 ...
·
 |
|---|
Okay, I know it's kind of an obvious question. But for some context, I wanna know what the purposes of these 2 accessories have. As I know, the Bahtinow mask helps Seastar see the stars better. But what purpose does The Dew Shield have? In any way, I can use that without driving the battery power of the device without turning on the Anti Dew option. But what is the other purpose? Does it help least control stray light from entering the lens, or what exactly does it do? I was looking to buy these 2, but I'm not familiar with their purpose. Could anyone tell me?
|
4.52
...
·
|
|---|
A dew shield blocks stray light and slows the formation of dew. A Bahtinov mask is typically used to help when manually focusing.
|
 ...
·
|
|---|
Shield just protects the optics from the elements ,with a second prize of helping reduce stray light from the local area. You will have to see if the shield on its own is enough for your typical observing conditions,or a particular time of year etc. I have just had to buy a shield for one of my telescopes as the very high humidity is ruining rare imaging time.Dew heaters alone were not enough so need a combined approach. on my SCT most of the time i can get away with just a dew shield but turn on the heat as a precaution on those nights when the equipment is sopping wet. The bahtinov mask is used as an aid attain sharp focus….. best wishes. |
...
·
|
|---|
A dew shield blocks stray light and slows the formation of dew. A Bahtinov mask is typically used to help when manually focusing. So, For short, if the autofocus fails, which it usually does sometimes. Then, I can place the Bahtinow mask on the lens, and that way, I can achieve better focusing? |
7.22
...
·
|
|---|
Szijártó Áron:A dew shield blocks stray light and slows the formation of dew. A Bahtinov mask is typically used to help when manually focusing. better focusing than if you eyeballed focus |
0.00
...
·
|
|---|
The Bahtinov mask is a type of diffraction grating designed to help focusing. Simply put, with the mask in place, if you image a star it will generate two patterns which look like an X and l shape. If the telescope is out of focus the two patterns will be offset from each other, so they make an easy visual guide for manual focusing. If you use a computer aided autofocus program it needs to be designed to work with the the patterns produced by the Bahtinov mask. Most autofocus software basically tries to make the stars as small as possible. Putting a Bahtinov mask on will absolutely not help this type of autofocuser. I don't know what sort of autofocus the Seastar uses so be sure to check. Dew Shields can be heated or not heated. They work by keeping the front of the telescope a little bit warmer than the dew point, so you don't get condensation forming on the glass. For modest sized telescopes they don't really need a lot of power to work properly. They also keep stray light out of the scope which is an added bonus. Aside from weight and the small power draw there are no real disadvantages to using a dew shield. On the other hand if you start getting condensation on your optics it will usually ruin your images for the rest of the evening. The Seastar has an electric heater which also prevents dew. Adding an external dew shield might allow you to keep the anti-dew heater switched off. Is there a reason you don't want to use the Seastars inbuilt dew heater? For such a small scope I wouldn't have thought the power usage was very much. |
...
·
|
|---|
James Ross: Ah I see. So I don't need to use the Bahtinow mask if I want the stars sharp. If I image something else, it won't work, only if I want to imagine a lonely star. So my only option for Imaging other stuff that can help in it is the dew shield then. |
|
0.00
...
·
|
|---|
If you're in focus for one star then you're also in focus for everything else. Properly using a bahtinov mask or autofocus etc should all give you sharp stars, they're just different methods to get to the same point. Bahtinov masks are helpful for manual focusing since human eyes are not good at minimising star FWHM. The autofocus routine on the Seastar doesn't have that limitation so it doesn't need the bahtimov mask. |
|
7.22
...
·
·
1
like
|
|---|
James Ross...If you use a computer-aided autofocus program, it needs to be designed to work with the the patterns produced by the Bahtinov mask. Most autofocus software basically tries to make the stars as small as possible. Putting a Bahtinov mask on will absolutely not help this type of autofocuser. I don't know what sort of autofocus the Seastar uses so be sure to check. just because the OP has an autofocuser doesn't mean he's forced to use AF I have an EAF, that doesn't mean I always use AF the bahtinov mask[b] [/b]will help the OP to get into better focus, if his AF is bad I checked Google, and the Seestar does have an option to do manual focus. I have tried to use my EAF correctly, and still, it skips the best focus point, I wouldn't be surprised if this is a common ZWO thing Szijártó Áron: >Ah I see. So I don't need to use the Bahtinow mask if I want the stars sharp. - yes, you don't need the bahtinov mask, but it will help >If I image something else, it won't work, only if I want to image a lonely star. - if you mean, about focusing with a bahtinov mask, not really, it can also be done in a thick star field, if there are bright stars in the field. - If you mean actual imaging, I can't comprehend what you mean I think, are you maybe thinking you have to keep the bahtinov mask on, during imaging? it's only for focusing; once you're done focusing, you take it off to start imaging. >So my only option for Imaging other stuff that can help in it is the dew shield then. James says the Seestar has a dew heater built in, so you don't need a dew shield |
|
0.00
...
·
·
1
like
|
|---|
Oscar: Absolutely. I was just emphasising that he shouldn't attempt to use the Seastar AF with the Bahtinov mask in place as the AF routine is almost certainly some sort of FWHM/HFD minimiser which won't appreciate the effects of a mask. |
|
7.22
...
·
|
|---|
James Ross:Oscar: oh, now I understand; I totally agree with that to simplify for the OP: the OP needs to use either the bahtinov mask or autofocus, not both at the same time |
