Free Shipping on ALL Products
camera reviewsbest cameraslens reviewsphotography tipscamera forumvideo toursphotography bookssupport me
It is currently Mon Dec 22, 2014 8:19 pm

All times are UTC




Post new topic Reply to topic  [ 5 posts ] 
Author Message
PostPosted: Mon Aug 20, 2012 7:37 pm 
Offline
User avatar

Joined: Sun May 25, 2008 12:48 pm
Posts: 8052
Location: UK
Image
Today's sun... all images are 100% crops from DMK41. Best 10% of 1000+ frames.

Image
Thought I'd have a go at the prominences close up. Far from easy... since I don't have any workable barlows at the moment, I decided to use eyepiece projection with a Hyperion to T-mount to DSLR to C-mount... this was my first capture of the prominences around 4 o'clock of the disc. I blew the surface here...

Image
Here I moved over to the prominences around 8 o'clock of the disc. I fiddled a bit more with the video settings and managed to get both prominences and surface detail at the same time.

Side note: I find when I stick more glass in the chain, I can get a diagonal stripe appearing near the centre of the image. It seems to be due to the optical chain, but I'm at a loss as to what causes it, or what could be done to eliminate it.

Now I'm wondering if I can get better detail out of a regular PST (single stack), or would there be better gains from going DS or a stage 1 mod to bigger aperture scope...

_________________
Canon DSLRs: 7D2, 7D1, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 10-18, 15-85
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 50/1.4A, 150 macro, 120-300 f/2.8 OS
Compacts: Sony HX9V, Fuji X100.


Top
 Profile  
 
PostPosted: Mon Aug 20, 2012 7:56 pm 
Offline

Joined: Thu Jul 31, 2008 4:31 am
Posts: 296
great work popo. What you are experiencing is the tilt filter inside the PST. in order to get modify the view with more surface details or more prominence, they tilt the filter to change the angstrom value which in return create an uneven illumination. You won't notice when you do visual but when you capture with an DMK, you will notice.

This is why Lunt came up with the Pressure Tuner. Instead of tilting they use air pressure to move the filter so the illumination is even on all side.

_________________
Canon T2i (550D)- Tamron 17-50 F2.8 Non-VC, Sigma 70-200mm F2.8 EX DG OS HSM, Canon EF-S 55-250mm F4.5-F5.6
http://www.astronomyphotography.com


Top
 Profile  
 
PostPosted: Mon Aug 20, 2012 8:56 pm 
Offline
User avatar

Joined: Sun May 25, 2008 12:48 pm
Posts: 8052
Location: UK
I'm not sure that's it, at least not in itself. The diagonal pattern, I would have to describe as like interference fringes. You can see a small patch of it in the 3rd pic just to the left of the filament bottom centre. It is in the same place and doesn't seem to change with etalon adjustment or focus. It probably is some interference effect, but where? It only appears when I try using higher magnifications.

_________________
Canon DSLRs: 7D2, 7D1, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 10-18, 15-85
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 50/1.4A, 150 macro, 120-300 f/2.8 OS
Compacts: Sony HX9V, Fuji X100.


Top
 Profile  
 
PostPosted: Mon Aug 20, 2012 9:31 pm 
Offline

Joined: Thu Jul 31, 2008 4:31 am
Posts: 296
Condensation or dust in the optical train maybe ? Like condensation mark on a barlow ?

_________________
Canon T2i (550D)- Tamron 17-50 F2.8 Non-VC, Sigma 70-200mm F2.8 EX DG OS HSM, Canon EF-S 55-250mm F4.5-F5.6
http://www.astronomyphotography.com


Top
 Profile  
 
PostPosted: Mon Aug 20, 2012 9:51 pm 
Offline
User avatar

Joined: Sun May 25, 2008 12:48 pm
Posts: 8052
Location: UK
It's too regular to be those I think. I've not seen condensation on a barlow, but I've seen the stripe effect both with a barlow, and with eyepiece projection as I used in this case. I guess saying that, it suggests it's something to do with the PST and there's not a lot in there...

_________________
Canon DSLRs: 7D2, 7D1, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 10-18, 15-85
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 50/1.4A, 150 macro, 120-300 f/2.8 OS
Compacts: Sony HX9V, Fuji X100.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
cron

All words, images, videos and layout, copyright 2005-2012 Gordon Laing. May not be used without permission.
/ How we test / Best Cameras / Advertising / Camera reviews / Supporting Camera Labs

Webdesign by Alphabase IT
Powered by phpBB® Forum Software © phpBB Group