reds as in the green so Oiii is certainly much easier to capture. Ha is pretty easy too though in my experience.

[multiweb]

Hi Doug I have tried bin2x2 for Ha (once) and I collected more noise from the other channels than just doing bin1x1 and keeping red only, discarding blue & green. Maybe I'm doing something wrong with bin2x2 but having said that I gave up the idea of binning so I don't have much more to say on it. Do you use bin2x2 a lot?

[h0ughy]

It is a good thread and full of useful stuff - I will be using this on the 127ED and the Vixen R200SS. I bought the MPCC and the spacer kit from Myastro a while back to use with the nagler eyepieces i had and the meade lightbridge 16 i owned at the time - then i got the qhy8. Reading this i can see the merits of the adjustable adapter. I clicked on the link but they don't list your adapter? is it that custom made that he doesn’t list it? Can you supply the cost of the unit and the exact details you asked him to make?

[marki]

Thats what I thought Marc, it always took longer to get good SII data with a mono and they are more sensitive then a OSC.

Mark

[Hagar]

Hi Marc, I used 2x2 a bit when I had the FS102 but since getting the FSQ the pixel scale is rather large when binned so I now just stick to 1 x 1 . Unbinned = 2.99 pixels / arc sec 2 x 2 binned = 5.94 pix / arc sec.

I haven't really given it a try but will get around to it at some stage and see what the results are like. For narrow band I tend to use the method I stated using nebulosity and keeping the Lum layer as the narrow band filters are quite selective in what is passed that you can get away with this method at least with 7 nm Ha or smaller filters. Detail is usually quite good and exposure times are not unreasonable.

[Hagar]

Hi David, Peter is a wonderfull dealer to deal with but you will need to send him an email and probably copy in Marcs image of the adapter and he will no doubt be able to help you. He has made me all sorts of bits and pieces over the last couple of years and makes them quite quickly and usually very reasonably priced. His email address is at the bottom of the page. His name is Peter Lee.

[multiweb]

Hi David, here's the basic drawing I sent to Peter. You'll have to tweak the distances to suit your scope but the basic concept is there. As PMd you'll have to discuss the specifics with Peter.

[multiweb]

Got it. I re-read the post. I use Neb2 as well but I never used the Keep LUM only option. I usually just load the raw FITS in CCDStack. Will try that - thanks. :thumbsup:

[h0ughy]

thanks - i wonder if there is a need to reinvent the wheel?;)

[multiweb]

More than likely he has kept the manufacturing drawings but that's all that I've got and that I've given him - he worked it out. What I'm saying about sizes is that I'm not familiar with your scopes but it'd be fair to assume it will work in a similar way.

[TheDecepticon]

Thanks for supplying the tech drawing of your adapter, I was going to ask you about this. I think it is brilliant.:eyepop:
Do you remember how much it cost. Also, guys, if several of us want it made, do we do it as a group and get a bulk order together, and one person can act as the agent, do the re-posting, payments, etc??:shrug:

[TheDecepticon]

And I forgot to ask, you use this in conjunction with the adapter kit that comes with the MPCC?

[DavidU]

Thats a fabulous adaptor Marc !

[multiweb]

Thanks guys. It makes sense to have something adjustable. I think there is too much money in the rings/spacers business so that would be why this is not mass produced or readily available IMHO :confuse3: Having said that talk to Peter about pricing. I know David is interested too so if he gets enough orders you might get a price for abulk. He might even consider making and stock it in the future, who knows?




I use it with the MPCC only. I don't use any rings that came with the MPCC kit. I also calculated the distances so I could get rid of the nose piece all together, but later on I still bought a null adapter.

[pmrid]

May I clarify an issue with the spacing of the MPCC in relation to the film plane (or plane of the CCD in the QHY8). I attach a snippet from the MMPC blurb from the manufacturer which suggests a distance of 55mm from the imageing chip to the outer rim of the T-Ring. Can this be right? I was having a look at Marc's tech drawings that were the basis of the variable adapter he had made by Peter Tan and started counting diatances again and now I am quite at sea over this whole issue. Can someone clariffy please?
Peter

[multiweb]

This is correct: 55mm +/-2mm is the recommended distance by the manufacturer. That may slightly vary depending on the scope/camera combinations you're using though but it's a good point to start from.

[pmrid]

OK. That 55mm +/- 2mm from the CCD image plane to the outer edge of the T-RIng. So with a standard DSLR there is probably no need for the variable adapter you had made. It's use would be with CCD cams such as a QHY8 or Orion where the distance from the CCD chip to the ouser edge of the camera would only be 10-12 mm or so. The variable adapter would allow you to take that up to 55mm and THEN you screw in the MMPC. Have I got that right?
Peter

[ejcruz]

QHY8 CCD chip have a distance of 7mm from the chip to the top of outside casing or ~21mm from the chip to the nose piece, therefore you will need ~34mm of adapter spacing to the MPCC.

Cheers
Eddie