#1  
Old 10-07-2017, 04:22 PM
Atmos's Avatar
Atmos (Colin)
Ultimate Noob

Atmos is offline
 
Join Date: Aug 2011
Location: Melbourne
Posts: 6,980
High Res at F/2.8-4 or Low Res at F/1.4?

My plan for this coming new moon has been to do a 36 panel mosaic of the Milky Way with my Nikon D7200 and a Sigma Art 85mm F/1.4. It's FOV will be kinda similar to that of my 14mm + D7200 but as a 3.5 gigapixel image.

The star shapes with the D7200 @ F/2.8 at the frame corners are reasonable, reasonable enough that I'd consider using it again although I may test dropping it a fraction slower to see how much things tighten up. I know that I would be able to get 2x300s images per panel per night so the end result would basically be the number of nights I spent out doing the imaging.

About an hour and a half ago I started thinking about the possibility of blowing the dust off of my D700, doing a 16 panel with an even larger FOV and running the Sigma @ F/1.4!

The D700 is a 12mp FX sensor with 8.445 micron pixels and an anti-aliasing filter. The D7200 is a 24mp APS-C sensor with 3.91 micron pixels and no anti-aliasing filter. In short, I think I could run the D700 @ F/1.4 and still have near perfect stars in the frame corners!

As much as I love the idea of the resolution that the D7200 achieves, there is a part of me that wants to see what the sky looks like with 30 minutes per panel (per night) @ F/1.4! There is another part of me that also knows that there is greater contrast to be achieved with higher resolution.

Thoughts? Comments? Suggestions?
Reply With Quote
  #2  
Old 10-07-2017, 04:56 PM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 17,877
The rule is that full frame always kicks APSc butt no matter how much the APSc crowd claim otherwise.

I recently shot Rho Ophiuchi with both my Sony A7R2 (full frame) and a Fuji XT2 (APSc). The difference was more than I expected in favour of full frame. I know the A7r2 sensor is the best there is at the moment but still the APSc sensor in the XT2 is also the best there is in APSc world. Its kind of not even close for this sort of thing. Sure you can get good results with an APSc but physics says Full frame is covering a 1.5 -1.6X more real estate catching light.

You'll need less panels, you'll get less noise, 12mp is plenty for a panorama and I don't think Milky Way shots look necessarily better in high MP shots. Its a low rez sort of target.

I mean look at the Proline 16803. Its almost medium format size yet its only less than 17mp! Yet I don't think too many would argue about its performance.

I just acquired 4 panels of Milky Way goodness with the Proline and a lens and plan to acquire more next new moon.


Greg.
Reply With Quote
  #3  
Old 10-07-2017, 06:33 PM
Camelopardalis's Avatar
Camelopardalis (Dunk)
Drifting from the pole

Camelopardalis is offline
 
Join Date: Feb 2013
Location: Brisbane
Posts: 5,425
That would be an interesting comparison Colin...start with the D700@1.4 and then move on to the 7200

There's no magic when it comes to the laws of physics, but I'd estimate that the sensor in the 7200 has better QE than that in the 700, it's just being compensated for by the larger pixels.

In Greg's example, I'd speculate that Sony is keeping technology (or perhaps smoothing algorithms...) to itself.

Full frame is always going to work out more convenient because of the fewer panels, but it if the aberrations towards the corner are more apparent on FF then you might need to crop more than you'd bargained for.
Reply With Quote
  #4  
Old 11-07-2017, 08:40 AM
sil's Avatar
sil (Steve)
Not even a speck of dust

sil is offline
 
Join Date: Jun 2012
Location: Canberra
Posts: 1,474
I would go outside asap and just take quick test shots to see. Maybe put the southern cross in the middle of both shots so you can compare detail with something familiar and also judge colour/contrast of milky way and nebulosity nearby and decide on that. Either way I think planes and satellites might be your biggest complaint either way in the end. Its the colour and constrast across the sky that makes the shots dramatic more than the teensy tiny stars.

My own experience stitching full sky is the wider the lens the more distortion there is (curvature) and mosaic stitching can have problems with that more than using a less wide lens and more shots.
Reply With Quote
  #5  
Old 11-07-2017, 01:00 PM
JA
.....

JA is offline
 
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 2,945
Quote:
Originally Posted by Atmos View Post
My plan for this coming new moon has been to do a 36 panel mosaic of the Milky Way with my Nikon D7200 and a Sigma Art 85mm F/1.4. It's FOV will be kinda similar to that of my 14mm + D7200 but as a 3.5 gigapixel image.

The star shapes with the D7200 @ F/2.8 at the frame corners are reasonable, reasonable enough that I'd consider using it again although I may test dropping it a fraction slower to see how much things tighten up. I know that I would be able to get 2x300s images per panel per night so the end result would basically be the number of nights I spent out doing the imaging.

About an hour and a half ago I started thinking about the possibility of blowing the dust off of my D700, doing a 16 panel with an even larger FOV and running the Sigma @ F/1.4!

The D700 is a 12mp FX sensor with 8.445 micron pixels and an anti-aliasing filter. The D7200 is a 24mp APS-C sensor with 3.91 micron pixels and no anti-aliasing filter. In short, I think I could run the D700 @ F/1.4 and still have near perfect stars in the frame corners!

As much as I love the idea of the resolution that the D7200 achieves, there is a part of me that wants to see what the sky looks like with 30 minutes per panel (per night) @ F/1.4! There is another part of me that also knows that there is greater contrast to be achieved with higher resolution.

Thoughts? Comments? Suggestions?
Hello Colin,

If you can get "near perfect stars" in the corner of your full-frame option (D700 @ f/1.4), it (the corners) will only get better with the same lens used at APS-C sensor size (referring to your 2nd paragraph,in which you say that the
D7200 @ F/2.8 is only "reasonable") .

The Sigma Art lens is a great choice of 85mm lens for low coma & astig. abberations.

In choosing beteween the D700 and D7200 for your task, I would also look at the difference in long exposure noise - Take dark frame images from both at your intended exposure and then even hype the sensitivity and exposure time further to see what differences can be revealed. Dark frame subtraction is not perfect (either in camera or post), so I'd opt for lowest noise out of camera as important, as evidenced by the amount of dark frame noise you see.

Whilst the D700 is a wonderful camera, with great big pixels, it comes from a while ago (2008) and the D7200 (circa 2015) has about 2 stops better dynamic range below 400-800 ISO and equal dynamic range above that. The D7200 also has much lower read noise, which is where I think its increased dynamic range advantage at lower ISO comes from. The D700 unfortunately also doesn't share the same 1 stop dynamic range advantage over other Nikon APS-C sensors across the board as the more recent Nikon FF DSLRs (D600, D610, D750, D800, D810, etc).

Best
JA

Last edited by JA; 11-07-2017 at 01:18 PM.
Reply With Quote
  #6  
Old 11-07-2017, 02:58 PM
RickS's Avatar
RickS (Rick)
PI cult recruiter

RickS is offline
 
Join Date: Apr 2010
Location: Brisbane
Posts: 10,584
Quote:
Originally Posted by JA View Post
Whilst the D700 is a wonderful camera, with great big pixels, it comes from a while ago (2008) and the D7200 (circa 2015) has about 2 stops better dynamic range below 400-800 ISO and equal dynamic range above that. The D7200 also has much lower read noise, which is where I think its increased dynamic range advantage at lower ISO comes from. The D700 unfortunately also doesn't share the same 1 stop dynamic range advantage over other Nikon APS-C sensors across the board as the more recent Nikon FF DSLRs (D600, D610, D750, D800, D810, etc).
The D700 has pixels with more than 4 times the area of the D7200 pixels. Unless Colin is taking short, heavily read noise limited subs, that's what matters when it comes to SNR.
Reply With Quote
  #7  
Old 11-07-2017, 04:18 PM
Atmos's Avatar
Atmos (Colin)
Ultimate Noob

Atmos is offline
 
Join Date: Aug 2011
Location: Melbourne
Posts: 6,980
Thanks for the comments.
Sensor technology wise the D7200 slaughters the D700 having a lower read noise at ISO100 (~2.1e-) than ISO1600 (~4.2e-) so the dynamic range of the D7200 is a little higher at ~13.85 vs ~10.

To give a bit of an idea of the optical cover up the D700 has, here is a comparison taken with my Nikkor 85mm F/1.8G lens, same subject but different cameras.

D700 @ F/1.8

D7200 @ F/4

Personally I think the best range for FX sensors is between 24-36mp (D750-D810), larger than that and it really starts stressing many of the lens' on the market.

Might do a little testing tonight and see how it gets. 1s exposures at ISO1600 should be all that's needed at F/1.4
Reply With Quote
  #8  
Old 11-07-2017, 06:31 PM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 17,877
Personally I think the best range for FX sensors is between 24-36mp (D750-D810), larger than that and it really starts stressing many of the lens' on the market.

Might do a little testing tonight and see how it gets. 1s exposures at ISO1600 should be all that's needed at F/1.4 [/QUOTE]

DXO measures lens performances. Lenses always score higher with higher MP sensors like A7r2 and Canon 5DSR than the same lens with a lower MP sensor. Its true you start to see some deficiencies with some lenses with higher MP sensors but night sky images are not as high res as a daytime landscape shot. So its not quite true that lower MP cameras match most lenses better. Its more true that you will get more res out of the same lens with the higher MP sensor. My Sony A7r2 with 42mp is better than the D800e and the earlier A7r (same 36mp sensor) in resolution (but not really in noise performance, perhaps a tad).
I would love to see your Sigma Art 85mm wide open at F1.4 to see how that works out. I am currently interested in the Sigma Art 14mm F1.8 but its expensive and as pointed out 14mm tends to curve the image a lot and put strain on the stitching software leaving elongated stars above the MW bow very often.
21mm does not do that.


Greg
Reply With Quote
  #9  
Old 11-07-2017, 09:21 PM
Atmos's Avatar
Atmos (Colin)
Ultimate Noob

Atmos is offline
 
Join Date: Aug 2011
Location: Melbourne
Posts: 6,980
Very limited in what I've been able to do with a near full moon and the horrible light pollution. I have however attached a 5s F/1.4 shot just sitting on a sturdy tripod. I did a fairly heavy gradient removal but it definitely needed a flat frame.

I think I will at least have to do some testing with the D700 under dark skies to see how it can perform.
Attached Thumbnails
Click for full-size image (F:1.4.jpg)
167.2 KB59 views
Reply With Quote
  #10  
Old 11-07-2017, 09:35 PM
Camelopardalis's Avatar
Camelopardalis (Dunk)
Drifting from the pole

Camelopardalis is offline
 
Join Date: Feb 2013
Location: Brisbane
Posts: 5,425
Yeah I used to have the 35mm Sigma f/1.4...it didn't need much exposure on a Canon 6D and reasonable ISO. I'm not convinced dark noise is going to be a big problem, unless you're shooting on a 40 degree night
Reply With Quote
  #11  
Old 11-07-2017, 09:58 PM
Atmos's Avatar
Atmos (Colin)
Ultimate Noob

Atmos is offline
 
Join Date: Aug 2011
Location: Melbourne
Posts: 6,980
Considering that my entire night imaging night is going to be below 0ºC, I am not too worried about thermal noise. Only the noises I make then I start loosing feeling in my fingers
Reply With Quote
  #12  
Old 12-07-2017, 07:44 AM
Camelopardalis's Avatar
Camelopardalis (Dunk)
Drifting from the pole

Camelopardalis is offline
 
Join Date: Feb 2013
Location: Brisbane
Posts: 5,425
Reply With Quote
  #13  
Old 12-07-2017, 08:32 AM
RickS's Avatar
RickS (Rick)
PI cult recruiter

RickS is offline
 
Join Date: Apr 2010
Location: Brisbane
Posts: 10,584
If you shiver enough there's no need to turn on dithering
Reply With Quote
  #14  
Old 12-07-2017, 04:06 PM
Atmos's Avatar
Atmos (Colin)
Ultimate Noob

Atmos is offline
 
Join Date: Aug 2011
Location: Melbourne
Posts: 6,980
If i have all of my numbers correct the D700 @ F/1.4 should be about 12x faster than the D7200 @ F/2.8. This includes me assuming a QE of 40% for the D700 and 60% for the D7200 (newer sensor).

On paper, one 8 hour stint with the D700 should be worth near a fortnight of D7200 8 hour runs!
Of course, there are a lot of things that are nice on paper but don't quite travel well into the real world
Reply With Quote
  #15  
Old 12-07-2017, 08:30 PM
Joshua Bunn's Avatar
Joshua Bunn (Joshua)
Registered User

Joshua Bunn is offline
 
Join Date: Oct 2011
Location: Albany, Western Australia
Posts: 1,459
Quote:
Originally Posted by Atmos View Post
If i have all of my numbers correct the D700 @ F/1.4 should be about 12x faster than the D7200 @ F/2.8.
Hi Colin, what were you taking into consideration when working this out... could you please elaborate?

Thankyou.
Reply With Quote
  #16  
Old 12-07-2017, 09:58 PM
Atmos's Avatar
Atmos (Colin)
Ultimate Noob

Atmos is offline
 
Join Date: Aug 2011
Location: Melbourne
Posts: 6,980
Quote:
Originally Posted by Joshua Bunn View Post
Hi Colin, what were you taking into consideration when working this out... could you please elaborate?

Thankyou.
There is 4x the amount of light from F/1.4 to F/2.8.
Each pixel of the D700 covers 4.67x more area.

Not taking QE into consideration that means that every pixel on the D700 would be receiving 18.67x more light!! I have taken a wild stab in the dark but with an ~10 year increase in technology the QE may be light 0.4 vs 0.6 or a 50% increase. This brings the overall system closer to 12.4x increase in detected light per pixel.
Reply With Quote
  #17  
Old 13-07-2017, 02:03 AM
Joshua Bunn's Avatar
Joshua Bunn (Joshua)
Registered User

Joshua Bunn is offline
 
Join Date: Oct 2011
Location: Albany, Western Australia
Posts: 1,459
Quote:
Originally Posted by Atmos View Post
There is 4x the amount of light from F/1.4 to F/2.8.
Each pixel of the D700 covers 4.67x more area.

Not taking QE into consideration that means that every pixel on the D700 would be receiving 18.67x more light!! I have taken a wild stab in the dark but with an ~10 year increase in technology the QE may be light 0.4 vs 0.6 or a 50% increase. This brings the overall system closer to 12.4x increase in detected light per pixel.
Makes sense, Thanks Colin.
Reply With Quote
  #18  
Old 13-07-2017, 11:46 AM
JA
.....

JA is offline
 
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 2,945
Quote:
Originally Posted by Atmos View Post
There is 4x the amount of light from F/1.4 to F/2.8.
Each pixel of the D700 covers 4.67x more area.

Not taking QE into consideration that means that every pixel on the D700 would be receiving 18.67x more light!! I have taken a wild stab in the dark but with an ~10 year increase in technology the QE may be light 0.4 vs 0.6 or a 50% increase. This brings the overall system closer to 12.4x increase in detected light per pixel.
Hi Colin,

I'd say that's a reasonably good stab, in terms of percentage increase. On Sensorgeninfo the D700 lists with a QE of 34% with the D7100 at 52%. So a 53% increase over the years. Unfortunately no D7200 QE data is listed there, but that's likely to be the ballpark.

For further info, see
http://www.sensorgen.info/

Best
JA
Reply With Quote
  #19  
Old 13-07-2017, 12:02 PM
Atmos's Avatar
Atmos (Colin)
Ultimate Noob

Atmos is offline
 
Join Date: Aug 2011
Location: Melbourne
Posts: 6,980
Quote:
Originally Posted by JA View Post
Hi Colin,

I'd say that's a reasonably good stab, in terms of percentage increase. On Sensorgeninfo the D700 lists with a QE of 34% with the D7100 at 52%. So a 53% increase over the years. Unfortunately no D7200 QE data is listed there, but that's likely to be the ballpark.

For further info, see
http://www.sensorgen.info/

Best
JA
I use that site to get an idea of sensor performance but have a look at both the D3 & D3s, both of which have exactly the same sensor as the D700!
Reply With Quote
  #20  
Old 13-07-2017, 12:21 PM
JA
.....

JA is offline
 
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 2,945
Quote:
Originally Posted by Atmos View Post
I use that site to get an idea of sensor performance but have a look at both the D3 & D3s, both of which have exactly the same sensor as the D700!
Yes there's a few doozies in there that's for sure, but even with the same sensor there can still be differences in the QE due to differences in the surrounding sensor analog electronics, but not to the extent of the D3 - that's has to be a mistake*, as are a few others. Unfortunately whenever that happens you tend to mistrust the lot and/or look for other data or have a desire to test it yourself.

Best
JA

*EDIT- looked at further there is clearly a mistake or anomaly of an order of magnitude in the data recorded for the D3 at ISO 6400 for Saturation and read noise.

Last edited by JA; 13-07-2017 at 12:47 PM.
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 09:07 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Advertisement
Bintel
Advertisement
Testar
Advertisement