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Fun test shot evening with old Pentax lens

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#1 rigel123

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Posted 06 December 2012 - 07:35 PM

I had posted earlier that I was trying out the lens off my old Pentax K1000 for some widefield imaging. It's a 55mm and I was able to attach it to my ED80T with an Orion Deluxe Steady Shot, kind of in a Rube Goldberg fashion!

So here are two of the shots I did. Only 1 hour integration each with 600 sec subs. I set the lens at f5 as the stars really looked bad with the iris wide open. This could be fun to work with even though it's not the best quality lens!

Here is NGC 1499 (Kind of fun to see the plate solving identify the constellation too!)

Posted Image

And here is the Orion Area (It was a bit murky but surprised at all the dust this short integration caught!)

Posted Image

And here is the setup I used.

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#2 David Ault

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Posted 06 December 2012 - 07:55 PM

That does look like it's going to be a lot of fun. Fantastic images Warren, I look forward to more like it. How wide a field of view are you getting with that setup? Something like 6° x 9°?

#3 yock1960

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Posted 06 December 2012 - 07:55 PM

Looks good Warren and looks like fun!

This is something that is on my to-do list. I have the LXD75 sitting idle and have some lenses laying about. Just waiting on me to get'r done.

Steve

#4 rigel123

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Posted 06 December 2012 - 08:54 PM

That does look like it's going to be a lot of fun. Fantastic images Warren, I look forward to more like it. How wide a field of view are you getting with that setup? Something like 6° x 9°?


Thanks David, good estimate, according to Astrobin it is 6.81 X 9.15 degrees.

#5 rigel123

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Posted 06 December 2012 - 08:55 PM

Looks good Warren and looks like fun!

This is something that is on my to-do list. I have the LXD75 sitting idle and have some lenses laying about. Just waiting on me to get'r done.

Steve


Thanks Steve, yeah, skies don't look too hopeful for a while around here!!

#6 mikotoy

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Posted 06 December 2012 - 10:25 PM

Awesome. I have been told that achieving focus with this set up (lens, filter wheel and CCD) was not possible, but apparently I have been lied to.

#7 buckeyestargazer

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Posted 06 December 2012 - 11:22 PM

Looks good Warren. How did you attach the lens to the filter wheel? Most lenses have a bayonet mount that won't attach directly to a CCD camera or filter wheel with T-threads.

#8 rigel123

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Posted 07 December 2012 - 12:09 AM

Looks good Warren. How did you attach the lens to the filter wheel? Most lenses have a bayonet mount that won't attach directly to a CCD camera or filter wheel with T-threads.


Joel, the old Pentax lens does not have a bayonet mount, it is threaded, so I attached a 5 mm spacer ring from Orion to the lens and then screwed that into the filter wheel.

I have quite a bit of play between where the lens is at infinity and where it actually comes to focus, and it held focus without any difficulty.

I'll see if I can set it up tomorrow and take some shots with it out of the Steady Shot Bracket and do some measurements so everyone can see the actual setup.

#9 rigel123

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Posted 07 December 2012 - 12:15 AM

Now that I know it will work I'll have to re-frame the Orion one so I can get all three belt stars in the image. I didn't realize I would be able to fit all of that in!

#10 buckeyestargazer

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Posted 07 December 2012 - 12:23 AM

Joel, the old Pentax lens does not have a bayonet mount, it is threaded, so I attached a 5 mm spacer ring from Orion to the lens and then screwed that into the filter wheel.

I have quite a bit of play between where the lens is at infinity and where it actually comes to focus, and it held focus without any difficulty.

I'll see if I can set it up tomorrow and take some shots with it out of the Steady Shot Bracket and do some measurements so everyone can see the actual setup.

I would really appreciate seeing a pic of the camera end of the lens. As you may recall I'm using an old minolta lens but because I have to use a bayonet to T adapter I don't have enough room to put my filter wheel in between the lens and camera. I think with this lens I may be able to do that. I may try to pick up one of these or a similar lens.

#11 rigel123

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Posted 07 December 2012 - 12:36 AM

I'll get some shots for you tomorrow Joel and post them.

#12 SL63 AMG

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Posted 07 December 2012 - 02:54 AM

That a really cool rig. Nice images too!

Have fun.

#13 ccs_hello

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Posted 07 December 2012 - 08:36 AM

Warren,

Just to make sure..
Your stated the old lens came from an old 35mm film K1000 SLR.
In that case, it should be a screw-mount M42 lens which has a flange back distance of 45.5mm.

Per your picture, with the 5mm ring, filterwheel, OAG, and CCD imager's own flange back (front-to-focal plane distance) added together, it's way more than 45.5mm.

This is very strange. Can you explain in details?

Clear Skies!

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#14 yock1960

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Posted 07 December 2012 - 10:05 AM

I don't know about Warren's camera, but my SXV-H9 is something like 16mm from the flange, plus 25mm for the Orion filter wheel, plus 5mm would be 46mm...pretty close.

Steve

#15 rigel123

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Posted 07 December 2012 - 10:27 AM

OK, here are some closeup shots of the rig. The first is the lens itself showing the threaded end, no bayonet. (It's actually from a Pentax 1000SP, not the K) Pic 2 is the lens with the 5mm adapter to allow me to attach it to the filter wheel (the "triggers" for the iris keep me from just attaching the lens directly to the FW) Pic 3 is the whole setup and my measurement from the back of the lens to where the chip actually is in the camera. Somewhere between 40 and 43mm. Pic 4 is the business end of the lens.

Hope this helps :grin:

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#16 buckeyestargazer

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Posted 07 December 2012 - 10:46 AM

Thanks for the pics. Did you have any trouble screwing on the 5mm spacer? It looks like that lens uses a "M42" mount, which is M42x1pitch, whereas the T-thread spacer is probably a M42x.75pitch Not a lot of difference, but enough that the threading would be very tight.

#17 rigel123

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Posted 07 December 2012 - 10:50 AM

I didn't notice it being overly tight, but with a 42 year old lens that I would often screw on and screw off to change to a telephoto over the years probably boogered the threads up enough to allow this to work! :lol:

#18 J.P.M

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Posted 07 December 2012 - 02:04 PM

Lovely system, you gonna have good time with it.

#19 rigel123

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Posted 07 December 2012 - 04:00 PM

Thanks JP, it really will open up additional opportunities for different objects without having to buy any additional equipment! (Of course, where's the fun in that!!) :roflmao:

#20 buckeyestargazer

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Posted 10 December 2012 - 05:21 PM

Warren,
I just had to try this for myself, so I picked up the same lens from ebay. I was easily able to attach the lens to my Atik filter wheel and 383L camera. Took some daylight shots of the neighbor's house (don't tell him) and it looks great. Can't wait to try it out!

Could you possibly post a single sub-exposure of your California test shot?

#21 buckeyestargazer

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Posted 10 December 2012 - 05:39 PM

I set the lens at f5 as the stars really looked bad with the iris wide open.


Warren,
Can you describe what the stars looked like at faster f-speed? Do you think the adverse stars were the result of too much curvature with the iris wide open?

#22 rigel123

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Posted 10 December 2012 - 10:13 PM

I set the lens at f5 as the stars really looked bad with the iris wide open.


Warren,
Can you describe what the stars looked like at faster f-speed? Do you think the adverse stars were the result of too much curvature with the iris wide open?


They almost looked like they were affected by coma across the field, possibly it was just harder to focus them with the iris wide open than with it closed down a bit.

Here is a single 10 minute sub of the California Nebula you requested. Just stretched with Levels.

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#23 Nicola

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Posted 11 December 2012 - 08:22 AM

Looking forward to see the colour version of these ones :)

#24 Orion64

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Posted 11 December 2012 - 10:12 AM

This looks like a lot of fun! I got myself the Geoptik adapter to connect my canon 50mm to my Atik 383. Haven't tried it out, but this certainly gives me the push to take these on a ride. I am not able to take all my heavy telescopes with me on holiday, but I am surely taking my canon lens to do some narrowband wide field experimenting! :yay:

#25 rigel123

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Posted 11 December 2012 - 10:18 AM

Good luck! Now I'm torn between using this setup on the next clear nights (hopefully tonight and the next couple!) or go with the ED80T on an object I've had my eye on!!






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