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About Whirlwind

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  1. But it's not zero and this is where the problem lies. Most astronomy filters have an OD value of 3 or 4 and for some science 5-6 (it's likely impossible to create one with no light leak). As such if you have a very bright source (the flu tube) compared to the background then in an OD 3/4 filter enough is likely to be detectable. On the other hand stars are much fainter in this regard so practically you may not need an OD 5-6 filter and is probably overkill for what we use it for.
  2. This isn't really a surprise. Most filters have some out of band transmission (this is usually referenced as their optical density (OD) value). Even the best filters transmit some light out of the desired passband even if it is a tiny fraction of a percent. If you put the filter in front of a very bright source then you will inevitably see the leakage (a fraction of a high luminosity can still be a high value etc). Even Baader don't claim a perfect filter (you can see some leakage in their filter profiles). Nevertheless for RGB filters you use these primarily to obtain colour data of a bro
  3. I'd agree. I've always thought that an imaging area per "/pixel is a more useful representation as to how 'fast' a system (as above) as there are other ways to increase the speed of your system through simple binning (excusing any noise differences from doing so)
  4. A well figured, well collimated substantially larger reflector (including RCs and Cass's) should always be able to provide better views than a smaller refractor. I don't think this should be in doubt. Unfortunately because of their general size and that is easier to make good reflectors relatively cheaply means that there is a general dearth of premium reflectors on the market (both from an optical and mechanical standpoint).
  5. I think this is a bit of a disingenuous comment - no one is stating "just stay with CCD", it hasn't even been mentioned - this is about whether to consider that for the purpose of the usage (ie. high usage at a remote site) that obtaining a version of the same CMOS sensor in its industrial form is a better option than a consumer version because the manufacturer stands by it having a longer lifespan before it fails. Whether CCD or CMOS it is better to have all the evidence so individuals can make a judgement as to whether the risk is acceptable. That some of the chips have a restricted us
  6. This is true but, they tend not to be used aggressively by consumers who likely only take a relatively short number of shots a year. In addition they are usually in high light conditions so exposures are in thousandths of seconds with less stress (no active cooling etc). As such 300 hours of photos is a lot.... On the other hand for astro imaging at a remote site wouldn't take that long in a year to get to 300 hours. Now 300 hours is only what Sony guarantee. They won't necessarily fail at this point but the company will have made a judgement as to the probability of any one failing
  7. I don't think the issue is between grade 1 and grade 2 in the way CCD sensors operated (which I'd be quite happy to say isn't a problem for astroimaging). There is generally little consumer information about the differences but I do note this on Astrographs site:- "Similar to area scan sensors, images produced by consumer grade sensors, provide a fast, high-resolution capture of the entire field of view. The main difference between them and industrial grade ones is that consumer sensors have a shorter life span, a shorter mean time before failure (MTBF) and, as a result, may cost much l
  8. Given the amount of time you are likely to image you may want to check what grade of sensor you get in the Atik. I've seen QHY have provided two versions before but also note Moravian now offer this sensor (plus the 2600MM equivalent) and note this on their website (C3 Series CMOS Cameras (gxccd.com)):- Assuming there is nothing untoward in the advertising here - any long term imaging at a remote observatory may well be worth considering the industrial grade as I assume that any operation above 300 hours may void the warranty if it goes bad (in effect more than 30 nights assuming 10 h
  9. The FLT91 is only just out so there are unlikely to be many real world users out there just yet. Nevertheless in theory it does guarantee a certain quality of lens (and you can ask for a report at an extra cost - which might incentivise to be given a better one, especially as an earlier adopter). In terms of practical use I always found their more integrated flattener/telescopes more easier to use - especially the variable adapters which gives a bit more scope to play with back focus. I also think a lot of the earlier mechanical issues are now resolved (poor focusers etc). They p
  10. I think this might all depend on what you prefer to image. If it is nebulae / clusters etc then a wider field is better and would look at the FSQ85/106 with your camera. If you prefer galaxy imaging then you probably want a longer focal instrument and something like the TSA120 / TOA130. You can also get reducers for these to help with imaging nebulae. Honestly I would have though the TOA130 (with an focuser upgrade) would be the lifetime scope because there is unlikely to be anything really better that would be noticeable.
  11. The difference is how it is being interpreted. You are using it as evidence that it does exist. The papers demonstrate that mathematically the laws we have in place cannot differentiate between the two possibilities. Therefore this suggests that there may be something about the laws that needs to be refined. The observations suggest that there is no difference in whether you look left or right. Whether that is experiments that measure radiation pressure, to spectrum of emissions and so forth. Mathematical formulations are just a different way of describing the same principle but it d
  12. That's not what we are saying at all. What is being said is that the approach you are taking to justify the rationale is the same principle used by people to justify the earth is flat (and also the same approach to make the Earth the centre of the cosmos hundreds of years ago). What you are doing is taking a principle and trying to use reasons to justify the empirical evidence which is the same approach. In effect what you are doing is trying to prove the principle correct, whereas science is about trying to prove your theory incorrect. Any theory can be *potentially* correct but it has to
  13. Yet this is exactly the problem. You are just claiming that you can do this without any empirical evidence. We can all do this, as noted before I can likely come up with some reasoning as to why stars are actually glowing marshmallows on the other side of the galaxy. It sounds unrealistic but I can just keep coming up with ever odd reasons for any argument against the idea but not put forward any way of testing that idea. It is not scientific method to respond to a criticism of theory by inventing something else to explain the criticism away. For example at a basic level, if you change c
  14. I'm sorry but this argument simply isn't science. You can create any number of arguments to argue against the evidence to hand (e.g. the spectroscopy doesn't work because you change frequency / length) and hence you end up with increasing divergence of physics just to 'prove' that a theory could be correct. This is the same as saying that all stars on the other side of the galaxy are made of bright glowing marshmallows because of any number of concoctions that can be thought up. It *could* be possible, because we can't physically check but all evidence suggests that it is not the case and h
  15. The standard back focus from the Vixen reducers is 63.5mm (confirmed here Vixen FL55SS fluorite apochromat with Flattener HD and Reducer HD (skypoint.it)). If you are just using the flattener then you get an extension with the HD Reducer set which is 76mm long (Vixen Flattener HD Kit for FL55SS | Vixen) so given the threads that would give about 130mm to play with when just using the flattener. When considering attachments the M60 adapter is less common to find. Vixen producer a 'rotator' that also converts to a standard t thread thought TS optics also do some other adapters to M68
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