Nope! The laws of optics apply the same way as regards DOF.difference between PORRO and ROOF?
Nope! The laws of optics apply the same way as regards DOF.difference between PORRO and ROOF?
This.Nope! The laws of optics apply the same way as regards DOF.
Yep. And for a more technical explanation cf. König, Albert & Horst Köhler (³1959) "Die Fernrohre und Entfernungsmesser", Berlin/Heidelberg: Springer, p. p.122-125. This stuff has been know for a long, long time.Unfortunately the most in-depth explanation of the subject that I have read so far is only available in German and it is too much for me to quickly translate.
Richtigstellung: Schärfentiefe von Ferngläsern
Hallo Gemeinde, eigentlich bin ich derzeit so mit Problemlösungen für meinen neuen Macintosh G5 und dessen neues Betriebssystem OS 10.3 beschäftigt, daß ich mich hier gar nicht zu Wort melden dürfte (und deshalb auch seit fast drei Wochen nicht präsent war). Aber Franks Verweis im neuen...forum-astronomie-de.translate.goog
Perhaps you could just explain the initial distinction he's trying to draw between Tiefenschärfe and Schärfentiefe... is it just wordplay?Unfortunately the most in-depth explanation of the subject that I have read so far is only available in German and it is too much for me to quickly translate.
Are you likely to give us a brief summation or general overview in the next day or two?…the most in-depth explanation of the subject that I have read so far is only available in German and it is too much for me to quickly translate.
No. That's why I linked it to google translate.Are you likely to give us a brief summation or general overview in the next day or two?
These two points you listed here are really helpful and also help in understanding not only how to address others misunderstandings as to the physics involved, but also equal misunderstandings by some trying to chase and correct others.Brief summary, apart from what we already have listed in the thread:
-- FoV plays a small role. Larger FoV, more light hits the eye, pupil constricts, slightly increased FoV
And something a member mentioned in the rest of the thread: field curvature can look as if the bino had a larger DoF, in case closer objects are also closer to the edge of the FoV so field curvature of the bino renders them sharp not the DoF.
This too is another interesting observation, not only on the exit pupil equation, but also the uncertainty of exacting accuracy in labeling a particular model with an easily digested magnification spec.…the true magnification of two binoculars has to be the same for the DOF to be the same…provided the exit pupil of both is larger than the eye's pupil by any amount.
Perhaps it's time to return to the original question. There is no theoretical reason why this would be the case, so we should ask how exactly you're judging DOF. Can you describe a certain scene observed with both, what you've focused on, which other elements seem sharp or don't, how far they are, etc? (Bear in mind that other factors may be involved too, for example field curvature reducing the area of best sharpness, so try to line elements up and do your DOF comparisons fairly close to the center.)
it should not affect the OP's comparison of an 8x25 and 8x42 at all
"Original post" or "original poster". The person, who started the thread -- so in this case, you .What do you mean with OP? You have written that before.
Thanks for pointing that out, I have no experience with Terra. Now we're back to the question, how much further can this really cause the pupil to contract?Maybe the effect was caused by the larger FoV of the SLC -- 7.8° vs. 6.8°.
No, neither is a flat-field design, which is why I brought up field curvature as a likely factor before. I've always supposed it has to be the primary explanation for claims like this. (Although offhand I'd expect SLC to have less than Terra...)Does the SLC have field flatteners? If not then in a larger FoV, curvature might be more prominent towards the edge, hence objects closer to the observer (which are also often closer to the edge of the FoV) might look in focus, suggesting a larger DoF that's not really there. Pure speculation on my part as I have never looked through either instrument.
No, don't apologize, investigate! The reason this topic just keeps coming up is that people never clarify what they've actually seen, and how they're (mis?)interpreting it as "DOF". If you can do that now, you'll confirm an explanation that we can offer with some confidence in the future. Which of these two has the larger zone of central sharpness, and does there still seem to be a difference in DOF within it?Interesting stuff. I am sorry I restarted this discussion/topic. I was not aware there are already a lot of threads about this topic.
You all left me puzzled, because I see what I see. Now I doubt what I saw.